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Sample records for solid polymers crosslinking

  1. Recycling and processing of several typical crosslinked polymer scraps with enhanced mechanical properties based on solid-state mechanochemical milling

    NASA Astrophysics Data System (ADS)

    Lu, Canhui; Zhang, Xinxing; Zhang, Wei

    2015-05-01

    The partially devulcanization or de-crosslinking of ground tire rubber (GTR), post-vulcanized fluororubber scraps and crosslinked polyethylene from cable scraps through high-shear mechanochemical milling (HSMM) was conducted by a modified solid-state mechanochemical reactor. The results indicated that the HSMM treated crosslinked polymer scraps can be reprocessed as virgin rubbers or thermoplastics to produce materials with high performance. The foamed composites of low density polyethylene/GTR and the blend of post-vulcanized flurorubber (FKM) with polyacrylate rubber (ACM) with better processability and mechanical properties were obtained. The morphology observation showed that the dispersion and compatibility between de-crosslinked polymer scraps and matrix were enhanced. The results demonstrated that HSMM is a feasible alternative technology for recycling post-vulcanized or crosslinked polymer scraps.

  2. Recycling and processing of several typical crosslinked polymer scraps with enhanced mechanical properties based on solid-state mechanochemical milling

    SciTech Connect

    Lu, Canhui; Zhang, Xinxing; Zhang, Wei

    2015-05-22

    The partially devulcanization or de-crosslinking of ground tire rubber (GTR), post-vulcanized fluororubber scraps and crosslinked polyethylene from cable scraps through high-shear mechanochemical milling (HSMM) was conducted by a modified solid-state mechanochemical reactor. The results indicated that the HSMM treated crosslinked polymer scraps can be reprocessed as virgin rubbers or thermoplastics to produce materials with high performance. The foamed composites of low density polyethylene/GTR and the blend of post-vulcanized flurorubber (FKM) with polyacrylate rubber (ACM) with better processability and mechanical properties were obtained. The morphology observation showed that the dispersion and compatibility between de-crosslinked polymer scraps and matrix were enhanced. The results demonstrated that HSMM is a feasible alternative technology for recycling post-vulcanized or crosslinked polymer scraps.

  3. Interfacial fracture between highly crosslinked polymer networks and a solid surface: Effect of interfacial bond density

    SciTech Connect

    STEVENS,MARK J.

    2000-03-23

    For highly crosslinked, polymer networks bonded to a solid surface, the effect of interfacial bond density as well as system size on interfacial fracture is studied molecular dynamics simulations. The correspondence between the stress-strain curve and the sequence of molecular deformations is obtained. The failure strain for a fully bonded surface is equal to the strain necessary to make taut the average minimal path through the network from the bottom solid surface to the top surface. At bond coverages less than full, nanometer scale cavities form at the surface yielding an inhomogeneous strain profile. The failure strain and stress are linearly proportional to the number of bonds at the interface unless the number of bonds is so few that van der Waals interactions dominate. The failure is always interfacial due to fewer bonds at the interface than in the bulk.

  4. All Solid-State Lithium Metal Batteries Using Cross-linked Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Pan, Qiwei; Li, Christopher; Soft Materials Team

    Nowadays, to prepare all solid-state lithium metal batteries with high rate capability and stability using solid polymer electrolytes (SPEs) is still a grand challenge because of the interfaces between the SPE and the electrodes. In this presentation, we report a series of hybrid SPEs with controlled network structures by using POSS as cross-linker. These hybrid network SPEs show promising ionic conductivity, mechanical properties, and lithium dendrite growth resistance. All solid-state LiFePO4/Li batteries were also prepared using these SPEs as the electrolytes to study the effect of conductivity and mechanical properties of the SPEs on the performance of the batteries. At 90 °C, the prepared cells show high rate capability and stability. Capacity up to 160 mAh/g can be obtained at a C/2 rate during the galvanostatic cycling. Capacity retention of the cells is higher than 80% after 250 cycles. Battery performance at 60 °C and decay mechanism of the batteries will also be discussed.

  5. Semi-interpenetrating solid polymer electrolyte based on thiol-ene cross-linker for all-solid-state lithium batteries

    NASA Astrophysics Data System (ADS)

    Suk, Jungdon; Lee, Yu Hwa; Kim, Do Youb; Kim, Dong Wook; Cho, Song Yun; Kim, Ji Man; Kang, Yongku

    2016-12-01

    We developed highly promising solid polymer electrolytes (SPEs) based on a novel cross-linker containing star-shaped phosphazene with poly(ethylene oxide) (PEO) branches with very high ionic conductivity (7.6 × 10-4 S cm-1), improved mechanical stability, and good electrochemical stability for all-solid-state lithium batteries. In particular, allyl groups were introduced at the ends of the cross-linker in order to overcome the easy self-polymerization of existing cross-linking acrylate end groups. A novel semi-interpenetrating network (semi-IPN) SPE was prepared by in-situ radical polymerization of a precursor solution containing lithium salt, poly(ethylene glycol) dimethyl ether as a plasticizer, and a mixture of pentaerythritol tetrakis(3-mercaptopropionate) and a synthesized hexakis(allyloxy)cyclotriphosphazene (thiol-ene PAL) as the cross-linker. Batteries employing LiFePO4 as the cathode, lithium foil as the anode, and the SPE thin film as the electrolyte were assembled and tested. At ambient temperature, the initial discharge capacity was 147 mAh/g at 0.1 °C and 132 mAh/g at 0.5 °C, and 97% of the capacity was retained at the 100th cycle. All-solid-state pouch-package lithium cells assembled with the SPEs exhibited stable electrochemical performance, even under a severely wrinkled state. These outstanding properties of SPEs based on thiol-ene PAL demonstrate feasibility for practical battery applications with improved reliability and safety.

  6. Dendrite Suppression by Synergistic Combination of Solid Polymer Electrolyte Crosslinked with Natural Terpenes and Lithium Powder Anode for Lithium Metal Batteries.

    PubMed

    Shim, Jimin; Lee, Jae Won; Bae, Ki Yoon; Kim, Hee Joong; Yoon, Woo Young; Lee, Jong-Chan

    2017-04-03

    Lithium metal anode has fundamental problems concerning formation and growth of lithium dendrites which prevents practical applications of next generation of high-capacity lithium metal batteries. The synergistic combination of solid polymer electrolyte (SPE) crosslinked with naturally occurring terpenes and lithium powder anode is promising solution to resolve the dendrite issues by substituting conventional liquid electrolyte/separator and lithium foil anode system. A series of SPEs based on polysiloxane crosslinked with natural terpenes are prepared by facile thiol-ene click reaction under mild condition and structural effect of terpene crosslinkers on electrochemical properties is studied. Lithium powder with large surface area is prepared by droplet emulsion technique (DET) and used as anode materials. The effect of physical state of electrolyte (solid/liquid) and morphology of lithium metal anode (powder/foil) on dendrite growth behavior is systematically studied. The synergistic combination of SPE and lithium powder anode suggests effective solution to suppress the dendrite growth due to formation of stable solid electrolyte interphase (SEI) layer and delocalized current density.

  7. Preparation of molecular imprinted polymers using bi-functional monomer and bi-crosslinker for solid-phase extraction of rutin.

    PubMed

    Zeng, Huan; Wang, Yuzhi; Liu, Xiaojie; Kong, Jinhuan; Nie, Chan

    2012-05-15

    Molecular imprinted polymers (MIPs) were prepared using rutin as the template, different reagents as the functional monomer and different reagents as the cross-linker by solution polymerization. Several parameters that would influence the performance of MIPs were investigated including the type of functional monomer (single or double) and cross-linker (single or double), and the molar ratio of the template, the functional monomer and the cross-linker. The optimum synthesis conditions of MIPs were found to be bi-monomers (acrylamide-co-2-vinyl pyridine, 3:1) and bi-crosslinker (ethylene glycol dimethacrylate-co-divinylbenzene, 3:1). The ratio of the template, the functional monomer and the cross-linker was found to be 1:6:20. MIPs synthesized under these conditions were filled into the cartridges as the adsorbents of solid-phase extraction (SPE). A competition test was conducted to authenticate the selectivity and the specificity of molecularly imprinted solid-phase extraction (MISPE) for rutin using the mixture solution of standard rutin and its structural analogs including quercetin, naringenin and kaempferol. Compared with purchased SPE including C(18), silica and PCX, MISPE showed better selectivity and enrichment property for rutin in the extracted solutions of Chinese medicinal plants than any others. The mean recoveries were 85.93% (RSD: 3.04%, n=3) for Saururus chinensis (Lour.) Bail and 88.61% (RSD: 3.36%, n=3) for Flos Sophorae, respectively, which indicated that the optimized rutin-MIPs possess the value of practical application. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1998-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  9. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1997-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  10. β-Cyclodextrin cross-linked polymer as solid-phase extraction material coupled with the spectrophotometric method for the analysis of serum albumin

    NASA Astrophysics Data System (ADS)

    Wu, Min; Zhu, Xiashi

    2010-12-01

    The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid-phase extraction material to preconcentrate/analysis bovine serum albumin (BSA) coupled with UV-vis spectroscopy. The method based on the complex (BSA-phenylfluorone (PF)) adsorbed on β-CDCP. Adsorption kinetics and various factors of the formation procedure of BSA-PF and its retention on β-CDCP were investigated. The linear range and detection limit (DL) was 20.0-200.0 and 0.03 mg/L, respectively. Moreover, the β-CDCP could be used repeatedly. The proposed method has been applied to analysis serum albumin with satisfactory results.

  11. β-cyclodextrin cross-linked polymer as solid-phase extraction material coupled with the spectrophotometric method for the analysis of serum albumin.

    PubMed

    Wu, Min; Zhu, Xiashi

    2010-12-01

    The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid-phase extraction material to preconcentrate/analysis bovine serum albumin (BSA) coupled with UV-vis spectroscopy. The method based on the complex (BSA-phenylfluorone (PF)) adsorbed on β-CDCP. Adsorption kinetics and various factors of the formation procedure of BSA-PF and its retention on β-CDCP were investigated. The linear range and detection limit (DL) was 20.0-200.0 and 0.03 mg/L, respectively. Moreover, the β-CDCP could be used repeatedly. The proposed method has been applied to analysis serum albumin with satisfactory results. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Crosslinking of water-soluble polymers

    NASA Astrophysics Data System (ADS)

    Lei, Cuiyue

    The crosslinking of water-soluble polymers is important in many industrial processes. In the oil industry, minimizing the concentration of polymers is desirable for technical and economic reasons. This dissertation provides a link between measurable polymer properties and the minimum concentration necessary for crosslinking. The influences of polymer type and concentration, crosslinker type, salt and additives on the crosslinking process were studied by steady shear test, creep test, oscillatory test, Atomic Force Microscopy and other techniques. Solution properties, crosslinked gel properties and the relationship between them were investigated. Test results indicate that the rheological properties of guar solutions and its derivatives are quite different. The critical overlap concentrations increase in the order GW-3, CMG, CMHPG, guar and HPG. And, the intrinsic viscosity increases in the order of HPG, guar, CMHPG, GW-3 and CMG. At low concentrations, steady shear viscosity decreases in the order of CMG, CMHPG, GW-3, guar and HPG, while at high concentrations, the steady shear viscosities decrease in the order of GW-3, guar, CMG, CMHPG and HPG. Addition of urea and sugar reduces the viscosity of guar solutions. The influence of salts on the viscosity of CMG solutions varies with salt types and polymer concentrations. The strength of crosslinked gels increases with polymer concentration. At low polymer concentrations, gel strength of guar derivatives increases in the order of HPG, guar, GW-3, CMG and CMHPG, while at high concentrations, gel strength increases in the order of CMG, CMHPG, HPG, guar and GW-3. The critical crosslinking concentration increases in the order of GW-3, CMG, CMHPG, guar and HPG. A mathematical model is developed to relate critical crosslinking concentration and critical crosslinking concentration. The relationship between them is scaled as a power law. Models of the plateau modulus dependence on concentration are also developed. The modulus

  13. Microbes encapsulated within crosslinkable polymers

    DOEpatents

    Chidambaram, Devicharan; Liu, Ying; Rafailovich, Miriam H

    2013-02-05

    The invention relates to porous films comprising crosslinked electrospun hydrogel fibers. Viable microbes are encapsulated within the crosslinked electrospun hydrogel fibers. The crosslinked electrospun hydrogel fibers are water insoluble and permeable. The invention also relates to methods of making and using such porous films.

  14. Viscoelastic behavior of polymers undergoing crosslinking reactions.

    NASA Technical Reports Server (NTRS)

    Moacanin, J.; Aklonis, J. J.

    1971-01-01

    Previously a method was developed for predicting the viscoelastic response of polymers undergoing scission reactions. These results are now extended to include crosslinking reactions. As for scission, at any given time the character of the network chains is determined by the instantaneous crosslink density. For scission all chains were assumed to carry the same stress; for crosslinking, however, the stress is distributed between the 'new' and 'old' chains. Equations for calculating the creep response of a system which experiences a step increase in crosslink density are derived.

  15. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, W.P. Jr.; Apen, P.G.; Mitchell, M.A.

    1998-01-20

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes. 1 fig.

  16. A Single Molecular Diels-Alder Crosslinker for Achieving Recyclable Cross-Linked Polymers.

    PubMed

    Chen, Shengli; Wang, Fenfen; Peng, Yongjin; Chen, Tiehong; Wu, Qiang; Sun, Pingchuan

    2015-09-01

    A triol-functional crosslinker combining the thermoreversible properties of Diels-Alder (DA) adducts in one molecule is designed, synthesized, and used as an ideal substitute of a traditional crosslinker to prepare thermal recyclable cross-linked polyurethanes with excellent mechanical properties and recyclability in a very simple and efficient way. The recycle property of these materials achieved by the DA/retro-DA reaction at a suitable temperature is verified by differential scanning calorimetry and in situ variable temperature solid-state NMR experiments during the cyclic heating and cooling processes. The thermal recyclability and remending ability of the bulk polyurethanes is demonstrated by three polymer processing methods, including hot-press molding, injection molding, and solution casting. It is notable that all the recycled cross-linked polymers display nearly invariable elongation/stress at break compared to the as-synthesized samples. Further end-group functionalization of this single molecular DA crosslinker provides the potential in preparing a wide range of recyclable cross-linked polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Crosslinked polymer nanoparticles containing single conjugated polymer chains

    NASA Astrophysics Data System (ADS)

    Ponzio, Rodrigo A.; Marcato, Yésica L.; Gómez, María L.; Waiman, Carolina V.; Chesta, Carlos A.; E Palacios, Rodrigo

    2017-06-01

    Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

  18. Crosslinked polymer nanoparticles containing single conjugated polymer chains.

    PubMed

    Ponzio, Rodrigo A; Marcato, Yésica L; Gómez, María L; Waiman, Carolina V; Chesta, Carlos A; Palacios, Rodrigo E

    2017-03-29

    Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

  19. Polymer Microstructures through Two-Photon Crosslinking.

    PubMed

    Schwärzle, David; Hou, Xiaoqang; Prucker, Oswald; Rühe, Jürgen

    2017-08-18

    Two-photon crosslinking of polymers (2PC) is proposed as a novel method for the fabrication of freestanding microstructures via two-photon lithography. During this process in the confocal volume, two-photon absorption leads to (formal) C,H-insertion reactions, and consequently to a strictly localized crosslinking of the polymer. To achieve this, the polymer is coated as a solvent-free (glassy) film onto an appropriate substrate, and the desired microstructure is written by 2PC into this glass. In all regions outside of the focal volume where no two-photon process occurs, the polymer remains uncrosslinked and can be washed away during a developing process. Using a self-assembled monolayer containing the same photoreactive group allows covalent attachment of the forming freestanding structures to the substrate, and thus guarantees an improved stability of these structures against shear-induced detachment. As the two photon process is carried out in the glassy state, in a simple way, multilayer structures can be used to write structures having a varying chemical composition perpendicular to the surface. As an example, the 2PC process is used to build a structure from both protein-repellent and protein-adsorbing polymers so that the resulting 3D structure exhibits spatially controlled protein adsorption. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Driven Polymer Translocation into a Crosslinked Gel

    NASA Astrophysics Data System (ADS)

    Sean, David; Slater, Gary

    2015-03-01

    In a typical polymer translocation setup, a thin membrane is used to separate two chambers and a polyelectrolyte is driven by an electric field to translocate from one side of the membrane to the other via a small nanopore. However, the high translocation rate that results from the forces required to drive this process makes optical and/or electrical analysis of the translocating polymer challenging. Using coarse-grained Langevin Dynamics simulations we investigate how the translocation process can be slowed down by placing a crosslinked gel on the trans-side of the membrane. Since the driving electric field is localized in the neighborhood of the nanopore, electrophoretic migration is only achieved by a ``pushing'' action from the polymer segment residing in the nanopore. For the case of a flexible polymer we find that the polymer fills the gel pores via multiple ``herniation'' processes, whereas for a semi-flexible chain in a tight gel there are no hernias and the polymer follows a smooth curvilinear path. Moreover, for the case of a semi-flexible polymer the gel makes the translocation process more uniform by reducing the acceleration at the end of the process.

  1. Mesoscopic Simulations of Crosslinked Polymer Networks

    NASA Astrophysics Data System (ADS)

    Megariotis, Grigorios; Vogiatzis, Georgios G.; Schneider, Ludwig; Müller, Marcus; Theodorou, Doros N.

    2016-08-01

    A new methodology and the corresponding C++ code for mesoscopic simulations of elastomers are presented. The test system, crosslinked ds-1’4-polyisoprene’ is simulated with a Brownian Dynamics/kinetic Monte Carlo algorithm as a dense liquid of soft, coarse-grained beads, each representing 5-10 Kuhn segments. From the thermodynamic point of view, the system is described by a Helmholtz free-energy containing contributions from entropic springs between successive beads along a chain, slip-springs representing entanglements between beads on different chains, and non-bonded interactions. The methodology is employed for the calculation of the stress relaxation function from simulations of several microseconds at equilibrium, as well as for the prediction of stress-strain curves of crosslinked polymer networks under deformation.

  2. Electrode-Impregnable and Cross-Linkable Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Polymer Electrolytes with High Ionic Conductivity and a Large Voltage Window for Flexible Solid-State Supercapacitors.

    PubMed

    Han, Jae Hee; Lee, Jang Yong; Suh, Dong Hack; Hong, Young Taik; Kim, Tae-Ho

    2017-10-04

    We present cross-linkable precursor-type gel polymer electrolytes (GPEs) that have large ionic liquid uptake capability, can easily penetrate electrodes, have high ion conductivity, and are mechanically strong as high-performance, flexible all-solid-state supercapacitors (SC). Our polymer precursors feature a hydrophilic-hydrophobic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock main-chain structure and trifunctional silane end groups that can be multi-cross-linked with each other through a sol-gel process. The cross-linked solid-state electrolyte film with moderate IL content (200 wt %) shows a well-balanced combination of excellent ionic conductivity (5.0 × 10(-3) S cm(-1)) and good mechanical stability (maximum strain = 194%). Moreover, our polymer electrolytes have various advantages including high thermal stability (decomposition temperature > 330 °C) and the capability to impregnate electrodes to form an excellent electrode-electrolyte interface due to the very low viscosity of the precursors. By assembling our GPE-impregnated electrodes and solid-state GPE film, we demonstrate an all-solid-state SC that can operate at 3 V and provides an improved specific capacitance (112.3 F g(-1) at 0.1 A g(-1)), better rate capability (64% capacity retention until 20 A g(-1)), and excellent cycle stability (95% capacitance decay over 10 000 charge/discharge cycles) compared with those of a reference SC using a conventional PEO electrolyte. Finally, flexible SCs with a high energy density (22.6 W h kg(-1) at 1 A g(-1)) and an excellent flexibility (>93% capacitance retention after 5000 bending cycles) can successfully be obtained.

  3. Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation-Crosslinked Poly (Vinyl Alcohol)-Based Solid Polymer Electrolytes Blended With LiOHṡH2O Salt

    NASA Astrophysics Data System (ADS)

    Khafagy, Rasha M.; Madani, M.; Badr, Y. A.

    2008-09-01

    Solid polymer electrolytes based on poly(vinyl alcohol) (PVA) blended with different concentrations of LiOHṡH2O salt were prepared using casting and γ-irradiation techniques. The structure and blending of the poly-electrolytes were studied by X-ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and these melting points change with the salt content. All characterizing techniques revealed the blend formation between LiOHṡH2O salt and the polymer matrix. To account for the performance of the prepared solid polymer electrolytes, thermally stimulated depolarization current (TSDC) studies of the prepared blends were done. Short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm-1 have been analyzed in the temperature range 300-410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly-blend system. The prepared solid polymer electrolytes showed good charge storage capacity, and moderate current density values near the ambient.

  4. Highly crosslinked silicon polymers for gas chromatography columns

    NASA Technical Reports Server (NTRS)

    Shen, Thomas C. (Inventor)

    1994-01-01

    A new highly crosslinked silicone polymer particle for gas chromatography application and a process for synthesizing such copolymer are described. The new copolymer comprises vinyltriethoxysilane and octadecyltrichlorosilane. The copolymer has a high degree of crosslinking and a cool balance of polar to nonpolar sites in the porous silicon polymer assuring fast separation of compounds of variable polarity.

  5. Crosslinkable low bandgap polymers for organic solar cells

    NASA Astrophysics Data System (ADS)

    Strohriegl, Peter; Saller, Christina; Knauer, Philipp; Köhler, Anna; Hahn, Tobias; Fischer, Florian; Kahle, Frank-Julian

    2016-09-01

    We present a number of polyfluorene based conjugated polymers with crosslinkable acrylate and oxetane units. These polymers can be crosslinked by free radical polymerization in the case of acrylates and by cationic ring opening polymerization for oxetanes. Upon polymerization densely crosslinked networks are formed which are completely insoluble. We show that the diffusion coefficient of C60 in polyfluorene is reduced by a factor of 1000 by crosslinking. MIS-CELIV measurements are used to monitor changes in the charge carrier mobility upon crosslinking. It shows that using appropriate conditions, e.g. low initiator concentrations or thermal crosslinking, the charge carrier mobility is not reduced by crosslinking. Solution processed three layer organic solar cells were realized with a crosslinkable fluorene based copolymer containing acrylate groups. The efficiency is increased from 1.4% for the reference to 1.8% in the three layer cell with a crosslinked exciton blocking layer. A critical issue of BHJ cells is the instability of the morphology of the polymer:fullerene blend over long operation times at elevated temperature. We present a crosslinkable derivative of the low bandgap polymer PFDTBT which contains oxetane units. BHJ cells with the crosslinked PFDTBT derivative and PCBM were tested in accelerated aging experiments at 100 °C for times up to 100 h. Stabilization was clearly observed in crosslinked BHJ cells compared to the non-crosslinked reference. We show for the first time that oxetane containing polymers can be thermally crosslinked without any added initiator. Initiator free crosslinking is particularly attractive as it avoids the formation of decomposition products, and thus potential electron traps and quenching sites from the initiator.

  6. Crosslinked crystalline polymer and methods for cooling and heating

    DOEpatents

    Salyer, Ival O.; Botham, Ruth A.; Ball, III, George L.

    1980-01-01

    The invention relates to crystalline polyethylene pieces having optimum crosslinking for use in storage and recovery of heat, and it further relates to methods for storage and recovery of heat using crystalline polymer pieces having optimum crosslinking for these uses. Crystalline polymer pieces are described which retain at least 70% of the heat of fusion of the uncrosslinked crystalline polymer and yet are sufficiently crosslinked for the pieces not to stick together upon being cycled above and below the melting point of said polymer, preferably at least 80% of the heat of fusion with no substantial sticking together.

  7. Solid polymer electrolytes

    DOEpatents

    Abraham, Kuzhikalail M.; Alamgir, Mohamed; Choe, Hyoun S.

    1995-01-01

    This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.

  8. Solid polymer electrolytes

    DOEpatents

    Abraham, K.M.; Alamgir, M.; Choe, H.S.

    1995-12-12

    This invention relates to Li ion (Li{sup +}) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF{sub 3}SO{sub 2}){sub 2}, LiAsF{sub 6}, and LiClO{sub 4}. 2 figs.

  9. Solid polymer electrolyte compositions

    DOEpatents

    Garbe, James E.; Atanasoski, Radoslav; Hamrock, Steven J.; Le, Dinh Ba

    2001-01-01

    An electrolyte composition is featured that includes a solid, ionically conductive polymer, organically modified oxide particles that include organic groups covalently bonded to the oxide particles, and an alkali metal salt. The electrolyte composition is free of lithiated zeolite. The invention also features cells that incorporate the electrolyte composition.

  10. Phase stability of weakly crosslinked interpenerating polymer networks

    NASA Technical Reports Server (NTRS)

    Binder, K.; Frisch, H. L.

    1984-01-01

    A phenomenological theory is formulated for chemically quenched binary interpenetrating polymer networks (IPNs), considering both simultaneously crosslinked networks and sequentially crosslinked networks, as well as pseudointerpenetrating networks (where only one component is crosslinked and the other is a linear polymer). The construction of free energy functionals for homogeneous weakly crosslinked IPNs and pseudo-IPNs and their spinodal curves and critical points of unmixing is described. These free energy functionals are augmented with gradient energy terms in order to consider effects due to spatially varying small inhomogeneities in the network chain concentration. The dynamic response and the initial spinodal decomposition of IPNs are discussed.

  11. Solid polymer membrane program

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The results are presented for a solid polymer electrolyte fuel cell development program. Failure mechanism was identified and resolution of the mechanism experienced in small stack testing was demonstrated. The effect included laboratory analysis and evaluation of a matrix of configurations and operational variables for effects on the degree of hydrogen fluoride released from the cell and on the degree of blistering/delamination occurring in the reactant inlet areas of the cell and to correlate these conditions with cell life capabilities. The laboratory evaluation tests were run at conditions intended to accelerate the degradation of the solid polymer electrolyte in order to obtain relative evaluations as quick as possible. Evaluation of the resolutions for the identified failure mechanism in space shuttle configuration cell assemblies was achieved with the fabrication and life testing of two small stack buildups of four cell assemblies and eight cells each.

  12. The effect of chain flexibility and chain mobility on radiation crosslinking of polymers

    NASA Astrophysics Data System (ADS)

    Jia Zhen, Sun

    2001-01-01

    Radiation crosslinking of polymers mainly depends on the structure of polymer chain. The flexibility and mobility of chain directly influence the possibility of the reactive radicals recombination. Flexible chain is easier to crosslink than rigid-chain polymer. The latter must be crosslinked at high temperature, as most polymers can only crosslink above their melting point. Structural effect also influences the mechanism of radiation crosslinking of polymers. We find from the results in literature and in our laboratory that, the flexibility chain polymer mainly crosslinked with H type, but the rigid chain polymer mainly crosslinked with Y type.

  13. A Demonstration of Polymer Crosslinking and Gel Formation Without Heating

    ERIC Educational Resources Information Center

    Ross, Joseph H.

    1977-01-01

    Describes an undergraduate experiment in which Gantrez AN polymer chains are crosslinked at the anhydride groups by the addition of the hydroxyl groups of triethanolamine, which also acts as a basic catalyst. (MLH)

  14. Covalently crosslinked diels-alder polymer networks.

    SciTech Connect

    Bowman, Christopher; Adzima, Brian J.; Anderson, Benjamin John

    2011-09-01

    This project examines the utility of cycloaddition reactions for the synthesis of polymer networks. Cycloaddition reactions are desirable because they produce no unwanted side reactions or small molecules, allowing for the formation of high molecular weight species and glassy crosslinked networks. Both the Diels-Alder reaction and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) were studied. Accomplishments include externally triggered healing of a thermoreversible covalent network via self-limited hysteresis heating, the creation of Diels-Alder based photoresists, and the successful photochemical catalysis of CuAAC as an alternative to the use of ascorbic acid for the generation of Cu(I) in click reactions. An analysis of the results reveals that these new methods offer the promise of efficiently creating robust, high molecular weight species and delicate three dimensional structures that incorporate chemical functionality in the patterned material. This work was performed under a Strategic Partnerships LDRD during FY10 and FY11 as part of a Sandia National Laboratories/University of Colorado-Boulder Excellence in Science and Engineering Fellowship awarded to Brian J. Adzima, a graduate student at UC-Boulder. Benjamin J. Anderson (Org. 1833) was the Sandia National Laboratories point-of-contact for this fellowship.

  15. Composite solid polymer electrolyte membranes

    DOEpatents

    Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

    2006-05-30

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  16. Composite solid polymer electrolyte membranes

    DOEpatents

    Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

    2001-06-19

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  17. Photocontrolled Cargo Release from Dual Cross-Linked Polymer Particles.

    PubMed

    Tan, Shereen; Cui, Jiwei; Fu, Qiang; Nam, Eunhyung; Ladewig, Katharina; Ren, Jing M; Wong, Edgar H H; Caruso, Frank; Blencowe, Anton; Qiao, Greg G

    2016-03-09

    Burst release of a payload from polymeric particles upon photoirradiation was engineered by altering the cross-linking density. This was achieved via a dual cross-linking concept whereby noncovalent cross-linking was provided by cyclodextrin host-guest interactions, and irreversible covalent cross-linking was mediated by continuous assembly of polymers (CAP). The dual cross-linked particles (DCPs) were efficiently infiltrated (∼80-93%) by the biomacromolecule dextran (molecular weight up to 500 kDa) to provide high loadings (70-75%). Upon short exposure (5 s) to UV light, the noncovalent cross-links were disrupted resulting in increased permeability and burst release of the cargo (50 mol % within 1 s) as visualized by time-lapse fluorescence microscopy. As sunlight contains UV light at low intensities, the particles can potentially be incorporated into systems used in agriculture, environmental control, and food packaging, whereby sunlight could control the release of nutrients and antimicrobial agents.

  18. Solid polymer electrolyte lithium batteries

    DOEpatents

    Alamgir, M.; Abraham, K.M.

    1993-10-12

    This invention pertains to Lithium batteries using Li ion (Li[sup +]) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride). 3 figures.

  19. Solid polymer electrolyte lithium batteries

    DOEpatents

    Alamgir, Mohamed; Abraham, Kuzhikalail M.

    1993-01-01

    This invention pertains to Lithium batteries using Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride).

  20. Mechanically Strong, Polymer Cross-linked Aerogels (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2006-01-01

    Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X

  1. Rechargeable solid polymer electrolyte battery cell

    DOEpatents

    Skotheim, Terji

    1985-01-01

    A rechargeable battery cell comprising first and second electrodes sandwiching a solid polymer electrolyte comprising a layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte adjacent said polymer blend and a layer of dry solid polymer electrolyte adjacent said layer of polymer blend and said second electrode.

  2. Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers.

    PubMed

    Hearon, K; Gall, K; Ware, T; Maitland, D J; Bearinger, J P; Wilson, T S

    2011-07-01

    Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, these new post-polymerization crosslinked SMPs can be processed into complex shapes by thermoplastic manufacturing methods and later crosslinked by heat exposure or by electron beam irradiation. Several series of linear, olefinic urethane polymers were made from 2-butene-1,4-diol, other saturated diols, and various aliphatic diisocyanates. These thermoplastics were melt-processed into desired geometries and thermally crosslinked at 200°C or radiation crosslinked at 50 kGy. The SMPs were characterized by solvent swelling and extraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, and qualitative shape-recovery analysis. Swelling and DMA results provided concrete evidence of chemical crosslinking, and further characterization revealed that the urethanes had outstanding mechanical properties. Key properties include tailorable transitions between 25 and 80°C, tailorable rubbery moduli between 0.2 and 4.2 MPa, recoverable strains approaching 100%, failure strains of over 500% at T(g), and qualitative shape-recovery times of less than 12 seconds at body temperature (37°C). Because of its outstanding thermo-mechanical properties, one polyurethane was selected for implementation in the design of a complex medical device. These post-polymerization crosslinked urethane SMPs are an industrially relevant class of highly processable shape-memory materials.

  3. Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers

    PubMed Central

    Hearon, K.; Gall, K.; Ware, T.; Maitland, D. J.; Bearinger, J. P.; Wilson, T. S.

    2011-01-01

    Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, these new post-polymerization crosslinked SMPs can be processed into complex shapes by thermoplastic manufacturing methods and later crosslinked by heat exposure or by electron beam irradiation. Several series of linear, olefinic urethane polymers were made from 2-butene-1,4-diol, other saturated diols, and various aliphatic diisocyanates. These thermoplastics were melt-processed into desired geometries and thermally crosslinked at 200°C or radiation crosslinked at 50 kGy. The SMPs were characterized by solvent swelling and extraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, and qualitative shape-recovery analysis. Swelling and DMA results provided concrete evidence of chemical crosslinking, and further characterization revealed that the urethanes had outstanding mechanical properties. Key properties include tailorable transitions between 25 and 80°C, tailorable rubbery moduli between 0.2 and 4.2 MPa, recoverable strains approaching 100%, failure strains of over 500% at Tg, and qualitative shape-recovery times of less than 12 seconds at body temperature (37°C). Because of its outstanding thermo-mechanical properties, one polyurethane was selected for implementation in the design of a complex medical device. These post-polymerization crosslinked urethane SMPs are an industrially relevant class of highly processable shape-memory materials. PMID:21572577

  4. Gelation threshold of cross-linked polymer brushes.

    PubMed

    Hoffmann, Max; Lang, Michael; Sommer, Jens-Uwe

    2011-02-01

    The cross-linking of polymer brushes is studied using the bond-fluctuation model. By mapping the cross-linking process into a two-dimensional (2D) percolation problem within the lattice of grafting points, we investigate the gelation transition in detail. We show that the particular properties of cross-linked polymer brushes can be reduced to the distribution of bonds which are formed between the grafted chains, and we propose scaling arguments to relate the gelation threshold to the chain length and the grafting density. The gelation threshold is lower than the percolation threshold for 2D bond percolation because of the longer range and broad distribution of bonds formed by the cross-linking process. We term this type of percolation problem star percolation. We observe a broad crossover from mean-field to critical percolation behavior by analyzing the cluster size distribution near the gelation threshold.

  5. EB—crosslinking of elastomers, how does it compare with radiation crosslinking of other polymers?

    NASA Astrophysics Data System (ADS)

    Zagórski, Z. P.

    2004-09-01

    Electron beam crosslinking of polyethylene (PE) is a well-established technology, applied commercially for decades. After successes with PE, our efforts have been directed towards the crosslinking of elastomers. As the representative elastomer, hydrogenated acrylonitrile-butadiene rubbers (HNBR) was chosen. It is the high technology material, rather expensive, and therefore excellent object of successful commercial radiation processing. Radiation chemistry of crosslinking of any polymer is governed by similar rules. Most important are steric effects that can prevent efficient crosslinking, second next are additives present in irradiated commercial material. Additive's role is visible in the function of increasing doses, on radiation yield of hydrogen, and the yield of crosslinking. Basics of mechanisms, common to all condensed phases, and therefore to different polymers, are interpreted as phenomena of single ionization spurs (80% of energy deposited) and multi-ionization spurs. Small spurs generate crosslinks of the X type, formed between neighboring macromolecules, whereas multi-ionization spurs, energy rich, cause chain scission. Some fragments of the chains form crosslinks, this time of the Y type, by reacting with their active end with undamaged chains present in the neighborhood. Similarity of mechanisms in PE and HNBR is illustrated by the diagram in Charlesby—Pinner coordinates.

  6. Functional polymer laminates from hyperthermal hydrogen induced cross-linking.

    PubMed

    Thompson, David B; Trebicky, Tomas; Crewdson, Patrick; McEachran, Matthew J; Stojcevic, Goran; Arsenault, Gilles; Lau, Woon M; Gillies, Elizabeth R

    2011-12-20

    The use of a hyperthermal hydrogen induced cross-linking process to prepare laminates comprising polypropylene, poly(isobutylene-co-isoprene), and poly(vinyl acetate) is described. In this new, milder alternative to conventional plasma techniques, neutral molecular hydrogen projectiles were used to create carbon radicals on impacted surfaces by collision-induced dissociation of C-H bonds, and this process was used to cross-link polymers on a polypropylene surface. It was demonstrated that multiple layers of cross-linked materials could be added, creating polymer laminates with each layer introducing new functionalities and properties. In particular, the present work shows that the process is largely nondestructive toward ester functionalities. First, the esters were grafted to become nonleachable. Then, the esters were subsequently hydrolyzed to convert the surface from hydrophobic to hydrophilic. Afterward, the esters could be recovered by simple esterification demonstrating that further chemical transformations were possible.

  7. Enzymatically Crosslinked Emulsion Gels Using Star-Polymer Stabilizers.

    PubMed

    Ma, Kai; An, Zesheng

    2016-10-01

    A novel type of emulsion gel based on star-polymer-stabilized emulsions is highlighted, which contains discrete hydrophobic oil and hydrophilic aqueous solution domains. Well-defined phenol-functionalized core-crosslinked star polymers are synthesized via reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization and are used as stabilizers for oil-in-water emulsions. Horseradish-peroxidase-catalyzed polymerization of the phenol moieties in the presence of H2 O2 enables rapid formation of crosslinked emulsion gels under mild conditions. The crosslinked emulsion gels exhibit enhanced mechanical strength, as well as widely tunable composition. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Process for crosslinking and extending conjugated diene-containing polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

    1977-01-01

    A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

  9. A computational molecular design framework for crosslinked polymer networks

    PubMed Central

    Eslick, J.C.; Ye, Q.; Park, J.; Topp, E.M.; Spencer, P.; Camarda, K.V.

    2013-01-01

    Crosslinked polymers are important in a very wide range of applications including dental restorative materials. However, currently used polymeric materials experience limited durability in the clinical oral environment. Researchers in the dental polymer field have generally used a time-consuming experimental trial-and-error approach to the design of new materials. The application of computational molecular design (CMD) to crosslinked polymer networks has the potential to facilitate development of improved polymethacrylate dental materials. CMD uses quantitative structure property relations (QSPRs) and optimization techniques to design molecules possessing desired properties. This paper describes a mathematical framework which provides tools necessary for the application of CMD to crosslinked polymer systems. The novel parts of the system include the data structures used, which allow for simple calculation of structural descriptors, and the formulation of the optimization problem. A heuristic optimization method, Tabu Search, is used to determine candidate monomers. Use of a heuristic optimization algorithm makes the system more independent of the types of QSPRs used, and more efficient when applied to combinatorial problems. A software package has been created which provides polymer researchers access to the design framework. A complete example of the methodology is provided for polymethacrylate dental materials. PMID:23904665

  10. Modular enzymatically crosslinked protein polymer hydrogels for in situ gelation

    PubMed Central

    Davis, Nicolynn E.; Ding, Sheng; Forster, Ryan; Pinkas, Daniel M.; Barron, Annelise E.

    2012-01-01

    Biomaterials that mimic the extracellular matrix in both modularity and crosslinking chemistry have the potential to recapitulate the instructive signals that ultimately control cell fate. Toward this goal, modular protein polymer-based hydrogels were created through genetic engineering and enzymatic crosslinking. Animal derived tissue transglutaminase (tTG) and recombinant human transglutaminase (hTG) enzymes were used for coupling two classes of protein polymers containing either lysine or glutamine, which have the recognition substrates for enzymatic crosslinking, evenly spaced along the protein backbone. Utilizing tTG under physiological conditions, crosslinking occurred within two minutes, as determined by particle tracking microrheology. Hydrogel composition impacted the elastic storage modulus of the gel over 4-fold and also influenced microstructure and degree of swelling, but did not appreciably effect degradation by plasmin. Mouse 3T3 and primary human fibroblasts were cultured in both 2- and 3-dimensions without a decrease in cell viability and displayed spreading in 2D. The properties of these gels, which are controlled through the specific nature of the protein polymer precursors, render these gels valuable for in situ therapies. Furthermore, the modular hydrogel composition allows tailoring of mechanical and physical properties for specific tissue engineering applications. PMID:20609472

  11. Mechanical properties of crosslinked polymer coatings

    NASA Technical Reports Server (NTRS)

    Csernica, Jeffrey

    1994-01-01

    The objectives of this experiment are to: fabricate and test thin films to explore relations between a polymer's structure and its mechanical properties; expose students to testing methods for hardness and impact energy that are simple to perform and which have results that are easy to comprehend; show importance of polymer properties in materials that students frequently encounter; illustrate a system which displays a tradeoff between strength and impact resistance, the combination of which would need to be optimized for a particular application; and to expose students to coatings technology and testing.

  12. Preparation of crosslinked 1,2,4-oxadiazole polymer

    NASA Technical Reports Server (NTRS)

    Rosser, R. W.; Shalhoub, I. M.; Kwong, H. (Inventor)

    1981-01-01

    New crosslinked 1,2,4-oxadiazole elastomers were prepared by thermally condensing a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming group such as nitrile or amidine or a mixture of such group with amidoxime, or a mixture of said monomer with R C(NOH)NH2 sub 2 with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer.

  13. Ionic liquids in a poly ethylene oxide cross-linked gel polymer as an electrolyte for electrical double layer capacitor

    NASA Astrophysics Data System (ADS)

    Chaudoy, V.; Tran Van, F.; Deschamps, M.; Ghamouss, F.

    2017-02-01

    In the present work, we developed a gel polymer electrolyte via the incorporation of a room temperature ionic liquid into a cross-linked polymer matrix. The cross-linked gel electrolyte was prepared using a free radical polymerization of methacrylate and dimethacrylate oligomers dissolved in 1-propyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide. Combining the advantages of the ionic liquids and of conventional polymers, the cross-linked gel polymer electrolyte was used both as a separator and as an electrolyte for a leakage-free and non-flammable EDLC supercapacitor. The quasi-all solid-state supercapacitors showed rather good capacitance, power and energy densities by comparison to a liquid electrolyte-based EDLC.

  14. Influence of curing modes on crosslink density in polymer structures.

    PubMed

    Soh, M S; Yap, Adrian U J

    2004-05-01

    This study investigates the influence of curing modes on the crosslinking density of dental composites. A light-cure unit (BISCO VIP) that allowed for independent command over time and intensity was selected. Four different light-curing modes with constant light energy density were investigated (control (C), pulse delay (PD), soft-start (SS) and pulse cure (PC)). The degree of crosslinking was assessed directly by measuring the glass transition temperature of 1 mm thick composite (Z100, 3M-ESPE) specimens using differential scanning calorimetry (DSC 2920). Polymer softening in ethanol was used as an indirect method for assessing the degree of crosslinking. After light-curing, specimens were stored in air at 37 degrees C for 24 h and subjected to hardness testing using a digital microhardness tester (n = 6, load=500 g; dwell time=15 s). The specimens were then placed in 75% ethanol-water solution at 37 degrees C for 24 h and post-conditioning hardness was determined. Mean hardness (KHN)/hardness deterioration (DeltaKHN) was computed and data was subjected to analysis using one-way ANOVA/Scheffe's test. Ranking of degree of crosslinking density by DSC was as follows: C>PC>SS>PD. For the indirect method of determining crosslinking density, DeltaKHN ranged from 10.8 to 12.9 and ranking was PC>SS>C>PD. Specimens polymerized with PD were significantly more susceptible to softening in ethanol than specimens cured with PC. Results of this study suggest that polymerization with PD resulted in a lower crosslink density and gave rise to polymers with an increased susceptibility to softening in ethanol.

  15. Simulation of Fracture Nucleation in Cross-Linked Polymer Networks

    NASA Astrophysics Data System (ADS)

    Moller, J. C.; Barr, S. A.; Schultz, E. J.; Breitzman, T. D.; Berry, R. J.

    2013-02-01

    A novel atomistic simulation method is developed whereby polymer systems can undergo strain-rate-controlled deformation while bond scission is enabled. The aim is to provide insight into the nanoscale origins of fracture. Various highly cross-linked epoxy systems including various resin chain lengths and levels of nonreactive dilution were examined. Consistent with the results of physical experiments, cured resin strength increased and ductility decreased with increasing cross-link density. An analysis of dihedral angle activity shows the locations in the molecular network that are most absorptive of mechanical energy. Bond scission occurred principally at cross-link sites as well as between phenyl rings in the bisphenol moiety. Scissions typically occurred well after yield and were accompanied by steady increases in void size and dihedral angle motion between bisphenol moieties and at cross-link sites. The methods developed here could be more broadly applied to explore and compare the atomistic nature of deformation for various polymers such that mechanical and fracture properties could be tuned in a rational way. This method and its results could become part of a solution system that spans multiple length and time scales and that could more completely represent such mechanical events as fracture.

  16. Water-stable crosslinked sulfonated polyimide-silica nanocomposite containing interpenetrating polymer network

    NASA Astrophysics Data System (ADS)

    Lee, Chang Hyun; Hwang, Shin Young; Sohn, Joon Yong; Park, Ho Bum; Kim, Ju Young; Lee, Young Moo

    Sulfonated polyimide (SPI) interpenetrating polymer network (IPN) (IXSPI)-silica (SiO 2) nanocomposite membranes were fabricated as proton conducting solid electrolytes for fuel cells. Urethane acrylate non-ionomers (UANs) were used as dispersants to homogeneously distribute nanosized SiO 2 and, simultaneously, as crosslinkers to induce IPN structure formation. IXSPI-SiO 2 nanocomposite membranes showed high proton conductivity and hydrolytic stability, and low methanol permeability as compared with those of pristine SPI. Interestingly, the casting solvent for membrane fabrication influenced membrane performances, especially proton conductivity. In particular, dimethyl sulfoxide exhibited a strong interaction with sulfonic acid groups in the polymer matrix, which hindered them from spontaneously releasing protons and reduced the proton conductivity and electrochemical performances of the resulting membranes. Crosslinkers with long polyethylene oxide chains also contributed to improved proton conductivity and increased single cell performances.

  17. Crosslinking Chemistry for Fluorocarbon Ether Bibenzoxazole Polymers

    DTIC Science & Technology

    1979-11-01

    soluble amber- colored gums which exhibited inherent viscosities in the range of 0.26 to 0.51 dl/g were obtained in yields of up to 90 percent. N -CF ) CH...dissolved to permit the formation of a viscous, amber- colored solution. The resultant gum exhibited an inherent viscosity of 0.20 dl/g. 3. POLYMER...reaction vessel. The excess copper and cuprous salts were filtered off, the organic layer separated, and the aqueous layer extracted with more

  18. Preparation and characterization of cross-linked composite polymer electrolytes

    SciTech Connect

    Hou, J.; Baker, G.L.

    1998-11-01

    Cross-linkable composite electrolytes were prepared from poly(ethylene glycol) dimethyl ether (PEGDME)-500, LiClO{sub 4}, fumed silica, and 10 wt % methyl, butyl, or octyl methacrylate. The silicas used were chemically modified by attaching methacrylate groups to the silica surface through C{sub 8} and C{sub 3} tethers. Before cross-linking, the electrolytes were thixotropic and had ionic conductivities of >2 {times} 10{sup {minus}4} S/cm. After ultraviolet (UV)-induced cross-linking, the electrolytes were rubbery and dimensionally stable, and the conductivities were unchanged. Conductivity, extraction, and thermal analysis data all support a model where the added methacrylate monomer and growing polymer chains phase separate from the electrolyte phase during photopolymerization to yield a methacrylate-rich silica/polymer phase and little or no polymer in the PEGDME-500 phase. Thus, the mechanical properties of the composite electrolyte and its ionic conductivity are decoupled and can be optimized independently.

  19. Solid lipid nanoparticles coated with cross-linked polymeric double layer for oral delivery of curcumin.

    PubMed

    Wang, Taoran; Ma, Xiaoyu; Lei, Yu; Luo, Yangchao

    2016-12-01

    Solid lipid nanoparticles (SLNs) are regarded as promising carriers to improve the safety and effectiveness of delivery for drugs and nutrients, however, the clinic applications for oral administration are limited by their poor stability in gastrointestinal conditions. In this study, surface modification was explored to confer new physicochemical properties to SLNs and thus achieve enhanced functionalities. Novel SLNs with biopolymeric double layer (DL) coating using two natural biopolymers, i.e. caseinate (NaCas) and pectin, were prepared to encapsulate and deliver curcumin, a lipophilic bioactive compound studied as a model drug/nutrient. The DL coating was chemically cross-linked by creating covalent bonds between NaCas and pectin, using two different cross-linkers, i.e. glutaraldehyde (GA) and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-Hydroxysuccinimide (EDC/NHS). Prior to cross-linking, the mean particle size, polydispersity index and zeta potential of DL-SLNs were 300-330nm, 0.25-0.30, -45-40mV, respectively. It was found that cross-linking with GA had a more prominent effect on particle size and polydispersity index than EDC/NHS. The cross-linking process significantly improved physicochemical properties of DL-SLNs, resulting in higher encapsulation efficiency and loading capacity, better stability and slower release profile in simulated gastrointestinal conditions. Particularly, an optimal zero-order release kinetic was observed for EDC/NHS crosslinked DL-SLNs. The electron microscopy revealed that both cross-linked DL-SLNs exhibited spherical shape with homogeneous size and smooth surface. Encapsulation of curcumin in SLNs dramatically enhanced its antioxidant activity in aqueous condition. The cross-linking process further helped spray drying of SLNs by forming homogenous powder particles. These results indicated that coating with cross-linked polymers could significantly improve the physicochemical properties of SLNs and expand their potentials as

  20. Molecular Recognition-Mediated Transformation of Single-Chain Polymer Nanoparticles into Crosslinked Polymer Films.

    PubMed

    Mahon, Clare S; McGurk, Christopher J; Watson, Scott M D; Fascione, Martin A; Sakonsinsiri, Chadamas; Turnbull, W Bruce; Fulton, David A

    2017-08-14

    We describe single-chain polymer nanoparticles (SCNPs) possessing intramolecular dynamic covalent crosslinks that can transform into polymer films through a molecular recognition-mediated crosslinking process. The SCNPs utilise molecular recognition with surface-immobilised proteins to concentrate upon a substrate, bringing the SCNPs into close spatial proximity with one another and allowing their dynamic covalent crosslinkers to undergo intra- to interpolymer chain crosslinking leading to the formation of polymeric film. SCNPs must possess both the capacity for specific molecular recognition and a dynamic nature to their intramolecular crosslinkers to form polymer films, and an investigation of the initial phase of film formation indicates it proceeds from features which form upon the surface then grow predominantly in the xy directions. This approach to polymer film formation presents a potential method to "wrap" surfaces displaying molecular recognition motifs-which could potentially include viral, cellular and bacterial surfaces or artificial surfaces displaying multivalent recognition motifs-within a layer of polymer film. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. Polymer-Fullerene Network Formation via Light-Induced Crosslinking.

    PubMed

    Sugawara, Yuuki; Hiltebrandt, Kai; Blasco, Eva; Barner-Kowollik, Christopher

    2016-09-01

    A facile and efficient methodology for the formation of polymer-fullerene networks via a light-induced reaction is reported. The photochemical crosslinking is based on a nitrile imine-mediated tetrazole-ene cycloaddition reaction, which proceeds catalyst-free under UV-light irradiation (λmax = 320 nm) at ambient temperature. A tetrazole-functionalized polymer (Mn = 6500 g mol(-1) , Ð = 1.3) and fullerene C60 are employed for the formation of the hybrid networks. The tetrazole-functionalized polymer as well as the fullerene-containing networks are carefully characterized by NMR spectrometry, size exclusion chromatography, infrared spectroscopy, and elemental analysis. Furthermore, thermal analysis of the fullerene networks and their precursors is carried out. The current contribution thus induces an efficient platform technology for fullerene-based network formation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Kinetics of Microphase Separation in Crosslinked Polymer Blend

    SciTech Connect

    Bettachy, A.; Benhamou, M.; Derouiche, A.; Fazni, A.

    2009-04-19

    The solvent effect on the early kinetics of the microphase separation (MPS) in binary crosslinked polymer was studied. In the presence of a good solvent, calculations were done using first the random phase approximation method and second an extended blob model, where a crosslinked chain is viewed as a sequence having blobs as new units. Kinetics were studied through the variation of the relaxation rate, {tau}{sub q}, upon the wave number, q, in the region around the spinodal temperature. When the temperature is changed from an initial value, T{sub i}, toward the final value, T{sub f}, very close to the critical point, the only motion allowed to the crosslinked chains is of Rouse type because of the presence of the crosslinks. The swelling effect on the MPS leads to a multiplicative renormalization of critical parameters of the molten state by factors as power of the overall monomer volume fraction, {phi}. The characteristic frequency, {omega}{sub (q)}, inverse of {tau}{sub q}, scales as {omega}(q) congruent with q{sup 6}{epsilon}{sup 3}, where {epsilon} stands for the traditional screening length. The study of kinetics of MPS is then extended in the presence of a theta solvent.

  3. Multiple Stages of Crosslinking and Scission in Coarse-Grained Polymers

    NASA Astrophysics Data System (ADS)

    Budzien, Joanne

    2015-03-01

    Coarse-grained polymer chains were crosslinked, deformed, crosslinked a second time, and deformed again with stress measured at each deformation. Scissioning of crosslinks occurred at various deformations. By varying the level of scissioning and crosslinking at the deformation states, information is gathered about effective crosslink density that includes contributions from physical entanglements. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575.

  4. Improving mechanical properties of carbon nanotube fibers through simultaneous solid-state cycloaddition and crosslinking

    NASA Astrophysics Data System (ADS)

    Lu, Xinyi; Hiremath, Nitilaksha; Hong, Kunlun; Evora, Maria C.; Ranson, Victoria H.; Naskar, Amit K.; Bhat, Gajanan S.; Kang, Nam-Goo; Mays, Jimmy W.

    2017-04-01

    Individual carbon nanotubes (CNTs) exhibit exceptional mechanical properties. However, difficulties remain in fully realizing these properties in CNT macro-assemblies, because the weak inter-tube forces result in the CNTs sliding past one another. Herein, a simple solid-state reaction is presented that enhances the mechanical properties of carbon nanotube fibers (CNTFs) through simultaneous covalent functionalization and crosslinking. This is the first chemical crosslinking proposed without the involvement of a catalyst or byproducts. The specific tensile strength of CNTFs obtained from the treatment employing a benzocyclobutene-based polymer is improved by 40%. Such improvement can be attributed to a reduced number of voids, impregnation of the polymer, and the formation of covalent crosslinks. This methodology is confirmed using both multiwalled nanotube (MWNT) powders and CNTFs. Thermogravimetric analysis, differential scanning calorimetry, x-ray photoelectron spectroscopy, and transmission electron microscopy of the treated MWNT powders confirm the covalent functionalization and formation of inter-tube crosslinks. This simple one-step reaction can be applied to industrial-scale production of high-strength CNTFs.

  5. Improving mechanical properties of carbon nanotube fibers through simultaneous solid-state cycloaddition and crosslinking

    DOE PAGES

    Lu, Xinyi; Hiremath, Nitilaksha; Hong, Kunlun; ...

    2017-03-13

    Individual carbon nanotubes (CNTs) exhibit exceptional mechanical properties. However, difficulties remain in fully realizing these properties in CNT macro-assemblies, because the weak inter-tube forces result in the CNTs sliding past one another. Here in this study, a simple solid-state reaction is presented that enhances the mechanical properties of carbon nanotube fibers (CNTFs) through simultaneous covalent functionalization and crosslinking. This is the first chemical crosslinking proposed without the involvement of a catalyst or byproducts. The specific tensile strength of CNTFs obtained from the treatment employing a benzocyclobutene-based polymer is improved by 40%. Such improvement can be attributed to a reduced numbermore » of voids, impregnation of the polymer, and the formation of covalent crosslinks. This methodology is confirmed using both multiwalled nanotube (MWNT) powders and CNTFs. Thermogravimetric analysis, differential scanning calorimetry, x-ray photoelectron spectroscopy, and transmission electron microscopy of the treated MWNT powders confirm the covalent functionalization and formation of inter-tube crosslinks. This simple one-step reaction can be applied to industrial-scale production of high-strength CNTFs.« less

  6. Improving mechanical properties of carbon nanotube fibers through simultaneous solid-state cycloaddition and crosslinking.

    PubMed

    Lu, Xinyi; Hiremath, Nitilaksha; Hong, Kunlun; Evora, Maria C; Ranson, Victoria H; Naskar, Amit K; Bhat, Gajanan S; Kang, Nam-Goo; Mays, Jimmy W

    2017-04-07

    Individual carbon nanotubes (CNTs) exhibit exceptional mechanical properties. However, difficulties remain in fully realizing these properties in CNT macro-assemblies, because the weak inter-tube forces result in the CNTs sliding past one another. Herein, a simple solid-state reaction is presented that enhances the mechanical properties of carbon nanotube fibers (CNTFs) through simultaneous covalent functionalization and crosslinking. This is the first chemical crosslinking proposed without the involvement of a catalyst or byproducts. The specific tensile strength of CNTFs obtained from the treatment employing a benzocyclobutene-based polymer is improved by 40%. Such improvement can be attributed to a reduced number of voids, impregnation of the polymer, and the formation of covalent crosslinks. This methodology is confirmed using both multiwalled nanotube (MWNT) powders and CNTFs. Thermogravimetric analysis, differential scanning calorimetry, x-ray photoelectron spectroscopy, and transmission electron microscopy of the treated MWNT powders confirm the covalent functionalization and formation of inter-tube crosslinks. This simple one-step reaction can be applied to industrial-scale production of high-strength CNTFs.

  7. Chemistry of crosslinking processes for self-healing polymers.

    PubMed

    Billiet, Stijn; Hillewaere, Xander K D; Teixeira, Roberto F A; Du Prez, Filip E

    2013-02-25

    Recent developments in material design have seen an exponential increase of polymers and polymer composites that can repair themselves in response to damage. In this review, a distinction is made between extrinsic materials, where the self-healing property is obtained by adding healing agents to the material to be repaired, and intrinsic materials, where self-healing is achieved by the material itself through its chemical nature. An overview of the crosslinking chemistries used in self-healing materials will be given, discussing the advantages and drawbacks of each system. The review is not only aiming to enable researchers to compare their ongoing research with the state-of-the-art but also to serve as a guide for the newcomers, which allows for a selection of the most promising self-healing chemistries.

  8. Gradiently crosslinked polymer electrolyte membranes in fuel cells

    NASA Astrophysics Data System (ADS)

    An, De; Wu, Bin; Zhang, Genlei; Zhang, Wen; Wang, Yuxin

    2016-01-01

    Polymer electrolyte membranes in fuel cells should be high in both ionic conductivity and mechanical strength. However, the two are often exclusive to each other. To solve this conundrum, a novel strategy is proposed in this paper, with extensively researched sulfonated poly (ether ether ketone) (SPEEK) membrane as a paradigm. A SPEEK membrane of high sulfonation degree is simply post-treated with NaBH4 and H2SO4 solution at ambient temperature for a certain time to afford the membrane with a gradient crosslinking structure. Measurements via 1H NMR, ATR-FTIR and SEM-EDS are conducted to verify such structural changes. The gradient crosslinks make practically no damage to proton conductance, but effectively restrain the membrane from over swelling and greatly enhance its tensile strength. A H2-O2 fuel cell with the gradiently crosslinked SPEEK membrane shows a maximal power density of 533 mW cm-2 at 80 °C, whereas the fuel cell with the pristine SPEEK membrane cannot be operated beyond 30 °C.

  9. Electroluminescent devices based on cross-linked polymer blends

    NASA Astrophysics Data System (ADS)

    Bozano, Luisa D.; Carter, Kenneth R.; Lee, Victor Y.; Miller, Robert D.; DiPietro, Richard; Scott, J. Campbell

    2003-09-01

    We report the electrical and optical properties of two-component blends of electron and hole transporting materials in single and bilayer structures for organic light emitting diode (OLED) applications. The materials considered were a blue-emitting bipolar transporting polyfluorene, poly(9,9-di-n-hexylfluorene) (DHF), and a hole-transporting material, poly-[4-nhexyltriphenylamine] (HTPA). We compare the steady state OLED performance, transport, and optical properties of devices and describe morphology studies of the polymer films based on cross-linkable (x) blends with the analogous non-cross-linkable blends. The cross-linkable blends exhibit highest efficiency at low concentrations of the hole transporting material. At these concentrations the single layer OLEDs reach efficiencies greater than 0.1%, and are higher than for single layer x-DHF or the binary non-cross-linkable blend by more than an order of magnitude. Bilayer structures with homogeneous x-HTPA as hole transport layer show efficiencies between 0.08% and 0.96%, depending on the blend concentration in the emitting layer and on the top contact. We interpret these results in terms of the relative degree of phase segregation in the cross-linked networks versus the non-cross-linkable blends.

  10. Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation-Crosslinked Poly (Vinyl Alcohol)-Based Solid Polymer Electrolytes Blended With LiOH{center_dot}H{sub 2}O Salt

    SciTech Connect

    Khafagy, Rasha M.; Madani, M.; Badr, Y. A.

    2008-09-23

    Solid polymer electrolytes based on poly(vinyl alcohol)(PVA) blended with different concentrations of LiOH{center_dot}H{sub 2}O salt were prepared using casting and {gamma}-irradiation techniques. The structure and blending of the poly-electrolytes were studied by X-ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and these melting points change with the salt content. All characterizing techniques revealed the blend formation between LiOH{center_dot}H{sub 2}O salt and the polymer matrix. To account for the performance of the prepared solid polymer electrolytes, thermally stimulated depolarization current (TSDC) studies of the prepared blends were done. Short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm{sup -1} have been analyzed in the temperature range 300-410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly-blend system. The prepared solid polymer electrolytes showed good charge storage capacity, and moderate current density values near the ambient.

  11. Exceptionally stable polymer electrolyte for a lithium battery based on cross-linking by a residue-free process

    NASA Astrophysics Data System (ADS)

    Daigle, Jean-Christophe; Asakawa, Yuichiro; Vijh, Ashok; Hovington, Pierre; Armand, Michel; Zaghib, Karim

    2016-11-01

    In this paper, we report the synthesis of cross-linked copolymers of glycidyl methacrylate (GMA) and poly (ethylene glycol) methyl methacrylate (PEGMA) for use as solid polymer electrolytes (SPE). The cross-linking is performed with volatile ethylene diamine, thus preventing the accumulation of undesirable precursors in the final membrane. The structure of the cross-linked polymer electrolyte was investigated by 13C solid NMR and its physical properties were examined by DSC, TGA and stress-strain tests. The ionic conductivities were determined by AC Impedance, which showed that the SPEs have good conductivities (10-5 Scm-1) at 80 °C. The highest capacity measured with these polymers was 151 mAh g-1 at C/6 and 80 °C for a LFP/SPE/Lithium battery. The retention capacity is high, at 97% after 80 cycles at different rates of cycling. The Young's modulus of the membranes is as high as 1 GPa. The SEM images showed no evidence of lithium dendrites and no degradation after cycling. Therefore, the polymer is a good candidate for battery operation over a long time. Especially important is the ability of this polymer to prevent growth of dendrites on the Li-metal electrode.

  12. The role of unsaturations in the Gamma irradiation of crosslinkable polymers

    NASA Astrophysics Data System (ADS)

    Satti, Angel J.; Ciolino, Andrés E.; Andreucetti, Noemí A.; Vallés, Enrique M.

    2015-10-01

    Nowadays, the understanding of the interaction of ionizing radiations with polymeric materials is becoming increasingly important. It is well known that many parameters regarding the synthesis of the polymers noticeably affect the irradiation process. In this work, an analysis of the effect of the type and the position of unsaturations in the molecular structure of crosslinkable polymers is performed. For such purpose, two solid semycristalline metallocenic ethylene 1-olefin copolymers (mEOC) which contain a low concentration of unsaturations from the synthesis, and their hydrogenated samples, were irradiated along with liquid poly(dimethylsiloxane) (PDMS) homo and copolymers containing different location and concentration of vinyl groups, which were structurally tailored through anionic synthesis. The source of irradiation was 60Co, under vacuum at room temperature, in all the cases. The results indicated that terminal vinyls drastically accelerate the crosslinking to lower doses, even at much lower concentrations than other type and location of unsaturations for both, mEOC and PDMS, type of polymers.

  13. Differentially photo-crosslinked polymers enable self-assembling microfluidics

    PubMed Central

    Jamal, Mustapha; Zarafshar, Aasiyeh M.; Gracias, David H.

    2012-01-01

    An important feature of naturally self-assembled systems such as leaves and tissues is that they are curved and have embedded fluidic channels that enable the transport of nutrients to, or removal of waste from, specific three-dimensional (3D) regions. Here, we report the self-assembly of photopatterned polymers, and consequently microfluidic devices, into curved geometries. We discovered that differentially photo-crosslinked SU-8 films spontaneously and reversibly curved upon film de-solvation and re-solvation. Photolithographic patterning of the SU-8 films enabled the self-assembly of cylinders, cubes, and bidirectionally folded sheets. We integrated polydimethylsiloxane (PDMS) microfluidic channels with these SU-8 films to self-assemble curved microfluidic networks. PMID:22068594

  14. Delayed in situ crosslinking of acrylamide polymers for oil recovery applications in high-temperature formations

    SciTech Connect

    Sydansk, R.D.

    1989-07-04

    This patent describes a process for plugging a region of a high-temperature hydrocarbon-bearing formation below an earthen surface with a cross-linked acrylamide polymer gel wherein the formation is penetrated by a wellbore in communication with the region. The process comprising: admixing a gelation system at the earthen surface comprising an aqueous solvent, an unhydrolyzed acrylamide polymer made up of monomeric groups, and a polyvalent metal crosslinking agent. Wherein less than about 1.0 mole percent of the monomeric groups in the unhydrolyzed acrylamide polymer contain a carboxylate constituent based on the total number of the monomeric groups in the polymer. Wherein the polyvalent metal crosslinking agent is a salt or a complex of a trivalent or quatravalent metal cation capable of crosslinking a partially hydrolyzed acrylamide polymer; injecting the gelation system into the treatment region of the formation wherein the formation has a temperature of at least about 60{sup 0}C, hydrolyzing the polymer in the region at the formation temperature such that more than about 1.0 mole percent of the monomeric groups in the polymer contain a carboxylate constituent based on the total number of the monomeric groups in the polymer; and crosslinking the gelation system in the region to substantial completion to form the continuous immobile crosslinked acrylamide polymer gel which plugs at least a portion of the treatment region.

  15. Mechanophore activation in a crosslinked polymer matrix via instrumented indentation

    NASA Astrophysics Data System (ADS)

    Davis, Chelsea; Forster, Aaron; Woodcock, Jeremiah; Wang, Muzhou; Gilman, Jeffrey; Material Measurement Laboratory Team

    Recent advances in mechanically-activated fluorophores will enable a host of unique scientific challenges and opportunities to be addressed. Several mechanophores (MPs) in polymers have been reported, yet the specific deformation required to activate these molecules in a bulk polymer network has not been sufficiently specified. In an effort to develop the mechano-activation/deformation relationship of a spirolactam-based MP, scratches were applied to a MP-functionalized glassy crosslinked material at varying normal loads and lateral displacement rates. This experimental design allowed strain and strain rate effects to be decoupled. The fluorescence activation was then observed with a laser scanning confocal microscope. Areas of elastic and plastic deformation as well as brittle fracture were observed within each scratch as the normal loading of the indenter increased. The fluorescence intensity increased with increasing strain. Contact mechanics models are employed to demonstrate that relatively high degrees of strain are required to initiate the ring-opening activation transition within the spirolactam-based MP. These self-reporting damage sensors can be incorporated within polymeric coatings to allow real time structural health monitoring for a myriad of applications.

  16. Elucidation of the Cross-Link Structure of Nadic-End-Capped Polyimides Using NMR of C-13-Labeled Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Johnston, J. Christopher; Cavano, Paul J.

    1997-01-01

    Solid NMR of C-13 isotope-labeled samples of PMR-15 was used to follow the cross-linking reaction of the nadic end cap. Some samples were labeled on one of the carbon atoms of the nadic end cap, and others on the methylene carbon atom of the methylenedianiline portion of the polymer. NMR spectra were run on these samples both before and after cross-linking. In this way, direct evidence of the major products of cross-linking under normal cure conditions is provided. The majority (approximately 85%) of the cross-linking derives from olefin polymerization through the double bond of the end cap. Approximately 15% of the products could come from a pathway involving a retro-Diels-Alder reaction. However, all of the products could be explained by a biradical intermediate without a retro-Diels-Alder reaction. Evidence is also presented that the methylene moiety in the methylenedianiline part of the polymer chain also participates in the cross-linking, albeit to a small extent, by a radical transfer reaction. Different cure conditions (higher temperatures, longer times) could change the relative distribution of the products.

  17. Cross-linking carbon nanotubes by glycidyl azide polymer via click chemistry.

    PubMed

    Wei, Zhong; Du, Liang; Wang, Lin

    2012-01-01

    Functionalization and cross linking of carbon nanotubes was necessary to fabricate nanotube composites with good interfacial properties and mechanical performance. Glycidyl azide polymer was used as cross-linker of carbon nanotubes via a simple clickable one step reaction initiated by decomposition of azide groups. Both heating and UV irradiation were used to carry out the reaction. FTIR and Raman spectra confirmed the decomposition of azide groups and the anchoring of glycidyl azide polymer onto the surface of carbon nanotubes. Thermal gravity analysis showed that the polymer anchored onto carbon nanotubes was about 10% of the total mass in the solid product, but the efficiency of the reaction was low. The result of tensile test using bulky paper infiltrated with 10% GAP showed that cross linking could bring forth a higher strength, about 4 times higher than the not cross linked. The success of cross linking carbon nanotubes by glycidyl azide polymer paves a new way to fabrication of ultra strong carbon nanotube composites.

  18. Process for crosslinking methylene-containing aromatic polymers with ionizing radiation

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

    1990-01-01

    A process for crosslinking aromatic polymers containing radiation-sensitive methylene groups (-CH2-) by exposing the polymers to ionizing radiation thereby causing crosslinking of the polymers through the methylene groups is described. Crosslinked polymers are resistant to most organic solvents such as acetone, alcohols, hydrocarbons, methylene, chloride, chloroform, and other halogenated hydrocarbons, to common fuels and to hydraulic fluids in contrast to readily soluble uncrosslinked polymers. In addition, the degree of crosslinking of the polymers depends upon the percentage of the connecting groups which are methylene which ranges from 5 to 50 pct and preferably from 25 to 50 pct of the connecting groups, and is also controlled by the level of irradiation which ranges from 25 to 1000 Mrads and preferably from 25 to 250 Mrads. The temperature of the reaction conditions ranges from 25 to 200 C and preferably at or slightly above the glass transition temperature of the polymer. The crosslinked polymers are generally more resistant to degradation at elevated temperatures such as greater than 150 C, have a reduced tendency to creep under load, and show no significant embrittlement of parts fabricated from the polymers.

  19. Reactions of Inorganic High Polymers as a Route to Tailored Solids

    DTIC Science & Technology

    1989-02-09

    polymers, liquid crystalline materials , bioerodable solids, solids with bioactive surfaces, solid electrolytes, semiconductors, or ultrastructures. Solids, Polymers, Phosphazenes, Synthesis, (Chemistry).

  20. Hyper-crosslinked cyclodextrin porous polymer: An efficient CO2 capturing material with tunable porosity

    DOE PAGES

    Meng, Bo; Li, Haiyang; East China Univ. of Science and Technology, Shanghai; ...

    2016-11-11

    We designed and synthesized the cyclodextrin (CD)-based hyper-crosslinked porous polymers (HCPPs) for selective CO2 adsorption and storage. We also explored the effect of monomer size on micropore formation, and determined a feasible way to tailor the porosity of the materials during the hyper-crosslinking process.

  1. Water and polymer dynamics in highly crosslinked polyamide membranes

    NASA Astrophysics Data System (ADS)

    Frieberg, Bradley; Chan, Edwin; Tyagi, Madhu; Stafford, Christopher; Soles, Christopher

    Highly crosslinked polyamides for reverse osmosis are the state-of-the-art active material in membranes for desalination. The thin film composite membrane structure that is used commercially has been empirically designed to selectively allow the passage of water molecules and minimize the passage of solutes such as salt. However, due to the large roughness and variability of the polyamide layer, there is a limited understanding of the structure-property relationship for these materials as well as the transport mechanism. To better understand the water transport mechanism we measure the water and polymer dynamics of polyamide membranes using quasi-elastic neutron scattering (QENS). By hydrating the membrane with deuterated water, we are able to isolate the dynamics of the hydrogenated membrane on the pico- and nanosecond time scales. By subsequently hydrating the membranes with hydrogenated water, the QENS measurements on the same times scales reveal information about both the translational and rotational dynamics of water confined within the polyamide membrane. Further understanding of the water diffusion mechanism will establish design rules in which the performance of future membrane materials can be improved.

  2. Tailoring single chain polymer nanoparticle thermo-mechanical behavior by cross-link density.

    PubMed

    Bae, Suwon; Galant, Or; Diesendruck, Charles E; Silberstein, Meredith N

    2017-04-12

    Single chain polymer nanoparticles (SCPNs) are formed from intrachain cross-linking of a single polymer chain, making SCPN distinct from other polymer nanoparticles for which the shape is predefined before polymerization. The degree of cross-linking in large part determines the internal architecture of the SCPNs and therefore their mechanical and thermomechanical properties. Here, we use molecular dynamics (MD) simulations to study thermomechanical behavior of individual SCPNs with different underlying structures by varying the ratio of cross-linking and the degree of polymerization. We characterize the particles in terms of shape, structure, glass transition temperature, mobility, and stress response to compressive loading. The results indicate that the constituent monomers of SCPNs become less mobile as the degree of cross-linking is increased corresponding to lower diffusivity and higher stress at a given temperature.

  3. Optimized polymer enhanced foam flooding for ordinary heavy oil reservoir after cross-linked polymer flooding.

    PubMed

    Sun, Chen; Hou, Jian; Pan, Guangming; Xia, Zhizeng

    2016-01-01

    A successful cross-linked polymer flooding has been implemented in JD reservoir, an ordinary heavy oil reservoir with high permeability zones. For all that, there are still significant volumes of continuous oil remaining in place, which can not be easily extracted due to stronger vertical heterogeneity. Considering selective plugging feature, polymer enhanced foam (PEF) flooding was taken as following EOR technology for JD reservoir. For low cost and rich source, natural gas was used as foaming gas in our work. In the former work, the surfactant systems CEA/FSA1 was recommended as foam agent for natural gas foam flooding after series of compatibility studies. Foam performance evaluation experiments showed that foaming volume reached 110 mL, half-life time reached 40 min, and dimensionless filter coefficient reached 1.180 when CEA/FSA1 reacted with oil produced by JD reservoir. To compare the recovery efficiency by different EOR technologies, series of oil displacement experiments were carried out in a parallel core system which contained cores with relatively high and low permeability. EOR technologies concerned in our work include further cross-linked polymer (C-P) flooding, surfactant-polymer (S-P) flooding, and PEF flooding. Results showed that PEF flooding had the highest enhanced oil recovery of 19.2 % original oil in place (OOIP), followed by S-P flooding (9.6 % OOIP) and C-P flooding (6.1 % OOIP). Also, produced liquid percentage results indicated PEF flooding can efficiently promote the oil recovery in the lower permeability core by modifying the injection profile.

  4. Characterization, molecular dynamics, and encapsulation ability of β-cyclodextrin polymers crosslinked by polyethylene glycol.

    PubMed

    Kono, Hiroyuki; Nakamura, Taichi; Hashimoto, Hisaho; Shimizu, Yuuichi

    2015-09-05

    A series of water-insoluble cyclodextrin polymers (CDP) was prepared by crosslinking β-cyclodextrin (CD) with polyethylene glycol diglycidyl ether (PEGDE). Similarly, a reference CDP was prepared using ethylene glycol diglycidyl ether (EGDE). Increasing the feed ratio of PEGDE to CD in the reaction mixture led to high degrees of crosslinking. Relaxation measurements revealed structural homogeneity among the CDPs, which exhibited mobilities that strongly depended on the chain lengths of the crosslinking agents. In addition, all the CDPs displayed high encapsulation abilities toward bisphenol A (BPA) in aqueous media. In particular, the CDP sample with a low degree of crosslinking by PEGDE showed the highest encapsulation ability toward BPA. In contrast, the CDP crosslinked by EGDE exhibited low encapsulation ability because its highly dense structure, which results from the short chain lengths of the crosslinking agents, hinders the penetration of BPA molecules.

  5. ROMP-based thermosetting polymers from modified castor oil with various cross-linking agents

    NASA Astrophysics Data System (ADS)

    Ding, Rui

    Polymers derived from bio-renewable resources are finding an increase in global demand. In addition, polymers with distinctive functionalities are required in certain advanced fields, such as aerospace and civil engineering. In an attempt to meet both these needs, the goal of this work aims to develop a range of bio-based thermosetting matrix polymers for potential applications in multifunctional composites. Ring-opening metathesis polymerization (ROMP), which recently has been explored as a powerful method in polymer chemistry, was employed as a unique pathway to polymerize agricultural oil-based reactants. Specifically, a novel norbornyl-functionalized castor oil alcohol (NCA) was investigated to polymerize different cross-linking agents using ROMP. The effects of incorporating dicyclopentadiene (DCPD) and a norbornene-based crosslinker (CL) were systematically evaluated with respect to curing behavior and thermal mechanical properties of the polymers. Isothermal differential scanning calorimetry (DSC) was used to investigate the conversion during cure. Dynamic DSC scans at multiple heating rates revealed conversion-dependent activation energy by Ozawa-Flynn-Wall analysis. The glass transition temperature, storage modulus, and loss modulus for NCA/DCPD and NCA/CL copolymers with different cross-linking agent loading were compared using dynamic mechanical analysis. Cross-link density was examined to explain the very different dynamic mechanical behavior. Mechanical stress-strain curves were developed through tensile test, and thermal stability of the cross-linked polymers was evaluated by thermogravimetric analysis to further investigate the structure-property relationships in these systems.

  6. Polymer composition and substrate influences on the adhesive bonding of a biomimetic, cross-linking polymer.

    PubMed

    Matos-Pérez, Cristina R; White, James D; Wilker, Jonathan J

    2012-06-06

    Hierarchical biological materials such as bone, sea shells, and marine bioadhesives are providing inspiration for the assembly of synthetic molecules into complex structures. The adhesive system of marine mussels has been the focus of much attention in recent years. Several catechol-containing polymers are being developed to mimic the cross-linking of proteins containing 3,4-dihydroxyphenylalanine (DOPA) used by shellfish for sticking to rocks. Many of these biomimetic polymer systems have been shown to form surface coatings or hydrogels; however, bulk adhesion is demonstrated less often. Developing adhesives requires addressing design issues including finding a good balance between cohesive and adhesive bonding interactions. Despite the growing number of mussel-mimicking polymers, there has been little effort to generate structure-property relations and gain insights on what chemical traits give rise to the best glues. In this report, we examine the simplest of these biomimetic polymers, poly[(3,4-dihydroxystyrene)-co-styrene]. Pendant catechol groups (i.e., 3,4-dihydroxystyrene) are distributed throughout a polystyrene backbone. Several polymer derivatives were prepared, each with a different 3,4-dihyroxystyrene content. Bulk adhesion testing showed where the optimal middle ground of cohesive and adhesive bonding resides. Adhesive performance was benchmarked against commercial glues as well as the genuine material produced by live mussels. In the best case, bonding was similar to that obtained with cyanoacrylate "Krazy Glue". Performance was also examined using low- (e.g., plastics) and high-energy (e.g., metals, wood) surfaces. The adhesive bonding of poly[(3,4-dihydroxystyrene)-co-styrene] may be the strongest of reported mussel protein mimics. These insights should help us to design future biomimetic systems, thereby bringing us closer to development of bone cements, dental composites, and surgical glues.

  7. Polymer Composition and Substrate Influences on the Adhesive Bonding of a Biomimetic, Cross-Linking Polymer

    PubMed Central

    Matos-Pérez, Cristina R.; White, James D.; Wilker, Jonathan J.

    2012-01-01

    Hierarchical biological materials such as bone, sea shells, and marine bioadhesives are providing inspiration for the assembly of synthetic molecules into complex structures. The adhesive system of marine mussels has been the focus of much attention in recent years. Several catechol-containing polymers are being developed to mimic the cross-linking of proteins containing 3,4-dihydroxyphenylalanine (DOPA) used by shellfish for sticking to rocks. Many of these biomimetic polymer systems have been shown to form surface coatings or hydrogels, however bulk adhesion is demonstrated less often. Developing adhesives requires addressing design issues including finding a good balance between cohesive and adhesive bonding interactions. Despite the growing number of mussel mimicking polymers, there has been little effort to generate structure-property relations and gain insights on what chemical traits give rise to the best glues. In this report, we examined the simplest of these biomimetic polymers, poly[(3,4-dihydroxystyrene)-co-styrene]. Pendant catechol groups (i.e., 3,4-dihydroxystyrene) were distributed throughout a polystyrene backbone. Several polymer derivatives were prepared, each with a different 3,4-dihyroxystyrene content. Bulk adhesion testing showed where the optimal middle ground of cohesive and adhesive bonding resides. Adhesive performance was benchmarked against commercial glues as well as the genuine material produced by live mussels. In the best case, bonding was similar to cyanoacrylate “Krazy” or “Super” glue. Performance was also examined using low (e.g., plastics) and high (e.g., metals, wood) energy surfaces. Adhesive bonding of poly[(3,4-dihydroxystyrene)-co-styrene] may be the strongest of reported mussel protein mimics. These insights should help us to design future biomimetic systems, thereby bringing us closer to development of bone cements, dental composites, and surgical glues. PMID:22582754

  8. Investigation of anisotropic thermal transport in cross-linked polymers

    NASA Astrophysics Data System (ADS)

    Simavilla, David Nieto

    Thermal transport in lightly cross-linked polyisoprene and polybutadine subjected to uniaxial elongation is investigated experimentally. We employ two experimental techniques to assess the effect that deformation has on this class of materials. The first technique, which is based on Forced Rayleigh Scattering (FRS), allows us to measure the two independent components of the thermal diffusivity tensor as a function of deformation. These measurements along with independent measurements of the tensile stress and birefringence are used to evaluate the stress-thermal and stress-optic rules. The stress-thermal rule is found to be valid for the entire range of elongations applied. In contrast, the stress-optic rule fails for moderate to large stretch ratios. This suggests that the degree of anisotropy in thermal conductivity depends on both orientation and tension in polymer chain segments. The second technique, which is based on infrared thermography (IRT), allows us to measure anisotropy in thermal conductivity and strain induced changes in heat capacity. We validate this method measurements of anisotropic thermal conductivity by comparing them with those obtained using FRS. We find excellent agreement between the two techniques. Uncertainty in the infrared thermography method measurements is estimated to be about 2-5 %. The accuracy of the method and its potential application to non-transparent materials makes it a good alternative to extend current research on anisotropic thermal transport in polymeric materials. A second IRT application allows us to investigate the dependence of heat capacity on deformation. We find that heat capacity increases with stretch ratio in polyisoprene specimens under uniaxial extension. The deviation from the equilibrium value of heat capacity is consistent with an independent set of experiments comparing anisotropy in thermal diffusivity and conductivity employing FRS and IRT techniques. We identify finite extensibility and strain

  9. Strain Hardening and Strain Softening of Reversibly Cross-linked Supramolecular Polymer Networks.

    PubMed

    Xu, Donghua; Craig, Stephen L

    2011-09-27

    The large amplitude oscillatory shear behavior of metallo-supramolecular polymer networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) solution is reported. The influence of scanning frequency, dissociation rate of cross-linkers, concentration of cross-linkers, and concentration of PVP solution on the large amplitude oscillatory shear behavior is explored. In semidilute unentangled PVP solutions, above a critical scanning frequency, strain hardening of both storage moduli and loss moduli is observed. In the semidilute entangled regime of PVP solution, however, strain softening is observed for samples with faster cross-linkers (k(d) ∼ 1450 s(-1)), whereas strain hardening is observed for samples with slower cross-linkers (k(d) ∼ 17 s(-1)). The mechanism of strain hardening is attributed primarily to a strain-induced increase in the number of elastically active chains, with possible contributions from non-Gaussian stretching of polymer chains at strains approaching network fracture. The divergent strain softening of samples with faster cross-linkers in semidilute entangled PVP solutions, relative to the strain hardening of samples with slower cross-linkers, is consistent with observed shear thinning/shear thickening behavior reported previously and is attributed to the fact that the average time that a cross-linker remains detached is too short to permit the local relaxation of polymer chain segments that is necessary for a net conversion of elastically inactive to elastically active cross-linkers. These and other observations paint a picture in which strain softening and shear thinning arise from the same set of molecular mechanisms, conceptually uniting the two nonlinear responses for this system.

  10. Strain Hardening and Strain Softening of Reversibly Cross-linked Supramolecular Polymer Networks

    PubMed Central

    Xu, Donghua; Craig, Stephen L.

    2011-01-01

    The large amplitude oscillatory shear behavior of metallo-supramolecular polymer networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) solution is reported. The influence of scanning frequency, dissociation rate of cross-linkers, concentration of cross-linkers, and concentration of PVP solution on the large amplitude oscillatory shear behavior is explored. In semidilute unentangled PVP solutions, above a critical scanning frequency, strain hardening of both storage moduli and loss moduli is observed. In the semidilute entangled regime of PVP solution, however, strain softening is observed for samples with faster cross-linkers (kd ∼ 1450 s−1), whereas strain hardening is observed for samples with slower cross-linkers (kd ∼ 17 s−1). The mechanism of strain hardening is attributed primarily to a strain-induced increase in the number of elastically active chains, with possible contributions from non-Gaussian stretching of polymer chains at strains approaching network fracture. The divergent strain softening of samples with faster cross-linkers in semidilute entangled PVP solutions, relative to the strain hardening of samples with slower cross-linkers, is consistent with observed shear thinning/shear thickening behavior reported previously and is attributed to the fact that the average time that a cross-linker remains detached is too short to permit the local relaxation of polymer chain segments that is necessary for a net conversion of elastically inactive to elastically active cross-linkers. These and other observations paint a picture in which strain softening and shear thinning arise from the same set of molecular mechanisms, conceptually uniting the two nonlinear responses for this system. PMID:22043083

  11. Structural Properties and Phase Behavior of Crosslinked Networks in Polymer Solutions.

    PubMed

    Benmouna, Farida; Zemmour, Samira; Benmouna, Mustapha

    2016-03-03

    Structural properties and phase behavior of crosslinked networks embedded in polymer solutions are theoretically investigated. The partial structure factor of the network is calculated using a matrix formulation of the random phase approximation and the forward scattering limit is correlated with the phase behavior. Swelling and deswelling processes are analyzed in terms of the polymer concentration, the mismatch of solvent quality with respect to polymer and network, the polymers incompatibility and their characteristic sizes. Most studies reported so far in the literature have focussed on the swelling of crosslinked networks and gels in pure solvents but the correlation of the structural properties with the phase behavior in the presence of high molecular weight polymers in solution has not been given sufficient attention. The present work is intended to fill this gap in view of the current efforts to develop novel drug encapsulating and targeted delivery devices.

  12. Structural Properties and Phase Behavior of Crosslinked Networks in Polymer Solutions

    PubMed Central

    Benmouna, Farida; Zemmour, Samira; Benmouna, Mustapha

    2016-01-01

    ABSTRACT Structural properties and phase behavior of crosslinked networks embedded in polymer solutions are theoretically investigated. The partial structure factor of the network is calculated using a matrix formulation of the random phase approximation and the forward scattering limit is correlated with the phase behavior. Swelling and deswelling processes are analyzed in terms of the polymer concentration, the mismatch of solvent quality with respect to polymer and network, the polymers incompatibility and their characteristic sizes. Most studies reported so far in the literature have focussed on the swelling of crosslinked networks and gels in pure solvents but the correlation of the structural properties with the phase behavior in the presence of high molecular weight polymers in solution has not been given sufficient attention. The present work is intended to fill this gap in view of the current efforts to develop novel drug encapsulating and targeted delivery devices. PMID:27134310

  13. Photochromic cross-link polymer for color changing and sensing surface

    NASA Astrophysics Data System (ADS)

    Fu, Richard; Shi, Jianmin; Forsythe, Eric; Srour, Merric

    2016-12-01

    Photochromic cross-link polymers were developed using patented ultraviolet (UV) photoinitiator and commercial photochromic dyes. The photochromic dyes have been characterized by measuring absorbance before and after UV activation using UV-visible (Vis) spectrometry with varying activation intensities and wavelengths. Photochromic cross-link polymers were characterized by a dynamic xenon and UV light activation and fading system. The curing processes on cloth were established and tested to obtain effective photochromic responses. Both PulseForge photonic curing and PulseForge plus heat surface curing processes had much better photochromic responses (18% to 19%, 16% to 25%, respectively) than the xenon lamp treatment (8%). The newly developed photochromic cross-link polymer showed remarkable coloration contrasts and fast and comparable coloration and fading rates. Those intelligent, controlled color changing and sensing capabilities will be used on flexible and "drapeable" surfaces, which will incorporate ultra-low power sensors, sensor indicators, and identifiers.

  14. Application of radiation-graft material for metal adsorbent and crosslinked natural polymer for healthcare product

    NASA Astrophysics Data System (ADS)

    Tamada, Masao; Seko, Noriaki; Yoshii, Fumio

    2004-09-01

    Graft polymerization and crosslinking in radiation processing are attractive techniques for modification of the chemical and physical properties of conventional polymers. The graft polymerization and subsequent chemical treatment can introduce a chelate agent function into a conventional polymer such as polyethylene. The obtained amidoxime fibrous adsorbent was applied to the recovery of uranium from seawater. Soaking of 350 kg adsorbent 12 times in seawater led to the collection of 1 kg of uranium. Natural polymers such as derivatives of starch and cellulose were radiation-crosslinked to form hydrogels. Mats of crosslinked carboxylmethyl cellulose were evaluated by 68 patients after surgical operation. No bedsore was observed in almost of all patients after operation. This product was commercialized as "Non-bedsore" in Japan.

  15. 3D Mapping of Polymer Crosslink Density with Magnetic Resonance Imaging

    SciTech Connect

    Herberg, J L; Gjersing, E L; Chinn, S C; Maxwell, R S

    2005-03-11

    Magnetic Resonance Imaging (MRI) techniques have been used to detect areas of low crosslink density in damaged silicone parts in an effort to develop a QA/QC protocol to be used in the development of new parts. Model materials of varying crosslink density first demonstrated the applicability of the method. Analysis of damaged pads has been shown to be clearly distinguishable by MRI. It is our belief that both the T{sub 2} weighted SPI NMR and the T{sub 2} weighted water/fat suppression MRI experiments can be used to map out the location of different cross-linking densities, ultimately determining the quality or homogeneity in polymers.

  16. Predicting the glass transition temperature as function of crosslink density and polymer interactions in rubber compounds

    NASA Astrophysics Data System (ADS)

    D'Escamard, Gabriella; De Rosa, Claudio; Auriemma, Finizia

    2016-05-01

    Crosslink sulfur density in rubber compounds and interactions in polymer blends are two of the composition elements that affect the rubber compound properties and glass transition temperature (Tg), which is a marker of polymer properties related to its applications. Natural rubber (NR), butadiene rubber (BR) and styrene-butadiene rubber (SBR) compounds were investigated using calorimetry (DSC) and dynamic mechanical analysis (DMA). The results indicate that the Di Marzio's and Schneider's Models predict with accuracy the dependence of Tg on crosslink density and composition in miscible blends, respectively, and that the two model may represent the base to study the relevant "in service" properties of real rubber compounds.

  17. Electron Beam Crosslinked Polyurethane Shape Memory Polymers with Tunable Mechanical Properties.

    PubMed

    Hearon, Keith; Nash, Landon D; Volk, Brent L; Ware, Taylor; Lewicki, James P; Voit, Walter E; Wilson, Thomas S; Maitland, Duncan J

    2013-06-01

    Novel electron beam crosslinked polyurethane shape memory polymers with advanced processing capabilities and tunable thermomechanical properties have been synthesized and characterized. We demonstrate the ability to manipulate crosslink density in order to finely tune rubbery modulus, strain capacity, ultimate tensile strength, recovery stress, and glass transition temperature. This objective is accomplished for the first time in a low-molecular-weight polymer system through the precise engineering of thermoplastic resin precursors suitable for mass thermoplastic processing. Neurovascular stent prototypes were fabricated by dip-coating and laser machining to demonstrate processability.

  18. Modification of biodegradable polymers by radiation crosslinking technique with polyfunctional monomers

    NASA Astrophysics Data System (ADS)

    Yoshii, Fumio; Suhartini, Meri; Nagasawa, Naotsugu; Mitomo, Hiroshi; Kume, Tamikazu

    2003-08-01

    Poly(ɛ-caprolactone) (PCL) and poly(butylene succinate-co-adipate) (PBSA) were electron beam-irradiated in the presence of five different polyfunctional monomers at ambient temperature. Trimethallyl isocyanurate (TMAIC) has been found to greatly enhance the radiation crosslinking of PCL and PBSA. It was pointed out that the optimum yield of gel fraction can be achieved when the polymers were irradiated at a dose of 50 kGy in the presence of 1% TMAIC. High gel fraction largely improves heat stability of PBSA, while biodegradability evaluated by soil burial test of the crosslinked polymers is slightly retarded, however they are effectively destroyed with a slightly smaller rate.

  19. Electron Beam Crosslinked Polyurethane Shape Memory Polymers with Tunable Mechanical Properties

    PubMed Central

    Hearon, Keith; Nash, Landon D.; Volk, Brent L.; Ware, Taylor; Lewicki, James P.; Voit, Walter E.; Wilson, Thomas S.

    2014-01-01

    Novel electron beam crosslinked polyurethane shape memory polymers with advanced processing capabilities and tunable thermomechanical properties have been synthesized and characterized. We demonstrate the ability to manipulate crosslink density in order to finely tune rubbery modulus, strain capacity, ultimate tensile strength, recovery stress, and glass transition temperature. This objective is accomplished for the first time in a low-molecular-weight polymer system through the precise engineering of thermoplastic resin precursors suitable for mass thermoplastic processing. Neurovascular stent prototypes were fabricated by dip-coating and laser machining to demonstrate processability. PMID:25411531

  20. Composite Electrolytes for Lithium Batteries: Ionic Liquids in APTES Crosslinked Polymers

    NASA Technical Reports Server (NTRS)

    Tigelaar, Dean M.; Meador, Mary Ann B.; Bennett, William R.

    2007-01-01

    Solvent free polymer electrolytes were made consisting of Li(+) and pyrrolidinium salts of trifluoromethanesulfonimide added to a series of hyperbranched poly(ethylene oxide)s (PEO). The polymers were connected by triazine linkages and crosslinked by a sol-gel process to provide mechanical strength. The connecting PEO groups were varied to help understand the effects of polymer structure on electrolyte conductivity in the presence of ionic liquids. Polymers were also made that contain poly(dimethylsiloxane) groups, which provide increased flexibility without interacting with lithium ions. When large amounts of ionic liquid are added, there is little dependence of conductivity on the polymer structure. However, when smaller amounts of ionic liquid are added, the inherent conductivity of the polymer becomes a factor. These electrolytes are more conductive than those made with high molecular weight PEO imbibed with ionic liquids at ambient temperatures, due to the amorphous nature of the polymer.

  1. UV cross-linked, lithium-conducting ternary polymer electrolytes containing ionic liquids

    NASA Astrophysics Data System (ADS)

    Kim, G. T.; Appetecchi, G. B.; Carewska, M.; Joost, M.; Balducci, A.; Winter, M.; Passerini, S.

    In this manuscript is reported an attempt to prepare high ionic conductivity lithium polymer electrolytes by UV cross-linking the poly(ethyleneoxide) (briefly called PEO) polymer matrix in presence of the plasticizing lithium salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and an ionic liquid of the pyrrolidinium family (N-alkyl- N-methylpyrrolidinium TFSI) having a common anion with the lithium salt. It is demonstrated that polymer electrolytes with room temperature ionic conductivities of nearly 10 -3 S cm -1 could be obtained as a result of the reduced crystallinity of the ternary electrolytes. The results clearly indicate that the cross-linked ternary electrolyte shows superior mechanical properties with respect to the non-cross-linked electrolytes and higher conductivities with respect to polymer electrolytes containing none or less ionic liquid.

  2. The sensitive and selective adsorption of aromatic compounds with highly crosslinked polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Shuqin; Chen, Darui; Zheng, Juan; Zeng, Lewei; Jiang, Jijun; Jiang, Ruifeng; Zhu, Fang; Shen, Yong; Wu, Dingcai; Ouyang, Gangfeng

    2015-10-01

    This study presents the preparation and characterization of a nanoscale Davankov-type hyper-crosslinked-polymer (HCP) as an adsorbent of benzene-ring-containing dyes and organic pollutants. HCP nanoparticles post-crosslinked from a poly(DVB-co-VBC) precursor were synthesized in this study, possessing ultrahigh surface area, hydrophobicity and stability. The as-synthesized Davankov-type HCP exhibited a rapid and selective adsorption ability towards the benzene-ring-containing dyes due to its highly conjugated structure. Besides, for the first time, the prepared HCP nanoparticles were adopted for the adsorption of nonpolar organic pollutants by means of solid-phase microextraction (SPME). Owing to its high hydrophobicity, diverse pore size distribution and highly conjugated structure, a 10 μm HCP coating exhibited excellent adsorption abilities towards benzene-ring-containing polycyclic aromatic hydrocarbons (PAHs) and benzene series compounds (benzene, toluene, ethylbenzene and o-xylene; abbreviated to BTEX) and to highly hydrophobic long-chain n-alkanes. Finally, the HCP-nanoparticles-coated SPME fiber was applied to the simultaneous analysis of five PAHs in environmental water samples and satisfactory recoveries were achieved. The findings could provide a new benchmark for the exploitation of superb HCPs as effective adsorbents for SPME or other adsorption applications.This study presents the preparation and characterization of a nanoscale Davankov-type hyper-crosslinked-polymer (HCP) as an adsorbent of benzene-ring-containing dyes and organic pollutants. HCP nanoparticles post-crosslinked from a poly(DVB-co-VBC) precursor were synthesized in this study, possessing ultrahigh surface area, hydrophobicity and stability. The as-synthesized Davankov-type HCP exhibited a rapid and selective adsorption ability towards the benzene-ring-containing dyes due to its highly conjugated structure. Besides, for the first time, the prepared HCP nanoparticles were adopted for the

  3. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity

    PubMed Central

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-01-01

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies. PMID:26677949

  4. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity.

    PubMed

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-12-18

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies.

  5. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity

    NASA Astrophysics Data System (ADS)

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-12-01

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies.

  6. Removal of Parabens from Aqueous Solution Using β-Cyclodextrin Cross-Linked Polymer

    PubMed Central

    Chin, Yuk Ping; Mohamad, Sharifah; Abas, Mhd Radzi Bin

    2010-01-01

    The removal of four parabens, methyl-, ethyl-, propyl-, and benzyl-paraben, by β-cyclodextrin (β-CD) polymer from aqueous solution was studied. Different β-CD polymers were prepared by using two cross-linkers, i.e., hexamethylene diisocyanate (HMDI) and toluene-2,6-diisocyanate (TDI), with various molar ratios of cross-linker. β-CD-HMDI polymer with molar ratio of 1:7 and β-CD-TDI polymer with ratio 1:4 gave the highest adsorption of parabens among the β-CD-HMDI and β-CD-TDI series, and were subsequently used for further studies. The adsorption capacity of β-CD-HMDI is 0.0305, 0.0376, 0.1854 and 0.3026 mmol/g for methyl-, ethyl-, propyl-, and benzyl-paraben, respectively. β-CD-TDI have higher adsorption capacities compared with β-CD-HMDI, the adsorption capacity are 0.1019, 0.1286, 0.2551, and 0.3699 mmol/g methyl-, ethyl-, propyl-, and benzyl-paraben respectively. The parameters studied were adsorption capacity, water retention, and reusability. Role of both cross-linker in adsorption, hydrophobicity of polymers, and adsorption capacity of different parabens were compared and discussed. All experiments were conducted in batch adsorption technique. These polymers were applied to real samples and showed positive results. PMID:20957106

  7. Removal of parabens from aqueous solution using β-cyclodextrin cross-linked polymer.

    PubMed

    Chin, Yuk Ping; Mohamad, Sharifah; Abas, Mhd Radzi Bin

    2010-09-20

    The removal of four parabens, methyl-, ethyl-, propyl-, and benzyl-paraben, by β-cyclodextrin (β-CD) polymer from aqueous solution was studied. Different β-CD polymers were prepared by using two cross-linkers, i.e., hexamethylene diisocyanate (HMDI) and toluene-2,6-diisocyanate (TDI), with various molar ratios of cross-linker. β-CD-HMDI polymer with molar ratio of 1:7 and β-CD-TDI polymer with ratio 1:4 gave the highest adsorption of parabens among the β-CD-HMDI and β-CD-TDI series, and were subsequently used for further studies. The adsorption capacity of β-CD-HMDI is 0.0305, 0.0376, 0.1854 and 0.3026 mmol/g for methyl-, ethyl-, propyl-, and benzyl-paraben, respectively. β-CD-TDI have higher adsorption capacities compared with β-CD-HMDI, the adsorption capacity are 0.1019, 0.1286, 0.2551, and 0.3699 mmol/g methyl-, ethyl-, propyl-, and benzyl-paraben respectively. The parameters studied were adsorption capacity, water retention, and reusability. Role of both cross-linker in adsorption, hydrophobicity of polymers, and adsorption capacity of different parabens were compared and discussed. All experiments were conducted in batch adsorption technique. These polymers were applied to real samples and showed positive results.

  8. Biodegradable Photo-Crosslinked Thin Polymer Networks Based on Vegetable Oil Hydroxyfatty Acids

    USDA-ARS?s Scientific Manuscript database

    Novel crosslinked thin polymer networks based on vegetable oil hydroxyfatty acids (HFAs) were prepared by UV photopolymerization and their mechanical properties were evaluated. Two raw materials, castor oil and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) were used as sources of mono- and di-HFAs, r...

  9. Polymers and Cross-Linking: A CORE Experiment to Help Students Think on the Submicroscopic Level

    ERIC Educational Resources Information Center

    Bruce, Mitchell R. M.; Bruce, Alice E.; Avargil, Shirly; Amar, Francois G.; Wemyss, Thomas M.; Flood, Virginia J.

    2016-01-01

    The Polymers and Cross-Linking experiment is presented via a new three phase learning cycle: CORE (Chemical Observations, Representations, Experimentation), which is designed to model productive chemical inquiry and to promote a deeper understanding about the chemistry operating at the submicroscopic level. The experiment is built on two familiar…

  10. A New Approach to Design of Cross-Linked Second-Order Nonlinear Optical Polymers

    DTIC Science & Technology

    1990-09-01

    PERSONI L ,UTH R(S) Skant rpa ty, Braja K. Mandal and Jayant Kumer 1. TYPE OFREPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month, Day) 15. PAGE...Processing of NLO Materials. VIITIT; I A NEW APPROACH TO DESIGN OF CROSS-LINKED SECOND-ORDER NONLINEAR OPTICAL POLYMERS BRAJA K. MANDAL, JUN Y. LEE

  11. Polymers and Cross-Linking: A CORE Experiment to Help Students Think on the Submicroscopic Level

    ERIC Educational Resources Information Center

    Bruce, Mitchell R. M.; Bruce, Alice E.; Avargil, Shirly; Amar, Francois G.; Wemyss, Thomas M.; Flood, Virginia J.

    2016-01-01

    The Polymers and Cross-Linking experiment is presented via a new three phase learning cycle: CORE (Chemical Observations, Representations, Experimentation), which is designed to model productive chemical inquiry and to promote a deeper understanding about the chemistry operating at the submicroscopic level. The experiment is built on two familiar…

  12. Evaluation of a cross-linked polyurethane acrylate as polymer electrolyte for lithium batteries

    SciTech Connect

    Santhosh, P.; Gopalan, A. . E-mail: algopal_99@yahoo.com; Vasudevan, T.; Lee, Kwang-Pill

    2006-06-15

    A cross-linked polyurethane acrylate (CL-PUA) was synthesized by end capping 2,6-toluene diisocyanate (TDI)/poly(ethylene glycol) (PEG) based prepolymer with hydroxybutyl methacrylate (HBMA). Differential scanning calorimetry (DSC) and Fourier transform infra-red (FT-IR) spectroscopy measurements reveal the possible presence of significant interactions between lithium ions and soft/hard segments of the CL-PUA, when CL-PUA was complexed with lithium perchlorate (LiClO{sub 4}). CL-PUA follows the VTF relationship for the ion transport. Predominant formation of contact ion pairs of LiClO{sub 4} has been observed through AC conductivity and DSC measurements. The lithium stripping-plating process is a reversible and implies better electrochemical stability in the working voltage range. Also, CL-PUA electrolyte shows better compatibility with lithium metal as inferred from impedance measurements and has a good cationic transference number suitable to be used as a solid polymer electrolyte. The addition of HBMA into PU matrix improves tensile strength of the CL-PUA. Swelling measurements of CL-PUA with plasticizer showed better dimensional stability. Also, a cell was constructed using CL-PUA as electrolyte and the performance was assessed.

  13. Effects of plasticization on ionic conductivity enhancement of crosslinked polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    He, Ruixuan; Kyu, Thein; Kyu's Team, Dr.

    Glass transition temperatures (Tg) of solid polymer electrolyte membranes (PEM), comprised of polyethylene glycol diacrylate (PEGDA) prepolymer, lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt, and succinonitrile (SCN) plasticizer, were systematically examined before and after crosslinking in the isotropic region guided by their ternary phase diagram. With increasing LiTFSI concentration, the Tg of uncured binary PEGDA/LiTFSI mixture increases drastically due to molecular complexation between lithium cation and ether oxygen, but ionic conductivity is very low (<10-6 S cm-1). Upon curing, this Tg increases and further reduces ionic conductivity. Upon adding SCN plasticizer, the Tg of PEM has significantly decreased to -60 oC and ionic conductivity also increased to the superionic conductor level of 10-3 S cm-1. The analysis of ionic conductivity vs. Tg behavior by Vogel-Tamman-Fulcher(VTF) equation revealed that this ionic conductivity enhancement is due to SCN plasticization resulting in lowering the network Tg as well as lowering the activation energy. Supported by NSF-DMR 1161070.

  14. Molecular dynamics simulations of highly cross-linked polymer networks: prediction of thermal and mechanical properties

    NASA Astrophysics Data System (ADS)

    Shenogina, Natalia; Tsige, Mesfin; Mukhopadhyay, Sharmila; Patnaik, Soumya

    2012-02-01

    We use all-atom molecular dynamics (MD) simulations to predict the mechanical and thermal properties of thermosetting polymers. Atomistic simulation is a promising tool which can provide detailed structure-property relationships of densely cross-linked polymer networks. In this work we study the thermo-mechanical properties of thermosetting polymers based on amine curing agents and epoxy resins and have focused on the DGEBA/DETDA epoxy system. At first we describe the modeling approach to construction of realistic all-atom models of densely cross-linked polymer matrices. Subsequently, a series of atomistic simulations was carried out to examine the simulation cell size effect as well as the role of cross-linking density and chain length of the resin strands on thermo-mechanical properties at different temperatures. Two different methods were used to deform the polymer networks. Both static and dynamic approaches to calculating the mechanical properties were considered and the thermo-mechanical properties obtained from our simulations were found in reasonable agreement with experimental values.

  15. Biomolecule-recognition gating membrane using biomolecular cross-linking and polymer phase transition.

    PubMed

    Kuroki, Hidenori; Ito, Taichi; Ohashi, Hidenori; Tamaki, Takanori; Yamaguchi, Takeo

    2011-12-15

    We present for the first time a biomolecule-recognition gating system that responds to small signals of biomolecules by the cooperation of biorecognition cross-linking and polymer phase transition in nanosized pores. The biomolecule-recognition gating membrane immobilizes the stimuli-responsive polymer, including the biomolecule-recognition receptor, onto the pore surface of a porous membrane. The pore state (open/closed) of this gating membrane depends on the formation of specific biorecognition cross-linking in the pores: a specific biomolecule having multibinding sites can be recognized by several receptors and acts as the cross-linker of the grafted polymer, whereas a nonspecific molecule cannot. The pore state can be distinguished by a volume phase transition of the grafted polymer. In the present study, the principle of the proposed system is demonstrated using poly(N-isopropylacrylamide) as the stimuli-responsive polymer and avidin-biotin as a multibindable biomolecule-specific receptor. As a result of the selective response to the specific biomolecule, a clear permeability change of an order of magnitude was achieved. The principle is versatile and can be applied to many combinations of multibindable analyte-specific receptors, including antibody-antigen and lectin-sugar analogues. The new gating system can find wide application in the bioanalytical field and aid the design of novel biodevices.

  16. Influence of radiation-crosslinking on flame retarded polymer materials-How crosslinking disrupts the barrier effect

    NASA Astrophysics Data System (ADS)

    Sonnier, Rodolphe; Caro-Bretelle, Anne-Sophie; Dumazert, Loïc; Longerey, Marc; Otazaghine, Belkacem

    2015-01-01

    Fire behavior of flame retardant-free and flame retarded PP/PA6 blends was studied using pyrolysis-combustion flow calorimeter, cone calorimeter and epiradiator equipped with infrared camera and pyrometer. Blends were previously γ-irradiated in presence of crosslinking agents at various doses (up to 100 kGy) in order to assess the influence of irradiation crosslinking on flame retardancy. Crosslinked specimens exhibit a solid-like behavior under high temperature gradient in cone calorimeter and then distort considerably. The influence of such a behavior depends on the material properties. When the flame retardancy is provided by heat shielding effect, heat distortion disrupts the top protective layer leading to a substantial increase of peak of heat release rate (pHRR). The barrier layer is no longer able to prevent the heat transfer to the underlying condensed phase. In other cases (flame retardant-free blends or flame retardancy provided by other effects than heat shielding), heat distortion has negligible influence on heat release rate curves in cone calorimeter tests.

  17. Photochemical Branching/Crosslinking of Preformed Polymers Using bis-Benzophenone

    NASA Astrophysics Data System (ADS)

    Carbone, Nicholas; Dickson, Mary; Koberstein, Jeffrey

    2008-03-01

    We show that bis-benzophenone (bis-BP) is an effective method to photochemically crosslink essentially any reformed polymer system that contains abstractable hydrogen atoms. When bis-BP is mixed into a polymer and exposed to UV radiation, it abstracts hydrogen atoms from any chains in proximity, thereby initiating a cascade of free radical reactions that include several mechanisms that can lead to covalent polymer crosslinking. Herein we study the early stages of branching reactions that precede gelation by following molecular weight changes in bis-BP modified polystyrene (PS) by Gel Permeation Chromatography. Quantitative molecular weight changes in PS:bis-BP thin films are studied as a function of irradiation time, PS:bis-BP molar ratio, and film height. AFM studies are employed qualitatively to investigate the relationship between molecular weight and the degree of dewetting of thin PS films deposited on silicon wafers.

  18. Tetraarylborate polymer networks as single-ion conducting solid electrolytes

    SciTech Connect

    Van Humbeck, Jeffrey F.; Aubrey, Michael L.; Alsbaiee, Alaaeddin; Ameloot, Rob; Coates, Geoffrey W.; Dichtel, William R.; Long, Jeffrey R.

    2015-06-23

    A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10-4 S cm-1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to tLi+ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for further development of this new class of solid electrolytes.

  19. Tetraarylborate polymer networks as single-ion conducting solid electrolytes

    DOE PAGES

    Van Humbeck, Jeffrey F.; Aubrey, Michael L.; Alsbaiee, Alaaeddin; ...

    2015-06-23

    A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10-4 S cm-1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to tLi+ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for furthermore » development of this new class of solid electrolytes.« less

  20. Light-scattering thermal cross-linking material using morphology of nanoparticle free polymer blends

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi

    2015-03-01

    A newly light-scattering thermal cross-linking material based on self-assembly for forming the morphology of nanoparticle free polymer blends was reported. The material design concept to use light-scattering thermal cross-linking material with high uniformity of light on display panel from LED for high quality such as brightness and evenness, mechanical properties, and gas and water barrier properties. The high light scattering rate of 8 % at 350-450 nm of wavelength, fast cure film at 140 ºC and 120 s, and thermal stability at 190 ºC in bake condition for high productivity were indicated in the light-scattering thermal cross-linking material using the nanoparticle free polymers with carboxylic acid functional groups. These novel system using morphology of nanoparticle free polymer blends in light-scattering package material for a LCD using LED was a valuable approach to the design of material formulations for newly light-scattering thermal cross-linking material.

  1. Lithium Polymer Electrolytes and Solid State NMR

    NASA Technical Reports Server (NTRS)

    Berkeley, Emily R.

    2004-01-01

    Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for

  2. Lithium Polymer Electrolytes and Solid State NMR

    NASA Technical Reports Server (NTRS)

    Berkeley, Emily R.

    2004-01-01

    Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for

  3. Order-Disorder Transitions in Cross-Linked Block Copolymer Solids

    SciTech Connect

    Das, J.

    2005-01-12

    With a view toward creating solid block copolymers wherein the order-disorder transition can be accessed many times they investigated the nature of order-disorder transitions in cross-linked diblock copolymer melts using synergistic theory and experiment. A mean-field theory based on a coarse grained free-energy and the Random Phase Approximation (RPA) is developed for the system of interest. The quenched distribution of cross-links is averaged using the replica method. The phase behavior of a particular A-B block copolymer melt with a randomly cross-linked B-Block is determined as a function of the Florry-Huggins interaction parameter ({chi}) and the average number of cross-links per chain N{sub c}. They find for a cross-link density greater than N*{sub c} the B monomers are localized within a region of size {zeta} {approx} (N{sub c} - N*{sub c}){sup -1/2}. The cross-links strongly oppose ordering in the system as {zeta} becomes comparable to the radius of gyration of the block copolymer chain. As such the order-disorder transition temperature T{sub ODT} decreases precipitously when N{sub c} > N*{sub c}. When N{sub c} < N*{sub c}, T{sub ODT} increases weakly with N{sub c}. Experiments were conducted on cross-linked polystyrene-block-polyisoprene copolymer samples wherein the polyisoprene block was selectively cross-linked at a temperature well above the order-disorder transition temperature of the pure block copolymer. Small angle X-ray scattering (SAXS) and birefringence measurements on the cross-linked samples are consistent with the theoretical prediction. T{sub ODT} decreases rapidly when the cross-linking density exceeds the critical cross-linking density.

  4. Computational exploration of polymer nanocomposite mechanical property modification via cross-linking topology

    SciTech Connect

    Lacevic, N; Gee, R; Saab, A; Maxwell, R

    2008-04-24

    Molecular dynamics simulations have been performed in order to study the effects of nanoscale filler cross-linking topologies and loading levels on the mechanical properties of a model elastomeric nanocomposite. The model system considered here is constructed from octa-functional polyhedral oligomeric silsesquioxane (POSS) dispersed in a poly(dimethylsiloxane) (PDMS) matrix. Shear moduli, G, have been computed for pure and for filled and unfilled PDMS as a function of cross-linking density, POSS fill loading level, and polymer network topology. The results reported here show that G increases as the cross-linking (covalent bonds formed between the POSS and the PDMS network) density increases. Further, G is found to have a strong dependence on cross-linking topology. The increase in shear modulus, G, for POSS filled PDMS is significantly higher than that for unfilled PDMS cross-linked with standard molecular species, suggesting an enhanced reinforcement mechanism for POSS. In contrast, in blended systems (POSS/PDMS mixture with no cross-linking) G was not observed to significantly increase with POSS loading. Finally, we find intriguing differences in the structural arrangement of bond strains between the cross-linked and the blended systems. In the unfilled PDMS the distribution of highly strained bonds appears to be random, while in the POSS filled system, the strained bonds form a net-like distribution that spans the network. Such a distribution may form a structural network 'holding' the composite together and resulting in increases in G compared to an unfilled, cross-linked system. These results are of importance for engineering of new POSS-based multifunctional materials with tailor-made mechanical properties.

  5. Computational exploration of polymer nanocomposite mechanical property modification via cross-linking topology.

    PubMed

    Lacevic, Naida; Gee, Richard H; Saab, Andrew; Maxwell, Robert

    2008-09-28

    Molecular dynamics simulations have been performed in order to study the effects of nanoscale filler cross-linking topologies and loading levels on the mechanical properties of a model elastomeric nanocomposite. The model system considered here is constructed from octafunctional polyhedral oligomeric silsesquioxane (POSS) dispersed in a poly(dimethylsiloxane) (PDMS) matrix. Shear moduli, G, have been computed for pure and for filled and unfilled PDMS as a function of cross-linking density, POSS fill loading level, and polymer network topology. The results reported here show that G increases as the cross-linking (covalent bonds formed between the POSS and the PDMS network) density increases. Further, G is found to have a strong dependence on cross-linking topology. The increase in shear modulus, G, for POSS filled PDMS is significantly higher than that for unfilled PDMS cross-linked with standard molecular species, suggesting an enhanced reinforcement mechanism for POSS. In contrast, in blended systems (POSS/PDMS mixture with no cross-linking) G was not observed to significantly increase with POSS loading. Finally, we find intriguing differences in the structural arrangement of bond strains between the cross-linked and the blended systems. In the unfilled PDMS the distribution of highly strained bonds appears to be random, while in the POSS filled system, the strained bonds form a netlike distribution that spans the network. Such a distribution may form a structural network "holding" the composite together and resulting in increases in G compared to an unfilled, cross-linked system. These results are of importance for engineering of new POSS-based multifunctional materials with tailor-made mechanical properties.

  6. Cross-Linked Nanoporous Materials from Reactive and Multifunctional Block Polymers

    SciTech Connect

    Seo, Myungeun; Amendt, Mark A.; Hillmyer, Marc A.

    2012-10-10

    Polylactide-b-poly(styrene-co-2-hydroxyethylmethacrylate) (PLA-b-P(S-co-HEMA)) and polylactide-b-poly(styrene-co-2-hydroxyethylacrylate) (PLA-b-P(S-co-HEA)) were synthesized by combination of ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization. {sup 1}H nuclear magnetic resonance spectroscopy and size exclusion chromatography data indicated that the polymerizations were controlled and that hydroxyl groups were successfully incorporated into the block polymers. The polymers were reacted with 4,4{prime}-methylenebis(phenyl isocyanate) (MDI) to form the corresponding cross-linked materials. The materials were annealed at 150 C to complete the coupling reaction. Robust nanoporous materials were obtained from the cross-linked polymers by treatment with aqueous base to hydrolyze the PLA phase. Small-angle X-ray scattering study combined with scanning electron microscopy showed that MDI-cross-linked PLA-b-P(S-co-HEMA)/PLA-b-P(S-co-HEA) can adopt lamellar, hexagonally perforated lamellar, and hexagonally packed cylindrical morphologies after annealing. In particular, the HPL morphology was found to evolve from lamellae due to increase in volume fraction of PS phase as MDI reacted with hydroxyl groups. The reaction also kinetically trapped the morphology by cross-linking. Bicontinuous morphologies were also observed when dibutyltin dilaurate was added to accelerate reaction between the polymer and MDI.

  7. Probing Rubber Cross-Linking Generation of Industrial Polymer Networks at Nanometer Scale.

    PubMed

    Gabrielle, Brice; Gomez, Emmanuel; Korb, Jean-Pierre

    2016-06-23

    We present improved analyses of rheometric torque measurements as well as (1)H double-quantum (DQ) nuclear magnetic resonance (NMR) buildup data on polymer networks of industrial compounds. This latter DQ NMR analysis allows finding the distribution of an orientation order parameter (Dres) resulting from the noncomplete averaging of proton dipole-dipole couplings within the cross-linked polymer chains. We investigate the influence of the formulation (filler and vulcanization systems) as well as the process (curing temperature) ending to the final polymer network. We show that DQ NMR follows the generation of the polymer network during the vulcanization process from a heterogeneous network to a very homogeneous one. The time variations of microscopic Dres and macroscopic rheometric torques present power-law behaviors above a threshold time scale with characteristic exponents of the percolation theory. We observe also a very good linear correlation between the kinetics of Dres and rheometric data routinely performed in industry. All these observations confirm the description of the polymer network generation as a critical phenomenon. On the basis of all these results, we believe that DQ NMR could become a valuable tool for investigating in situ the cross-linking of industrial polymer networks at the nanometer scale.

  8. Extremely stretchable thermosensitive hydrogels by introducing slide-ring polyrotaxane cross-linkers and ionic groups into the polymer network.

    PubMed

    Bin Imran, Abu; Esaki, Kenta; Gotoh, Hiroaki; Seki, Takahiro; Ito, Kohzo; Sakai, Yasuhiro; Takeoka, Yukikazu

    2014-10-08

    Stimuli-sensitive hydrogels changing their volumes and shapes in response to various stimulations have potential applications in multiple fields. However, these hydrogels have not yet been commercialized due to some problems that need to be overcome. One of the most significant problems is that conventional stimuli-sensitive hydrogels are usually brittle. Here we prepare extremely stretchable thermosensitive hydrogels with good toughness by using polyrotaxane derivatives composed of α-cyclodextrin and polyethylene glycol as cross-linkers and introducing ionic groups into the polymer network. The ionic groups help the polyrotaxane cross-linkers to become well extended in the polymer network. The resulting hydrogels are surprisingly stretchable and tough because the cross-linked α-cyclodextrin molecules can move along the polyethylene glycol chains. In addition, the polyrotaxane cross-linkers can be used with a variety of vinyl monomers; the mechanical properties of the wide variety of polymer gels can be improved by using these cross-linkers.

  9. Crosslinked hydrogels—a promising class of insoluble solid molecular dispersion carriers for enhancing the delivery of poorly soluble drugs

    PubMed Central

    Sun, Dajun D.; Lee, Ping I.

    2014-01-01

    Water-insoluble materials containing amorphous solid dispersions (ASD) are an emerging category of drug carriers which can effectively improve dissolution kinetics and kinetic solubility of poorly soluble drugs. ASDs based on water-insoluble crosslinked hydrogels have unique features in contrast to those based on conventional water-soluble and water-insoluble carriers. For example, solid molecular dispersions of poorly soluble drugs in poly(2-hydroxyethyl methacrylate) (PHEMA) can maintain a high level of supersaturation over a prolonged period of time via a feedback-controlled diffusion mechanism thus avoiding the initial surge of supersaturation followed by a sharp decline in drug concentration typically encountered with ASDs based on water-soluble polymers. The creation of both immediate- and controlled-release ASD dosage forms is also achievable with the PHEMA based hydrogels. So far, ASD systems based on glassy PHEMA have been shown to be very effective in retarding precipitation of amorphous drugs in the solid state to achieve a robust physical stability. This review summarizes recent research efforts in investigating the potential of developing crosslinked PHEMA hydrogels as a promising alternative to conventional water-soluble ASD carriers, and a related finding that the rate of supersaturation generation does affect the kinetic solubility profiles implications to hydrogel based ASDs. PMID:26579361

  10. Photoisomerization of azobenzene moiety in crosslinking polymer materials

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Chen, Wei-Qiang; Jin, Feng; Dong, Xian-Zi; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2012-10-01

    In this study, a series of acryloyloxy-substituted azobenzene derivatives, 3-(tert-butyl)-4,4'-bisacryoloxy-azobenzene (tBu-Azo-AO), 3-(tert-butyl)-4,4'-bis[3-(acryoloxy)propoxy]-azobenzene (tBu-Azo-AO3) and 3-(tert-butyl)-4,4'-bis[6-(acryoloxy)hexyloxy]-azobenzene (tBu-Azo-AO6) were synthesized and employed as monomers to prepare polymer films by copolymerizing dipentaerythritol hexaacrylate (DPE-6A) and methyl methacrylate (MMA), respectively. When exposed to a nanosecond laser beam at the wavelength of 355 nm, ultraviolet-visible (UV-Vis) absorption spectra of the resultant polymer films with different irradiation time were monitored. On the basis of the absorbance of the π-π* electronic transition, the kinetics of trans-to-cis photoisomerization of three kinds of azobenzene moieties were demonstrated and found to be influenced by both the pump energy and azobenzene concentration.

  11. Graft copolymerization onto polybutadiene: Cross-linking and thermal degradation of vinyl polymers and copolymers

    NASA Astrophysics Data System (ADS)

    Jiang, Dayue (David)

    This work consists of three parts. In Part I, the graft copolymerization of methyl methacrylate, methyl acrylate, methacylic acid and acrylic acid onto polybutadiene and its copolymers by benzoyl peroxide, BPO, or 2, 2'azobis(2-methylpropionitrile), AIBN, initiation were explored. The results show that these monomers can be grafted onto butadiene region of butadiene-containing polymers. The extent of both graft copolymerization and homopolymerization are dependent on the time and temperature of the reaction and the concentration of all of the reactants. One must specify the monomer, initiator and solvent for the efficient graft copolymerization. The methyl methacrylate adds directly to the radical sites which are formed on the backbone by the interaction of the polymer and the primary radical form the initiator, while for the other three monomers, the graft copolymerization occurs by addition of macro-radical to the double bonds. In Part II, the cross-linking of polybutadiene, butadiene-styrene copolymers, and polystyrene by irradiation, thermal and chemical processes, and Friedel-Crafts chemistry and the effect of cross-linking on the thermal stability were investigated. The proof of cross-linking of the polymer comes from the insolubility of the product after the cross-linking reaction and is characterized by gel content and swelling ratio. The results show that the thermal stability of the polymer can be improved by cross-linking. In Part III, the thermal degradation of three vinyl polymers, poly(vinylsulfonic acid) and its sodium salt and poly(vinylphosphonic acid) were studied by combination technique: TGA/FTIR. The results show that TGA/FTIR combined with analysis of residues provides an excellent opportunity to understand the degradation pathway of the compounds. The observation of foaming indicates that the char which is formed contains carbon as well as the inorganic salts which have been observed. The carbon is in a partially graphitized form. The salts

  12. Hyper-crosslinked cyclodextrin porous polymer: An efficient CO2 capturing material with tunable porosity

    SciTech Connect

    Meng, Bo; Li, Haiyang; Mahurin, Shannon Mark; Liu, Honglai; Dai, Sheng

    2016-11-11

    We designed and synthesized the cyclodextrin (CD)-based hyper-crosslinked porous polymers (HCPPs) for selective CO2 adsorption and storage. We also explored the effect of monomer size on micropore formation, and determined a feasible way to tailor the porosity of the materials during the hyper-crosslinking process.

  13. Solid polymer MEMS-based fuel cells

    DOEpatents

    Jankowski, Alan F.; Morse, Jeffrey D.

    2008-04-22

    A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

  14. Fabrication of nanobeads from nanocups by controlling scission/crosslinking in organic polymer materials.

    PubMed

    Oyama, Tomoko Gowa; Oshima, Akihiro; Washio, Masakazu; Tagawa, Seiichi

    2012-12-14

    The development of several kinds of micro/nanofabrication techniques has resulted in many innovations in the micro/nanodevices that support today's science and technology. With feature miniaturization, the fabrication tools have shifted from light to ionizing radiation. Here, we propose a simple micro/nanofabrication technique for organic materials using a scanning beam (SB) of ionizing radiation. By controlling the scission/crosslinking of the material via three-dimensional energy-deposition distribution of the SB, appropriate solvents can easily peel off only the crosslinked region from the bulk material. The technique was demonstrated using a focused ion beam and a chlorinated organic polymer. The polymer underwent main-chain scission upon irradiation, but it crosslinked after high-dose irradiation. Appropriate solvents could easily peel off only the crosslinked region from the bulk material. The technique, 'nanobead from nanocup', enabled the production of desired structures such as nanowires and nanomembranes. It can be also applied to the micro/nanofabrication of functional materials.

  15. Thermoreversibly crosslinked poly(ε-caprolactone) as recyclable shape-memory polymer network.

    PubMed

    Defize, Thomas; Riva, Raphaël; Raquez, Jean-Marie; Dubois, Philippe; Jérôme, Christine; Alexandre, Michaël

    2011-08-17

    A new concept to build shape memory polymers (SMP) combining outstanding fixity and recovery ratios (both above 99% after only one training cycle) typical of chemically crosslinked SMPs with reprocessability restricted to physically crosslinked SMPs is demonstrated by covalently bonding, through thermoreversible Diels-Alder (DA) adducts, star-shaped poly(ε-caprolactones) (PCL) end-functionalized by furan and maleimide moieties. A PCL network is easily prepared by melt-blending complementary end-functional star polymers in retro DA regime, then by curing at lower temperature to favour the DA cycloaddition. Such covalent network can be reprocessed when heated again at the retro DA temperature. The resulting SMP shows still excellent shape memory properties attesting for its good recyclability. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A new environmentally safe crosslinked polymer for fluid-loss control

    SciTech Connect

    Cole, R.C.; Ali, S.A.; Foley, K.A.

    1995-12-31

    The adverse effects of inadequate fluid-loss control associated with gravel-packed completions is well known. Controlling fluid losses to the formation before and after pack placement is critical to ultimately achieving optimum productivity from a given well. This paper introduces a new environmentally safe, crosslinkable polymer that can help achieve abrupt fluid-loss control without the introduction of particulates of any kind. The polymer is a double-derivatized HEC (DDHEC). This paper presents laboratory data on the DDHEC, including physical properties, crosslinking and breaker chemistry, regainable permeability, degree of fluid-loss control, and rheology. In addition, field case histories are presented to document the efficient fluid-loss control and little or no formation damage in moderate to high-permeability formations.

  17. Controlled thermal oxidative crosslinking of polymers of intrinsic microporosity towards tunable molecular sieve membranes

    NASA Astrophysics Data System (ADS)

    Song, Qilei; Cao, Shuai; Pritchard, Robyn H.; Ghalei, Behnam; Al-Muhtaseb, Shaheen A.; Terentjev, Eugene M.; Cheetham, Anthony K.; Sivaniah, Easan

    2014-09-01

    Organic open frameworks with well-defined micropore (pore dimensions below 2 nm) structure are attractive next-generation materials for gas sorption, storage, catalysis and molecular level separations. Polymers of intrinsic microporosity (PIMs) represent a paradigm shift in conceptualizing molecular sieves from conventional ordered frameworks to disordered frameworks with heterogeneous distributions of microporosity. PIMs contain interconnected regions of micropores with high gas permeability but with a level of heterogeneity that compromises their molecular selectivity. Here we report controllable thermal oxidative crosslinking of PIMs by heat treatment in the presence of trace amounts of oxygen. The resulting covalently crosslinked networks are thermally and chemically stable, mechanically flexible and have remarkable selectivity at permeability that is three orders of magnitude higher than commercial polymeric membranes. This study demonstrates that controlled thermochemical reactions can delicately tune the topological structure of channels and pores within microporous polymers and their molecular sieving properties.

  18. Controlled thermal oxidative crosslinking of polymers of intrinsic microporosity towards tunable molecular sieve membranes.

    PubMed

    Song, Qilei; Cao, Shuai; Pritchard, Robyn H; Ghalei, Behnam; Al-Muhtaseb, Shaheen A; Terentjev, Eugene M; Cheetham, Anthony K; Sivaniah, Easan

    2014-09-04

    Organic open frameworks with well-defined micropore (pore dimensions below 2 nm) structure are attractive next-generation materials for gas sorption, storage, catalysis and molecular level separations. Polymers of intrinsic microporosity (PIMs) represent a paradigm shift in conceptualizing molecular sieves from conventional ordered frameworks to disordered frameworks with heterogeneous distributions of microporosity. PIMs contain interconnected regions of micropores with high gas permeability but with a level of heterogeneity that compromises their molecular selectivity. Here we report controllable thermal oxidative crosslinking of PIMs by heat treatment in the presence of trace amounts of oxygen. The resulting covalently crosslinked networks are thermally and chemically stable, mechanically flexible and have remarkable selectivity at permeability that is three orders of magnitude higher than commercial polymeric membranes. This study demonstrates that controlled thermochemical reactions can delicately tune the topological structure of channels and pores within microporous polymers and their molecular sieving properties.

  19. Synthesis of three-dimensional porous hyper-crosslinked polymers via thiol–yne reaction

    PubMed Central

    Lang, Mathias; Schade, Alexandra

    2016-01-01

    Herein we report the syntheses of two porous hyper-crosslinked polymers (HCPs) via thiol–yne reaction with rigid tetrahedral and pseudo-octahedral core structures. Sorption measurements with nitrogen gas at 77 K revealed BET-surface areas up to 650 m²/g. Those networks also showed a high thermal stability as well as insolubility in common organic solvents. PMID:28144326

  20. Thiol-functionalized nanogels as reactive plasticizers for crosslinked polymer networks.

    PubMed

    Saraswathy, Manju; Stansbury, Jeffrey W; Nair, Devatha P

    2017-10-01

    Significant efforts have been expended to mitigate plasticizer migration from crosslinked methacrylic and poly(vinyl chloride) polymer networks by synthesizing reactive plasticizers that can blend homogenously within the networks to reduce polymer property change, acute toxicity and downstream environmental effects of plasticizer migration with limited and varying amount of success. We hypothesized that appropriate thiol-functionalized nanogels synthesized using the same monomers as the parent network to generate highly compact, crosslinked structures will form thermally stable, homogenous networks and perform as optimal reactive plasticizers. Nanogels were synthesized via a thiol-Michael addition solution polymerization and incorporated at different mass ratios within a polyethylene glycol 400 urethane dimethacrylic monomer to form photo-crosslinked networks. While maintaining the inherent hydrolytic stability, thermal stability and biocompatibility of the parent matrix at ~99% acrylic group conversion, the PEG400 urethane dimethacrylic -nanogel networks retained optical clarity with >90% visible light transmission at 20wt% nanogel concentration within the matrix. The addition of the nanogels also enhanced the elongation of the parent matrix by up to 320%, while a 37°C reduction in glass transition temperature (∆Tg) and ≥50% reduction in modulus was observed. A 52% reduction in the shrinkage stress of the material was also noted. The results indicate that the application of thiol-functionalized nanogels as plasticizers to alter the bulk properties of the parent matrix while mitigating plasticizer migration by covalently crosslinking the nanogels within the polymer matrix provides a simple yet efficient technique to generate network-specific plasticizers with the ability to alter targeted properties within polymers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effects of sensitizer length on radiation crosslinked shape-memory polymers

    NASA Astrophysics Data System (ADS)

    Ware, Taylor; Voit, Walter; Gall, Ken

    2010-04-01

    Shape-memory polymers (SMPs) are smart materials that can be designed to retain a metastable state and upon activation, recover a preprogrammed shape. In this study, poly(methyl acrylate) (PMA) is blended with poly(ethylene glycol) diacrylate (PEGDA) of various molecular weights in various concentrations and subsequently exposed to ionizing radiation. PEGDA sensitizes the radiation crosslinking of PMA, lowering the minimum absorbed dose for gelation and increasing the rubbery modulus, after crosslinking. Minimum dose for gelation, as determined by the Charlesby-Pinner equation, decreases from 25.57 kGy for unblended PMA to 2.06 kGy for PMA blended with 10.00 mole% PEGDA. Moreover, increase in the blend concentration of PEGDA increases the crosslinking density of the resulting networks. Sensitizer length, namely Mn of PEGDA, also affects crosslinking and final mechanical properties. Increase in the length of the PEGDA molecule at a constant molar ratio increases the efficacy of the molecule as a radiation sensitizer as determined by the increase in gel fraction and rubbery modulus across doses. However, at a constant weight ratio of PEGDA to PMA, shorter PEGDA chains sensitize more crosslinking because they have more reactive ends per weight fraction. Sensitized samples of PMA with PEGDA were tested for shape-memory properties and showed shape fixity of greater than 99%. Samples had a glass transition temperature near 28 °C and recovered between 97% and 99% of the induced strain when strained to 50%.

  2. Effective-medium approach for stiff polymer networks with flexible cross-links

    NASA Astrophysics Data System (ADS)

    Broedersz, C. P.; Storm, C.; Mackintosh, F. C.

    2009-06-01

    Recent experiments have demonstrated that the nonlinear elasticity of in vitro networks of the biopolymer actin is dramatically altered in the presence of a flexible cross-linker such as the abundant cytoskeletal protein filamin. The basic principles of such networks remain poorly understood. Here we describe an effective-medium theory of flexibly cross-linked stiff polymer networks. We argue that the response of the cross-links can be fully attributed to entropic stiffening, while softening due to domain unfolding can be ignored. The network is modeled as a collection of randomly oriented rods connected by flexible cross-links to an elastic continuum. This effective medium is treated in a linear elastic limit as well as in a more general framework, in which the medium self-consistently represents the nonlinear network behavior. This model predicts that the nonlinear elastic response sets in at strains proportional to cross-linker length and inversely proportional to filament length. Furthermore, we find that the differential modulus scales linearly with the stress in the stiffening regime. These results are in excellent agreement with bulk rheology data.

  3. Statistics of randomly cross-linked polymer models to interpret chromatin conformation capture data

    NASA Astrophysics Data System (ADS)

    Shukron, O.; Holcman, D.

    2017-07-01

    Polymer models are used to describe chromatin, which can be folded at different spatial scales by binding molecules. By folding, chromatin generates loops of various sizes. We present here a statistical analysis of the randomly cross-linked (RCL) polymer model, where monomer pairs are connected randomly, generating a heterogeneous ensemble of chromatin conformations. We obtain asymptotic formulas for the steady-state variance, encounter probability, the radius of gyration, instantaneous displacement, and the mean first encounter time between any two monomers. The analytical results are confirmed by Brownian simulations. Finally, the present results are used to extract the mean number of cross links in a chromatin region from conformation capture data.

  4. Highly conductive solid polymer electrolyte membranes based on polyethylene glycol-bis-carbamate dimethacrylate networks

    NASA Astrophysics Data System (ADS)

    Fu, Guopeng; Dempsey, Janel; Izaki, Kosuke; Adachi, Kaoru; Tsukahara, Yasuhisa; Kyu, Thein

    2017-08-01

    In an effort to fabricate highly conductive, stable solid-state polymer electrolyte membranes (PEM), polyethylene glycol bis-carbamate (PEGBC) was synthesized via condensation reaction between polyethylene glycol diamine and ethylene carbonate. Subsequently, dimethacrylate groups were chemically attached to both ends of PEGBC to afford polyethylene glycol-bis-carbamate dimethacrylate (PEGBCDMA) precursor having crosslinking capability. The melt-mixed ternary mixtures consisting of PEGBCDMA, succinonitrile plasticizer, and lithium trifluorosulphonyl imide salt were completely miscible in a wide compositional range. Upon photo-crosslinking, the neat PEGBCDMA network was completely amorphous exhibiting higher tensile strength, modulus, and extensibility relative to polyethylene glycol diacrylate (PEGDA) counterpart. Likewise, the succinonitrile-plasticized PEM network containing PEGBCDMA remained completely amorphous and transparent upon photo-crosslinking, showing superionic conductivity, improved thermal stability, and superior tensile properties with improved capacity retention during charge/discharge cycling as compared to the PEGDA-based PEM.

  5. Diffusion Coefficients of Water and Leachables in Methacrylate-based Crosslinked Polymers using Absorption Experiments

    PubMed Central

    Parthasarathy, Ranganathan; Misra, Anil; Park, Jonggu; Ye, Qiang; Spencer, Paulette

    2012-01-01

    The diffusion of water into dentin adhesive polymers and leaching of unpolymerized monomer from the adhesive are linked to their mechanical softening and hydrolytic degradation. Therefore, diffusion coefficient data are critical for the mechanical design of these polymeric adhesives. In this study, diffusion coefficients of water and leachables were obtained for sixteen methacrylate-based crosslinked polymers using absorption experiments. The experimental mass change data was interpreted using numerical solution of the two-dimensional diffusion equations. The calculated diffusion coefficients varied from 1.05 × 10−8 cm2/sec (co-monomer TMTMA) to 3.15 × 10−8 cm2/sec (co-monomer T4EGDMA). Correlation of the diffusion coefficients with crosslink density and hydrophilicity showed an inverse trend (R2 = 0.41). The correlation of diffusion coefficient with crosslink density and hydrophilicity are closer for molecules differing by simple repeat units (R2 = 0.95). These differences in the trends reveal mechanisms of interaction of the diffusing water with the polymer structure. PMID:22430592

  6. Emerging synthetic strategies for core cross-linked star (CCS) polymers and applications as interfacial stabilizers: bridging linear polymers and nanoparticles.

    PubMed

    Chen, Qijing; Cao, Xueteng; Xu, Yuanyuan; An, Zesheng

    2013-10-01

    Core cross-linked star (CCS) polymers become increasingly important in polymer science and are evaluated in many value-added applications. However, limitations exist to varied degrees for different synthetic methods. It is clear that improvement in synthetic efficiency is fundamental in driving this field moving even further. Here, the most recent advances are highlighted in synthetic strategies, including cross-linking with cross-linkers of low solubility, polymerization-induced self-assembly in aqueous-based heterogeneous media, and cross-linking via dynamic covalent bonds. The understanding of CCS polymers is also further refined to advocate their role as an intermediate between linear polymers and polymeric nanoparticles, and their use as interfacial stabilizers is rationalized within this context. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries.

    PubMed

    Shim, Jimin; Bae, Ki Yoon; Kim, Hee Joong; Lee, Jin Hong; Kim, Dong-Gyun; Yoon, Woo Young; Lee, Jong-Chan

    2015-12-21

    Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4)  Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Solid polymer electrolyte from phosphorylated chitosan

    SciTech Connect

    Fauzi, Iqbal Arcana, I Made

    2014-03-24

    Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component’s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it’s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10{sup −6} S/cm up to 6.01 × 10{sup −4} S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10{sup −3} S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.

  9. Synthesis of chitosan molecularly imprinted polymers for solid-phase extraction of methandrostenolone.

    PubMed

    Wang, Yun; Wang, Enlan; Wu, Ziming; Li, Huan; Zhu, Zhi; Zhu, Xinsheng; Dong, Ying

    2014-01-30

    Chitosan molecularly imprinted polymers (CHI-MIPs) for selective extraction of methandrostenolone (MA) was synthesized by cross-linking of chitosan with epichlorohydrin in the presence of MA as the template molecule. Systematic investigations of the influences of template, functional polymer, cross-linker as well as porogen concentrations on the rebinding capacity of CHI-MIPs were carried out. Adsorption and kinetic binding experiments indicated that the synthesized CHI-MIPs had high adsorption and excellent affinity to MA. Solid-phase extraction (SPE) using the prepared CHI-MIPs as adsorbent was then investigated, and the optimum loading and eluting conditions for SPE of the MA were established. The optimized SPE procedure was used to extract the MA from several spiked samples and a good sample clean-up was obtained with the average recoveries ranged from 95.97 to 101.79%.

  10. Flexible solid polymer electrolyte membran formed by photopolymerization

    NASA Astrophysics Data System (ADS)

    Cao, Jinwei; Kyu, Thein

    2014-03-01

    Binary and ternary phase diagrams of poly(ethylene glycol) dimethacrylate (PEGDMA,succinonitrile(SCN), and bis(trifluoromethane)sulfonimide (LiTFSI) blends have been established to provide guidance to fabricationof polymer electrolyte membrane (PEM). The phase diagram of binary PEGDMA/SCN mixture is of a typical eutectic typ, whereas the binary PEGDMA/LiTFSI mixture reveals a eutectic trend exhibiting a wide single phase region at intermediate composition. Likewise, the ternary phase diagram of PEGDMA/SCN/LiTFSI mixture shows a wide isotropic regio. The PEM network, formed by UV-crosslinking of PEGDMA in the isotropic region, is a solid amorphous network, but flexible and stretchable. Ion conductivity of PEMwas measured as a function of temperature at different ratios of PEGDMA/SCN and SCN/LiTFSI. Of particular importance is that these PEM networks possessvery high roo-temperature ion conductivity on the order of 10-3 S cm-1, which reaches the level of 10-2 S cm-1 at elevated temperatures of 60-70 °C. The electrochemical stability of the solid PEM will be evaluated by cyclic voltammetry and its potential applicabilityinflexible lithium ion battery will be discussed.

  11. Effect of arm exchange on the liquid-solid transition of dense suspensions of star polymers.

    PubMed

    Puaud, Fanny; Nicolai, Taco; Benyahia, Lazhar; Nicol, Erwan

    2013-10-10

    Star polymers with dynamic arm exchange are formed in water by self-assembly of amphiphilic diblock copolymers based on poly(ethylene oxide) end capped with a small hydrophobic block. The arm exchange was arrested in situ by photo-cross-linking of the core. The effect of dynamic arm exchange on the osmotic compressibility and viscosity was investigated systematically as a function of the concentration and temperature. The discontinuous liquid-solid transition reported for dense polymeric micelle suspensions was found to be preserved after dynamic arm exchange was arrested in situ. The effect of cross-linking and aggregation number on the liquid-solid transition was investigated.

  12. Optimum design of amphiphilic polymers bearing hydrophobic groups for both cell surface ligand presentation and intercellular cross-linking.

    PubMed

    Takeo, Masafumi; Li, Cuicui; Matsuda, Masayoshi; Nagai, Hiroko; Hatanaka, Wataru; Yamamoto, Tatsuhiro; Kishimura, Akihiro; Mori, Takeshi; Katayama, Yoshiki

    2015-01-01

    Amphiphilic polymers bearing hydrophobic alkyl groups are expected to be applicable for both ligand presentation on the cell surface and intercellular crosslinking. To explore the optimum design for each application, we synthesized eight different acyl-modified dextrans with varying molecular weight, alkyl length, and alkyl modification degree. We found that the behenate-modified polymers retained on the cell surface longer than the palmitate-modified ones. Since the polymers were also modified with biotin, streptavidin can be presented on the cell surface through biotin-streptavidin recognition. The duration of streptavidin on the cell surface is longer in the behenate-modified polymer than the palmitate-modified one. As for the intercellular crosslinking, the palmitate-modified polymers were more efficient than the behenate-modified polymers. The findings in this research will be helpful to design the acyl-modified polymers for the cell surface engineering.

  13. Photochemical Crosslinking of Preformed Glassy and Amorphous Polymers Through bis-Benzophenone Mediated Covalent Bridging

    NASA Astrophysics Data System (ADS)

    Carbone, Nicholas; Dickson, Mary; Lancaster, Jeffrey; Carroll, Greg; Koberstein, Jeffrey

    2009-03-01

    We show that bis-benzophenone (bis-BP) is an effective method to photochemically crosslink essentially any solvent-free glassy or amorphous preformed polymer system that contains abstractable hydrogen atoms. When bis-BP is mixed into a polymer and exposed to UV radiation, it abstracts hydrogen atoms from any chains in proximity, thereby initiating a cascade of free radical reactions that include several mechanisms that can lead to covalent polymer crosslinking. Herein we study the early stages of branching reactions that precede gelation by following molecular weight changes in bis-BP modified glassy polystyrene (PS) and amorphous poly(n-butyl acrylate) (PnBA) thin films on silicon wafers by Gel Permeation Chromatography. Quantitative molecular weight changes in PS:bis-BP and PnBA:bis-BP thin films are studied as a function of irradiation time, polymer:bis-BP molar ratio, and film height. Increases in molecular weight and polydispersity are quantified and model equations are developed.

  14. Adsorption and recovery of nonylphenol ethoxylate on a crosslinked beta-cyclodextrin-carboxymethylcellulose polymer.

    PubMed

    Bonenfant, Danielle; Niquette, Patrick; Mimeault, Murielle; Hausler, Robert

    2010-01-01

    A study of adsorption/recovery of nonylphenol 9 mole ethoxylate (NP9EO) on a crosslinked beta-cyclodextrin-carboxymethylcellulose (beta-CD-CMC) polymer was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies. The adsorption was performed in mixtures containing 500 mg of the beta-CD-CMC polymer and aqueous NP9EO solutions at concentrations 12-82 mg/L, whereas the recovery of NP9EO was effectuated by shaking the beta-CD-CMC polymer loaded with methanol. The assays were made at 25 degrees C and atmospheric pressure under agitation. The results have shown that the adsorption is a rapid process and the beta-CD-CMC polymer exhibits a high NP9EO adsorption capacity of 83-92 w% (1.1-6.8 mg NP9EO/g beta-CD-CMC polymer) dependent of the initial NP9EO concentration in liquid phase. This adsorption may involve the formation of an inclusion complex beta-CD-NP9EO and a physical adsorption in the polymer network. The adsorption equilibrium measurements, which were analyzed using the Langmuir isotherm, have indicated a monolayer coverage and the homogeneous distribution of active sites at the surface of the beta-CD-CMC polymer. Moreover, the negative value obtained for the free energy change (-13.2 kJ/mol) has indicated that the adsorption process is spontaneous. In parallel, the beta-CD-CMC polymer exhibited a high NP9EO recovery efficiency of 97 w% that may occur through a decrease of binding strength between beta-CD-CMC polymer and NP9EO. Together, these results suggest that the beta-CD-CMC polymer could constitute a good adsorbent for removing nonylphenol ethoxylates from wastewater due to its high adsorption capacity and non-toxic character of beta-CD and CMC to environment.

  15. Improved lithium-metal/vanadium pentoxide polymer battery incorporating crosslinked ternary polymer electrolyte with N-butyl-N-methylpyrrolidinium bis(perfluoromethanesulfonyl)imide

    NASA Astrophysics Data System (ADS)

    Osada, Irene; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

    2014-12-01

    Li metal polymer batteries incorporating crosslinked ternary PEO/PYR14TFSI/LiTFSI solid polymer electrolyte (SPE) have been prepared, using V2O5 as active cathode material. As a result of the optimization of the SPE as well as the cell assembly and cycling conditions, V2O5 lithium metal polymer batteries allow reaching 796 Wh kg-1 (of V2O5) at C/10 at 40 °C and maintaining 663 Wh kg-1 after 200 cycles at 40 °C. This is higher than the theoretical specific energy of LiCoO2 vs. Li of 609 Wh kg-1. Cycling at 80 °C allows reaching 270 mAh g-1 at C/2 and 210 mAh g-1 at 1 C, while at 20 °C it is still possible to reach a discharge capacity of almost 100 mAh g-1 at low rates. Post-cycling SEM and EDX imaging showed that, after 200 cycles at 40 °C, if the plating of Li is not fully homogeneous, no sign of dendrite growth nor obvious vanadium dissolution and redeposition on the anode side occurred.

  16. Magnetically Controllable Polymer Nanotubes from a Cyclized Crosslinker for Site-Specific Delivery of Doxorubicin.

    PubMed

    Newland, Ben; Leupelt, Daniel; Zheng, Yu; Thomas, Laurent S V; Werner, Carsten; Steinhart, Martin; Wang, Wenxin

    2015-12-01

    Externally controlled site specific drug delivery could potentially provide a means of reducing drug related side effects whilst maintaining, or perhaps increasing therapeutic efficiency. The aim of this work was to develop a nanoscale drug carrier, which could be loaded with an anti-cancer drug and be directed by an external magnetic field. Using a single, commercially available monomer and a simple one-pot reaction process, a polymer was synthesized and crosslinked within the pores of an anodized aluminum oxide template. These polymer nanotubes (PNT) could be functionalized with iron oxide nanoparticles for magnetic manipulation, without affecting the large internal pore, or inherent low toxicity. Using an external magnetic field the nanotubes could be regionally concentrated, leaving areas devoid of nanotubes. Lastly, doxorubicin could be loaded to the PNTs, causing increased toxicity towards neuroblastoma cells, rendering a platform technology now ready for adaptation with different nanoparticles, degradable pre-polymers, and various therapeutics.

  17. Magnetically Controllable Polymer Nanotubes from a Cyclized Crosslinker for Site-Specific Delivery of Doxorubicin

    PubMed Central

    Newland, Ben; Leupelt, Daniel; Zheng, Yu; Thomas, Laurent S. V.; Werner, Carsten; Steinhart, Martin; Wang, Wenxin

    2015-01-01

    Externally controlled site specific drug delivery could potentially provide a means of reducing drug related side effects whilst maintaining, or perhaps increasing therapeutic efficiency. The aim of this work was to develop a nanoscale drug carrier, which could be loaded with an anti-cancer drug and be directed by an external magnetic field. Using a single, commercially available monomer and a simple one-pot reaction process, a polymer was synthesized and crosslinked within the pores of an anodized aluminum oxide template. These polymer nanotubes (PNT) could be functionalized with iron oxide nanoparticles for magnetic manipulation, without affecting the large internal pore, or inherent low toxicity. Using an external magnetic field the nanotubes could be regionally concentrated, leaving areas devoid of nanotubes. Lastly, doxorubicin could be loaded to the PNTs, causing increased toxicity towards neuroblastoma cells, rendering a platform technology now ready for adaptation with different nanoparticles, degradable pre-polymers, and various therapeutics. PMID:26619814

  18. New polymer gel dosimeters consisting of less toxic monomers with radiation-crosslinked gel matrix

    NASA Astrophysics Data System (ADS)

    Hiroki, A.; Yamashita, S.; Sato, Y.; Nagasawa, N.; Taguchi, M.

    2013-06-01

    New polymer gel dosimeters consisting of less toxic methacrylate-type monomers such as 2-hydroxymethyl methacrylate (HEMA) and polyethylene glycol 400 dimethacrylate (9G) with hydroxypropyl cellulose (HPC) gel were prepared. The HPC gels were obtained by using a radiation-induced crosslinking technique to be applied in a matrix instead of a gelatin, which is conventionally used in earlier dosimeters, for the polymer gel dosimeters. The prepared polymer gel dosimeters showed cloudiness by exposing to 60Co γ-ray, in which the cloudiness increased with the dose up to 10 Gy. At the same dose, the increase in the cloudiness appeared with increasing concentration of 9G. As a result of the absorbance measurement, it was found that the dose response depended on the composition ratio between HEMA and 9G.

  19. Magnetically Controllable Polymer Nanotubes from a Cyclized Crosslinker for Site-Specific Delivery of Doxorubicin

    NASA Astrophysics Data System (ADS)

    Newland, Ben; Leupelt, Daniel; Zheng, Yu; Thomas, Laurent S. V.; Werner, Carsten; Steinhart, Martin; Wang, Wenxin

    2015-12-01

    Externally controlled site specific drug delivery could potentially provide a means of reducing drug related side effects whilst maintaining, or perhaps increasing therapeutic efficiency. The aim of this work was to develop a nanoscale drug carrier, which could be loaded with an anti-cancer drug and be directed by an external magnetic field. Using a single, commercially available monomer and a simple one-pot reaction process, a polymer was synthesized and crosslinked within the pores of an anodized aluminum oxide template. These polymer nanotubes (PNT) could be functionalized with iron oxide nanoparticles for magnetic manipulation, without affecting the large internal pore, or inherent low toxicity. Using an external magnetic field the nanotubes could be regionally concentrated, leaving areas devoid of nanotubes. Lastly, doxorubicin could be loaded to the PNTs, causing increased toxicity towards neuroblastoma cells, rendering a platform technology now ready for adaptation with different nanoparticles, degradable pre-polymers, and various therapeutics.

  20. Dual responsive Pickering emulsions stabilized by constructed core crosslinked polymer nanoparticles via reversible covalent bonds.

    PubMed

    Guo, Huazhang; Yang, Duanguang; Yang, Mei; Gao, Yong; Liu, Yijiang; Li, Huaming

    2016-12-06

    In this study, pH- and glucose-responsive Pickering emulsions stabilized by core crosslinked polymer nanoparticles, which were constructed via reversible covalent bonds, were presented for the first time. Firstly, well-defined PDMA-b-PAPBA (poly(N,N-dimethylacrylamide)-b-poly(3-acrylamidophenylboronic acid)) diblock copolymers were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization reactions. By means of complexation of PBA units of PDMA-b-PAPBA with PVA in basic water, core crosslinked polymer nanoparticles (CCPNs) with a core-shell structure were formed. The PAPBA/PVA crosslinked network and PDMA acted as the core and shell, respectively. Because of the reversible B-O chemical bonds in the core, the as-produced CCPNs showed structural transitions in response to the external stimuli involving pH and glucose. Investigation of the interfacial activities revealed that CCPNs exhibited high emulsifying performances, and oil in water (o/w) Pickering emulsions could be formed at a low particle content. The formed Pickering emulsions showed high stability at room temperature without any disturbances, whereas de-emulsification was observed upon improving the pH or adding glucose at a given pH. This is the first report on a responsive Pickering emulsion whose stability can be manipulated by glucose, and this type of fabricated manipulative Pickering emulsions are expected to provide useful guidance in the fields of oil recovery, interfacial reactions, etc.

  1. Ultralow stress, thermally stable cross-linked polymer films of polydivinylbenzene (PDVB)

    DOE PAGES

    Lepro, Xavier; Ehrmann, Paul; Menapace, Joseph; ...

    2017-05-10

    Although closely related to polystyrene, poly(divinylbenzene) (PDVB) has found limited utility due to the difficulties associated with its synthesis. As a highly cross-linked polymer, PDVB is infusible and insoluble and thus nearly impossible to shape into films by either melt or solvent-based processes. Here, we report the initiated chemical vapor deposition (iCVD) of nearly stress-free, highly transparent, free-standing films of PDVB up to 25 μm thick. Films initially grow under tensile intrinsic stress but become more compressive with thickness and eventually converge to zero-stress values once they reach ≥10 μm in thickness. Upon initial heating, the evaporative loss of unreactedmore » monomer left in the polymer matrix induces between 35 and 45 MPa of tensile stress in the films. Afterward, subsequent heating cycles induce reversible stress and film expansion behaviors. We estimate the degree of cross-linking to be 44%, resulting in high thermal stability (up to 300 °C) and mechanical stiffness (Young’s modulus of 5.2 GPa). As a result, the low stress combined with high cross-linking makes iCVD PDVB an excellent candidate for protective coatings in harsh environments.« less

  2. Microporous Organic Polymers Based on Hyper-Crosslinked Coal Tar: Preparation and Application for Gas Adsorption.

    PubMed

    Gao, Hui; Ding, Lei; Bai, Hua; Li, Lei

    2017-02-08

    Hyper-crosslinked polymers (HCPs) are promising materials for gas capture and storage, but high cost and complicated preparation limit their practical application. In this paper, a new type of HCPs (CTHPs) was synthesized through a one-step mild Friedel-Crafts reaction with low-cost coal tar as the starting material. Chloroform was utilized as both solvent and crosslinker to generate a three-dimensional crosslinked network with abundant micropores. The maximum BET surface area of the prepared CTHPs could reach up to 929 m(2)  g(-1) . Owing to the high affinity between the heteroatoms on the coal-tar building blocks and the CO2 molecules, the adsorption capacity of CTHPs towards CO2 reached up to 14.2 wt % (1.0 bar, 273 K) with a high selectivity (CO2 /N2 =32.3). Furthermore, the obtained CTHPs could adsorb 1.27 wt % H2 at 1.0 bar and 77.3 K, and also showed capacity for the capture of high organic vapors at room temperature. In comparison with other reported porous organic polymers, CTHPs have the advantages of low-cost, easy preparation, and high gas-adsorption performance, making them suitable for mass production and practical use in the future.

  3. Citric acid-derived in situ crosslinkable biodegradable polymers for cell delivery

    PubMed Central

    Gyawali, Dipendra; Nair, Parvathi; Zhang, Yi; Tran, Richard T.; Zhang, Chi; Samchukov, Mikhail; Makarov, Marina; Kim, Harry; Yang, Jian

    2010-01-01

    Herein, we report the first citric acid (CA)-derived in situ crosslinkable biodegradable polymer, poly(ethylene glycol) maleate citrate (PEGMC). The synthesis of PEGMC could be carried out via a one-pot polycondensation reaction without using organic solvents or catalysts. PEGMC could be in-situ crosslinked into elastomeric PPEGMC hydrogels. The performance of hydrogels in terms of swelling, degradation, and mechanical properties were highly dependent on the molar ratio of monomers, crosslinker concentration, and crosslinking mechanism used in the synthesis process. Cyclic conditioning tests showed that PPEGMC hydrogels could be compressed up to 75% strain without permanent deformation and with negligible hysteresis. Water-soluble PEGMC demonstrated excellent cytocompatibilty in vitro. The degradation products of PPEGMC also showed minimal cytotoxicity in vitro. Animal studies in rats clearly demonstrated the excellent injectability of PEGMC and degradability of the in situ-formed PPEGMC. PPEGMC elicited minimal inflammation in the early stages post-injection and was completely degraded within 30 days in rats. In conclusion, the development of CA-derived injectable biodegradable PEGMC presents numerous opportunities for material innovation and offers excellent candidate materials for in situ tissue engineering and drug delivery applications. PMID:20800893

  4. Silica nanoparticle supported molecularly imprinted polymer layers with varied degrees of crosslinking for lysozyme recognition.

    PubMed

    Chen, Huachang; Yuan, Dongying; Li, Yiya; Dong, Mingjie; Chai, Zhihua; Kong, Juan; Fu, Guoqi

    2013-05-24

    Surface imprinting over nanosized support materials is particularly suitable for protein templates, considering the problems with mass transfer limitation and low binding capacity. Previously we have demonstrated a strategy for surface protein imprinting over vinyl-modified silica nanopartiles with lysozyme as a model template by polymerization in high-dilution monomer solution to prevent macrogelation. Herein, the synthesis process was further studied toward enhancement of the imprinting performance by examining the effect of several synthesis conditions. Interestingly, the feed crosslinking degree was found to have a great impact on the thickness of the formed imprinting polymer layers and the recognition properties of the resulting imprinted materials. The imprinted particles with a crosslinking degree up to 50% showed the best imprinting effect. The imprinting factor achieved 2.89 and the specific binding reached 23.3 mg g(-1), which are greatly increased compared to those of the lowly crosslinked imprinted materials reported previously. Moreover, the relatively high crosslinking degree led to no significant retarding of the binding kinetics to the imprinted particles, and the saturated adsorption was reached within 10 min. Therefore, this may be a promising method for protein imprinting. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Size-exclusion partitioning of neutral solutes in crosslinked polymer networks: A Monte Carlo simulation study

    SciTech Connect

    Quesada-Pérez, Manuel; Maroto-Centeno, José Alberto; Adroher-Benítez, Irene

    2014-05-28

    In this work, the size-exclusion partitioning of neutral solutes in crosslinked polymer networks has been studied through Monte Carlo simulations. Two models that provide user-friendly expressions to predict the partition coefficient have been tested over a wide range of volume fractions: Ogston's model (especially devised for fibrous media) and the pore model. The effects of crosslinking and bond stiffness have also been analyzed. Our results suggest that the fiber model can acceptably account for size-exclusion effects in crosslinked gels. Its predictions are good for large solutes if the fiber diameter is assumed to be the effective monomer diameter. For solutes sizes comparable to the monomer dimensions, a smaller fiber diameter must be used. Regarding the pore model, the partition coefficient is poorly predicted when the pore diameter is estimated as the distance between adjacent crosslinker molecules. On the other hand, our results prove that the pore sizes obtained from the pore model by fitting partitioning data of swollen gels are overestimated.

  6. Size-exclusion partitioning of neutral solutes in crosslinked polymer networks: a Monte Carlo simulation study.

    PubMed

    Quesada-Pérez, Manuel; Adroher-Benítez, Irene; Maroto-Centeno, José Alberto

    2014-05-28

    In this work, the size-exclusion partitioning of neutral solutes in crosslinked polymer networks has been studied through Monte Carlo simulations. Two models that provide user-friendly expressions to predict the partition coefficient have been tested over a wide range of volume fractions: Ogston's model (especially devised for fibrous media) and the pore model. The effects of crosslinking and bond stiffness have also been analyzed. Our results suggest that the fiber model can acceptably account for size-exclusion effects in crosslinked gels. Its predictions are good for large solutes if the fiber diameter is assumed to be the effective monomer diameter. For solutes sizes comparable to the monomer dimensions, a smaller fiber diameter must be used. Regarding the pore model, the partition coefficient is poorly predicted when the pore diameter is estimated as the distance between adjacent crosslinker molecules. On the other hand, our results prove that the pore sizes obtained from the pore model by fitting partitioning data of swollen gels are overestimated.

  7. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    DOEpatents

    Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  8. Rheological and chemical analysis of reverse gelation in a covalently crosslinked Diels-Alder polymer network

    PubMed Central

    Adzima, Brian J.; Aguirre, H. Alan; Kloxin, Christopher J.; Scott, Timothy F.; Bowman, Christopher N.

    2009-01-01

    A network polymer, incorporating dynamic and reversible crosslinks, was synthesized using the Diels-Alder reaction. Fourier transform infrared (FTIR) spectroscopy was used to characterize the reaction rate and thermodynamic equilibrium over a broad temperature range. Equilibrium conversion of the furan and maleimide varied from 74% at 85°C to 24% at 155°C, demonstrating significant depolymerization via the retro-Diels-Alder reaction. The gel point temperature, as determined by rheometry using the Winter-Chambon criterion, was 92°C, corresponding to a gel-point conversion of 71%, consistent with the Flory-Stockmayer equation. The scaling exponents for the complex moduli, viscosity, and plateau modulus, in the vicinity of the gel-point, were determined and compared with experimental and theoretical literature values. Further, the material exhibited a low frequency relaxation owing to dynamic rearrangement of crosslinks by the Diels-Alder and retro-Diels-Alder reactions. PMID:20711364

  9. Investigation of cross-linked and additive containing polymer materials for membranes with improved performance in pervaporation and gas separation.

    PubMed

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-10-22

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes.

  10. Investigation of Cross-Linked and Additive Containing Polymer Materials for Membranes with Improved Performance in Pervaporation and Gas Separation

    PubMed Central

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B. Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-01-01

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes. PMID:24958427

  11. A Synthetic Fibrin-Crosslinking Polymer for Modulating Clot Properties and Inducing Hemostasis

    PubMed Central

    Chan, Leslie W.-G.; Wang, Xu; Wei, Hua; Pozzo, Lilo D.; White, Nathan J.; Pun, Suzie H.

    2015-01-01

    Clotting factor replacement is the standard management of acute bleeding in congenital and acquired bleeding disorders. We present a synthetic approach to hemostasis using an engineered hemostatic polymer (PolySTAT) that circulates innocuously in the blood, identifies sites of vascular injury, and promotes clot formation to stop bleeding. PolySTAT induces hemostasis by crosslinking the fibrin matrix within clots, mimicking the function of the transglutaminase Factor XIII. Furthermore, synthetic PolySTAT binds specifically to fibrin monomers and is uniformly integrated into fibrin fibers during fibrin polymerization, resulting in a fortified, hybrid polymer network with enhanced resistance to enzymatic degradation. In vivo hemostatic activity was confirmed in a rat model of trauma and fluid resuscitation in which intravenous administration of PolySTAT improved survival by reducing blood loss and resuscitation fluid requirements. PolySTAT-induced fibrin crosslinking is a novel approach to hemostasis utilizing synthetic polymers for non-invasive modulation of clot architecture with potentially wide-ranging therapeutic applications. PMID:25739763

  12. Thermally cross-linkable hole transport polymers for solution-based organic light-emitting diodes.

    PubMed

    Cha, Seung Ji; Cho, Se-Na; Lee, Woo-Hyung; Chung, Ha-Seul; Kang, In-Nam; Suh, Min Chul

    2014-04-01

    Two thermally cross-linkable hole transport polymers that contain phenoxazine and triphenylamine moieties, X-P1 and X-P2, are developed for use in solution-processed multi-stack organic light-emitting diodes (OLEDs). Both X-P1 and X-P2 exhibit satisfactory cross-linking and optoelectronic properties. The highest occupied molecular orbital (HOMO) levels of X-P1 and X-P2 are -5.24 and -5.16 eV, respectively. Solution-processed super yellow polymer devices (ITO/X-P1 or X-P2/PDY-132/LiF/Al) with X-P1 or X-P2 hole transport layers of various thicknesses are fabricated with the aim of optimizing the device characteristics. The fabricated multi-stack yellow devices containing the newly synthesized hole transport polymers exhibit satisfactory currents and power efficiencies. The optimized X-P2 device exhibits a device efficiency that is dramatically improved by more than 66% over that of a reference device without an HTL.

  13. Chemical and radiation crosslinked polymer electrolyte membranes prepared from radiation-grafted ETFE films for DMFC applications

    NASA Astrophysics Data System (ADS)

    Chen, Jinhua; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

    To develop a highly chemically stable polymer electrolyte membrane for application in a direct methanol fuel cell (DMFC), doubly crosslinked membranes were prepared by chemical crosslinking using bifunctional monomers, such as divinylbenzene (DVB) and bis(p, p-vinyl phenyl) ethane (BVPE), and by radiation crosslinking. The membranes were prepared by grafting of m, p-methylstyrene (MeSt) and p-tert-butylstyrene (tBuSt) into poly(ethylene- co-tetrafluoroethylene) (ETFE) films and subsequent sulfonation. The effects of the DVB and BVPE crosslinkers on the grafting kinetics and the properties of the prepared membranes, such as water uptake, proton conductivity and chemical stability were investigated. Radiation crosslinking was introduced by irradiation of the ETFE base film, the grafted film or the sulfonated membrane. The membrane crosslinked by DVB and BVPE crosslinkers and post-crosslinked by γ-ray irradiation of the corresponding grafted film possessed the highest chemical stability among the prepared membranes, a significantly lower methanol permeability compared to Nafion ® membranes, and a better DMFC performance for high methanol feed concentration. Therefore, this doubly crosslinked membrane was promising for application in a DMFC where relatively high methanol concentration could be fed.

  14. Solid Polymer Electrolyte Fuel Cell Technology Program

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Work is reported on phase 5 of the Solid Polymer Electrolyte (SPE) Fuel Cell Technology Development program. The SPE fuel cell life and performance was established at temperatures, pressures, and current densities significantly higher than those previously demonstrated in sub-scale hardware. Operation of single-cell Buildup No. 1 to establish life capabilities of the full-scale hardware was continued. A multi-cell full-scale unit (Buildup No. 2) was designed, fabricated, and test evaluated laying the groundwork for the construction of a reactor stack. A reactor stack was then designed, fabricated, and successfully test-evaluated to demonstrate the readiness of SPE fuel cell technology for future space applications.

  15. Rheology of cross-linked polymers and polymer foams: Theory and experimental results

    NASA Astrophysics Data System (ADS)

    Herman, John N.

    Typical polymers have a time-dependent response to loading which results in stress relaxation or creep. Models using springs/dashpots or Volterra integrals are capable of predicting the material response, but place little or no emphasis on the reasoning behind the response. This research proposes a microscopic reasoning behind polymer chain movement, while developing a model to predict the creep and stress relaxation of a polymer foam. Based on the theorized slip/stick of polymer chains as they slide past each other, this model successfully predicts the behavior of a PMI polymer foam under tensile loads. This model lends insights into polymer microscopic behavior, which may be used for the development of future polymer materials. When possible, industry standard test methods are used to obtain tensile creep and stress relaxation results from rectangular specimens of Rohacell 31 IG foam. A common set of material parameters is fitted to the data, validating the micromechanic reasoning to polymer chain movement. To gain insight into observed test result variability, an investigation of the elastic modulus and material density relationship is performed using nominal foam densities of 31 kg/m3, 51 kg/m3,, 71 kg/m3. Additional testing and modeling is performed to validate the model under load/partial-unload/ hold, load/unload/recovery, and load/instantaneous-unload test cycles. The model successfully captures the observed material nuances during these more complex loading cycles.

  16. Near-ambient solid polymer fuel cell

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.

    1993-01-01

    Fuel cells are extremely attractive for extraterrestrial and terrestrial applications because of their high energy conversion efficiency without noise or environmental pollution. Among the various fuel cell systems the advanced polymer electrolyte membrane fuel cells based on sulfonated fluoropolymers (e.g., Nafion) are particularly attractive because they are fairly rugged, solid state, quite conductive, of good chemical and thermal stability and show good oxygen reduction kinetics due to the low specific adsorption of the electrolyte on the platinum catalyst. The objective of this program is to develop a solid polymer fuel cell which can efficiently operate at near ambient temperatures without ancillary components for humidification and/or pressurization of the fuel or oxidant gases. During the Phase 1 effort we fabricated novel integral electrode-membrane structures where the dispersed platinum catalyst is precipitated within the Nafion ionomer. This resulted in electrode-membrane units without interfacial barriers permitting unhindered water diffusion from cathode to anode. The integral electrode-membrane structures were tested as fuel cells operating on H2 and O2 or air at 1 to 2 atm and 10 to 50 C without gas humidification. We demonstrated that cells with completely dry membranes could be self started at room temperature and subsequently operated on dry gas for extended time. Typical room temperature low pressure operation with unoptimized electrodes yielded 100 mA/cm(exp 2) at 0.5V and maximum currents over 300 mA/cm(exp 2) with low platinum loadings. Our results clearly demonstrate that operation of proton exchange membrane fuel cells at ambient conditions is feasible. Optimization of the electrode-membrane structure is necessary to assess the full performance potential but we expect significant gains in weight and volume power density for the system. The reduced complexity will make fuel cells also attractive for smaller and portable power supplies and as

  17. Solid-polymer-electrolyte fuel cells

    SciTech Connect

    Fuller, T.F.

    1992-07-01

    A transport model for polymer electrolytes is presented, based on concentrated solution theory and irreversible thermodynamics. Thermodynamic driving forces are developed, transport properties are identified and experiments devised. Transport number of water in Nafion 117 membrane is determined using a concentration cell. It is 1.4 for a membrane equilibrated with saturated water vapor at 25{degrees}C, decreases slowly as the membrane is dehydrated, and falls sharply toward zero as the water content approaches zero. The relation between transference number, transport number, and electroosmotic drag coefficient is presented, and their relevance to water-management is discussed. A mathematical model of transport in a solid-polymer-electrolyte fuel cell is presented. A two-dimensional membrane-electrode assembly is considered. Water management, thermal management, and utilization of fuel are examined in detail. The membrane separators of these fuel cells require sorbed water to maintain conductivity; therefore it is necessary to manage the water content in membranes to ensure efficient operation. Water and thermal management are interrelated. Rate of heat removal is shown to be a critical parameter in the operation of these fuel cells. Current-voltage curves are presented for operation on air and reformed methanol. Equations for convective diffusion to a rotating disk are solved numerically for a consolute point between the bulk concentration and the surface. A singular-perturbation expansion is presented for the condition where the bulk concentration is nearly equal to the consolute-point composition. Results are compared to Levich's solution and analysis.

  18. Solid-polymer-electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Fuller, T. F.

    1992-07-01

    A transport model for polymer electrolytes is presented, based on concentrated solution theory and irreversible thermodynamics. Thermodynamic driving forces are developed, transport properties are identified and experiments devised. Transport number of water in Nafion 117 membrane is determined using a concentration cell. It is 1.4 for a membrane equilibrated with saturated water vapor at 25 C, decreases slowly as the membrane is dehydrated, and falls sharply toward zero as the water content approaches zero. The relation between transference number, transport number, and electroosmotic drag coefficient is presented, and their relevance to water-management is discussed. A mathematical model of transport in a solid-polymer-electrolyte fuel cell is presented. A two-dimensional membrane-electrode assembly is considered. Water management, thermal management, and utilization of fuel are examined in detail. The membrane separators of these fuel cells require sorbed water to maintain conductivity; therefore it is necessary to manage the water content in membranes to ensure efficient operation. Water and thermal management are interrelated. Rate of heat removal is shown to be a critical parameter in the operation of these fuel cells. Current-voltage curves are presented for operation on air and reformed methanol. Equations for convective diffusion to a rotating disk are solved numerically for a consolute point between the bulk concentration and the surface. A singular-perturbation expansion is presented for the condition where the bulk concentration is nearly equal to the consolute-point composition. Results are compared to Levich's solution and analysis.

  19. Solid particle erosion of polymers and composites

    NASA Astrophysics Data System (ADS)

    Friedrich, K.; Almajid, A. A.

    2014-05-01

    After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

  20. Method of synthesizing polymers from a solid electrolyte

    DOEpatents

    Skotheim, Terje A.

    1985-01-01

    A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte wherein an assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

  1. Method of synthesizing polymers from a solid electrolyte

    DOEpatents

    Skotheim, T.A.

    1984-10-19

    A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte is disclosed. An assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

  2. Fabrication of Hollow Microporous Carbon Spheres from Hyper-Crosslinked Microporous Polymers.

    PubMed

    Wang, Kewei; Huang, Liang; Razzaque, Shumaila; Jin, Shangbin; Tan, Bien

    2016-06-01

    Porous carbon materials prepared from the porous organic polymers are currently the subject of extensive investigation. On the basis of their interesting applications, it is highly desirable to develop new synthetic methodologies to obtain carbon materials with controllable pore size and morphology. Herein, a facile synthesis of hollow microporous carbon spheres (HCSs) from hollow microporous organic capsules (HMOCs) with a good control over the pore morphology, hollow cavity, and the shell thickness is reported. The highly porous hollow carbon spheres are prepared by the pyrolysis of HMOCs-based microporous polymers. The synthetic parameters, such as hypercrosslinking and pyrolysis conditions, are optimized to modify the porous structures and the properties. The morphology and porosity as well as energy storage applications of the microporous structures HCSs, derived through a combination of divinylbenzene-crosslinking and micropore-generating hypercrosslinking, are discussed. These findings provide a new benchmark for fabricating well-defined HCSs with great promise for various applications.

  3. New design of shape memory polymers based on natural rubber crosslinked via oxa-Michael reaction.

    PubMed

    Lin, Tengfei; Ma, Siwei; Lu, Yang; Guo, Baochun

    2014-04-23

    Shape memory polymers (SMPs) based on natural rubber were fabricated by crosslinking epoxidized natural rubber with zinc diacrylate (ZDA) using the oxa-Michael reaction. These SMPs possessed excellent shape fixity and recovery. The glass transition largely accounted for the fixing of the SMPs temporary shape. Increasing the ZDA content allowed the trigger temperature (20-46 °C) and recovery time (14-33 s) of the SMPs to be continuously tuned. Nanosized silica (nanosilica) was incorporated into the neat polymers to further increase the flexibility and tune the recovery stress. The nanosilica-SMPs exhibited exceptionally high strength in a rubbery state (>20 MPa). The nanosilica-SMPs exhibited high transparency, making them suitable in visible heat-shrinkable tubes.

  4. Thermo- and photo-driven soft actuators based on crosslinked liquid crystalline polymers

    NASA Astrophysics Data System (ADS)

    Gu, Wei; Wei, Jia; Yu, Yanlei

    2016-09-01

    Crosslinked liquid crystalline polymers (CLCPs) are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks. The anisotropic deformation of the CLCPs takes place when the mesogens experience order to disorder change in response to external stimuli; therefore, they can be utilized to fabricate smart actuators, which have potential applications in artificial muscles, micro-optomechanical systems, optics, and energy-harvesting fields. In this review the recent development of thermo- and photo-driven soft actuators based on the CLCPs are summarized. Project supported by the National Natural Science Foundation of China (Grant Nos. 21134003, 21273048, 51225304, and 51203023) and Shanghai Outstanding Academic Leader Program, China (Grant No. 15XD1500600).

  5. Ultrasonic elasticity determination of 45S5 Bioglass(®)-based scaffolds: influence of polymer coating and crosslinking treatment.

    PubMed

    Li, Wei; Pastrama, Maria-Ioana; Ding, Yaping; Zheng, Kai; Hellmich, Christian; Boccaccini, Aldo R

    2014-12-01

    Highly porous 45S5 Bioglass(®)-based scaffolds with interconnected pore structure are promising candidates for bone tissue engineering due to their bioactivity, biocompatibility, osteogenic and angiogenic effects. In the present study, to ensure the mechanical competence of the 45S5 Bioglass(®)-based scaffolds, their stiffness was adjusted by applying polymer coatings and further crosslinking treatment. A non-destructive ultrasonic technique was used to determine the stiffness of the scaffolds. The stiffness of uncoated scaffolds was shown to increase by applying polymer coatings, and a further increase was achieved by crosslinking the used polymer coatings. All uncoated and polymer-coated scaffolds were confirmed to exhibit stiffness values in the range of reported values in the literature for cancellous bone. A statistical evaluation of combined multiscale ultrasound-nanoindentation measurements indicated that the stiffness of the coated scaffold is directly dependent on the stiffness of the polymer coating.

  6. Long-Term Biostability of Self-Assembling Protein Polymers in the Absence of Covalent Crosslinking

    PubMed Central

    Sallach, Rory E.; Cui, Wanxing; Balderrama, Fanor; Martinez, Adam W.; Wen, Jing; Haller, Carolyn A.; Taylor, Jeannette V.; Wright, Elizabeth R.; Long, Robert C.; Chaikof, Elliot L.

    2009-01-01

    Unless chemically crosslinked, matrix proteins, such as collagen or silk, display a limited lifetime in vivo with significant degradation observed over a period of weeks. Likewise, amphiphilic peptides, lipopeptides, or glycolipids that self-assemble through hydrophobic interactions to form thin films, fiber networks, or vesicles do not demonstrate in vivo biostability beyond a few days. We report herein that a self-assembling, recombinant elastin-mimetic triblock copolymer elicited minimal inflammatory response and displayed robust in vivo stability for periods exceeding 1 year, in the absence of either chemical or ionic crosslinking. Specifically, neither a significant inflammatory response nor calcification was observed upon implantation of test materials into the peritoneal cavity or subcutaneous space of a mouse model. Moreover, serial quantitative magnetic resonance imaging, evaluation of pre- and post-explant ultrastructure by cryo-high resolution scanning electron microscopy, and an examination of implant mechanical responses revealed substantial preservation of form, material architecture, and biomechanical properties, providing convincing evidence of a non-chemically or ionically crosslinked protein polymer system that exhibits long-term stability in vivo. PMID:19854505

  7. Removal of anionic azo dyes from aqueous solution by functional ionic liquid cross-linked polymer.

    PubMed

    Gao, Hejun; Kan, Taotao; Zhao, Siyuan; Qian, Yixia; Cheng, Xiyuan; Wu, Wenli; Wang, Xiaodong; Zheng, Liqiang

    2013-10-15

    A novel functional ionic liquid based cross-linked polymer (PDVB-IL) was synthesized from 1-aminoethyl-3-vinylimidazolium chloride and divinylbenzene for use as an adsorbent. The physicochemical properties of PDVB-IL were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The adsorptive capacity was investigated using anionic azo dyes of orange II, sunset yellow FCF, and amaranth as adsorbates. The maximum adsorption capacity could reach 925.09, 734.62, and 547.17 mg/g for orange II, sunset yellow FCF and amaranth at 25°C, respectively, which are much better than most of the other adsorbents reported earlier. The effect of pH value was investigated in the range of 1-8. The result shows that a low pH value is found to favor the adsorption of those anionic azo dyes. The adsorption kinetics and isotherms are well fitted by a pseudo second-order model and Langmuir model, respectively. The adsorption process is found to be dominated by physisorption. The introduction of functional ionic liquid moieties into cross-linked poly(divinylbenzene) polymer constitutes a new and efficient kind of adsorbent.

  8. Mechanical behavior of highly cross-linked polymer networks and its links to microscopic structure.

    PubMed

    Mukherji, Debashish; Abrams, Cameron F

    2009-06-01

    Highly cross-linked polymer (HCP) networks are becoming increasingly important as high-performance adhesives and multifunctional composite materials. Because of their cross-linked molecular architectures, HCPs can be strong but brittle. One key goal in improving the performance of an HCP is to increase toughness without sacrificing strength. Using large scale molecular-dynamics simulation, we compare and characterize the mechanical behavior of two model HCPs under tensile deformation. In the first case, bond angles among any three connected monomers are unconstrained and in the second case we impose harmonic tetrahedral bond angle constraints. We perform a detailed microstructural analysis that establishes a unique correlation between macroscopic mechanical behavior and the microscopic structure of an HCP. While, in the unconstrained system, strain-hardening behavior is observed that is attributed to the formation of microvoids, the void growth is completely arrested in the constrained system and no strain hardening is observed. Moreover, after the initial strain-hardening phase, the unconstrained system displays the same stress-strain behavior as that of a constrained network. Strain hardening makes the unconstrained system ductile while it retains the same tensile strength as the constrained system. We suggest that bond angle flexibility of cross-linkers might be a possible means to control ductility in an HCP network at a constant cross-linker density. We have also studied the effect of temperature, strain rate, and intermonomer nonbonded interaction strength on the stress-strain behavior. Interestingly at a strong intermonomer nonbonded interaction strength, no strain hardening is observed even in the unconstrained system and fracture sets in at around 1% strain, similar to what is observed in an experimental system such as epoxy and vinyl-ester based thermosets. This indicates that strong nonbonded interactions play a key role in making an HCP strong but

  9. Langevin dynamcis simulations of driven polymer translocation into a cross-linked gel.

    PubMed

    Sean, David; Slater, Gary W

    2017-03-01

    We investigate the dynamics of driving a polyelectrolyte such as DNA through a nanopore and into a cross-linked gel. Placing the gel on the trans-side of the nanopore can increase the translocation time while not negatively affecting the capture rates. Thus, this setup combines the mechanics of gel electrophoresis with nanopore translocation. However, contrary to typical gel electrophoresis scenarios, the effect of the field is localized in the immediate vicinity of the nanopore and becomes negligible inside the gel matrix. Thus, we investigate the process by which a semiflexible polymer can be pushed into a gel matrix via a localized field and we describe how the dynamics of gel penetration depends upon the field intensity, polymer stiffness, and gel pore size. Our simulation results show that a semiflexible polymer enters the gel region with two distinct mechanisms depending upon the ratio between the bending length scale and the gel pore size. In both regimes, the gel fibers cause a net increase in the mean translocation time. Interestingly, the translocation rate is found to be constant (a potentially useful feature for many applications) during the predominant part of the translocation process when the polymer is stiff over a length scale comparable to the gel pore size. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Simulation and theory of self-assembly and network formation in reversibly cross-linked equilibrium polymers

    NASA Astrophysics Data System (ADS)

    Kindt, James T.

    2005-10-01

    A simulation model of hard spheres capable of reversible assembly into chains, which then may reversibly cross-link into networks, has been studied through grand canonical Monte Carlo simulation. Effects of varying intra- and interchain bond strengths, chain flexibilities, and restrictions on cross-linking angle were investigated. Observations including chain-length distributions and phase separation could be captured in most cases using a simple model theory. The coupling of chain growth to cross-linking was shown to be highly sensitive to the treatment of cross-linking by chain ends. In some systems, ladderlike domains of several cross-links joining two chains were common, resulting from cooperativity in the cross-linking. Extended to account for this phenomenon, the model theory predicts that such cooperativity will suppress phase separation in weakly polymerizing chains and at high cross-link concentration. In the present model, cross-linking stabilizes the isotropic phase with respect to the nematic phase, causing a shift in the isotropic-nematic transition to higher monomer concentration than in simple equilibrium polymers.

  11. Solid-polymer-electrolyte fuel cells

    SciTech Connect

    Fuller, T.F.

    1992-07-01

    A transport model for polymer electrolytes is presented, based on concentrated solution theory and irreversible thermodynamics. Thermodynamic driving forces are developed, transport properties are identified and experiments devised. Transport number of water in Nafion 117 membrane is determined using a concentration cell. It is 1.4 for a membrane equilibrated with saturated water vapor at 25{degrees}C, decreases slowly as the membrane is dehydrated, and falls sharply toward zero as the water content approaches zero. The relation between transference number, transport number, and electroosmotic drag coefficient is presented, and their relevance to water-management is discussed. A mathematical model of transport in a solid-polymer-electrolyte fuel cell is presented. A two-dimensional membrane-electrode assembly is considered. Water management, thermal management, and utilization of fuel are examined in detail. The membrane separators of these fuel cells require sorbed water to maintain conductivity; therefore it is necessary to manage the water content in membranes to ensure efficient operation. Water and thermal management are interrelated. Rate of heat removal is shown to be a critical parameter in the operation of these fuel cells. Current-voltage curves are presented for operation on air and reformed methanol. Equations for convective diffusion to a rotating disk are solved numerically for a consolute point between the bulk concentration and the surface. A singular-perturbation expansion is presented for the condition where the bulk concentration is nearly equal to the consolute-point composition. Results are compared to Levich`s solution and analysis.

  12. Inorganic-organic composite solid polymer electrolytes

    SciTech Connect

    Abraham, K.M.; Koch, V.R.; Blakley, T.J.

    2000-04-01

    Inorganic-organic composite solid polymer electrolytes (CSPEs) have been prepared from the poly(ethylene oxide) (PEO)-like electrolytes of the general formula polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-PEO{sub n}-LiX and Li{sup +}-conducting ceramic powders. In the PEO-like electrolytes, PVdF-HFP is the copolymer of PVdF and HFP, PEO{sub n} is a nonvolatile oligomeric polyethylene oxide of {approximately}400 g/mol molecular weight, and LiX is lithium bis(trifluoroethylsulfonyl)imide. Two types of inorganic oxide ceramic powders were used: a highly Li{sup +}-conducting material of the composition 14 mol % Li{sub 2}O-9Al{sub 2}O{sub 3}-38TiO{sub 2}-39P{sub 2}O{sub 5}, and the poorly Li{sup +}-conducting Li-silicates Li{sub 4{minus}x}M{sub x}SiO{sub 4} where M is Ca or Mg and x is 0 or 0.05. The composite electrolytes can be prepared as thin membranes in which the Li{sup +} conductivity and good mechanical strength of the Li{sup +}-conducting inorganic ceramics are complemented by the structural flexibility and high conductivity of organic polymer electrolytes. Excellent electrochemical and thermal stabilities have been demonstrated for the electrolyte films. Li//composite electrolyte//LiCoO{sub 2} rechargeable cells have been fabricated and cycled at room temperature and 50 C.

  13. New Aptes Cross-linked Polymers from Poly(ethylene oxide)s and Cyanuric Chloride for Lithium Batteries

    NASA Technical Reports Server (NTRS)

    Tigelaar, Dean M.; Meador, Mary Ann B.; Kinder, James D.; Bennett, William R.

    2005-01-01

    A new series of polymer electrolytes for use as membranes for lithium batteries are described. Electrolytes were made by polymerization between cyanuric chloride and diamino-terminated poly(ethylene oxide)s, followed by cross-linking via a sol-gel process. Thermal analysis and lithium conductivity of freestanding polymer films were studied. The effects of several variables on conductivity were investigated, such as length of backbone PEO chain, length of branching PEO chain, extent of branching, extent of cross-linking, salt content, and salt counterion. Polymer films with the highest percentage of PEO were found to be the most conductive, with a maximum lithium conductivity of 3.9 x 10(exp -5) S/cm at 25 C. Addition of plasticizer to the dry polymers increased conductivity by an order of magnitude.

  14. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

    PubMed Central

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

    2016-01-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

  15. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

    NASA Astrophysics Data System (ADS)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

    2016-05-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.

  16. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries.

    PubMed

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G; Lee, Yoon-Sung; Kim, Dong-Won

    2016-05-18

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.

  17. Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

    PubMed

    Lim, Sanghyun; Chu, Hodong; Lee, Kukjoo; Yim, Taeeun; Kim, Young-Jun; Mun, Junyoung; Kim, Tae-Hyun

    2015-10-28

    Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

  18. Extremely stretchable thermosensitive hydrogels by introducing slide-ring polyrotaxane cross-linkers and ionic groups into the polymer network

    PubMed Central

    Bin Imran, Abu; Esaki, Kenta; Gotoh, Hiroaki; Seki, Takahiro; Ito, Kohzo; Sakai, Yasuhiro; Takeoka, Yukikazu

    2014-01-01

    Stimuli-sensitive hydrogels changing their volumes and shapes in response to various stimulations have potential applications in multiple fields. However, these hydrogels have not yet been commercialized due to some problems that need to be overcome. One of the most significant problems is that conventional stimuli-sensitive hydrogels are usually brittle. Here we prepare extremely stretchable thermosensitive hydrogels with good toughness by using polyrotaxane derivatives composed of α-cyclodextrin and polyethylene glycol as cross-linkers and introducing ionic groups into the polymer network. The ionic groups help the polyrotaxane cross-linkers to become well extended in the polymer network. The resulting hydrogels are surprisingly stretchable and tough because the cross-linked α-cyclodextrin molecules can move along the polyethylene glycol chains. In addition, the polyrotaxane cross-linkers can be used with a variety of vinyl monomers; the mechanical properties of the wide variety of polymer gels can be improved by using these cross-linkers. PMID:25296246

  19. Increasing the maximum achievable strain of a covalent polymer gel through the addition of mechanically invisible cross-links.

    PubMed

    Kean, Zachary S; Hawk, Jennifer L; Lin, Shaoting; Zhao, Xuanhe; Sijbesma, Rint P; Craig, Stephen L

    2014-09-10

    Hydrogels and organogels made from polymer networks are widely used in biomedical applications and soft, active devices for which the ability to sustain large deformations is required. The strain at which polymer networks fracture is typically improved through the addition of elements that dissipate energy, but these materials require extra work to achieve a given, desired level of deformation. Here, the addition of mechanically "invisible" supramolecular crosslinks causes substantial increases in the ultimate gel properties without incurring the added energetic costs of dissipation.

  20. Polymer Crosslinked 3-D Assemblies of Nanoparticles: Mechanically Strong Lightweight Porous Materials

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2005-01-01

    In analogy to supramolecular assemblies, which are pursued because of properties above and beyond those of the individual molecules, self-standing monolithic three-dimensional assemblies of nanoparticles also have unique properties attributed to their structure. For example, ultra low-density 3-D assemblies of silica nanoparticles, known as silica aerogels, are characterized by large internal void space, high surface area and very low thermal conductivity. Aerogels, however, are also extremely fragile materials, limiting their application to a few specialized environments, e.g., in nuclear reactors as Cerenkov radiation detectors, in space (refer to NASA's Stardust Program) and aboard certain planetary vehicles (thermal insulators on Mars Rovers in 1997 and 2004). The fragility problem is traced to well-defined weak points in the aerogel skeletal framework, the interparticle necks. Using the surface functionality of the nanoparticle building blocks as a focal point, we have directed attachment of a conformal polymer coating over the entire framework, rendering all necks wider. Thus, although the bulk density may increase only by 3x, the mesoporosity (pores in the range 2-50 nm) remains unchanged, while the strength of the material increases by up to 300... Having addressed the fragility problem, aerogels are now robust materials, and a variety of applications, ranging from thermal/acoustic insulators to catalyst supports, to platform for sensors, and dielectrics are all within reach. Our approach employs molecular science to manipulate nanoscopic matter for achieving useful macroscopic properties, and in our view it resides at the core of what defines nanotechnology. In that spirit, this technology is expandable in three directions. Thus, we have already crosslinked successfully amine-modified silica, and we anticipate that more rich chemistry will be realized by been creative with the nanoparticle surface modifiers. On the other hand, although we do not expect

  1. Radiation-crosslinking of shape memory polymers based on poly(vinyl alcohol) in the presence of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Basfar, A. A.; Lotfy, S.

    2015-01-01

    Shape memory polymers based on poly(vinyl alcohol) (SM-PVA) in the presence of 2-carboxyethyl acrylate oligomers (CEA) and multi-wall carbon nanotubes (MWCNTs) crosslinked by ionizing radiation were investigated. Chemical-crosslinking of PVA by glutaraldehyde in the presence of CEA and MWCNTs was also studied. The swelling and gel fraction of the radiation-crosslinked SM-PVA and chemically crosslinked systems were evaluated. Analysis of the swelling and gel fraction revealed a significant reduction in swelling and an increase in the gel fraction of the material that was chemically crosslinked with glutaraldehyde. The radiation-crosslinked SM-PVA demonstrated 100% gelation at an irradiation dose of 50 kGy. In addition, radiation-crosslinked SM-PVA exhibited good temperature responsive shape-memory behavior. A scanning electron microscopy (SEM) analysis was performed. The thermal properties of radiation-crosslinked SM-PVA were investigated by a thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The ability of the material to return or store energy (E‧), to its ability to lose energy (E″), and the ratio of these effects (Tanδ), which is called damping were examined via DMA. The temperature of Tanδ in the radiation-crosslinked SM-PVA decreased significantly by 6 and 13 °C as a result of the addition of MWCNTs. In addition, the temperature of Tanδ for SM-PVA increased as the irradiation dose increased. These radiation-crosslinked SM-PVA materials show promising shape-memory behavior based on the range of temperatures at which Tanδ appears.

  2. Solid electrolyte material manufacturable by polymer processing methods

    DOEpatents

    Singh, Mohit; Gur, Ilan; Eitouni, Hany Basam; Balsara, Nitash Pervez

    2012-09-18

    The present invention relates generally to electrolyte materials. According to an embodiment, the present invention provides for a solid polymer electrolyte material that is ionically conductive, mechanically robust, and can be formed into desirable shapes using conventional polymer processing methods. An exemplary polymer electrolyte material has an elastic modulus in excess of 1.times.10.sup.6 Pa at 90 degrees C. and is characterized by an ionic conductivity of at least 1.times.10.sup.-5 Scm-1 at 90 degrees C. An exemplary material can be characterized by a two domain or three domain material system. An exemplary material can include material components made of diblock polymers or triblock polymers. Many uses are contemplated for the solid polymer electrolyte materials. For example, the present invention can be applied to improve Li-based batteries by means of enabling higher energy density, better thermal and environmental stability, lower rates of self-discharge, enhanced safety, lower manufacturing costs, and novel form factors.

  3. Novel biobased photo-crosslinked polymer networks prepared from vegetable oil and 2,5-furan diacrylate

    USDA-ARS?s Scientific Manuscript database

    Novel biobased crosslinked polymer networks were prepared from vegetable oil with 2,5-furan diacrylate as a difunctional stiffener through UV photopolymerization, and the mechanical properties of the resulting films were evaluated. The vegetable oil raw materials used were acrylated epoxidized soybe...

  4. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers

    PubMed Central

    Hearon, Keith; Smith, Sarah E.; Maher, Cameron A.; Wilson, Thomas S.; Maitland, Duncan J.

    2012-01-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities—that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150°C for up to five hours or to 125°C for up to 24 hours if stabilized with 10,000 ppm BQ and could also be heated to 125°C for up to 5 hours if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal

  5. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers.

    PubMed

    Hearon, Keith; Smith, Sarah E; Maher, Cameron A; Wilson, Thomas S; Maitland, Duncan J

    2013-02-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities-that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150°C for up to five hours or to 125°C for up to 24 hours if stabilized with 10,000 ppm BQ and could also be heated to 125°C for up to 5 hours if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization

  6. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers

    NASA Astrophysics Data System (ADS)

    Hearon, Keith; Smith, Sarah E.; Maher, Cameron A.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-02-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities—that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because the thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150 °C for up to 5 h or to 125 °C for up to 24 h if stabilized with 10,000 ppm BQ and could also be heated to 125 °C for up to 5 h if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization of

  7. Protein adsorption resistance and oxygen permeability of chemically crosslinked phospholipid polymer hydrogel for ophthalmologic biomaterials.

    PubMed

    Goda, Tatsuro; Matsuno, Ryosuke; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

    2009-04-01

    The biomimetic structure of a polymer hydrogel bearing phosphorylcholine groups was obtained from 2-methacryloyloxyethylphosphorylcholline (MPC) and a novel crosslinker, 2-(methacryloyloxy)ethyl-N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), to prepare biocompatible ocular materials. MMPC is a dimethacrylate with phosphorylcholine-analogous linkage. Previous reports clarified that the affinity of MMPC to MPC enables the water contents and mechanical properties of the poly(MPC) hydrogels to be varied without disturbing the bulk phases. In this study, we examined the protein adsorption resistance, water wettability, oxygen permeability, and electrolyte permeability of the mechanically enhanced poly(MPC) hydrogel crosslinked with MMPC. The amount of protein adsorbed on this hydrogel was 0.9 microg/cm(2), which accounted for 30% of Omafilcon A and 3% of Etafilcon A. Water contact angle experiments revealed the high wettability of the poly(MPC) hydrogels. The oxygen permeability and NaCl diffusion constant of the poly(MPC) hydrogels were 64 barrer and 48 x 10(-6) cm(2)/s, respectively. This high permeability resulted from the high water content, similar to the case of the human cornea. These results suggested that poly(MPC) hydrogels have good potential for use in ophthalmologic biomaterials.

  8. Construction of Monomer-free, Highly Crosslinked, Water-compatible Polymers

    PubMed Central

    Dailing, E.A.; Lewis, S.H.; Barros, M.D.; Stansbury, J.W.

    2014-01-01

    Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect. We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. Monomers of various hydrophilic or hydrophobic characteristics were copolymerized into particulate nanogels bearing internal and external polymerizable functionality. Nanogel dispersions were stable at high concentrations in acetone or, with some exceptions, in water and produced networks with a wide range of mechanical properties. Networks formed rapidly upon light activation and reached high conversion with extremely low volumetric shrinkage. Prepolymerizing monomers into reactive nanostructures significantly changes how hydrophobic materials respond to water compared with networks obtained from polymerizations involving free monomer. The modulus of fully hydrated networks formed solely from nanogels was shown to equal or exceed the modulus in the dry state for networks based on nanogels containing a hydrophobic dimethacrylate and hydrophilic monomethacrylate, a result that was not observed in a hydroxyethyl methacrylate (HEMA) homopolymer or in networks formed from nanogels copolymerized with HEMA. These results highlight the unique approach to network development from nanoscale precursors and properties that have direct implications in functional dental materials. PMID:25248612

  9. Flexible Electronic Substrate Film Fabricated Using Natural Clay and Wood Components with Cross-Linking Polymer.

    PubMed

    Takahashi, Kiyonori; Ishii, Ryo; Nakamura, Takashi; Suzuki, Asami; Ebina, Takeo; Yoshida, Manabu; Kubota, Munehiro; Nge, Thi Thi; Yamada, Tatsuhiko

    2017-03-01

    Requirements for flexible electronic substrate are successfully accomplished by green nanocomposite film fabricated with two natural components: glycol-modified biomass lignin and Li(+) montmorillonite clay. In addition to these major components, a cross-linking polymer between the lignin is incorporated into montmorillonite. Multilayer-assembled structure is formed due to stacking nature of high aspect montmorillonite, resulting in thermal durability up to 573 K, low thermal expansion, and oxygen barrier property below measurable limit. Preannealing for montmorillonite and the cross-linking formation enhance moisture barrier property superior to that of industrial engineering plastics, polyimide. As a result, the film has advantages for electronic film substrate. Furthermore, these properties can be achieved at the drying temperature up to 503 K, while the polyimide films are difficult to fabricate by this temperature. In order to examine its applicability for substrate film, flexible electrodes are finely printed on it and touch sensor device can be constructed with rigid elements on the electrode. In consequence, this nanocomposite film is expected to contribute to production of functional materials, progresses in expansion of biomass usage with low energy consumption, and construction of environmental friendly flexible electronic devices.

  10. Crosslinkable high k polymer dielectrics for low voltage organic field-effect transistor memories (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wu, Hung-Chin; Hung, Chih-Chien; Chiu, Yu-Cheng; Tung, Shih-Huang; Chen, Wen-Chang

    2016-09-01

    High Performance organic field-effect transistor (OFET) memory devices were successfully prepared using new dielectric materials, poly(N-(hydroxymethyl)acrylamide-co-5 -(9-(5-(diethylamino)pentyl)-2-(4-vinylphenyl)-9H-fluorene (P(NMA-co-F6NSt)), which contained chemical cross-linkable segment (NMA) and hole trapping building block (F6NSt). The high k characteristics of P(NMA-co-F6NSt)) led to a low voltage operation, a small power consumption, and a good digital information storage capacity. Such P(NMA-co-F6NSt) dielectrics in OFET memories with variant NMA/F6NSt molar ratios (100/0 (P1), 95/5 (P2), 80/20 (P3), and 67/33 (P4)) showed excellent insulating properties and good charge storage performance under a low operating voltage below ±5V, due to the tightly network structures after crosslinking and well-dispersed trapping cites (i.e. fluorene moieties). P3-based memory device, in particular, exhibited largest memory window of 4.13 V among the studied polymers, and possessed stable data retention stability over 104 s with a high on/off current ratio (i.e. 104) and good endurance characteristics of more than 200 write-read-write-erase (WRER) cycles. The above results suggested that a high-performance OFET memory device could be facilely achieved using the novel synthesized high-k copolymers.

  11. Hydrogels Containing Core Cross-Linked Block Co-Polymer Micelles.

    PubMed

    Lu, Changhai; Mikhail, Andrew S; Wang, Xinyue; Brook, Michael A; Allen, Christine

    2012-01-01

    Poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels loaded with core cross-linked PEG-b-PCL micelles with different morphologies (spherical and rod-like) were prepared and evaluated for use as drugeluting soft contact lenses. The relationship between the composition of micelle-loaded pHEMA hydrogels and properties such as transparency and swelling were determined. The incorporation of core crosslinked micelles into pHEMA hydrogels led to the formation of different internal nanostructures which were dependent on the amount and morphology of the micelles added. 7-Hydroxy-9H-(1,3-dichloro-9,9'-dimethylacridin-2-one) (DDAO), a hydrophobic fluorescent dye, was loaded into the micelles prior to their incorporation within the hydrogel matrix. The in vitro release of DDAO demonstrated the potential of the micelles/pHEMA hydrogels to provide controlled drug delivery for at least 14 days. This study demonstrates the feasibility of both chemical and physical incorporation of block co-polymer micelles within pHEMA hydrogels as a means to achieve sustained release of drugs for potential application in ophthalmic therapies.

  12. Photo-Induced Bending Behavior of Post-Crosslinked Liquid Crystalline Polymer/Polyurethane Blend Films.

    PubMed

    Pang, Xinlei; Xu, Bo; Qing, Xin; Wei, Jia; Yu, Yanlei

    2017-06-30

    Photoresponsive blend films with post-crosslinked liquid crystalline polymer (CLCP) as a photosensitive component and flexible polyurethane (PU) as the matrix are successfully fabricated. After being uniaxially stretched, even at low concentration, the azobenzene-containing CLCP effectively transfers its photoresponsiveness to the photoinert PU matrix, resulting in the fast photo-induced bending behavior of whole blend film thanks to the effective dispersion of CLCP. Specifically, the blend film shows photo-induced deformations upon exposure to unpolarized UV light at ambient temperature. The film unbends after thermal treatment, and the randomly orientated mesogens in the film can be realigned by the mechanical stretching, which endows the film with a reversible deformation behavior. The photosensitive blend film possesses favorable mechanical property and good processability at low cost, and it is a promising candidate for a new generation of actuators. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Photomobile polymer materials with crosslinked liquid-crystalline structures: molecular design, fabrication, and functions.

    PubMed

    Ube, Toru; Ikeda, Tomiki

    2014-09-22

    Crosslinked liquid-crystalline polymer materials that macroscopically deform when irradiated with light have been extensively studied in the past decade because of their potential in various applications, such as microactuators and microfluidic devices. The basic motions of these materials are contraction-expansion and bending-unbending, which are observed mainly in polysiloxanes and polyacrylates that contain photochromic moieties. Other sophisticated motions such as twisting, oscillation, rotation, and translational motion have also been achieved. In recent years, efforts have been made to improve the photoresponsive and mechanical properties of this novel class of materials through the modification of molecular structures, development of new fabrication methods, and construction of composite structures. Herein, we review structures, functions, and working mechanisms of photomobile materials and recent advances in this field.

  14. Functional crosslinked polymer particles synthesized by precipitation polymerization for liquid chromatography.

    PubMed

    Perrier-Cornet, R; Héroguez, V; Thienpont, A; Babot, O; Toupance, T

    2008-01-25

    Highly crosslinked functional polymer particles with narrow size distribution have been produced by precipitation copolymerization of divinylbenzene, ethylene glycol dimethacrylate and vinylbenzyl chloride using a simple reflux protocol. After establishing the satisfactory synthesis conditions, we produced uniform chlorobenzyl particles with different size depending on the polymerization times. The porosity of those particles was modulated from microporous to mesoporous structure by using various porogens such as toluene, dodecanol, cyclohexanol and polypropylene glycol. These particles were tested as stationary phase in high-performance liquid chromatography for the separation of polycyclic aromatic hydrocarbons in reversed-phase mode. The separation was observed even for elution 100% organic (methanol) without any participation of water fraction in the eluent composition. The influences of particles size, specific surface area and packing conditions on the separation behavior were investigated.

  15. “Zero-length” Cross-linking in Solid State as an Approach for Analysis of Protein -Protein Interactions

    SciTech Connect

    Elshafey, Ahmed; Tolic, Nikola; Young, Malin M.; Sale, Kenneth L.; Smith, Richard D.; Kery, Vladimir

    2006-03-01

    Analyzing the architecture of protein complexes is a difficult task. Chemical cross-linking is often used in combination with mass spectrometric analysis to elucidate the interaction interfaces between proteins. We have developed a new approach for the analysis of interacting interfaces in protein complexes based on cross-linking in the solid state. Protein complexes are freeze-dried under vacuum and cross-links are introduced in the solid phase by dehydrating the protein in a non-water solvent, thus, creating peptide bonds between amino and carboxyl groups of the interacting peptides. Cross-linked proteins are digested into peptides with trypsin in both H216O and H218O and then readily distinguished in mass spectra by characteristic 8 atomic mass unit (amu) shifts reflecting incorporation of two 18O atoms into each C-terminus of proteolytic peptides. Computer analysis of mass spectrometry (MS) and MS/MS data is used to identify the cross-linked peptides.We demonstrated our method by cross-linking homooligomeric protein complexes alone or in a mixture of many other proteins. Cross-linking in the solid state was shown to be specific and reproducible. Glutathione-S-transferase (GST) from Schistosoma japonicum was studied in more detail. Twenty-seven unique intra-molecular and two inter-molecular cross-linked peptides were identified using tryptic mapping followed by LTQ-MS analysis. Identified cross-links were predominantly of amide origin, but six esters and thioesters were also found. Identified cross-linked peptides were validated by computational (visualization of cross-links in the three-dimensional [3D] structure of GST) and experimental (MS/MS) analyses. Most of the identified cross-links matched interacting peptides in the native 3D structure of GST indicating that the structure of GST and its oligomeric complex remained primarily intact after freeze drying. The pattern of oligomeric GST obtained in solid state was the same as that obtained in solution by Ru

  16. Advances in solid polymer electrochemical capacitors for high rate applications

    NASA Astrophysics Data System (ADS)

    Lian, Keryn; Gao, Han

    2011-06-01

    All solid electrochemical capacitors (EC) have been demonstrated using proton conducting silicotungstic acid (SiWA) and poly(vinyl alcohol) (PVA) based polymer electrolytes. Graphite electrodes were utilized for electrochemical double layer capacitors (EDLC), while RuO2 electrodes were employed as pseudocapacitive electrodes. Both solid EDLC and pseudocapacitors exhibited very high charge/discharge rate capability. Especially for solid EDLC, a charge/discharge rate of 25 V/s and a 10 ms time constant ("factor of merit") were obtained. The rate capability of the solid EC is attributable to thin film thickness, good proton conductivity of the polymer electrolyte, and intimate contact between electrode and electrolyte. These results demonstrate promise of polymer electrolytes as enablers of high rate and high performance solid EC devices.

  17. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    PubMed

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively.

  18. [Preparation of a novel polymer monolith using atom transfer radical polymerization method for solid phase extraction].

    PubMed

    Shen, Ying; Qi, Li; Qiao, Juan; Mao, Lanqun; Chen, Yi

    2013-04-01

    In this study, a novel polymer monolith based solid phase extraction (SPE) material has been prepared by two-step atom transfer radical polymerization (ATRP) method. Firstly, employing ethylene glycol dimethacrylate (EDMA) as a cross-linker, a polymer monolith filled in a filter head has been in-situ prepared quickly under mild conditions. Then, the activators generated by electron transfer ATRP (ARGET ATRP) was used for the modification of poly(2-(dimethylamino)ethyl-methacrylate) (PDMAEMA) on the monolithic surface. Finally, this synthesized monolith for SPE was successfully applied in the extraction and enrichment of steroids. The results revealed that ATRP can be developed as a facile and effective method with mild reaction conditions for monolith construction and has the potential for preparing monolith in diverse devices.

  19. Convenient solid phase extraction of cephalosporins in milk using a molecularly imprinted polymer.

    PubMed

    Quesada-Molina, Carolina; Claude, Bérengère; García-Campaña, Ana M; del Olmo-Iruela, Monsalud; Morin, Philippe

    2012-11-15

    In this paper, a molecularly imprinted polymer (MIP) for cephalosporin molecules (cephalexin (CFL) and cephapirin (CFP)), was prepared by non covalent molecular imprinting approach and applied to solid phase extraction (SPE). For MIP synthesis, a tributylammonium cefadroxil salt (TBA-CFD) was used as template with methacrylic acid and ethylene glycol dimethacrylate as monomer and cross-linker, respectively, in acetone-methanol 92/8 (v/v) mixture. The selectivity of MIP versus non imprinted polymer (NIP) was confirmed for CFL, CFD and CFP in standard solutions as well as in milk samples. The efficiency of the synthesized MIP was evaluated by means of the application of the proposed MIP-SPE procedure to spiked milk samples previous to the HPLC method for the detection of cephalosporins. The MIP-SPE recoveries were higher than 60% for the three target analytes in spiked milk.

  20. Adsorption properties of cross-linked cellulose-epichlorohydrin polymers in aqueous solution.

    PubMed

    Udoetok, Inimfon A; Dimmick, Raquel M; Wilson, Lee D; Headley, John V

    2016-01-20

    Cellulose was cross-linked with epichlorohydrin (EP) at variable levels (CLE-0.5, CLE-2 and CLE-4), where CLE-i denotes the cellulose to EP mole ratios. The cross-linked products were characterized by TGA and FT-IR spectroscopy, pH at the point of zero charge (pHpzc), water swelling, and dye-adsorption methods employing two types of dyes [phenolphthalein (phth) and p-nitrophenol (PNP)]. The characterization methods provide evidence of cross-linking of cellulose in accordance with variations in surface area, PZC, available surface hydroxyl groups, and thermal stability when compared against pristine cellulose. The pHpzc of the sorbent materials was ∼ 6.5 indicating a negative surface charge occurs above pHpzc. The cross-linked polymers possess greater swelling properties relative to pristine cellulose. Detailed adsorption studies were carried out at pH 9 for cellulose and CLE-i with five types single component carboxylate anions [2-hexyldecanoic acid (S1), trans-4-pentylcyclohexanecarboxylic acid (S2), 2-dicyclohexylacetic acid (S3), adamantane carboxylic acid (S4), and cyclohexane carboxylic acid (S5)] at 295 K. The uptake properties of PNP with cellulose and CLE-i were also compared at pH 5 and 9, respectively. CLE-2 had the highest uptake of PNP (Qm=1.22 × 10(-1)mmol/g, pH 9) and S1 (Qm=4.27 mg/g) while cellulose and CLE-4 had the strongest binding affinity (1.43 L/mmol and 5.90 × 10(-2)L/mg), respectively. Uptake of PNP by CLE-0.5 at pH 5 (Q m=5.30 × 10(-2)mmol/g) was higher than uptake at pH 9 (Qm=3.11 × 10(-2)mmol/g). Sorption of CLE-4 with S1, S2 and S3 showed that relative uptake of the surrogates had the following order: S3>S2>S1, where S2 had the strongest binding affinity to CLE-i. CLE-2 had the highest sorption capacity towards Si in an equimolar mixture with evidence of molecular selective uptake. At pH 9, low uptake was mainly related to electrostatic repulsion between the negatively charged sorbent surface and the carboxylate head groups of Si.

  1. New Solid Polymer Electrolytes for Improved Lithium Batteries

    NASA Technical Reports Server (NTRS)

    Hehemann, David G.

    2002-01-01

    The objective of this work was to identify, synthesize and incorporate into a working prototype, next-generation solid polymer electrolytes, that allow our pre-existing solid-state lithium battery to function better under extreme conditions. We have synthesized polymer electrolytes in which emphasis was placed on the temperature-dependent performance of these candidate electrolytes. This project was designed to produce and integrate novel polymer electrolytes into a lightweight thin-film battery that could easily be scaled up for mass production and adapted to different applications.

  2. “Zero-length” cross-linking in solid state as an approach for analysis of protein–protein interactions

    PubMed Central

    El-Shafey, Ahmed; Tolic, Nikola; Young, Malin M.; Sale, Kenneth; Smith, Richard D.; Kery, Vladimir

    2006-01-01

    We have developed a new approach for the analysis of interacting interfaces in protein complexes and protein quaternary structure based on cross-linking in the solid state. Protein complexes are freeze-dried under vacuum, and cross-links are introduced in the solid phase by dehydrating the protein in a nonaqueous solvent creating peptide bonds between amino and carboxyl groups of the interacting peptides. Cross-linked proteins are digested into peptides with trypsin in both H216O and H218O and then readily distinguished in mass spectra by characteristic 8 atomic mass unit (amu) shifts reflecting incorporation of two 18O atoms into each C terminus of proteolytic peptides. Computer analysis of mass spectrometry (MS) and MS/MS data is used to identify the cross-linked peptides. We demonstrated specificity and reproducibility of our method by cross-linking homo-oligomeric protein complexes of glutathione-S-transferase (GST) from Schistosoma japonicum alone or in a mixture of many other proteins. Identified cross-links were predominantly of amide origin, but six esters and thioesters were also found. The cross-linked peptides were validated against the GST monomer and dimer X-ray structures and by experimental (MS/MS) analyses. Some of the identified cross-links matched interacting peptides in the native 3D structure of GST, indicating that the structure of GST and its oligomeric complex remained primarily intact after freeze-drying. The pattern of oligomeric GST obtained in solid state was the same as that obtained in solution by Ru (II) Bpy32+ catalyzed, oxidative “zero-length” cross-linking, confirming that it is feasible to use our strategy for analyzing the molecular interfaces of interacting proteins or peptides. PMID:16501223

  3. Remarkable swelling capability of amino acid based cross-linked polymer networks in organic and aqueous medium.

    PubMed

    Roy, Saswati Ghosh; Haldar, Ujjal; De, Priyadarsi

    2014-03-26

    This work reports design and synthesis of side chain amino acid based cross-linked polymeric gels, able to switch over from organogel to hydrogel by a simple deprotection reaction and showing superabsorbancy in water. Amino acid based methacrylate monomers, tert-butoxycarbonyl (Boc)-l/d-alanine methacryloyloxyethyl ester (Boc-l/d-Ala-HEMA), have been polymerized in the presence of a cross-linker via conventional free radical polymerization (FRP) and the reversible addition-fragmentation chain transfer (RAFT) technique for the synthesis of cross-linked polymer gels. The swelling behaviors of these organogels are investigated in organic solvents, and they behave as superabsorbent materials for organic solvents such as dichloromethane, acetone, tetrahydrofuran, etc. Swollen cross-linked polymer gels release the absorbed organic solvent rapidly. After Boc group deprotection from the pendant alanine moiety, the organogels transform to the hydrogels due to the formation of side chain ammonium (-NH3(+)) groups, and these hydrogels showed a significantly high swelling ratio (∼560 times than their dry volumes) in water. The morphology of organogels and hydrogels is studied by field emission scanning electron microscopy (FE-SEM). Amino acid based cross-linked gels could find applications as absorbents for oil spilled on water as well as superabsorbent hydrogels.

  4. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    DOEpatents

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  5. Ionic Transport Across Interfaces of Solid Glass and Polymer Electrolytes

    SciTech Connect

    Tenhaeff, Wyatt E; Yu, Xiang; Hong, Kunlun; Perry, Kelly A; Dudney, Nancy J

    2011-01-01

    A study of lithium cation transport across solid-solid electrolyte interfaces to identify critical resistances in nanostructured solid electrolytes is reported. Bilayers of glass and polymer thin film electrolytes were fabricated and characterized for this study. The glass electrolyte was lithium phosphorous oxynitride (Lipon), and two polymer electrolytes were studied: poly(methyl methacrylate-co-poly(ethylene glycol) methyl ether methacrylate) and poly(styrene-co-poly(ethylene glycol) methyl ether methacrylate). Both copolymers contained LiClO{sub 4} salt. In bilayers where polymer electrolyte layers are fabricated on top of Lipon, the interfacial resistance dominates transport. At 25 C, the interfacial resistance is at least three times greater than the sum of the Lipon and polymer electrolyte resistances. By reversing the structure and fabricating Lipon on top of the polymer electrolytes, the interfacial resistance is eliminated. Experiments to elucidate the origin of the interfacial resistance in the polymer-on-Lipon bilayers reveal that the solvent mixtures used to fabricate the polymer layers do not degrade the Lipon layer. The importance of the polymer electrolytes' mechanical properties is also discussed.

  6. FTIR spectroscopy and thermodynamics of hydrogen adsorbed in a cross-linked polymer.

    PubMed

    Spoto, Giuseppe; Vitillo, Jenny G; Cocina, Donato; Damin, Alessandro; Bonino, Francesca; Zecchina, Adriano

    2007-09-28

    The adsorption of H(2) in a cross-linked poly(styrene-co-divinylbenzene) (St-DVB) microporous polymer (BET surface area 920 m(2) g(-1)) is studied by volumetric and gravimetric methods, FTIR spectroscopy at variable temperature (300-14 K) and ab initio calculations. At 77 K the polymer reversibly stores up to 1.3 mass% H(2) at a pressure of 1 bar and 1.8 mass% at 10 bar. The adsorption process involves the specific interaction of H(2) with the structural phenyl rings through weak dispersive forces. The interacting molecules become IR active and give rise to vibrational and rotational-vibrational manifestations which are affected by the temperature, the contact time and the H(2) equilibrium pressure. The spectra of the H(2)/St-DVB system reported here represent the first IR evidence of the adsorption of hydrogen on unsaturated molecules. The adsorption enthalpy is evaluated by the VTIR (variable temperature IR spectroscopy) method (C. Otero Areán et al., Phys. Chem. Chem. Phys., 2007, DOI: 10.1039/b615535a) and compared with the results of ab initio calculations for the H(2)/benzene interaction and with literature data.

  7. Silica-shell cross-linked micelles encapsulating fluorescent conjugated polymers for targeted cellular imaging.

    PubMed

    Tan, Happy; Zhang, Yu; Wang, Miao; Zhang, Zhongxing; Zhang, Xinhai; Yong, Anna Marie; Wong, Siew Yee; Chang, Alex Yuang-chi; Chen, Zhi-Kuan; Li, Xu; Choolani, Mahesh; Wang, John

    2012-01-01

    A bioinspired silification approach was successfully used to encapsulate fluorescent conjugated polymers inside silica-shell cross-linked polymeric micelles (CP-SSCL) in the highly benign synthesis environment of room temperature and near-neutral aqueous environment. Four different conjugated polymers were employed to demonstrate the versatility of the bioinspired silification, resulting in the formation of CP-SSCL with different emission wavelengths across the visible spectrum. The CP-SSCL are characterized by a large absorption coefficient and high quantum yield, indicating that they exhibit the required high fluorescence brightness for cellular imaging application. In addition, the CP-SSCL also exhibit a high colloidal stability and low cytotoxicity. The in vitro studies of using MDA-MB-231 breast cancer cells show that the CP-SSCL are successfully uptaken by the cancer cells and located at the cytoplasm of the cells. Furthermore, by conjugating folic acid on their surfaces, the uptake of CP-SSCL by MDA-MB-231 cells was enhanced significantly, suggesting their great potential for targeted imaging and early detection of cancer cells. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Fracture Simulation of Highly Crosslinked Polymer Networks: Triglyceride-Based Adhesives

    NASA Astrophysics Data System (ADS)

    Lorenz, Christian; Stevens, Mark; Wool, Richard

    2003-03-01

    The ACRES program at the U. of Delaware has shown that triglyceride oils derived from plants are a favorable alternative to the traditional adhesives. The triglyceride networks are formed from an initial mixture of styrene monomers, free-radical initiators and triglycerides. We have performed simulations to study the effect of physical composition and physical characteristics of the triglyceride network on the strength of triglyceride network. A coarse-grained, bead-spring model of the triglyceride system is used. The average triglyceride consists of 6 beads per chain, the styrenes are represented as a single bead and the initiators are two bead chains. The polymer network is formed using an off-lattice 3D Monte Carlo simulation, in which the initiators activate the styrene and triglyceride reactive sites and then bonds are randomly formed between the styrene and active triglyceride monomers producing a highly crosslinked polymer network. Molecular dynamics simulations of the network under tensile and shear strains were performed to determine the strength as a function of the network composition. The relationship between the network structure and its strength will also be discussed.

  9. Prediction of crosslink density of solid propellant binders. [curing of elastomers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.

    1976-01-01

    A quantitative theory is outlined which allows calculation of crosslink density of solid propellant binders from a small number of predetermined parameters such as the binder composition, the functionality distributions of the ingredients, and the extent of the curing reaction. The parameter which is partly dependent on process conditions is the extent of reaction. The proposed theoretical model is verified by independent measurement of effective chain concentration and sol and gel fractions in simple compositions prepared from model compounds. The model is shown to correlate tensile data with composition in the case of urethane-cured polyether and certain solid propellants. A formula for the branching coefficient is provided according to which if one knows the functionality distributions of the ingredients and the corresponding equivalent weights and can measure or predict the extent of reaction, he can calculate the branching coefficient of such a system for any desired composition.

  10. Prediction of crosslink density of solid propellant binders. [curing of elastomers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.

    1976-01-01

    A quantitative theory is outlined which allows calculation of crosslink density of solid propellant binders from a small number of predetermined parameters such as the binder composition, the functionality distributions of the ingredients, and the extent of the curing reaction. The parameter which is partly dependent on process conditions is the extent of reaction. The proposed theoretical model is verified by independent measurement of effective chain concentration and sol and gel fractions in simple compositions prepared from model compounds. The model is shown to correlate tensile data with composition in the case of urethane-cured polyether and certain solid propellants. A formula for the branching coefficient is provided according to which if one knows the functionality distributions of the ingredients and the corresponding equivalent weights and can measure or predict the extent of reaction, he can calculate the branching coefficient of such a system for any desired composition.

  11. Instantaneous Pulsed-Light Cross-Linking of a Polymer Gate Dielectric for Flexible Organic Thin-Film Transistors.

    PubMed

    Kim, Soo Jin; Jang, Mi; Yang, Hee Yeon; Cho, Jinhan; Lim, Ho Sun; Yang, Hoichang; Lim, Jung Ah

    2017-04-05

    We report the instantaneous pulsed-light cross-linking of polymer gate dielectrics on a flexible substrate by using intensely pulsed white light (IPWL) irradiation. Irradiation with IPWL for only 1.8 s of a poly(4-vinylphenol) (PVP) thin film with the cross-linking agent poly(melamine-co-formaldehyde) (PMF) deposited on a plastic substrate was found to yield fully cross-linked PVP films. It was confirmed that the IPWL-cross-linked PVP films have smooth pinhole-free surfaces and exhibit a low leakage current density, organic solvent resistance, and good compatibility with organic semiconductor, and that they can be used as replacements for typical PVP dielectrics that are cross-linked with time and energy intensive thermal heating processes. The synchronization of the IPWL irradiation with substrate transfer was found to enable the preparation of cross-linked PVP films on large area substrates with a highly uniform capacitance. Flexible OTFT based on IPWL-cross-linked PVP dielectrics were found to exhibit good electrical performance that is comparable to that of devices with thermally cross-linked PVP dielectric, as well as excellent deformation stability even at a bending radius of 3 mm.

  12. Solution-processed cross-linkable hole selective layer for polymer solar cells in the inverted structure

    NASA Astrophysics Data System (ADS)

    Sun, Yanming; Gong, Xiong; Hsu, Ben B. Y.; Yip, Hin-Lap; Jen, Alex K.-Y.; Heeger, Alan J.

    2010-11-01

    Solution-processed cross-linkable tetraphenyldiamine-containing material (TPD-BVB) as a highly efficient hole selective transport layer was demonstrated. Polymer solar cells (PSCs) with an inverted structure fabricated with a thin cross-linked TPD-BVB film show comparable efficiency and superior long-term air stability when compared to devices fabricated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Thus, solution-processed TPD-BVB is an attractive alternative to PEDOT:PSS as a hole extraction layer in inverted structure PSCs.

  13. Crosslinking of trimethylene carbonate and D, L-lactide (co-) polymers by gamma irradiation in the presence of pentaerythritol triacrylate.

    PubMed

    Bat, Erhan; van Kooten, Theo G; Feijen, Jan; Grijpma, Dirk W

    2011-07-07

    High-molecular-weight (co)polymers of trimethylene carbonate and D,L-lactide are efficiently crosslinked using PETA during gamma irradiation. Form-stable networks with gel contents of 86 ± 5 to 96 ± 1 are obtained from non-crystalline (co)polymers. Glass transition temperatures and elastic moduli of the networks can be varied by adjusting the copolymer composition. The PETA-containing (co)polymer networks are not cytotoxic. Upon incubation in macrophage cultures for 14 d, all (co)polymer films and PETA-containing network films erode to varying extents, showing that these materials can be degraded by cell-mediated erosion processes. This method is very useful for the facile preparation of TMC- and DLLA-containing form-stable networks from high-molecular-weight polymers. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Polymer electrolyte based on crosslinked poly(glycidyl methacrylate) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

    SciTech Connect

    Fei, Beatrice Wong Chui; Hanifah, Sharina Abu; Ahmad, Azizan; Hassan, Nur Hasyareeda

    2015-09-25

    Polymer electrolytes based on crosslinked poly(glycidyl methacrylate) as polymer host and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimTFSI) as incorporated salt were prepared by in-situ photopolymerization technique. The complexes with different mass ratio of glycidyl methacrylate (GMA) monomer to BmimTFSI were investigated. The ionic conductivity of the polymer electrolyte was increased and reach the highest value of 7.50 × 10{sup −4} S cm{sup −1} at the ratio of 3:7 (GMA: BmimTFSI). The interaction between the polymer host and ionic liquid was proved by Attenuated Total Reflectance-Fourier Transformation Infra-Red Spectroscopy (ATR-FTIR). Meanwhile, the X-ray diffraction analysis shows the amorphousity of the polymer electrolyte film increase with the ionic liquid ratio.

  15. Solid polymer electrolytes for rechargeable batteries. Final report

    SciTech Connect

    Narang, S.C.; Ventura, S.C.

    1992-02-01

    SRI International has synthesized and tested new, dimensionally stable polymer electrolytes for high energy density rechargeable lithium batteries. We have prepared semi-interpenetrating networks of sulfur-substituted polyethyleneoxide with tetmethylorthosilicate (TEOS). The in situ hydrolysis of TEOS produces a mechanically stable three-dimensional network that entangles the polymer electrolytes and makes the film dimensionally flexible and stable. With this approach, the best dimensionally stable polymer electrolyte of this type produced so far, has a room temperature lithium ion conductivity of 7.5 {times} 10{sup {minus}4} S cm{sup {minus}1}. Another type of solid polymer electrolytes, polydiacetylene-based single-ion conductors with high room temperature proton conductivity were also developed. The best conductivity of these polymers is two orders of magnitude higher than that of Nafion under comparable experimental conditions. With further appropriate chemical modification, the new polymers could be used in fuel cells.

  16. Suppression of lithium dendrite growth using cross-linked polyethylene/poly(ethylene oxide) electrolytes: a new approach for practical lithium-metal polymer batteries.

    PubMed

    Khurana, Rachna; Schaefer, Jennifer L; Archer, Lynden A; Coates, Geoffrey W

    2014-05-21

    Solid polymer electrolyte (SPE) membranes are a critical component of high specific energy rechargeable Li-metal polymer (LMP) batteries. SPEs exhibit low volatility and thus increase the safety of Li-based batteries compared to current state-of-the-art Li-ion batteries that use flammable small-molecule electrolytes. However, most SPEs exhibit low ionic conductivity at room temperature, and often allow the growth of lithium dendrites that short-circuit the batteries. Both of these deficiencies are significant barriers to the commercialization of LMP batteries. Herein we report a cross-linked polyethylene/poly(ethylene oxide) SPE with both high ionic conductivity (>1.0 × 10(-4) S/cm at 25 °C) and excellent resistance to dendrite growth. It has been proposed that SPEs with shear moduli of the same order of magnitude as lithium could be used to suppress dendrite growth, leading to increased lifetime and safety for LMP batteries. In contrast to the theoretical predictions, the low-modulus (G' ≈ 1.0 × 10(5) Pa at 90 °C) cross-linked SPEs reported herein exhibit remarkable dendrite growth resistance. These results suggest that a high-modulus SPE is not a requirement for the control of dendrite proliferation.

  17. AIE-Active Tetraphenylethylene Cross-Linked N-Isopropylacrylamide Polymer: A Long-Term Fluorescent Cellular Tracker.

    PubMed

    Ma, Hengchang; Qi, Chunxuan; Cheng, Chao; Yang, Zengming; Cao, Haiying; Yang, Zhiwang; Tong, Jinhui; Yao, Xiaoqiang; Lei, Ziqiang

    2016-04-06

    There is a great demand to understand cell transplantation, migration, division, fusion, and lysis. Correspondingly, illuminant object-labeled bioprobes have been employed as long-term cellular tracers, which could provide valuable insights into detecting these biological processes. In this work, we designed and synthesized a fluorescent polymer, which was comprised of hydrophilic N-isopropylacrylamide polymers as matrix and a hydrophobic tetraphenylethene (TPE) unit as AIE-active cross-linkers (DDBV). It was found that when the feed molar ratio of N-isopropylacrylamides to cross-linkers was 22:1, the produced polymers demonstrated the desirable LCST at 37.5 °C. And also, the temperature sensitivity of polymers could induce phase transfer within a narrow window (32-38 °C). Meanwhile, phase transfer was able to lead the florescent response. And thus, we concluded that two responses occur when one stimulus is input. Therefore, the new cross-linker of DDBV rendered a new performance from PNIPAm and a new chance to create new materials. Moreover, the resulted polymers demonstrated very good biocompatibility with living A549 human lung adenocarcinoma cells and L929 mouse fibroblast cells, respectively. Both of these cells retained very active viabilities in the concentration range of 7.8-125 μL/mg of polymers. Notably, P[(NIPAm)22-(DDBV)1] (P6) could be readily internalized by living cells with a noninvasive manner. The cellular staining by the fluorescent polymer is so indelible that it enables cell tracing for at least 10 passages.

  18. On the influence of crosslinker on template complexation in molecularly imprinted polymers: a computational study of prepolymerization mixture events with correlations to template-polymer recognition behavior and NMR spectroscopic studies.

    PubMed

    Shoravi, Siamak; Olsson, Gustaf D; Karlsson, Björn C G; Nicholls, Ian A

    2014-06-12

    Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer-crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity.

  19. On the Influence of Crosslinker on Template Complexation in Molecularly Imprinted Polymers: A Computational Study of Prepolymerization Mixture Events with Correlations to Template-Polymer Recognition Behavior and NMR Spectroscopic Studies

    PubMed Central

    Shoravi, Siamak; Olsson, Gustaf D.; Karlsson, Björn C. G.; Nicholls, Ian A.

    2014-01-01

    Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer–crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity. PMID:24927149

  20. Solid polymer battery electrolyte and reactive metal-water battery

    DOEpatents

    Harrup, Mason K.; Peterson, Eric S.; Stewart, Frederick F.

    2000-01-01

    In one implementation, a reactive metal-water battery includes an anode comprising a metal in atomic or alloy form selected from the group consisting of periodic table Group 1A metals, periodic table Group 2A metals and mixtures thereof. The battery includes a cathode comprising water. Such also includes a solid polymer electrolyte comprising a polyphosphazene comprising ligands bonded with a phosphazene polymer backbone. The ligands comprise an aromatic ring containing hydrophobic portion and a metal ion carrier portion. The metal ion carrier portion is bonded at one location with the polymer backbone and at another location with the aromatic ring containing hydrophobic portion. The invention also contemplates such solid polymer electrolytes use in reactive metal/water batteries, and in any other battery.

  1. Polyethylene glycol as a solid polymer electrolyte

    SciTech Connect

    Cha, D.K.; Park, S.M.

    1997-12-01

    Polymer electrolytes were prepared from polyethylene glycol (PEG)-lithium perchlorate complexes and characterized at a stainless steel electrode using a variety of electrochemical techniques. The charge transfer process was affected by the oxide film on the stainless steel electrode surface in the early stages of redox processes. The polymer electrolytes showed a transference number of 0.2 for Li{sup +}. The conductivity of the PEG-10000 electrolyte has been determined to be 4.7 {times} 10{sup {minus}5} S/cm. This rather high value is attributed to the anionic end groups increasing the polarity of the matrix.

  2. Nanostructure enhanced ionic transport in fullerene reinforced solid polymer electrolytes.

    PubMed

    Sun, Che-Nan; Zawodzinski, Thomas A; Tenhaeff, Wyatt E; Ren, Fei; Keum, Jong Kahk; Bi, Sheng; Li, Dawen; Ahn, Suk-Kyun; Hong, Kunlun; Rondinone, Adam J; Carrillo, Jan-Michael Y; Do, Changwoo; Sumpter, Bobby G; Chen, Jihua

    2015-03-28

    Solid polymer electrolytes, such as polyethylene oxide (PEO) based systems, have the potential to replace liquid electrolytes in secondary lithium batteries with flexible, safe, and mechanically robust designs. Previously reported PEO nanocomposite electrolytes routinely use metal oxide nanoparticles that are often 5-10 nm in diameter or larger. The mechanism of those oxide particle-based polymer nanocomposite electrolytes is under debate and the ion transport performance of these systems is still to be improved. Herein we report a 6-fold ion conductivity enhancement in PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI)-based solid electrolytes upon the addition of fullerene derivatives. The observed conductivity improvement correlates with nanometer-scale fullerene crystallite formation, reduced crystallinities of both the (PEO)6:LiTFSI phase and pure PEO, as well as a significantly larger PEO free volume. This improved performance is further interpreted by enhanced decoupling between ion transport and polymer segmental motion, as well as optimized permittivity and conductivity in bulk and grain boundaries. This study suggests that nanoparticle induced morphological changes, in a system with fullerene nanoparticles and no Lewis acidic sites, play critical roles in their ion conductivity enhancement. The marriage of fullerene derivatives and solid polymer electrolytes opens up significant opportunities in designing next-generation solid polymer electrolytes with improved performance.

  3. Photoinduced bending behavior of cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone.

    PubMed

    Lv, Jiu-an; Wang, Weiru; Xu, Jixiang; Ikeda, Tomiki; Yu, Yanlei

    2014-07-01

    Cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation.

  4. Self-healing of covalently cross-linked polymers by reshuffling thiuram disulfide moieties in air under visible light.

    PubMed

    Amamoto, Yoshifumi; Otsuka, Hideyuki; Takahara, Atsushi; Matyjaszewski, Krzysztof

    2012-08-02

    Self-healing of covalently cross-linked polymers under an ambient visible light in the bulk state, in air, at room temperature using radical exchange of thiuram disulfide units is reported. The successful attachment of surfaces of cut pieces proceeded under ambient conditions under exposure to visible light from a commercial tabletop lamp, as confirmed by bending and tensile tests. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fine-tuned characterization at the solid/solution interface of organotin compounds grafted onto cross-linked polystyrene by using high-resolution MAS NMR spectroscopy.

    PubMed

    Martins, José C; Mercier, Frédéric A G; Vandervelden, Alexander; Biesemans, Monique; Wieruszeski, Jean-Michel; Humpfer, Eberhard; Willem, Rudolph; Lippens, Guy

    2002-08-02

    The structural characterization of organotin compounds that are grafted onto insoluble cross-linked polymers has necessarily been limited to elemental analysis, infrared spectroscopy, and in a few instances, solid-state NMR spectroscopy. This important bottleneck in the development of such grafted systems has been addressed by using high-resolution magic angle spinning (hr-MAS) NMR spectroscopy. The great potential of this technique is demonstrated through the structural characterization of diphenylbutyl-(3,4) and dichlorobutylstannanes (5,6), grafted onto divinylbenzene cross-linked polystyrene by means of a suitable linker (1, 2). First, conditions suitable for the application of hr-MAS NMR spectroscopy were identified by characterizing the (1)H resonance line widths of the grafted organotin moiety following swelling of the functionalized beads in eight representative solvents. The presence of clearly identifiable tin coupling patterns in both the 1D (13)C and 2D (1)H-(13)C HSQC spectra, and the incorporation of (119)Sn chemical shift and connectivity information from hr-MAS 1D (119)Sn and 2D (1)H-(119)Sn HMQC spectra, provide an unprecedented level of characterization of grafted organotins directly at the solid/liquid interface. In addition, the use of hr-MAS (119)Sn NMR for reaction monitoring, impurity detection, and quantification and assessment of the extent of coordination reveals its promise as a novel tool for the investigation of polymer-grafted organotin compounds. The approach described here should be sufficiently general for extension to a variety of other nuclei of interest in polymer-supported organometallic chemistry.

  6. Ionically Cross-Linked Polymer Networks for the Multiple-Month Release of Small Molecules

    PubMed Central

    2016-01-01

    Long-term (multiple-week or -month) release of small, water-soluble molecules from hydrogels remains a significant pharmaceutical challenge, which is typically overcome at the expense of more-complicated drug carrier designs. Such approaches are payload-specific and include covalent conjugation of drugs to base materials or incorporation of micro- and nanoparticles. As a simpler alternative, here we report a mild and simple method for achieving multiple-month release of small molecules from gel-like polymer networks. Densely cross-linked matrices were prepared through ionotropic gelation of poly(allylamine hydrochloride) (PAH) with either pyrophosphate (PPi) or tripolyphosphate (TPP), all of which are commonly available commercial molecules. The loading of model small molecules (Fast Green FCF and Rhodamine B dyes) within these polymer networks increases with the payload/network binding strength and with the PAH and payload concentrations used during encapsulation. Once loaded into the PAH/PPi and PAH/TPP ionic networks, only a few percent of the payload is released over multiple months. This extended release is achieved regardless of the payload/network binding strength and likely reflects the small hydrodynamic mesh size within the gel-like matrices. Furthermore, the PAH/TPP networks show promising in vitro cytocompatibility with model cells (human dermal fibroblasts), though slight cytotoxic effects were exhibited by the PAH/PPi networks. Taken together, the above findings suggest that PAH/PPi and (especially) PAH/TPP networks might be attractive materials for the multiple-month delivery of drugs and other active molecules (e.g., fragrances or disinfectants). PMID:26811936

  7. Initial Drug Dissolution from Amorphous Solid Dispersions Controlled by Polymer Dissolution and Drug-Polymer Interaction.

    PubMed

    Chen, Yuejie; Wang, Shujing; Wang, Shan; Liu, Chengyu; Su, Ching; Hageman, Michael; Hussain, Munir; Haskell, Roy; Stefanski, Kevin; Qian, Feng

    2016-10-01

    To identify the key formulation factors controlling the initial drug and polymer dissolution rates from an amorphous solid dispersion (ASD). Ketoconazole (KTZ) ASDs using PVP, PVP-VA, HMPC, or HPMC-AS as polymeric matrix were prepared. For each drug-polymer system, two types of formulations with the same composition were prepared: 1. Spray dried dispersion (SDD) that is homogenous at molecular level, 2. Physical blend of SDD (80% drug loading) and pure polymer (SDD-PB) that is homogenous only at powder level. Flory-Huggins interaction parameters (χ) between KTZ and the four polymers were obtained by Flory-Huggins model fitting. Solution (13)C NMR and FT-IR were conducted to investigate the specific drug-polymer interaction in the solution and solid state, respectively. Intrinsic dissolution of both the drug and the polymer from ASDs were studied using a Higuchi style intrinsic dissolution apparatus. PXRD and confocal Raman microscopy were used to confirm the absence of drug crystallinity on the tablet surface before and after dissolution study. In solid state, KTZ is completely miscible with PVP, PVP-VA, or HPMC-AS, demonstrated by the negative χ values of -0.36, -0.46, -1.68, respectively; while is poorly miscible with HPMC shown by a positive χ value of 0.23. According to solution (13)C NMR and FT-IR studies, KTZ interacts with HPMC-AS strongly through H-bonding and dipole induced interaction; with PVPs and PVP-VA moderately through dipole-induced interactions; and with HPMC weakly without detectable attractive interaction. Furthermore, the "apparent" strength of drug-polymer interaction, measured by the extent of peak shift on NMR or FT-IR spectra, increases with the increasing number of interacting drug-polymer pairs. For ASDs with the presence of considerable drug-polymer interactions, such as KTZ/PVPs, KTZ/PVP-VA, or KTZ /HPMC-AS systems, drug released at the same rate as the polymer when intimate drug-polymer mixing was ensured (i.e., the SDD systems

  8. Porous Polystyrene Monoliths and Microparticles Prepared from Core Cross-linked Star (CCS) Polymers-Stabilized Emulsions.

    PubMed

    Chen, Qijing; Shi, Ting; Han, Fei; Li, Zihan; Lin, Chao; Zhao, Peng

    2017-08-17

    A hydrophobic CCS polymer of poly(benzyl methacrylate) (PBzMA) was prepared in toluene by reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization. The CCS polymer, with poly(benzyl methacrylate) as the arm and crosslinked N, N'-bis(acryloyl)cystamine (BAC) as the core, was confirmed by characterization with gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. Three kinds of oils (toluene, anisole and styrene) were chosen to study the emulsification properties of PBzMA CCS polymer. The oils can be emulsified by CCS polymer to form water-in-oil (w/o) emulsions. Moreover, w/o high internal phase emulsions (HIPEs) can be obtained with the increase of toluene and styrene volume fractions from 75% to 80%. Porous polystyrene monolith and microparticles were prepared from the emulsion templates and characterized by the scanning electronic microscopy (SEM). With the internal phase volume fraction increased, open-pore porous monolith was obtained.

  9. Solid Rocket Fuel Constitutive Theory and Polymer Cure

    NASA Technical Reports Server (NTRS)

    Ream, Robert

    2006-01-01

    Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

  10. Solid-state NMR characterization of cross-linking in EPDM/PP blends from 1H-13C polarization transfer dynamics.

    PubMed

    Aluas, Mihaela; Filip, Claudiu

    2005-05-01

    A novel approach for solid-state NMR characterization of cross-linking in polymer blends from the analysis of (1)H-(13)C polarization transfer dynamics is introduced. It extends the model of residual dipolar couplings under permanent cross-linking, typically used to describe (1)H transverse relaxation techniques, by considering a more realistic distribution of the order parameter along a polymer chain in rubbers. Based on a systematic numerical analysis, the extended model was shown to accurately reproduce all the characteristic features of the cross-polarization curves measured on such materials. This is particularly important for investigating blends of great technological potential, like thermoplastic elastomers, where (13)C high-resolution techniques, such as CP-MAS, are indispensable to selectively investigate structural and dynamical properties of the desired component. The validity of the new approach was demonstrated using the example of the CP build-up curves measured on a well resolved EPDM resonance line in a series of EPDM/PP blends.

  11. Solid Polymer Electrolyte (SPE) fuel cell technology program

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The overall objectives of the Phase IV Solid Polymer Electrolyte Fuel Cell Technology Program were to: (1) establish fuel cell life and performance at temperatures, pressures and current densities significantly higher than those previously demonstrated; (2) provide the ground work for a space energy storage system based on the solid polymer electrolyte technology (i.e., regenerative H2/O2 fuel cell); (3) design, fabricate and test evaluate a full-scale single cell unit. During this phase, significant progress was made toward the accomplishment of these objectives.

  12. Plasticization and crosslinking effects of acetone-formaldehyde and tannin resins on wheat protein-based natural polymers.

    PubMed

    Zhang, Xiaoqing; Do, My Dieu

    2009-07-06

    Efficient plasticization and sufficient crosslinking were achieved by using an acetone-formaldehyde (AF) resin as an additive in the thermal processing of wheat protein-based natural polymers. The mobile AF resin and its strong intermolecular interactions with a wheat protein matrix produced sufficient flexibility for the plastics, while the covalent bonds formed between AF and the protein chains also caused the water-soluble resin to be retained in the materials under wet conditions. The mechanical properties of the materials were also enhanced as an additional benefit due to the formation of crosslinked networks through the polymer matrix. Tensile strength was further enhanced when using AF in conjunction with tannin resin (AFTR) in the systems as rigid aromatic structures were formed in the crosslinking segments. Different components in wheat proteins (WPs) or wheat gluten (WG) (e.g., proteins, residual starch and lipids) displayed different capabilities in interaction and reaction with the AFTR additives, and thus resulted in different performances when the ratio of these components varied in the materials. The application of the AFTR additives provides a feasible methodology to thermally process wheat protein-based natural polymers with improved mechanical performance and water-resistant properties.

  13. Removing Cr(VI) from aqueous solutions using a functional ionic liquid-based cross-linked polymer.

    PubMed

    Gao, Hejun; Wang, Yun; Zheng, Liqiang

    2014-05-01

    A novel functional ionic liquid-based cross-linked polymer was synthesized from 1-aminoethyl-3-vinylimidazolium chloride hydrochloride and divinylbenzene. The physicochemical properties of the adsorbent were investigated using scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The adsorption capacity of the novel cross-linked polymer with respect to Cr(VI) was investigated using a batch adsorption procedure and the kinetics and thermodynamics of the adsorption process were further investigated. It was found that the adsorption kinetics was well fitted by a pseudo-second-order model and the adsorption isotherms agreed well with the Langmuir model. The maximum adsorption capacity after 5 min at room temperature (25 °C) was found to be 391.4 mg/g, which was much better than the most of the previously reported adsorbents. The adsorption process was found to be dominated by electrostatic interactions. The introduction of functional ionic liquid moieties into cross-linked poly(divinylbenzene) polymer constitutes a new and efficient kind of adsorbent. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Regulation Mechanism of Salt Ions for Superlubricity of Hydrophilic Polymer Cross-Linked Networks on Ti6Al4V.

    PubMed

    Zhang, Caixia; Liu, Yuhong; Liu, Zhifeng; Zhang, Hongyu; Cheng, Qiang; Yang, Congbin

    2017-03-07

    Poly(vinylphosphonic acid) (PVPA) cross-linked networks on Ti6Al4V show superlubricity behavior when sliding against polytetrafluoroethylene in water-based lubricants. The superlubricity can occur but only with the existence of salt ions in the polymer cross-linked networks. This is different from the phenomenon in most polymer brushes. An investigation into the mechanism revealed that cations and anions in the lubricants worked together to yield the superlubricity even under harsh conditions. It is proposed that the preferential interactions of cations with PVPA molecules rather than water molecules are the main reason for the superlubricity in water-based lubricants. The interaction of anions with water molecules regulates the properties of the tribological interfaces, which influences the magnitude of the friction coefficient. Owing to the novel cross-linked networks and the interactions between cations and polymer molecules, their superlubricity can be maintained even at a high salt ion concentration of 5 M. These excellent properties make PVPA-modified Ti6Al4V a potential candidate for application in artificial implants.

  15. Biomimetic Submicroarrayed Cross-Linked Liquid Crystal Polymer Films with Different Wettability via Colloidal Lithography.

    PubMed

    Zhan, Yuanyuan; Zhao, Jianqiang; Liu, Wendong; Yang, Bai; Wei, Jia; Yu, Yanlei

    2015-11-18

    Photoresponsive cross-linked liquid crystal polymer (CLCP) films with different surface topographies, submicropillar arrays, and submicrocone arrays were fabricated through colloidal lithography technique by modulating different types of etching masks. The prepared submicropillar arrays were uniform with an average pillar diameter of 250 nm and the cone bottom diameter of the submicrocone arrays was about 400 nm, which are much smaller than previously reported CLCP micropillars. More interestingly, these two species of films with the same chemical structure represented completely different wetting behavior of water adhesion and mimicked rose petal and lotus leaf, respectively. Both the submicropillar arrayed film and the submicrocone arrayed film exhibited superhyrophobicity with a water contact angle (CA) value of 144.0 ± 1.7° and 156.4 ± 1.2°, respectively. Meanwhile, the former demonstrated a very high sliding angle (SA) greater than 90°, and thus, the water droplet was pinned on the surface as rose petal. On the contrary, the SA of the submicrocone arrayed CLCP film consisting of micro- and nanostructure was only 3.1 ± 2.0°, which is as low as that of lotus leaf. Furthermore, the change on the wettability of the films was also investigated under alternating irradiation of visible light with two different wavelengths, blue light and green light.

  16. Optimization of β-cyclodextrin cross-linked polymer for monitoring of quercetin.

    PubMed

    Zhu, Xiashi; Ping, Wenhui

    2014-11-11

    A novel method for the separation/analysis of quercetin was described, which was based on the investigation of the inclusion interactions of β-cyclodextrin cross-linked polymer (β-CDCP) with quercetin (Qu) and the adsorption behavior of Qu on β-CDCP. The inclusion interaction of β-CDCP with Qu was studied through FTIR, TGA and 13C NMR. Under the optimum conditions, the preconcentration factor of the proposed method was approximately 8.8, the β-CDCP could be used repeatedly for 30 times and offered better recovery. The linear range, limit of detection (LOD) and the relative standard deviation (RSD) was found to be 0.10-12.0 μg mL(-1), 4.6 ng mL(-1) and 3.10% (n=3, c=2.0 μg mL(-1)) respectively. This technique had been successfully applied to the determination of Qu in real samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Optimization of β-cyclodextrin cross-linked polymer for monitoring of quercetin

    NASA Astrophysics Data System (ADS)

    Zhu, Xiashi; Ping, Wenhui

    2014-11-01

    A novel method for the separation/analysis of quercetin was described, which was based on the investigation of the inclusion interactions of β-cyclodextrin cross-linked polymer (β-CDCP) with quercetin (Qu) and the adsorption behavior of Qu on β-CDCP. The inclusion interaction of β-CDCP with Qu was studied through FTIR, TGA and 13C NMR. Under the optimum conditions, the preconcentration factor of the proposed method was approximately 8.8, the β-CDCP could be used repeatedly for 30 times and offered better recovery. The linear range, limit of detection (LOD) and the relative standard deviation (RSD) was found to be 0.10-12.0 μg mL-1, 4.6 ng mL-1 and 3.10% (n = 3, c = 2.0 μg mL-1) respectively. This technique had been successfully applied to the determination of Qu in real samples.

  18. Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Primo, Gastón A.; Alvarez Igarzabal, Cecilia I.; Pino, Gustavo A.; Ferrero, Juan C.; Rossa, Maximiliano

    2016-04-01

    This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

  19. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, Terje A.; Lee, Hung S.; Okamoto, Yoshiyuki

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  20. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, T.A.; Lee, H.S.; Okamoto, Yoshiyuki.

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  1. Deformation and Fracture Maps for Polymer-Foams, Solid Polymers and Polymer-Composites.

    DTIC Science & Technology

    1984-04-01

    b . J . ?is. L The 3-dimansional structure of open and closed- call foin, idealised. The cal~l walls meet so that loads cause bending moments to...obeale o ~ . . -,aaI. .n-. " j "" T,’ b " ,3 .’-1/ - b ,"ch yie "-’.’,."w C"-" ESI-- S-AIN. %.:.1i a nl., i.7 ",." 7ig. 2 The typical shape of. th:e st.,e...Krevelen, D.W. (1976) "Properties of Polymers", Elsevier, Amsterdam, * Ch.15, Section B . Ward, 1.11. (1971) "Mechanical Properties-of Solid

  2. Injectable biodegradable polymer composites based on poly(propylene fumarate) crosslinked with poly(ethylene glycol)-dimethacrylate.

    PubMed

    He, S; Yaszemski, M J; Yasko, A W; Engel, P S; Mikos, A G

    2000-12-01

    New injectable, in situ crosslinkable biodegradable polymer composites were investigated consisting of poly(propylene fumarate) (PPF), poly(ethylene glycol)-dimethacrylate (PEG-DMA), and beta-tricalcium phosphate (beta-TCP). We examined the effects of the PEG-DMA/PPF double-bond ratio and beta-TCP content on the crosslinking characteristics of the composites including the maximum crosslinking temperature and the gel point, as well as the properties of the crosslinked composites such as the compressive strength and modulus, and the water-holding capacity. The maximum crosslinking temperature was constant averaging 39.7 degrees C for the composite formulations tested. The gel points varied from 8.0 +/- 1.0 to 12.6 +/- 2.5 min and were not affected by the relative amounts of PEG-DMA. The compressive strength at yield of PEG-DMA/PPF composites without beta-TCP increased from 5.9 +/- 1.0 to 11.2 +/- 2.2 MPa as the double-bond ratio of PEG-DMA/PPF increased from 0.38 to 1.88. An increase in compressive modulus was also observed from 30.2 +/- 3.5 to 58.4 +/- 6.2 MPa for the same range of the PEG-DMA/PPF double-bond ratio. Also, the addition of beta-TCP (33 wt%) enhanced the mechanical properties of all composites. The equilibrium water content of networks without beta-TCP increased from 21.7 +/- 0.2 to 30.6 +/- 0.2% for a double-bond ratio of PEG-DMA/PPF ranging from 0.38 to 1.88. However, the mechanical properties of the swollen composites under compression were smaller than the dry ones. These data demonstrate the feasibility of fabricating injectable biodegradable polymer composites with engineered mechanical properties for orthopedic tissue engineering.

  3. Adsorption study of a commonly used antidepressant drug, fluoxetine hydrochloride, onto a crosslinked β-cyclodextrin-carboxymethylcellulose polymer.

    PubMed

    Bonenfant, Danielle; Mimeault, Murielle; Niquette, Patrick; Hausler, Robert

    2012-01-01

    A study was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies to establish the efficiency of adsorption of fluoxetine hydrochloride (FLU), onto a crosslinked β-cyclodextrin-carboxymethylcellulose (β-CD-CMC) polymer. The adsorption was performed in mixtures containing aqueous FLU solution at 20 mg/L and 0.01-0.30 g of the β-CD-CMC polymer, at 25 °C, and atmospheric pressure under stirring. The results have revealed that the adsorption is a rapid process and the polymer possesses a high affinity for FLU with an adsorption capacity of 5.076 mg of FLU/g of polymer. This adsorption may involve the formation of a stable inclusion compound β-CD-CMC/FLU through the penetration of the FLU aromatic ring (A and/or B) into the β-CD cavity, and a physical adsorption with the polymer network. The inclusion compound can be stabilized by the formation of H-bonds between the -CF(3) group of FLU and the 6'-OH group of β-CD, and van der Waals interactions between the FLU aromatic ring and β-CD cavity. The data from a kinetic study have also indicated that the adsorption process was well described by the pseudo-second-order kinetic model, in which the initial adsorption rate and constant were estimated at 1.938 mg/g min and 0.075 g/mg min, respectively. Moreover, the results of adsorption equilibrium fitted the Freundlich isotherm, indicating a multilayer coverage and heterogeneous surface. Together, these results suggest that the adsorption of FLU onto the crosslinked β-CD-CMC polymer could constitute an advantageous technology for removing this commonly used antidepressant drug from wastewater due to the high adsorption capacity of the polymer and non-toxic character of β-CD to humans and environment.

  4. Quantifying the Solid State Charge Transport Characteristics of Radical Polymers

    NASA Astrophysics Data System (ADS)

    Baradwaj, Aditya; Rostro, Lizbeth; Boudouris, Bryan

    2014-03-01

    Radical polymers are an emerging class of functional macromolecules that have shown immense potential to transport charge in electrolyte-supported applications. However, quantifying the ability of these non-conjugated macromolecules to conduct charge has not been as well-studied in the solid state. Here, we present the characterization of the charge transport capability of a radical polymer, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA) with well-defined molecular properties in the solid state. We show that charge transport occurs across the singularly occupied molecular orbital (SOMO) level of PTMA, and that this level is 5.2 eV removed from free vacuum. Additionally, we have measured the space-charge limited hole and electron mobility values of PTMA. We find that the mobility values of these radical polymers are of the same order (10-4 cm2 V-1 s-1) of many common conjugated polymers [ e . g . , poly(3-hexylthiophene) (P3HT)]. Furthermore, because the polymer backbone is non-conjugated, these macromolecules are extremely transparent. As such, we anticipate that radical polymers could become an important component of many transparent flexible electronic applications.

  5. Design of Hybrid Solid Polymer Electrolytes: Structure and Properties

    NASA Technical Reports Server (NTRS)

    Bronstein, Lyudmila M.; Karlinsey, Robert L.; Ritter, Kyle; Joo, Chan Gyu; Stein, Barry; Zwanziger, Josef W.

    2003-01-01

    This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.

  6. Fabrication of Si negative electrodes for Li-ion batteries (LIBs) using cross-linked polymer binders

    NASA Astrophysics Data System (ADS)

    Jang, Suk-Yong; Han, Sien-Ho

    2016-12-01

    Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g-1). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible.

  7. Fabrication of Si negative electrodes for Li-ion batteries (LIBs) using cross-linked polymer binders

    PubMed Central

    Jang, Suk-Yong; Han, Sien-Ho

    2016-01-01

    Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g−1). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible. PMID:27991497

  8. Modulated in Vitro Biocompatibility of a Unique Cross-Linked Salicylic Acid-Poly(ε-caprolactone)-Based Biodegradable Polymer.

    PubMed

    Bhaskar, Nitu; Padmavathy, Nagarajan; Jain, Shubham; Bose, Suryasarathi; Basu, Bikramjit

    2016-11-02

    Herein, we report the development of a unique architecture by chemically cross-linking salicylic acid (SA)-based poly(anhydride ester) onto a biodegradable amine-functionalized poly(caprolactone) (PCL), using lactic acid as a spacer. The ester and amide linkages in the SA-PCL polymer, synthesized through melt condensation, were confirmed by NMR and FT-IR spectroscopic techniques. The enzymatic and nonenzymatic hydrolytic degradation profile exhibited linear degradation kinetics over an extended time period (>5 weeks). The compatibility and growth of C2C12 myoblast cells were found to be significantly improved on the fast-degrading SA-PCL substrates compared to those over neat PCL and amine-functionalized PCL. Further, the decreased red blood cell damage, illustrated by 0.39% hemolysis activity and a minimal number of platelet adhesion on a SA-PCL polymeric surface confirmed good hemocompatibility of the as-synthesized polymer. Together with a moderate bactericidal property, the spectrum of properties of this novel polymer can be attributed to the synergistic effect of the presence of chemical moieties of SA and amine groups in PCL. In summary, it is considered that a SA-PCL-based cross-linked composite can be utilized as a new biodegradable polymer.

  9. Clinical safety and wear resistance of the phospholipid polymer-grafted highly cross-linked polyethylene liner.

    PubMed

    Moro, Toru; Takatori, Yoshio; Tanaka, Sakae; Ishihara, Kazuhiko; Oda, Hiromi; Kim, Yoon Taek; Umeyama, Takashige; Fukatani, Eisei; Ito, Hideya; Kyomoto, Masayuki; Oshima, Hirofumi; Tanaka, Takeyuki; Kawaguchi, Hiroshi; Nakamura, Kozo

    2016-11-03

    To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly cross-linked polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly cross-linked polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly cross-linked polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly cross-linked polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly cross-linked polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2

  10. Fabrication and characterization of solid-state, conducting polymer actuators

    SciTech Connect

    Xie, J.; Sansinena, J. M.; Gao, J.; Wang, H. L.

    2004-01-01

    We report here the fabrication and characterization of solid-state, conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhere to a lever arm of an force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torques generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, current, on the bending angle and displacement is also studied using square wave potential.

  11. All solid-state comb-like network polymer electrolytes based on poly(methylsiloxane)

    NASA Astrophysics Data System (ADS)

    Jiang, Hui; Fang, Shibi

    All solid-state comb-like network polymer electrolytes (CNPE) based on poly(methylsiloxane) with pendant PEO chains as internal plasticizing chains (IPC) have been designed and synthesized. Ultraviolet (UV) polymerization method was applied for the curing of CNPEs. Effects of the network structure on the conductive properties and mechanical properties were discussed in details. Ionic conductivity of the prepared CNPE is one order of magnitude larger than those without IPCs, which suggests that the expected drop of conductivity caused by crosslinking has been well compensated by the introduction of IPCs. Maximum conductivity of 1.01 × 10 -4 S cm -1 and maximum tensile strength of 0.66 MPa were obtained at 30 °C. Electrochemical stability and electrolyte/electrodes interfacial stability properties were evaluated by cyclic voltammetry and ac impedance, respectively.

  12. Patterned Attachment of Ultrathin Polymer Layers to Solid Substrates

    NASA Astrophysics Data System (ADS)

    Hammond, Matthew R.; Kramer, Edward J.

    2001-03-01

    A recently reported method for photochemical attachment of ultrathin polymer layers to solid surfaces ^2 is extended to allow lateral patterning of these layers using standard photolithographic equipment. Silane-modified benzophenone molecules are synthesized and deposited as a monolayer on a SiO x surface. A polymer layer placed on top of this monolayer is then bound to the photoreactive benzophenone moieties by illumination with UV light, exposed through a standard photomask. Non-bonded polymer is then washed away, allowing a second polymer to be attached in previously unoccupied areas by subsequent coating and illumination steps. ^2 Prucker, O.; Naumann, C. A.; Rühe, J.; Knoll, W.; Frank, C. W. J. Am. Chem. Soc. 1999, 121, 8766.

  13. Reference electrodes for solid polymer electrolytes

    SciTech Connect

    Johnson, C.S.; Dees, D.W.

    1993-12-31

    Electrochemical experiments were conducted on a binary metallic lithium-tin alloy that may be suitable as a reference electrode of the first kind in studies of lithium-polymer batteries. Two types of tin electrodes were tested: bulk tin foil and tin thin films deposited on a stainless steel substrate. Electrochemical test cells were fabricated, with tin, metallic lithium, poly(ethylene oxide), and lithium trifluoromethanesulfonate as electrodes and polymer electrolyte material. To form the alloy, the tin electrodes were galvanostatically loaded in situ with lithium. Each cell reached one or more steady-state voltage plateaus during the electrochemical reduction of lithium cations at the tin electrode surface. The lithiated tin foil electrode (1 C/cm{sup 2} of charge passed; area {approx} 5 cm{sup 2}; thickness = 1.0 mm) demonstrated good voltage stability over months under open-circuit conditions. This electrode maintained an average open circuit voltage of 0.7336 V with only {plus_minus}0.17 mV variance. Composition of phases in the thin film electrodes (x in Li{sub x}Sn) was coulometrically varied via reversible lithium loading and unloading reactions. Results show that three different, two-phase compositions may be formed that maintain flat voltage regions at approximately 0.53, 0.63, and 0.73 V vs lithium metal.

  14. Removal of highly crosslinked resists and hybrid polymers for single micro parts fabrication and nanoimprint stamp rework

    NASA Astrophysics Data System (ADS)

    Voigt, Anja; Engelke, Rainer; Ahrens, Gisela; Bullerjahn, Franziska; Schleunitz, Arne; Klein, Jan J.; Grützner, Gabi

    2014-03-01

    Thick photoresists, e.g. up to 1 mm layer thickness, are widely used for the manufacture of high aspect ratio microstructures, e.g. as mould for the fabrication of metallic micro parts. Such resists or materials exhibit high mechanical and chemical stability to non-deformably withstand a pattern transfer process, e.g. by electroplating. After the pattern transfer a solvent based removal is difficult or not possible in many cases. A selective mould removal - without the damage of electroplated metal structures - is required for the fabrication of single micro parts. As second application example UV curable and strongly crosslinkable inorganic-organic hybrid polymers such as OrmoComp ® and OrmoStamp ® are used in UV moulding. The cleaning and rework of these moulds or also of stamps for nanoimprint lithography (NIL) is a challenging task with increasing importance. The life time of an expensive master mould or stamp as well as of the replicated working stamps is important, and therefore the ability to rework such stamps without any defect or decreased resolution. Hence, we demonstrate the application of a plasma-assisted removal using the STP 2020 etching tool from MUEGGE [1] for remote dry etching of strongly crosslinked materials, i.e. the development of processes for the isotropical etching of highly crosslinked photoresists and hybrid polymer materials will be presented. In combination with this specific etching tool this technique shows a high potential to make plasma-assisted removal ready for industrial production.

  15. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  16. Field-theoretical Renormalization-Group approach to critical dynamics of crosslinked polymer blends

    NASA Astrophysics Data System (ADS)

    Benhamou, M.; Chahid, M.

    2008-09-01

    We consider a crosslinked polymer blend that may undergo a microphase separation. When the temperature is changed from an initial value towards a final one very close to the spinodal point, the mixture is out equilibrium. The aim is the study of dynamics at a given time t , before the system reaches its final equilibrium state. The dynamics is investigated through the structure factor, S(q, t) , which is a function of the wave vector q , temperature T , time t , and reticulation dose D . To determine the phase behavior of this dynamic structure factor, we start from a generalized Langevin equation (model C) solved by the time composition fluctuation. Beside the standard de Gennes Hamiltonian, this equation incorporates a Gaussian local noise, ζ . First, by averaging over ζ , we get an effective Hamiltonian. Second, we renormalize this dynamic field theory and write a Renormalization-Group equation for the dynamic structure factor. Third, solving this equation yields the behavior of S(q, t) , in space of relevant parameters. As result, S(q, t) depends on three kinds of lengths, which are the wavelength q-1, a time length scale R(t) thicksim t1/z , and the mesh size ξ* . The scale R(t) is interpreted as the size of growing microdomains at time t . When R(t) becomes of the order of ξ* , the dynamics is stopped. The final time, t * , then scales as t * thicksim ξ{ast z} , with the dynamic exponent z = 6 - η . Here, η is the usual Ising critical exponent. Since the final size of microdomains ξ* is very small (few nanometers), the dynamics is of short time. Finally, all these results we obtained from renormalization theory are compared to those we stated in some recent work using a scaling argument.

  17. Crosslinked membranes of sulfonated polyimides for polymer electrolyte fuel cell applications

    NASA Astrophysics Data System (ADS)

    Yaguchi, Kazuaki; Chen, Kangcheng; Endo, Nobutaka; Higa, Mitsuru; Okamoto, Ken-ichi

    Polymer electrolyte fuel cell performance of crosslinked membranes of sulfonated polyimides based on 2,2‧-bis(3-sulfophenoxy) benzidine was investigated at higher temperatures of 90-110 °C, relative humidities of 82-27% RH and pressures of 0.3-0.1 MPa. The operation conditions of temperature, pressure and relative humidity largely affected the PEFC performance in connection with each other. At 90 °C and relatively high humidification of 82/68% RH for hydrogen/air, the cell performance was hardly affected by the pressure and was kept in a high level even at 0.1 MPa. At low humidification of 48% and 27% RH, the cell performance was still kept in a reasonably high level at high pressures above 0.2 MPa, but it largely decreased at low pressures below 0.15 MPa. A slight decrease in ion exchange capacity (IEC) of membrane caused a relatively large decrease in the cell performance at a low relative humidity. With an increase in temperature from 90 to 110 °C, the cell performance largely decreased. For example, the membrane (MX2) with a relatively high IEC of 1.9 mequiv g -1 showed a low maximum output (W max) of 0.30 W cm -2 at 110 °C, 0.2 MPa and 49% RH, which was less than a half of the corresponding value (0.71 W cm -2) at 90 °C. These results indicate that the back-diffusion of water formed at cathode into membrane became less effective at the lower pressure and the higher temperature and for membrane with the lower IEC, resulting in the larger decrease in through-plane proton conductivity under PEFC operation. At 110 °C, 0.3 MPa and 49% RH, MX2 showed the fairly high PEFC performance and durability.

  18. TOPICAL REVIEW: Solid polymer electrolytes: materials designing and all-solid-state battery applications: an overview

    NASA Astrophysics Data System (ADS)

    Agrawal, R. C.; Pandey, G. P.

    2008-11-01

    Polymer electrolytes are promising materials for electrochemical device applications, namely, high energy density rechargeable batteries, fuel cells, supercapacitors, electrochromic displays, etc. The area of polymer electrolytes has gone through various developmental stages, i.e. from dry solid polymer electrolyte (SPE) systems to plasticized, gels, rubbery to micro/nano-composite polymer electrolytes. The polymer gel electrolytes, incorporating organic solvents, exhibit room temperature conductivity as high as ~10-3 S cm-1, while dry SPEs still suffer from poor ionic conductivity lower than 10-5 S cm-1. Several approaches have been adopted to enhance the room temperature conductivity in the vicinity of 10-4 S cm-1 as well as to improve the mechanical stability and interfacial activity of SPEs. In this review, the criteria of an ideal polymer electrolyte for electrochemical device applications have been discussed in brief along with presenting an overall glimpse of the progress made in polymer electrolyte materials designing, their broad classification and the recent advancements made in this branch of materials science. The characteristic advantages of employing polymer electrolyte membranes in all-solid-state battery applications have also been discussed.

  19. Molecularly imprinted polymers-curcuminoids and its application for solid phase extraction

    NASA Astrophysics Data System (ADS)

    Wulandari, Meyliana; Amran, M. B.; Lopez, A. B. Descalzo; Urraca, J. L.; Moreno-Bondi, M. C.

    2014-03-01

    Molecularly Imprinted Polymers (MIPs) for the selective recognition properties of curcumin (CUR), a cancer chemopreventive agent were obtained by a non-covalent imprinting approach with bisdemetoxycurcumin (BDMC) as the template molecule. The double bond of BDMC has been reduced in order not to be involved in polymerization and make the template molecules easy to be eluted. Several functional monomers have been evaluated to maximize the interactions with the template molecule during polymerization. MIPs prepared by bulk of N-(2-aminoethyl) metacrylamid hydrochlorideas functional monomer, ethylene glycol dimethacrylate as crosslinker, 2,2'-azobis (2'4-dimethyl valeronitril) as initiator and acetonitrile as porogen. Non-imprinted polymer (NIP) have been also synthesized for reference purposes. UV-vis spectroscopy has been used to predict the template to functional monomer ratio which indicates the formation of 2:1 complexes between monomer and curcumin and the association constants (K11 = 2529 μM and K12 = 1960.75 μM in acetonitrile). The capacity and imprinting factor have been evaluated as stationary phases in high-pressure liquid chromatography to CUR and BDMC. The binding properties and the homogeneity of the binding sites of the different polymers have been studied by Freundlich isotherm modeling and weight average affinity and number of binding sites. One of the foremost applications of molecular imprinting has been in molecularly imprinted solid phase extraction and it has the ability to separate and preconcentrate between closely related compounds in curcuminoids.

  20. Molecularly imprinted polymer microspheres for solid-phase extraction of protocatechuic acid in Rhizoma homalomenae.

    PubMed

    Chen, Fang-Fang; Wang, Guo-Ying; Shi, Yan-Ping

    2011-10-01

    Molecularly imprinted polymers (MIPs) had been prepared by precipitation polymerization method using acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, acetonitrile as the porogen solvent and protocatechuic acid (PA), one of phenolic acids, as the template molecule. The MIPs were characterized by scanning electron microscopy and Fourier transform infrared, and their performance relative to non-imprinted polymers was assessed by equilibrium binding experiments. Six structurally similar phenolic acids, including p-hydroxybenzoic acid, gallic acid, salicylic acid, syringic acid, vanillic acid, ferulic acid were selected to assess the selectivity and recognition capability of the MIPs. The MIPs were applied to extract PA from the traditional Chinese medicines as a solid-phase extraction sorbent. The resultant cartridge showed that the MIPs have a good extraction performance and were able to selectively extract almost 82% of PA from the extract of Rhizoma homalomenae. Thus, the proposed molecularly imprinted-solid phase extraction-high performance liquid chromatography method can be successfully used to extract and analyse PA in traditional Chinese medicines.

  1. Toward electrochromic device using solid electrolyte with polar polymer host.

    PubMed

    Nguyen, Chien A; Xiong, Shanxin; Ma, Jan; Lu, Xuehong; Lee, Pooi See

    2009-06-11

    Polymer electrolyte is an important component in many multilayer devices such as batteries, fuel cells, and electrochromic devices. The effects of polymer electrolyte solidification on the ionic movement and device performance are presented based on near-infrared (IR) (860-2500 nm) electrochromic (EC) devices using the conducting polymer polyaniline. EC devices using electrolyte with polar polymer host of P(VDF-TrFE) show stable and reversible light modulation up to 65% in gel state and 30% in solid state. This is significantly improved when compared to devices with solidified nonpolar polymer host which retains less than 10% light modulation. Electrochemical impedance combined with in situ light modulation measurement identifies various key characteristics exerted by the electrolyte states on device performance. Gel-state devices are affected by the amount of dissociated ions while ionic movement in the electrolyte bulk and through the electrolyte/EC material interface dictates the light modulation in semisolid devices. For solid-state devices, electronic leakage, ionic dissociation, and interaction with electrochrome molecules have been found to limit the operation.

  2. Analysis physical properties of composites polymer from cocofiber and polypropylene plastic waste with maleic anhydrate as crosslinking agent

    NASA Astrophysics Data System (ADS)

    Pelita, E.; Hidayani, T. R.; Akbar, A.

    2017-07-01

    This research was conducted with the aim to produce composites polymer with polypropylene plastic waste materials and cocofiber which aims to produce wood replacement material in the home furnishings industry. This research was conducted with several stages. The first stage is the process of soaking coco fiber with detergent to remove oil and 2% NaOH. The second stage is to combine the polypropylene plastic waste with cocofiber is a chemical bond, modification by adding maleic anhydride as a crosslinking agent and benzoyl peroxide as an initiator each as much as 1%. Mixing materials done by reflux method using xylene solvent. In this study, carried out a wide range of weight variation of coco fiber are added to the 10, 20, 30, 40 and 50%. The third stage is a polymer composite molding process using hot press at a temperature of 158°C. The results of polymer composites Showed optimum condition on the addition of 40% cocofiber with supple tensile strength value of 90.800 kgf /cm2 and value of elongation break at 3.6726 x 104 (kgf/cm2), melting point at 160.02°C, burning point 463.43°C, residue of TGA is 19%, the density of 0.84 g/mL. From these data, conclude that the resulting polymer composites meet the SNI 03-2105-2006 about ordinary composite polymer and polymer composite structural type 8 regular types from 17.5 to 10.5.

  3. Properties of radiation cured vinyl-divinyl copolymers. Part I. Thermomechanical properties of crosslinked methyl methacrylate polymers

    SciTech Connect

    Micko, M.M.; Paszner, L.

    1980-01-01

    Radiation copolymerization (crosslinking) of methyl methacrylate (MMA) with a series of divinyl monomers containing 1 to 4 ethyleneglycol connecting units between the terminal reactive divinyl units was found to provide numerous improvements in the thermomechanical properties of the copolymers. Thermoplastic poly-MMA was converted to a thermoset copolymer with only small additions (2 to 5%) of the divinyl crosslinking agent. When the measured thermomechanical properties (glass transition temperature, Tg, thermal distortion temperature, TDT; and thermomechanical deformation degree, TDD) of the above crosslinked copolymers were related to the respective crosslink densities (expressed by the copolymer connection number, CN/sub co/) the crosslink efficiency increased in terms of the above parameters in a reverse order as observed for acceleration, i.e., TEGDMA < TrEGDMA < DEGDMA < EGDMA. This observation is readily explained by the relation between segmental mobility of the respective macromolecules of the copolymers formed and the critical thermomechanical parameters which can be determined for such solid copolymers. Segmental mobility of the crosslinking agent increases with increasing molecular bridge length and hence the increased temperature sensitivity of the copolymers to thermal softening and distortion as the bridge length increases from a single ethyleneglycol (EGDMA) to four ethyleneglycol (TEGDMA) units in the bridge connecting the vinyl functions of the divinyl monomers. For all copolymers of this study, the linear thermomechanical deformation coefficient, representing thermal deformation between the plastic and rubbery states, remained relatively constant across a broad temperature interval until the respective TDT temperatures are reached, and decreased exponentially with the divinyl monomer concentration in the copolymer regardless of the connecting bridge length.

  4. SRM (Solid Rocket Motor) propellant and polymer materials structural modeling

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1988-01-01

    The following investigation reviews and evaluates the use of stress relaxation test data for the structural analysis of Solid Rocket Motor (SRM) propellants and other polymer materials used for liners, insulators, inhibitors, and seals. The stress relaxation data is examined and a new mathematical structural model is proposed. This model has potentially wide application to structural analysis of polymer materials and other materials generally characterized as being made of viscoelastic materials. A dynamic modulus is derived from the new model for stress relaxation modulus and is compared to the old viscoelastic model and experimental data.

  5. Quasi Solid Polymer Electrolytes for Dye Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Dissanayake, M. A. K. Lakshman

    2013-07-01

    Dye-sensitized solar cell (DSSC) has been considered as an alternative to the conventional silicon solar cell because of low cost, easy fabrication and relatively high conversion efficiency. A DSSC consists of a dye-sensitized nanoparticulated TiO2 electrode, an electrolyte containing redox couple and a Pt coated counter electrode. Such solar cells based on an I-/I3- redox couple in an organic solvent usually have conversion efficiencies reaching around 11%. However, a major drawback of these solution based solar cells, originally developed by Gratzel and coworkers is the lack of long-term stability due to liquid leakage, usage of volatile liquids such as acetonitrile, electrode corrosion, and photodecomposition of the dye in the solvent medium. Therefore considerable research efforts have been made in recent years to replace the liquid electrolytes with solid polymer or quasi-solid polymer (gel) electrolytes. Among these approaches, the use of gel polymer electrolytes appears to give rise to successful results in terms of conversion efficiency. Conventional poly (ethylene oxide)(PEO)-based solid polymer electrolytes exhibit poor ionic conductivities at room temperature, which is not sufficient for practical applications. Therefore, most of the recent studies have been directed to the preparation and characterization of gel polymer electrolytes which exhibit higher ionic conductivity at ambient temperature while maintain quai-solid structure. These gel polymer electrolytes prepared by incorporating a liquid electrolyte into a matrix polymer such as polyacrylonitrile(PAN), poly(vinylidene fluoride)(PVdF), poly (methyl methacrylate) (PMMA) and PEO have been employed in quasi-solid-state DSSCs to achieve power conversion efficiencies of more than 5%. Significant improvements have been achieved in recent years by modifications of the electrolytes by optimizing the ionic salt, introducing additives such as inorganic nanofillers, organic molecules and ionic liquids in

  6. Particulate Composite Materials: Numerical Modeling of a Cross-Linked Polymer Reinforced With Alumina-Based Particles

    NASA Astrophysics Data System (ADS)

    Máša, B.; Náhlík, L.; Hutař, P.

    2013-09-01

    The macroscopic mechanical properties of a particulate composite under uniaxial tensile loading have been estimated. The composite studied consisted of a polymer matrix in a rubbery state (polymethylmethacrylate - PMMA) and alumina-based particles (Al2O3). A numerical modeling by using the finite-element method (FEM) was performed to determine the stress-strain behavior of the particulate composite. The numerical simulation took into account the hyperelastic properties of the cross-linked polymer matrix, which was described by the three-parameter Mooney-Rivlin material model. A representative volume element (RVE) was chosen for FE analyses to model the microstructure of the composite. Various compositions of particles and their different shape and orientation were considered in the study. Various directions of loading of the RVE were also investigated. A progressive damage model was implemented into the numerical models. The mechanical characteristics obtained from computations, which included the damage model, were compared with experimental data, and a good agreement has been found to exist between them. The procedure presented can be used for estimating the mechanical properties of new particulate composites with a cross-linked polymer matrix, and it also contributes to the clarification of damage development and failure in composites of the type studied.

  7. Polyimide aerogels with amide cross-links: a low cost alternative for mechanically strong polymer aerogels.

    PubMed

    Meador, Mary Ann B; Alemán, Christian R; Hanson, Katrina; Ramirez, Nakaira; Vivod, Stephanie L; Wilmoth, Nathan; McCorkle, Linda

    2015-01-21

    Polyimide aerogels combine high porosity, low thermal conductivity, flexibility, and low density with excellent mechanical properties. However, previously used cross-linkers, such as 1,3,5-triaminophenoxybenzene (TAB), 2,4,6-tris(4-aminophenyl)pyridine (TAPP), or octa(aminophenoxy)silsesquioxane (OAPS), either are not commercially available or are prohibitively expensive. Finding more cost efficient cross-linkers that are commercially available to synthesize these aerogels is crucial for making large scale manufacturing attractive. Herein, we describe an approach to making polyimide aerogels starting with amine capped oligomers that are cross-linked with 1,3,5-benzenetricarbonyl trichloride (BTC). BTC is a lower cost, commercially available alternative to TAB, TAPP, or OAPS. Aerogels made in this way have the same or higher modulus and higher surface area compared to those previously reported with either TAB or OAPS cross-links at the same density. While the cross-link structure is an amide, the thermal stability is not compromised most likely because the cross-link is only a small part of the composition of the aerogel. Onset of decomposition depends primarily on the backbone chemistry with 4,4'-oxidianiline (ODA) being more thermally stable than 2,2'-dimethylbenzidine (DMBZ), similar to those previously reported with other cross-links.

  8. Synthesis and Characterization of Cross-linked Polymer Electrolyte Membranes for Supercapacitor

    NASA Astrophysics Data System (ADS)

    Rosi, Memoria; Ekaputra, Muhamad Prama; Abdullah, Mikrajuddin; Khairurrijal

    2010-10-01

    Cross-linked polyvinyl alcohol (PVA) electrolyte membranes have been synthesized by using a solution casting method. In this study, PVA was blended with oxidative cross-linked agent (zinc acetate) and nano-sized silica as filler to stabilize PVA matrix and enhance conductivity. The cross-linked membranes were immersed into lithium hydroxide (LiOH) aqueous solution to increase their ionic conductivity. Two techniques were used to characterize the resulted membranes including Fourier transform infra red (FTIR) and AC impedance spectroscopies. The results showed that absorption peaks of C-O-C group and Si-O-Si are presence in the FTIR spectra attributed to the cross-linking process. Impedance spectra indicated that the contribution of ionic dopant (LiOH) to enhance conductivity is insignificant. The highest conductivity of the studied cross-linked PVA membrane is 1.34×10-3 S cm-1 corresponding to 5% LiOH dopant concentration of cross-linked PVA-zinc acetate-nano silica membrane. The present study also suggested that the solution casting is appropriate for cross-linked membrane synthesis.

  9. Effect of crosslinking density of polymers and chemical structure of amine-containing monomers on the neutralization capacity of dentin adhesives.

    PubMed

    Ge, Xueping; Ye, Qiang; Song, Linyong; Spencer, Paulette; Laurence, Jennifer S

    2015-10-01

    Neutralization of the acidic micro-environment at the tooth/material interface is expected to provide enhanced durability for dental composite restorations. The objective of this study is to explore the effect of amine-containing monomer formulations and the crosslinking density of the resultant polymers on the neutralization capacity. The co-monomer system was varied systematically to obtain different proportions of Bisphenol A glycerolate dimethacrylate (BisGMA) and 2-hydroxyethyl methacrylate (HEMA), while maintaining a constant amount of amine-containing methacrylate monomer. A series of amine-containing monomers covering a range of pKa values were examined. Crosslinking density of formed copolymers was controlled by adjusting the weight content of the dimethacrylate monomer BisGMA. Lactic acid (LA) was used as a probe to analyze the effectiveness of the basic polymers to neutralize acid. The neutralization capacity of each amine-containing crosslinked copolymer was characterized by measuring pH as a function of time when the specimens were soaked in 1-mM LA solution, and the results were compared to the control formulations composed solely of BisGMA and HEMA. Polymer surfaces were examined using the methyl orange (MO) assay to quantify the amount of accessible amine groups. For each amine-containing crosslinked co-polymer, the neutralization capacity is enhanced by decreasing crosslinking density (e.g., by reducing BisGMA concentration in the formulation). In addition, more amine groups were accessible when crosslinking density was decreased. For different amine-containing polymers with the same BisGMA concentration, the neutralization capacity is higher when the amino monomers with higher pKa values were used in the formulations. This is the first time that the neutralization capacity based on crosslinked dental polymers has been studied. The information is important for future development of durable dentin adhesives. Copyright © 2015. Published by Elsevier

  10. Reciprocated suppression of polymer crystallization toward improved solid polymer electrolytes: Higher ion conductivity and tunable mechanical properties

    SciTech Connect

    Bi, Sheng; Sun, Che-Nan; Zawodzinski, Thomas A.; Ren, Fei; Keum, Jong Kahk; Ahn, Suk-Kyun; Li, Dawen; Chen, Jihua

    2015-08-06

    Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl) imide and polymer matrix were extensively studied in the past due to their excellent potential in a broad range of energy related applications. Poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) are among the most examined polymer candidates as solid polymer electrolyte matrix. In this paper, we study the effect of reciprocated suppression of polymer crystallization in PVDF/PEO binary matrix on ion transport and mechanical properties of the resultant solid polymer electrolytes. With electron and X-ray diffractions as well as energy filtered transmission electron microscopy, we identify and examine the appropriate blending composition that is responsible for the diminishment of both PVDF and PEO crystallites. Laslty, a three-fold conductivity enhancement is achieved along with a highly tunable elastic modulus ranging from 20 to 200 MPa, which is expected to contribute toward future designs of solid polymer electrolytes with high room-temperature ion conductivities and mechanical flexibility.

  11. Highly Conductive, Stretchable, and Transparent Solid Polymer Electrolyte Membrane

    NASA Astrophysics Data System (ADS)

    He, Ruixuan; Echeverri, Mauricio; Kyu, Thein

    2014-03-01

    With the guidance of ternary phase diagrams, completely amorphous polymer electrolyte membranes (PEM) were successfully prepared by melt processing for lithium-ion battery. The PEM under consideration consisted of poly (ethylene glycol diacrylate) (PEGDA), succinonitrile (SCN) and Lithium bis(trifluoro-methane)sulfonamide (LiTFSI). After UV-crosslinking, the PEM is transparent and light-weight. Addition of SCN plastic crystal affords not only dissociation of the lithium salt, but also plasticization to the crosslinked PEGDA network. Of particular importance is the achievement of room-temperature ionic conductivity of ~10-3 S/cm, which is comparable to that of commercial liquid electrolyte. Higher ionic conductivities were achieved at elevated temperatures or with use of a moderately higher molecular weight of PEGDA. In terms of electrochemical and chemical stability, the PEM exhibited oxidative stability up to 5 V against lithium reference electrode. Stable interface behavior between the PEM and lithium electrode is also seen with ageing time. In the tensile tests, samples containing low molecular weight PEGDA are stiffer, whereas the high molecular weight PEGDA is stretchable up to 80% elongation. Supported by NSF-DMR 1161070.

  12. Polymer donors of nitric oxide improve the treatment of experimental solid tumours with nanosized polymer therapeutics.

    PubMed

    Šírová, Milada; Horková, Veronika; Etrych, Tomáš; Chytil, Petr; Říhová, Blanka; Studenovský, Martin

    2017-08-07

    Polymer carriers based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers with incorporated organic nitrates as nitric oxide (NO) donors were designed with the aim to localise NO generation in solid tumours, thus highly increasing the enhanced permeability and retention (EPR) effect. The NO donors were coupled to the polymer carrier either through a stable bond or through a hydrolytically degradable, pH sensitive, bond. In vivo, the co-administration of the polymer NO donor and HPMA copolymer-bound cytotoxic drug (doxorubicin; Dox) resulted in an improvement in the treatment of murine EL4 T-cell lymphoma. The polymer NO donors neither potentiated the in vitro toxicity of the cytotoxic drug nor exerted any effect on in vivo model without the EPR effect, such as BCL1 leukaemia. Thus, an increase in passive accumulation of the nanomedicine carrying cytotoxic drug via NO-enhanced EPR effect was the operative mechanism of action. The most significant improvement in the therapy was observed in a combination treatment with such a polymer conjugate of Dox, which is characterised by increased circulation in the blood and efficient accumulation in solid tumours. Notably, the combination treatment enabled the development of an anti-tumour immune response, which was previously demonstrated as an important feature of HPMA-based polymer cytotoxic drugs.

  13. Formation of wheat-protein-based biomaterials through polymer grafting and crosslinking reactions to introduce new functional properties.

    PubMed

    Kurniawan, Lusiana; Qiao, Greg G; Zhang, Xiaoqing

    2009-01-09

    An insoluble wheat proteins-based polymer networks with new functional groups and positive charges were prepared through grafting-coupling reactions. The networks were also flexible with a lower glass transition temperature since the existence of the grafted mobile segments. The multi-component/multi-phase systems became relatively homogeneous on a scale of 20-30 nm due to strong intermolecular interactions and chemical cross-linking in the materials. This demonstrates that the grafting-coupling reaction is an effective methodology to develop biomaterials with modified functional and mechanical properties from proteins.

  14. Single- and double-ion type cross-linked polysiloxane solid electrolytes for lithium cells

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Hiromori; Yamamoto, Masahiro; Morita, Masayuki; Matsuda, Yoshiharu; Nakamura, Takashi; Asai, Hiroyuki

    Polymeric solid electrolytes, that have poly(dimethylsiloxane) (PMS) backbone and cross-linked network, were applied to a rechargeable lithium battery system. Single- (PMS-Li) and double-ion type (PMS-LiClO 4) electrolytes were prepared from the same prepolymers. Lithium electrode in the both electrolytes showed reversible stripping and deposition of lithium. Intercalation and deintercalation processes of lithium ion between lithium-manganese composite oxide (Li xMnO 2) electrode and the electrolytes were also confirmed by cyclic voltammetry, however, peak current decreased with several cycles in both cases. The model cell, Li/PMS-Li/Li xMnO 2 cell had 1.4 mA h g -1 (per 1 g of active material, current density: 3.77 μA cm -2), and the Li/PMS-LiClO 4/Li xMnO 2 cell had 1.6 mA h g -1 (current density: 75.3 μA cm -2).

  15. New paradigm for stabilization of liquid polymer films on solids

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Jiang, Naisheng; Wang, Jiaxun; di, Xiaoyu; Cheung, Justin; Endoh, Maya

    2015-03-01

    We report that wetting/dewetting behavior of liquid polymer films on solids can be controlled by nanoscale architectures of polymer chains irreversibly adsorbed on the impenetrable surfaces. Monodisperse polystyrene (PS) ultrathin films (20 nm in thickness) with different molecular weights on silicon (Si) substrates with a natural amorphous Si dioxide layer were used as models. The PS thin films were annealed at high temperatures at T>Tg (Tg is the bulk glass transition temperature) for several days, and the surface structures were studied by using optical and atomic force microscopes. At the same time, the annealed PS films were further leached with a good solvent and the residue films (i.e., irreversibly adsorbed layers) were characterized by x-ray reflectivity. The experimental data reveals a strong correlation between the conformations of the adsorbed polymer chains and the stability of the liquid films on top. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  16. Novel Molecular Architectures Developed for Improved Solid Polymer Electrolytes for Lithium Polymer Batteries

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Kinder, James D.; Bennett, William R.

    2002-01-01

    Lithium-based polymer batteries for aerospace applications need the ability to operate in temperatures ranging from -70 to 70 C. Current state-of-the-art solid polymer electrolytes (based on amorphous polyethylene oxide, PEO) have acceptable ionic conductivities (10-4 to 10-3 S/cm) only above 60 C. Higher conductivity can be achieved in the current systems by adding solvent or plasticizers to the solid polymer to improve ion transport. However, this can compromise the dimensional and thermal stability of the electrolyte, as well as compatibility with electrode materials. One of NASA Glenn Research Center's objectives in the PERS program is to develop new electrolytes having unique molecular architectures and/or novel ion transport mechanisms, leading to good ionic conductivity at room temperature and below without solvents or plasticizers.

  17. Elastin-Mimetic Protein Polymers Capable of Physical and Chemical Crosslinking

    PubMed Central

    Sallach, Rory E.; Cui, Wanxing; Wen, Jing; Martinez, Adam; Conticello, Vincent P.; Chaikof, Elliot L.

    2008-01-01

    We report the synthesis of a new class of recombinant elastin-mimetic triblock copolymer capable of both physical and chemical crosslinking. These investigations were motivated by a desire to capture features unique to both physical and chemical crosslinking schemes so as to exert optimal control over a wide range of potential properties afforded by protein-based mutiblock materials. We postulated that by chemically locking a multiblock protein assembly in place, functional responses that are linked to specific domain structures and morphologies may be preserved over a broader range of loading conditions that would otherwise disrupt microphase structure solely stabilized by physical crosslinking. Specifically, elastic modulus was enhanced and creep strain reduced through the addition of chemical crosslinking sites. Additionally, we have demonstrated excellent in vivo biocompatibility of glutaraldehyde treated multiblock systems. PMID:18954902

  18. Defects in electro-optically active polymer solids

    NASA Technical Reports Server (NTRS)

    Martin, David C.

    1993-01-01

    There is considerable current interest in the application of organic and polymeric materials for electronic and photonic devices. The rapid, non-linear optical (NLO) response of these materials makes them attractive candidates for waveguides, interferometers, and frequency doublers. In order to realize the full potential of these systems, it is necessary to develop processing schemes which can fabricate these molecules into ordered arrangements. There is enormous potential for introducing well-defined, local variations in microstructure to control the photonic properties of organic materials by rational 'defect engineering.' This effort may eventually become as technologically important as the manipulation of the electronic structure of solid-state silicon based devices is at present. The success of this endeavor will require complimentary efforts in the synthesis, processing, and characterization of new materials. Detailed information about local microstructure will be necessary to understand the influence of symmetry breaking of the solid phases near point, line, and planar defects. In metallic and inorganic polycrystalline materials, defects play an important role in modifying macroscopic properties. To understand the influence of particular defects on the properties of materials, it has proven useful to isolate the defect by creating bicrystals between two-component single crystals. In this way the geometry of a grain boundary defect and its effect on macroscopic properties can be determined unambiguously. In crystalline polymers it would be valuable to establish a similar depth of understanding about the relationship between defect structure and macroscopic properties. Conventionally processed crystalline polymers have small crystallites (10-20 nm), which implies a large defect density in the solid state. Although this means that defects may play an important or even dominant role in crystalline or liquid crystalline polymer systems, it also makes it difficult

  19. Defects in electro-optically active polymer solids

    NASA Technical Reports Server (NTRS)

    Martin, David C.

    1993-01-01

    There is considerable current interest in the application of organic and polymeric materials for electronic and photonic devices. The rapid, non-linear optical (NLO) response of these materials makes them attractive candidates for waveguides, interferometers, and frequency doublers. In order to realize the full potential of these systems, it is necessary to develop processing schemes which can fabricate these molecules into ordered arrangements. There is enormous potential for introducing well-defined, local variations in microstructure to control the photonic properties of organic materials by rational 'defect engineering.' This effort may eventually become as technologically important as the manipulation of the electronic structure of solid-state silicon based devices is at present. The success of this endeavor will require complimentary efforts in the synthesis, processing, and characterization of new materials. Detailed information about local microstructure will be necessary to understand the influence of symmetry breaking of the solid phases near point, line, and planar defects. In metallic and inorganic polycrystalline materials, defects play an important role in modifying macroscopic properties. To understand the influence of particular defects on the properties of materials, it has proven useful to isolate the defect by creating bicrystals between two-component single crystals. In this way the geometry of a grain boundary defect and its effect on macroscopic properties can be determined unambiguously. In crystalline polymers it would be valuable to establish a similar depth of understanding about the relationship between defect structure and macroscopic properties. Conventionally processed crystalline polymers have small crystallites (10-20 nm), which implies a large defect density in the solid state. Although this means that defects may play an important or even dominant role in crystalline or liquid crystalline polymer systems, it also makes it difficult

  20. Enhanced performance of polymer solar cell with ZnO nanoparticle electron transporting layer passivated by in situ cross-linked three-dimensional polymer network

    NASA Astrophysics Data System (ADS)

    Wu, Zhongwei; Song, Tao; Xia, Zhouhui; Wei, Huaixin; Sun, Baoquan

    2013-12-01

    An in situ cross-linked three-dimensional polymer network has been developed to passivate ZnO nanoparticles as an electron transporting layer (ETL) to improve the performance of inverted organic solar cells. The passivated ZnO ETL-based devices achieve efficiencies of 3.26% for poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 7.37% for poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

  1. Estimation of the macroscopic stress-strain curve of a particulate composite with a crosslinked polymer matrix

    NASA Astrophysics Data System (ADS)

    Náhlík, L.; Hutař, P.; Dušková, M.; Dušek, K.; Máša, B.

    2012-01-01

    The main focus of the present paper is the estimation of the macroscopic stress-strain behavior of a particulate composite. A composite with a cross-linked polymer matrix in a rubbery state filled with an alumina-based mineral filler is investigated by means of the finite-element method. The hyperelastic material behavior of the matrix is described by the Mooney-Rivlin material model. Numerical models on the basis of unit cells are developed. The existence of a discontinuity (breaking) in the matrix at higher loading levels is taken into account to obtain a more accurate estimate for the stress-strain behavior of the particulate composite investigated. The numerical results obtained are compared with an experimental stress-strain curve, and a good agreement is found to exist. The paper can contribute to a better understanding of the behavior and failure of particulate composites with a polymer matrix.

  2. Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates

    NASA Astrophysics Data System (ADS)

    Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M.; Zhu, Xiang; Dai, Sheng

    2014-04-01

    High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energyand environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to ‘classical’ methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes.

  3. An automated spin-assisted approach for molecular layer-by-layer assembly of crosslinked polymer thin films

    SciTech Connect

    Chan, Edwin P.; Chung, Jun Young; Stafford, Christopher M.; Lee, Jung-Hyun

    2012-11-15

    We present the design of an automated spin-coater that facilitates fabrication of polymer films based on molecular layer-by-layer (mLbL) assembly. Specifically, we demonstrate the synthesis of ultrathin crosslinked fully-aromatic polyamide (PA) films that are chemically identical to polymer membranes used in water desalination applications as measured by X-ray photoelectron spectroscopy. X-ray reflectivity measurements indicate that the automated mLbL assembly creates films with a constant film growth rate and minimal roughness compared with the traditional interfacial polymerization of PA. This automated spin-coater improves the scalability and sample-to-sample consistency by reducing human involvement in the mLbL assembly.

  4. Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates.

    PubMed

    Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M; Zhu, Xiang; Dai, Sheng

    2014-04-16

    High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to 'classical' methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes.

  5. EB radiation crosslinking of elastomers [rapid communication

    NASA Astrophysics Data System (ADS)

    Bik, J.; Głuszewski, W.; Rzymski, W. M.; Zagórski, Z. P.

    2003-06-01

    Radiation-induced crosslinking is proposed as successful alternative to conventional, chemical methods of crosslinking of elastomers. Hydrogenated acrylonitrile-butadiene rubber was irradiated with 10 MeV electron beam to doses up to 300 kGy. Irradiated samples were investigated for the extent of crosslinking and for properties important for understanding of mechanisms. It follows from sol-gel analysis, that for 100 crosslinking acts there are 6-9 acts of chain scission. It is less than expected from the 20% participation of multi-ionization spurs, also in the solid state, as announced during the previous 9th Tihany Conference (Radiat. Phys. Chem. 56 (1999) 559). However, the apparent too low yield of multi-ionization spurs could be explained by partial conversion of scission products into crosslinks of specific trifunctional Y type. Our investigations confirm the usefulness of consideration of different radiation spurs in polymers, as well as in all, low LET irradiated media.

  6. Molecularly imprinted polymers immobilized on 3D printed scaffolds as novel solid phase extraction sorbent for metergoline.

    PubMed

    De Middeleer, Gilke; Dubruel, Peter; De Saeger, Sarah

    2017-09-15

    In the present work, a novel solid phase extraction (SPE) sorbent was developed based on molecularly imprinted polymers (MIPs) immobilized on 3D-printed scaffolds using polymer networks as MIP-immobilizing layer. MIPs were produced by precipitation polymerization in acetonitrile (ACN) using methacrylic acid (MAA) as functional monomer, trimethylolpropane trimethacrylate (TRIM) as crosslinker and metergoline as model template which allows final recognition of ergot alkaloid mycotoxins. Scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses showed an average MIP particle size of 457 ± 145 nm. Functional MIP analysis revealed dissociation constants (KD) of 0.29 and 38.90 μM for high and low affinity binding sites respectively. Subsequently, crosslinking of polymer network building blocks was applied as MIP immobilization method on poly-ε-caprolactone (PCL) which was selected as polymer model. Methodology optimization and subsequent evaluation were first realized on 2D PCL surfaces. Based on analyses such as optical evaluation of MIP availability after immobilization through SEM and depth profilometry, an optimal polymer network building block concentration of 7.5 w/w% was selected. In a final part, transfer of MIP immobilization to 3D PCL scaffolds was successfully realized. Functional analysis showed that the newly developed SPE sorbents were able to rebind 44.87 ± 8.30% of a 1 μM metergoline solution. In conclusion, a new type of SPE sorbent was developed for the detection of metergoline by the use of MIP-functionalized polymer scaffolds. The applied technology opens up future possibilities for the extraction of a broad range of components such as other mycotoxins. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Electrode-Electrolyte Interfaces in Solid Polymer Lithium Batteries

    NASA Astrophysics Data System (ADS)

    Hu, Qichao

    This thesis studies the performance of solid polymer lithium batteries from room temperature to elevated temperatures using mainly electrochemical techniques, with emphasis on the bulk properties of the polymer electrolyte and the electrode-electrolyte interfaces. Its contributions include: 1) Demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence, and improved the conductivity of the graft copolymer electrolyte (GCE) by almost an order of magnitude by changing the ion-conducting block from poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). 2) Identified the rate-limiting step in the battery occurs at the cathode-electrolyte interface using both full cell and symmetric cell electrochemical impedance spectroscopy (EIS), improved the battery rate capability by using the GCE as both the electrolyte and the cathode binder to reduce the resistance at the cathode-electrolyte interface, and used TEM and SEM to visualize the polymer-particle interface (full cells with LiFePO4 as the cathode active material and lithium metal as the anode were assembled and tested). 3) Applied the solid polymer battery to oil and gas drilling application, performed high temperature (up to 210 °C) cycling (both isothermal and thermal cycling), and demonstrated for the first time, current exchange between a solid polymer electrolyte and a liquid lithium metal. Both the cell open-circuit-voltage (OCV) and the overall GCE mass remained stable up to 200 °C, suggesting that the GCE is electrochemically and gravimetrically stable at high temperatures. Used full cell EIS to study the behavior of the various battery parameters as a function of cycling and temperature. 4) Identified the thermal instability of the cell was due to the reactivity of lithium metal and its passivation film at high temperatures, and used Li/GCE/Li symmetric cell

  8. Synthesis, Characterisation, and Evaluation of a Cross-Linked Disulphide Amide-Anhydride-Containing Polymer Based on Cysteine for Colonic Drug Delivery

    PubMed Central

    Lim, Vuanghao; Peh, Kok Khiang; Sahudin, Shariza

    2013-01-01

    The use of disulphide polymers, a low redox potential responsive delivery, is one strategy for targeting drugs to the colon so that they are specifically released there. The objective of this study was to synthesise a new cross-linked disulphide-containing polymer based on the amino acid cysteine as a colon drug delivery system and to evaluate the efficiency of the polymers for colon targeted drug delivery under the condition of a low redox potential. The disulphide cross-linked polymers were synthesised via air oxidation of 1,2-ethanedithiol and 3-mercapto-N-2-(3-mercaptopropionamide)-3-mercapto propionic anhydride (trithiol monomers) using different ratio combinations. Four types of polymers were synthesised: P10, P11, P151, and P15. All compounds synthesised were characterised by NMR, IR, LC-MS, CHNS analysis, Raman spectrometry, SEM-EDX, and elemental mapping. The synthesised polymers were evaluated in chemical reduction studies that were performed in zinc/acetic acid solution. The suitability of each polymer for use in colon-targeted drug delivery was investigated in vitro using simulated conditions. Chemical reduction studies showed that all polymers were reduced after 0.5–1.0 h, but different polymers had different thiol concentrations. The bacterial degradation studies showed that the polymers were biodegraded in the anaerobic colonic bacterial medium. Degradation was most pronounced for polymer P15. This result complements the general consensus that biodegradability depends on the swellability of polymers in an aqueous environment. Overall, these results suggest that the cross-linked disulphide-containing polymers described herein could be used as coatings for drugs delivered to the colon. PMID:24351841

  9. Synthesis, characterisation, and evaluation of a cross-linked disulphide amide-anhydride-containing polymer based on cysteine for colonic drug delivery.

    PubMed

    Lim, Vuanghao; Peh, Kok Khiang; Sahudin, Shariza

    2013-12-18

    The use of disulphide polymers, a low redox potential responsive delivery, is one strategy for targeting drugs to the colon so that they are specifically released there. The objective of this study was to synthesise a new cross-linked disulphide-containing polymer based on the amino acid cysteine as a colon drug delivery system and to evaluate the efficiency of the polymers for colon targeted drug delivery under the condition of a low redox potential. The disulphide cross-linked polymers were synthesised via air oxidation of 1,2-ethanedithiol and 3-mercapto-N-2-(3-mercaptopropionamide)-3-mercapto propionic anhydride (trithiol monomers) using different ratio combinations. Four types of polymers were synthesised: P10, P11, P151, and P15. All compounds synthesised were characterised by NMR, IR, LC-MS, CHNS analysis, Raman spectrometry, SEM-EDX, and elemental mapping. The synthesised polymers were evaluated in chemical reduction studies that were performed in zinc/acetic acid solution. The suitability of each polymer for use in colon-targeted drug delivery was investigated in vitro using simulated conditions. Chemical reduction studies showed that all polymers were reduced after 0.5-1.0 h, but different polymers had different thiol concentrations. The bacterial degradation studies showed that the polymers were biodegraded in the anaerobic colonic bacterial medium. Degradation was most pronounced for polymer P15. This result complements the general consensus that biodegradability depends on the swellability of polymers in an aqueous environment. Overall, these results suggest that the cross-linked disulphide-containing polymers described herein could be used as coatings for drugs delivered to the colon.

  10. In situ infrared spectroscopic and density-functional studies of the cross-linked structure of one-dimensional C{sub 60} polymer

    SciTech Connect

    Takashima, A.; Onoe, J.; Nishii, T.

    2010-08-15

    We have examined the infrared (IR) spectra of electron-beam (EB) irradiated C{sub 60} films, using in situ IR spectroscopy in the temperature range of 60-300 K. The irradiation-time evolution of the IR spectra shows that two highly intense new peaks finally appear around 565 and 1340 cm{sup -1} when the EB-induced C{sub 60} polymerization was saturated. To determine the cross-linked structure of the polymer explicitly, we have compared the IR spectra with theoretical spectra obtained from the cross-linked structure of all C{sub 120} stable isomers derived from the general Stone-Wales (GSW) rearrangement, using first-principles density-functional calculations. Since each C{sub 120} isomer has the same cross-linked structure as that of its corresponding one-dimensional (1D) C{sub 60} polymer, the IR modes obtained from the cross-linked structure of C{sub 120} are close to those obtained from the corresponding 1D polymer. Comparison between the experimental and theoretical IR spectra suggests that the 1D peanut-shaped C{sub 60} polymer has a cross-linked structure roughly similar to that of the P08 peanut-shaped C{sub 120} isomer.

  11. Mechanisms underlying molecularly imprinted polymer molecular memory and the role of crosslinker: resolving debate on the nature of template recognition in phenylalanine anilide imprinted polymers.

    PubMed

    Olsson, Gustaf D; Karlsson, Björn C G; Shoravi, Siamak; Wiklander, Jesper G; Nicholls, Ian A

    2012-02-01

    A series of molecular dynamics simulations of prepolymerization mixtures for phenylalanine anilide imprinted co-(ethylene glycol dimethacrylate-methacrylic acid) molecularly imprinted polymers have been employed to investigate the mechanistic basis for template selective recognition in these systems. This has provided new insights on the mechanisms underlying template recognition, in particular the significant role played by the crosslinking agent. Importantly, the study supports the occurrence of template self-association events that allows us to resolve debate between the two previously proposed models used to explain this system's underlying recognition mechanisms. Moreover, the complexity of the molecular level events underlying template complexation is highlighted by this study, a factor that should be considered in rational molecularly imprinted polymer design, especially with respect to recognition site heterogeneity.

  12. Fabrication and characterization of solid state conducting polymer actuators

    NASA Astrophysics Data System (ADS)

    Xie, Jian; Sansinena, Jose-Maria; Gao, Junbo; Wang, Hsing-Lin

    2004-07-01

    We report here the fabrication and characterization of solid-state conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhered to a lever arm of a force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torque generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, and current, on the bending angle and displacement is also studied using square wave potential.

  13. Study of Hydrophobic and Ionizable Hydrophilic Copolymers at Polymer/Solid and Polymer/Liquid Interfaces

    SciTech Connect

    Perahia, Dvora

    2011-11-01

    Joint experimental-computational efforts were set to characterize the interfacial effects on the structure and dynamics of polymers consisting of highly rigid hydrophilic-ionizable and hydrophobic sub-units within one polymeric chain casted into thin films of several molecular dimensions. Focusing on the ultra thin film region we separate out the interfacial effects from bulk characteristics. Specifically, the study sought to: identify the parameters that control the formation of a stable polymer-solid interface. The study consists of two components, experimental investigations and computational efforts. The experimental component was designed to derive empirical trends that can be used to correlate the set of coupled polymer molecular parameters with the interfacial characteristics of these polymers, and their response to presence of solvents. The computational study was designed to provide molecular insight into the ensemble averages provided by the experimental efforts on multiple length scales from molecular dimensions, to the nanometer lengths to a macroscopic understanding of solvent interactions with structured polymers. With the ultimate goal of correlating molecular parameters to structure, dynamics and properties of ionic polymers, the first stage of the research began with the study of two systems, one which allowed tailoring the flexibility of the backbone without the presence of ionic groups, but with a potential to sulfonate groups at a later stage, and a polymer whose backbone is rigid and the density of the ionic group can be varied. The combined experimental and computational studies significantly extended the understanding of polymers at interfaces from model systems to polydispersed copolymers with blocks of varying nature and complexity. This new insight directly affects the design of polymers for sustainable energy applications from batteries and fuel cells to solar energy.

  14. Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer

    PubMed Central

    Niamlang, Sumonman; Buranut, Tawansorn; Niansiri, Amornrat; Sirivat, Anuvat

    2013-01-01

    The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene), PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene)/polyacrylamide hydrogel (aloin-doped PPV/PAAM). In the passive release, the diffusion of aloin from five aloin-doped PPV/PAAM hydrogel systems each was delayed ranging from during the first three hours to during the first 14 h due to the ionic interaction between the anionic drug and PPV. After the delayed periods, aloin could diffuse continuously into the buffer solution through the PAAM matrix. The amount of aloin released from the aloin-doped PPV/PAAM rose with increasing electric field strength as a result of the three mechanisms: the expansion of PPV chains inside the hydrogel, iontophoresis, and the electroporation of the matrix pore size, combined. Furthermore, the conductive polymer and the electric field could be used in combination to regulate the amount of release drug to a desired level, to control the release rate, and to switch the drug delivery on/off. PMID:28788360

  15. Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer.

    PubMed

    Niamlang, Sumonman; Buranut, Tawansorn; Niansiri, Amornrat; Sirivat, Anuvat

    2013-10-22

    The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene), PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene)/polyacrylamide hydrogel (aloin-doped PPV/PAAM). In the passive release, the diffusion of aloin from five aloin-doped PPV/PAAM hydrogel systems each was delayed ranging from during the first three hours to during the first 14 h due to the ionic interaction between the anionic drug and PPV. After the delayed periods, aloin could diffuse continuously into the buffer solution through the PAAM matrix. The amount of aloin released from the aloin-doped PPV/PAAM rose with increasing electric field strength as a result of the three mechanisms: the expansion of PPV chains inside the hydrogel, iontophoresis, and the electroporation of the matrix pore size, combined. Furthermore, the conductive polymer and the electric field could be used in combination to regulate the amount of release drug to a desired level, to control the release rate, and to switch the drug delivery on/off.

  16. Solving the Problem of Building Models of Crosslinked Polymers: An Example Focussing on Validation of the Properties of Crosslinked Epoxy Resins

    PubMed Central

    Hall, Stephen A.; Howlin, Brendan J; Hamerton, Ian; Baidak, Alex; Billaud, Claude; Ward, Steven

    2012-01-01

    The construction of molecular models of crosslinked polymers is an area of some difficulty and considerable interest. We report here a new method of constructing these models and validate the method by modelling three epoxy systems based on the epoxy monomers bisphenol F diglycidyl ether (BFDGE) and triglycidyl-p-amino phenol (TGAP) with the curing agent diamino diphenyl sulphone (DDS). The main emphasis of the work concerns the improvement of the techniques for the molecular simulation of these epoxies and specific attention is paid towards model construction techniques, including automated model building and prediction of glass transition temperatures (Tg). Typical models comprise some 4200–4600 atoms (ca. 120–130 monomers). In a parallel empirical study, these systems have been cast, cured and analysed by dynamic mechanical thermal analysis (DMTA) to measure Tg. Results for the three epoxy systems yield good agreement with experimental Tg ranges of 200–220°C, 270–285°C and 285–290°C with corresponding simulated ranges of 210–230°C, 250–300°C, and 250–300°C respectively. PMID:22916182

  17. Solving the problem of building models of crosslinked polymers: an example focussing on validation of the properties of crosslinked epoxy resins.

    PubMed

    Hall, Stephen A; Howlin, Brendan J; Hamerton, Ian; Baidak, Alex; Billaud, Claude; Ward, Steven

    2012-01-01

    The construction of molecular models of crosslinked polymers is an area of some difficulty and considerable interest. We report here a new method of constructing these models and validate the method by modelling three epoxy systems based on the epoxy monomers bisphenol F diglycidyl ether (BFDGE) and triglycidyl-p-amino phenol (TGAP) with the curing agent diamino diphenyl sulphone (DDS). The main emphasis of the work concerns the improvement of the techniques for the molecular simulation of these epoxies and specific attention is paid towards model construction techniques, including automated model building and prediction of glass transition temperatures (T(g)). Typical models comprise some 4200-4600 atoms (ca. 120-130 monomers). In a parallel empirical study, these systems have been cast, cured and analysed by dynamic mechanical thermal analysis (DMTA) to measure T(g). Results for the three epoxy systems yield good agreement with experimental T(g) ranges of 200-220°C, 270-285°C and 285-290°C with corresponding simulated ranges of 210-230°C, 250-300°C, and 250-300°C respectively.

  18. Fabrication of cross-linked hydrazone covalent organic frameworks by click chemistry and application to solid phase microextraction.

    PubMed

    Wu, Mingxue; Chen, Gang; Ma, Jiutong; Liu, Ping; Jia, Qiong

    2016-12-01

    Covalent organic frameworks (COFs) are an emerging class of porous organic frameworks with diverse promising applications. Herein, we presented the first example of cross-linked hydrazone COFs (cross-linked COFs) coating via thiol-ene click chemistry for solid phase microextraction (SPME). Strong covalent bonds and interlayer of the prepared networks ensured the adsorption capacity and durability of the novel SPME fiber. π-π conjugated structure existed because of abundant phenyl rings and -C=N groups in the cross-lined COFs. A series of characterizations indicated that the cross-linked COFs possessed large surface areas, high porosities and stabilities as well as hydrophobicities. The fiber was applied to SPME of pesticide residues coupled with gas chromatography with an electron capture detector (GC-ECD). Under the optimum experimental conditions, enhancement factors in the range of 2190-10,998 were obtained, illustrating that the cross-linked COFs possessed remarkable preconcentration ability. The low detection limits of 0.0003-0.0023ngkg(-1) were achieved with relative standard deviations (RSDs) in the range of 3.4-7.6% (intra-batch) and 5.7-11.6% (inter-batch), respectively. Recovery values in the range of 78.2-107.0% were obtained when the SPME-GC method was applied to the analysis of pesticides in cucumber samples.

  19. Nanosecond laser-induced periodic surface structuring of cross-linked azo-polymer films

    NASA Astrophysics Data System (ADS)

    Berta, Marco; Biver, Émeric; Maria, Sébastien; Phan, Trang N. T.; D'Aleo, Anthony; Delaporte, Philippe; Fages, Frederic; Gigmes, Didier

    2013-10-01

    In this work we discuss the response to laser ablation of a poly(4-vinylbenzyl azide-random-methyl methacrylate) (p((S-N3)-r-MMA)) random copolymer. This material is cross-linkable thermally and upon exposure to UV light, and on cross-linked films the irradiation with a 248 nm ns KrF laser induces the formation of laser induced periodical surface structure (LIPSS). The LIPSS morphology is dependent on the amount of 4-vinylbenzyl azide (S-N3) groups in the pristine copolymer. We propose a crosslinking mechanism based on the scission of azide with formation of azo groups and we discuss the possible relationship between this chemical modifications and the formation of ripples on the bottom of laser ablation cavities.

  20. All-solid-state reference electrodes based on conducting polymers.

    PubMed

    Kisiel, Anna; Marcisz, Honorata; Michalska, Agata; Maksymiuk, Krzysztof

    2005-12-01

    A novel construction of solution free (pseudo)reference electrodes, compatible with all-solid-state potentiometric indicator electrodes, has been proposed. These electrodes use conducting polymers (CP): polypyrrole (PPy) or poly(3,4-ethylenedioxythiophene) (PEDOT). Two different arrangements have been tested: solely based on CP and those where the CP phase is covered with a poly(vinyl chloride) based outer membrane of tailored composition. The former arrangement was designed to suppress or compensate cation- and anion-exchange, using mobile perchlorate ions and poly(4-styrenesulfonate) or dodecylbenzenesulfonate anions as immobilized dopants. The following systems were used: (i) polypyrrole layers doped simultaneously by two kinds of anions, both mobile and immobilized in the polymer layer; (ii) bilayers of polypyrrole with anion exchanging inner layer and cation-exchanging outer layer; (iii) polypyrrole doped by surfactant dodecylbenzenesulfonate ions, which inhibit ion exchange on the polymer/solution interface. For the above systems, recorded potentials have been found to be practically independent of electrolyte concentration. The best results, profound stability of potentials, have been obtained for poly(3,4-ethylenedioxythiophene) or polypyrrole doped by poly(4-styrenesulfonate) anions covered by a poly(vinyl chloride) based membrane, containing both anion- and cation-exchangers as well as solid potassium chloride and silver chloride with metallic silver. Differently to the cases (i)-(iii) these electrodes are much less sensitive to the influence of redox and pH interferences. This arrangement has been also characterized using electrochemical impedance spectroscopy and chronopotentiometry.

  1. Cross-linked poly (vinyl alcohol)/sulfosuccinic acid polymer as an electrolyte/electrode material for H2-O2 proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ebenezer, D.; Deshpande, Abhijit P.; Haridoss, Prathap

    2016-02-01

    Proton exchange membrane fuel cell (PEMFC) performance with a cross-linked poly (vinyl alcohol)/sulfosuccinic acid (PVA/SSA) polymer is compared with Nafion® N-115 polymer. In this study, PVA/SSA (≈5 wt. % SSA) polymer membranes are synthesized by a solution casting technique. These cross-linked PVA/SSA polymers and Nafion are used as electrolytes and ionomers in catalyst layers, to fabricate different membrane electrode assemblies (MEAs) for PEMFCs. Properties of each MEA are evaluated using scanning electron microscopy, contact angle measurements, impedance spectroscopy and hydrogen pumping technique. I-V characteristics of each cell are evaluated in a H2-O2 fuel cell testing fixture under different operating conditions. PVA/SSA ionomer causes only an additional ≈4% loss in the anode performance compared to Nafion ionomer. The maximum power density obtained from PVA/SSA based cells range from 99 to 117.4 mW cm-2 with current density range of 247 to 293.4 mA cm-2. Ionic conductivity of PVA/SSA based cells is more sensitive to state of hydration of MEA, while maximum power density obtained is less sensitive to state of hydration of MEA. Maximum power density of cross-linked PVA/SSA membrane based cell is about 35% that of Nafion® N-115 based cell. From these results, cross-linked PVA/SSA polymer is identified as potential candidate for PEMFCs.

  2. A Structural Approach to Establishing a Platform Chemistry for the Tunable, Bulk Electron Beam Cross-Linking of Shape Memory Polymer Systems.

    PubMed

    Hearon, Keith; Besset, Celine J; Lonnecker, Alexander T; Ware, Taylor; Voit, Walter E; Wilson, Thomas S; Wooley, Karen L; Maitland, Duncan J

    2013-11-26

    The synthetic design and thermomechanical characterization of shape memory polymers (SMPs) built from a new polyurethane chemistry that enables facile, bulk and tunable cross-linking of low-molecular weight thermoplastics by electron beam irradiation is reported in this study. SMPs exhibit stimuli-induced geometry changes and are being proposed for applications in numerous fields. We have previously reported a polyurethane SMP system that exhibits the complex processing capabilities of thermoplastic polymers and the mechanical robustness and tunability of thermomechanical properties that are often characteristic of thermoset materials. These previously reported polyurethanes suffer practically because the thermoplastic molecular weights needed to achieve target cross-link densities severely limit high-throughput thermoplastic processing and because thermally unstable radiation-sensitizing additives must be used to achieve high enough cross-link densities to enable desired tunable shape memory behavior. In this study, we demonstrate the ability to manipulate cross-link density in low-molecular weight aliphatic thermoplastic polyurethane SMPs (Mw as low as ~1.5 kDa) without radiation-sensitizing additives by incorporating specific structural motifs into the thermoplastic polymer side chains that we hypothesized would significantly enhance susceptibility to e-beam cross-linking. A custom diol monomer was first synthesized and then implemented in the synthesis of neat thermoplastic polyurethane SMPs that were irradiated at doses ranging from 1 to 500 kGy. Dynamic mechanical analysis (DMA) demonstrated rubbery moduli to be tailorable between 0.1 and 55 MPa, and both DMA and sol/gel analysis results provided fundamental insight into our hypothesized mechanism of electron beam cross-linking, which enables controllable bulk cross-linking to be achieved in highly processable, low-molecular weight thermoplastic shape memory polymers without sensitizing additives.

  3. Chitosan-gold-Lithium nanocomposites as solid polymer electrolyte.

    PubMed

    Begum, S N Suraiya; Pandian, Ramanathaswamy; Aswal, Vinod K; Ramasamy, Radha Perumal

    2014-08-01

    Lithium micro batteries are emerging field of research. For environmental safety biodegradable films are preferred. Recently biodegradable polymers have gained wide application in the field of solid polymer electrolytes. To make biodegradable polymers films plasticizers are usually used. However, use of plasticizers has disadvantages such as inhomogenities in phases and mechanical instability that will affect the performance of Lithium micro batteries. We have in this research used gold nanoparticles that are environmentally friendly, instead of plasticizers. Gold nanoparticles were directly template upon chitosan membranes by reduction process so as to enhance the interactions of Lithium with the polymer. In this article, for the first time the characteristics of Chitosan-gold-Lithium nanocomposite films are investigated. The films were prepared using simple solution casting technique. We have used various characterization tools such as Small Angle Neutron Scattering (SANS), XRD, FTIR, Raman, FESEM, and AFM, Light scattering, Dielectric and electrical conductivity measurements. Our investigations show that incorporation of gold results in enhancement of conductivity in Lithium containing Chitosan films. Also it affects the dielectric characteristics of the films. We conclude through various characterization tools that the enhancement in the conductivity was due to the retardation of crystal growth of lithium salt in the presence of gold nanoparticles. A model is proposed regarding the formation of the new nanocomposite. The conductivity of these biodegradable films is comparable to those of the current inorganic Lithium micro batteries. This new chitosan-Au-Li nanocomposite has potential applications in the field of Lithium micro batteries.

  4. Fuel cells with solid polymer electrolyte and their application on vehicles

    SciTech Connect

    Fateev, V.

    1996-04-01

    In Russia, solid polymer electrolyte MF-4-SK has been developed for fuel cells. This electrolyte is based on perfluorinated polymer with functional sulfogroups. Investigations on electrolyte properties and electrocatalysts have been carried out.

  5. Photocured PEO-based solid polymer electrolyte and its application to lithium-polymer batteries

    NASA Astrophysics Data System (ADS)

    Kang, Yongku; Kim, Hee Jung; Kim, Eunkyoung; Oh, Bookeun; Cho, Jae Hyun

    A solid polymer electrolyte (SPE) based on polyethylene oxide (PEO) is prepared by photocuring of polyethylene glycol acrylates. The conductivity is greatly enhanced by adding low molecular weight poly(ethylene glycol) dimethylether (PEGDME). The maximum conducticity is 5.1×10 -4 S cm -1 at 30°C. These electrolytes display oxidation stability up to 4.5 V against a lithium reference electrode. Reversible electrochemical plating/stripping of lithium is observed on a stainless steel electrode. Li/SPE/LiMn 2O 4 as well as C(Li)/SPE/LiCoO 2 cells have been fabricated and tested to demonstrate the applicability of the resulting polymer electrolytes in lithium-polymer batteries.

  6. Solid hemoglobin-polymer phantoms for evaluation of biophotonic systems.

    PubMed

    Jang, Hyounguk; Pfefer, T Joshua; Chen, Yu

    2015-09-15

    Stable tissue phantoms that incorporate the spectral absorption properties of hemoglobin would benefit a wide range of biophotonic technologies. Toward this end, we have developed and validated a novel polymer material incorporating hemoglobin. Our solid hemoglobin-polymer (SHP) material is fabricated by mixing liquid silicone base with a hemoglobin solution, followed by sonication and low temperature curing. The optical properties of samples were determined over 450-1000 nm using the inverse adding-doubling method and the Beer-Lambert law. Measurements indicated SHP optical stability over four months. Near-infrared spectroscopy and hyperspectral imaging measurements of SHP samples were performed to demonstrate the utility of this approach. SHP materials have the potential to improve tissue-simulating phantoms used for development, evaluation, and standardization of optical devices for oximetry and other applications.

  7. Adhesive force assisted imprinting of soft solid polymer films by flexible foils.

    PubMed

    Mukherjee, Rabibrata; Sharma, Ashutosh; Gonuguntla, Manoj; Patil, Ganesh K

    2008-07-01

    We report a simple, rapid, room temperature, pressure-less and large area (approximately cm2) imprinting technique for high fidelity patterning of soft solid polymer films and surfaces like cross-linked polydimethylsiloxane (PDMS) and polyacrylamide (PAA) based hydrogels, both on planar and curved surfaces. The key element of the method is the use of patterned thin flexible foils that readily and rapidly attain a conformal contact with soft (shear modulus < 0.1 MPa) solid surfaces because of adhesive interfacial interactions. The conformal contact is established at all length scales by bending of the foil at scales larger than the feature size, in conjunction with the spontaneous elastic deformations of the surface on the scale of the features. For example, we used the protective aluminum foils of commercial data storage discs, both with or without data stored, for micron and sub-micron pattern transfer. The patterns are made permanent by UV-ozone treatment (for PDMS) or by controlled drying (for hydrogels). Interestingly, elastic contact imprinting of very thin (< 300 nm) films results in about 50% miniaturization of the original foil feature sizes. Complex two dimensional patterns could also be formed even by using a simple one dimensional master by multiple imprinting. The technique can be particularly useful for the bulk nano applications requiring routine fabrication of templates, for example, in the study of confined chemistry phenomena, nanofluidics, bio-MEMS, micro-imprinting, optical coatings and controlled dewetting.

  8. Ion conducting polymers and polymer blends for alkali metal ion batteries

    DOEpatents

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Vitale, Alessandra

    2017-08-29

    Electrolyte compositions for batteries such as lithium ion and lithium air batteries are described. In some embodiments the compositions are liquid compositions comprising (a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and (b) an alkali metal salt dissolved in said solvent system. In other embodiments the compositions are solid electrolyte compositions comprising: (a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and (b) an alkali metal ion salt dissolved in said polymer. Batteries containing such compositions as electrolytes are also described.

  9. Anisotropy and oxidative resistance of highly crosslinked UHMWPE after deformation processing by solid-state ram extrusion.

    PubMed

    Kurtz, Steven M; Mazzucco, Dan; Rimnac, Clare M; Schroeder, Dave

    2006-01-01

    Solid-state deformation processing is a promising technique for modifying the physical and mechanical properties of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) beyond simple thermal treatment cycles that have been employed previously. This study evaluates anisotropy and oxidative resistance in a novel, radiation crosslinked (50 kGy) UHMWPE material (ArComXL: Biomet, Inc., Warsaw, IN), incorporating solid-state, deformation processing by extrusion below the melt transition for application in total hip arthroplasty. Tensile, compression, and small punch tests were conducted to evaluate the material properties in the three principal axes of the resulting material. Furthermore, short-term oxidative resistance was evaluated using Fourier transform infrared spectroscopy and the small punch test in conjunction with accelerated shelf aging protocols. The results of this testing indicate that the material is anisotropic, with significantly enhanced strength oriented along the long axis of the rod. For certain other properties, the magnitude of the anisotropy was relatively slight, especially in the elastic regime, in which only a 20% difference was noted between the long axis of the rod and the orthogonal, radial direction. The highly crosslinked material contains detectable free radicals, at a concentration that is 90% less than control, gamma inert sterilized UHMWPE. An unexpected finding of this study was evidence of oxidative stability of the deformation-processed material, even after 4 weeks of accelerated aging in a pressure vessel containing five atmospheres of oxygen (ASTM F2003), which resulted in macroscopic embrittlement of the control material. The oxidative stability observed in ArComXL suggests that the deformation-processed material may be suitable for air-permeable packaging and gas sterilization, which has thus far been reserved for remelted highly crosslinked UHMWPE.

  10. Ozone electrosynthesis in an electrolyzer with solid polymer electrolyte

    SciTech Connect

    Babak, A.A.; Fateev, V.N.; Amadelli, R.; Potapova, G.F.

    1994-06-01

    Environmental problems have provided a focus of growing attention within the past few years. Of particular interest are preparation techniques for ozone, which is known to be an environmentally clean oxidant applicable to conditioning of potable water, sewage treatment, and disinfection of various domestic media. It also can be employed in chemical synthesis and a number of other applications. An electrolyzer with PbO{sub 2}-covered anode pressed against a membrane of a solid polymer electrolyte of sulfocationite type is shown to exhibit high operational qualities in electrochemical production of ozone.

  11. Electrolytic hydrogen fuel production with solid polymer electrolyte technology.

    NASA Technical Reports Server (NTRS)

    Titterington, W. A.; Fickett, A. P.

    1973-01-01

    A water electrolysis technology based on a solid polymer electrolyte (SPE) concept is presented for applicability to large-scale hydrogen production in a future energy system. High cell current density operation is selected for the application, and supporting cell test performance data are presented. Demonstrated cell life data are included to support the adaptability of the SPE system to large-size hydrogen generation utility plants as needed for bulk energy storage or transmission. The inherent system advantages of the acid SPE electrolysis technology are explained. System performance predictions are made through the year 2000, along with plant capital and operating cost projections.

  12. Electrolytic hydrogen fuel production with solid polymer electrolyte technology.

    NASA Technical Reports Server (NTRS)

    Titterington, W. A.; Fickett, A. P.

    1973-01-01

    A water electrolysis technology based on a solid polymer electrolyte (SPE) concept is presented for applicability to large-scale hydrogen production in a future energy system. High cell current density operation is selected for the application, and supporting cell test performance data are presented. Demonstrated cell life data are included to support the adaptability of the SPE system to large-size hydrogen generation utility plants as needed for bulk energy storage or transmission. The inherent system advantages of the acid SPE electrolysis technology are explained. System performance predictions are made through the year 2000, along with plant capital and operating cost projections.

  13. Recent advances in solid polymer electrolyte fuel cell technology

    SciTech Connect

    Ticianelli, E.A.; Srinivasan, S.; Gonzalez, E.R.

    1988-01-01

    With methods used to advance solid polymer electrolyte fuel cell technology, we are close to obtaining the goal of 1 A/cm/sup 2/ at 0.7. Higher power densities have been reported (2 A/cm/sup 2/ at 0.5 V) but only with high catalyst loading electrodes (2 mg/cm/sup 2/ and 4 mg/cm/sup 2/ at anode and cathode, respectively) and using a Dow membrane with a better conductivity and water retention characteristics. Work is in progress to ascertain performances of cells with Dow membrane impregnated electrodes and Dow membrane electrolytes. 5 refs., 6 figs.

  14. High-Voltage Solid Polymer Batteries for Electric Drive Vehicles

    SciTech Connect

    Eitouni, Hany; Yang, Jin; Pratt, Russell; Wang, Xiao; Grape, Ulrik

    2014-09-29

    The purpose of this project was for Seeo to develop a high energy lithium based technology with targets of over 500 Wh/l and 325 Wh/kg. Seeo would leverage the work already achieved with its unique proprietary solid polymer DryLyteTM technology in cells which had a specific energy density of 220 Wh/kg. The development work was focused on establishing a dual electrolyte system, coated cathode particle techniques, various types of additives, and different conductive salts. The program had a duration of three years, with Seeo delivering the final cells at the end of 2014 for evaluation by a DOE laboratory.

  15. Potential of ion imprinted polymers synthesized by trapping approach for selective solid phase extraction of lanthanides.

    PubMed

    Moussa, Manel; Pichon, Valérie; Mariet, Clarisse; Vercouter, Thomas; Delaunay, Nathalie

    2016-12-01

    Ion imprinted polymers (IIPs) specific to lanthanides were synthesized using neodymium ions (Nd(3+)) as template ions. Nd(3+) ions form binary complex ions with 5,7-dichloroquinoline-8-ol (DCQ) or vinylpyridine (VP), or ternary complex ions with both DCQ and VP in 2-methoxyethanol, before copolymerization in the presence of styrene and divinylbenzene as monomer and cross-linker, respectively. DCQ was expected to be trapped in the synthesized polymers pores. The template ion removal was then optimized. For the first time, the DCQ leakage was determined by HPLC-UV during the template removal and the sedimentation steps before solid-phase extraction (SPE) packing. It was observed that the trapped DCQ was unfortunately lost in significant amounts, up to 51%, and that this amount varied from one synthesis to another. The grinded and sieved polymers were next packed in SPE cartridges. The study of the SPE profiles obtained with the IIPs synthesized either with the binary or the ternary complex confirmed the prominent role of DCQ on the selectivity of an IIP by comparison with a non-imprinted polymer (NIP), i.e. a polymer synthesized under the same conditions as those of the IIP but without template ions. The influence of the porogenic solvent on the selectivity was also investigated by replacing 2-methoxyethanol by acetonitrile or dimethylsulfoxyde (DMSO). The polymers synthesized in DMSO led to the most repeatable results when elution solutions with a gradual decrease in pH were percolated through the cartridge. This is why DMSO was used to optimize the SPE protocol in order to maximize the difference of extraction yield between the IIP and the NIP, i.e. promoting a selective retention on the IIP. A value of about 30% was obtained for La(3+), Ce(3+), Nd(3+), and Sm(3+). Nevertheless, with the optimized SPE protocol, IIPs from different syntheses did not have the same SPE behavior, which may result from different random leakages of DCQ. This demonstrates for the first

  16. Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase extraction.

    PubMed

    Chrzanowska, Anna M; Poliwoda, Anna; Wieczorek, Piotr P

    2015-04-01

    Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1',1'-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) permitted the characterization and evaluation of synthesized polymers. The adsorption capacity of obtained MIPs was checked by using the binding testing. All synthesized polymers were evaluated as solid-phase extraction (SPE) sorbents for isolation and preconcentration of biochanin A and its analogues, daidzein and genistein. The MIPs exhibited higher affinity for biochanin A over competitive compounds.

  17. Compressed antisolvent precipitation and photopolymerization for the formation of crosslinked polymer microparticles useful for controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Owens, Jennifer Lani

    This work presents novel antisolvent processing technique entitled Compressed Antisolvent Precipitation and Photopolymerization (CAPP) useful for forming crosslinked polymer microparticles. In this process, an organic solvent dissolves monomer and polymerization photoinitiators to form a homogeneous solution. Photopolymerization and microparticle formation occur when the homogeneous solution is sprayed into a compressed antisolvent while being simultaneously exposed to initiating light. We investigated the method of particle formation in the CAPP process to explain the repeatable bimodal particle size distribution obtained under a variety of operating conditions. Ternary phase diagrams of antisolvent, monomer, and solvent solutions were constructed and specific spray paths from the resulting ternary phase diagrams were investigated and the significance of crossing the binodal, as well as the importance of where the binodal was crossed, was discovered. In addition, manipulation of injection conditions, varying process residence times, and nucleation rate calculations were explored to further investigate the means of particle formation. We demonstrate the feasibility of encapsulating therapeutic agents into highly crosslinked polymer particles using the CAPP process. Ion-paired tacrine, erythromycin, erythromycin estolate, and erythromycin ethyl succinate were CAPP processed with poly(ethylene glycol) diacrylate monomers of several molecular weights so that the resulting particles would entrap different sized drugs in networks with varying mesh sizes. In vitro drug release profiles were obtained for all of the various drug-monomer combinations. Diffusion coefficients were estimated by fitting a short time approximation of Fickian release from a sphere of fixed diameter to the release data and were applied to a model of Fickian release from polydisperse spheres, and the results were compared to the in vitro release data. CAPP particle processing was explored in

  18. Stationary market applications potential of solid oxide and solid polymer fuel cell systems

    SciTech Connect

    Baker, J.N.; Fletcher, W.H.

    1996-12-31

    The UK DTI`s Advanced Fuel Cells Programme currently focuses on two main fuel cell technologies, namely the solid oxide and solid polymer systems (SOFC and SPFC), respectively. The provision of accurate and timely market data is regarded as an important part of the overall programme objectives, such as to assist both Government and industry in their appraisals of the technologies. The present study was therefore commissioned against this background, with a complementary study addressing transportation and mobile applications. The results reported herein relate to the stationary market applications potential of both SOFC and SPFC systems.

  19. Preparation of a deuterated polymer: Simulating to produce a solid tritium radioactive source

    NASA Astrophysics Data System (ADS)

    Hu, Rui; Kan, Wentao; Xiong, Xiaoling; Wei, Hongyuan

    2017-08-01

    The preparation of a deuterated polymer was performed in order to simulate the production of the corresponding tritiated polymer as a solid tritium radioactive source. Substitution and addition reaction were used to introduce deuterium into the polymer. Proton nuclear magnetic resonance and FT-IR spectroscopy were used to investigate the extent and location of deuterium in the polymer, indicating an effectively deuterated polymer was produced. The thermal analysis showed that the final polymer product could tolerate the environmental temperature below 125 °C in its application. This research provides a prosperous method to prepare solid tritium radioactive source.

  20. Development of minimal models of the elastic properties of flexible and stiff polymer networks with permanent and thermoreversible cross-links

    PubMed Central

    Lin, David C.

    2010-01-01

    We review the elasticity of flexible and stiff polymer networks with permanent cross-links and synthesize these results into a unifying polymer chain network model. This framework is then used to address how the network elasticity becomes modified when the network cross-linking is thermoreversible in nature, changes in the stability of the network with deformation, and the effect of a variable rate of network deformation on the non-linear elastic response. Comparisons are made between this class of simplified network models with elasticity measurements performed on flexible chain and stiff fiber networks, both with permanent and associative cross-links. Although these network models are highly idealized, they are apparently able to capture many aspects of the elastic properties of diverse real networks. PMID:21113355

  1. Molecularly imprinted polymer grafted to porous polyethylene frits: a new selective solid-phase extraction format.

    PubMed

    Barahona, Francisco; Turiel, Esther; Martín-Esteban, Antonio

    2011-10-07

    In this paper, a novel format for selective solid-phase extraction based on a molecularly imprinted polymer (MIP) is described. A small amount of MIP has been synthesized within the pores of commercial polyethylene (PE) frits and attached to its surface using benzophenone (BP), a photo-initiator capable to start the polymerisation from the surface of the support material. Key properties affecting the obtainment of a proper polymeric layer, such as polymerisation time and kind of cross-linker were optimised. The developed imprinted material has been applied as a selective sorbent for cleaning extracts of thiabendazole (TBZ), as model compound, from citrus samples. The use of different solvents for loading the analyte in the imprinted frits was investigated, as well as the binding capacity of the imprinted polymer. Imprinted frits showed good selectivity when loads were performed using toluene and a linear relationship was obtained for the target analyte up to 1000 ng of loaded analyte. Prepared composite material was applied to the SPE of TBZ in real samples extracts, showing an impressive clean-up ability. Calibrations showed good linearity in the concentration range of 0.05-5.00 μg g(-1), referred to the original solid sample, and the regression coefficients obtained were greater than 0.996. The calculated detection limit was 0.016 μg g(-1), low enough to satisfactory analysis of TBZ in real samples. RSDs at different spiking levels ranged below 15% in all the cases and imprinted frits were reusable without loss in their performance.

  2. Hologram formation reconsidered in dichromated polyvinylalcohol: polymer cross-linking around chromium (V)

    NASA Astrophysics Data System (ADS)

    Bolte, Michele; Israeli, Yael; Djouani, Fatma; Rivaton, Agnes; Frezet, Lawrence; Lessard, Roger A.

    2005-04-01

    The photochemical behavior of dichromated polyvinylalcohol (DCPVA) films was analysed upon exposure at 365 nm in connection with the hologram quality recorded in such a photosensitive material. The evolution of both involved species, chromium and polyvinylalcohol, were quantified by implementing an innovative approach. This approach combines the monitoring of the structural modification of the polymeric matrix and the fate of the various chromium species ((VI), (V) and (III)). For the first time, it was established that chromium (V) was at the origin of the cross-linking implied in the hologram formation by acting as a bridge between hydroxyl groups of the polymeric chains. A second unanswered question was also elucidated. The improvement brought by ammonium dichromate with respect to potassium dichromate involves amide groups as additional chelating sites for chromium (V) resulting in the increase of the matrix cross-linking.

  3. Chemical cross-linking of polypropylenes towards new shape memory polymers.

    PubMed

    Raidt, Thomas; Hoeher, Robin; Katzenberg, Frank; Tiller, Joerg C

    2015-04-01

    In this work, syndiotactic polypropylene (sPP) as well as isotactic polypropylene (iPP) are cross-linked to gain a shape memory effect. Both prepared PP networks exhibit maximum strains of 700%, stored strains of up to 680%, and recoveries of nearly 100%. While x-iPP is stable for many cycles, x-sPP ruptures after the first shape-memory cycle. It is shown by wide-angle X-ray scattering (WAXS) experiments that cross-linked iPP exhibits homoepitaxy in the temporary, stretched shape but in contrast to previous reports it contains a higher amount of daughter than mother crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Inexpensive cross-linked polymeric separators made from water soluble polymers

    NASA Technical Reports Server (NTRS)

    Hsu, L. C.; Sheibley, D. W.

    1979-01-01

    Polyvinyl alcohol (PVA) crosslinked chemically with aldehyde reagents produces membranes which demonstrate oxidation resistance, dimensional stability, low ionic resistivity, low zincate diffusivity, and low zinc dendrite penetration rate which make them suitable for use as alkaline battery separators. They are intrinsically low in cost and environmental health and safety problems associated with commercial production appear minimal. Preparation, property measurements, and cell test results in Ni/Zn and Ag/Zn cells are described and discussed.

  5. Tailoring the dependency between rigidity and water uptake of a microfabricated hydrogel with the conformational rigidity of a polymer cross-linker.

    PubMed

    Schmidt, John J; Jeong, Jae Hyun; Chan, Vincent; Cha, Chaenyung; Baek, Kwanghyun; Lai, Mei-Hsiu; Bashir, Rashid; Kong, Hyunjoon

    2013-05-13

    Many diverse applications utilize hydrogels as carriers, sensors, and actuators, and these applications rely on the refined control of physical properties of the hydrogel, such as elastic modulus and degree of swelling. Often, hydrogel properties are interdependent; for example, when elastic modulus is increased, degree of swelling is decreased. Controlling these inverse dependencies remains a major barrier for broader hydrogel applications. We hypothesized that polymer cross-linkers with varied chain flexibility would allow us to tune the inverse dependency between the elastic modulus and the degree of swelling of the hydrogels. We examined this hypothesis by using alginate and poly(acrylic acid) (PAA) modified with a controlled number of methacrylic groups as model inflexible and flexible cross-linkers, respectively. Interestingly, the polyacrylamide hydrogel cross-linked by the inflexible alginate methacrylates exhibited less dependency between the degree of swelling and the elastic modulus than the hydrogel cross-linked by flexible PAA methacrylates. This critical role of the cross-linker's inflexibility was related to the difference of the degree of hydrophobic association between polymer cross-linkers, as confirmed with pyrene probes added in pregel solutions. Furthermore, hydrogels cross-linked with alginate methacrylates could tune the projection area of adhered cells by solely altering elastic moduli. In contrast, gels cross-linked with PAA methacrylates failed to modulate the cellular adhesion morphology due to a lower, and smaller, elastic modulus range to be controlled. Overall, the results of this study will significantly advance the controllability of hydrogel properties and greatly enhance the performance of hydrogels in various biological applications.

  6. Oxidation increases mucin polymer cross-links to stiffen airway mucus gels.

    PubMed

    Yuan, Shaopeng; Hollinger, Martin; Lachowicz-Scroggins, Marrah E; Kerr, Sheena C; Dunican, Eleanor M; Daniel, Brian M; Ghosh, Sudakshina; Erzurum, Serpel C; Willard, Belinda; Hazen, Stanley L; Huang, Xiaozhu; Carrington, Stephen D; Oscarson, Stefan; Fahy, John V

    2015-02-25

    Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates. Copyright © 2015, American Association for the Advancement of Science.

  7. Oxidation increases mucin polymer cross-links to stiffen airway mucus gels

    PubMed Central

    Yuan, Shaopeng; Hollinger, Martin; Lachowicz-Scroggins, Marrah E.; Kerr, Sheena C.; Dunican, Eleanor M.; Daniel, Brian M.; Ghosh, Sudakshina; Erzurum, Serpel C.; Willard, Belinda; Hazen, Stanley L.; Huang, Xiaozhu; Carrington, Stephen D.; Oscarson, Stefan; Fahy, John V.

    2015-01-01

    Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates. PMID:25717100

  8. Removal of copper ions from water using epichlorohydrin cross-linked beta-cyclodextrin polymer: characterization, isotherms and kinetics.

    PubMed

    Sikder, M Tajuddin; Islam, Md Shariful; Kikuchi, Tohru; Suzuki, Junichi; Saito, Takeshi; Kurasaki, Masaaki

    2014-04-01

    Beta-cyclodextrin (beta-CD) cross-linked with epichlorohydrin to form water insoluble beta-cyclodextrin polymer (beta-CDP) has been shown to be an effective sorbent for sorption of organic particles, but the sorption of copper (Cu2+) in aqueous solutions by beta-CDP has not been conducted. The objective of this study was to explore the sorption mechanism of beta-CDP for copper. The effects of different experimental conditions such as pH, ionic strength, contact time, and temperature were inspected using a batch method. In addition, binding scheme was estimated by using Fourier transform infrared (FTIR) spectroscopy, Xray photoelectron spectroscopy (XPS), a scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) analysis. The adsorption of Cu2+ was observed to be higher at pH 6.0. The kinetic study revealed that the adsorption is fitted well by the pseudo-second-order kinetic model. The maximum binding of Cu2+ was estimated to be 111.11 mg/g through the Langmuir isotherm model--much higher than the existing sorption technologies. Hence, the adsorption-desorption trends of epichlorohydrin cross-linked with beta-CD, along with its good recyclability, establish an alternative, effective, and novel remediation technology for the removal of Cu2+ from aqueous solutions.

  9. Advanced Sodium Ion Battery Anode Constructed via Chemical Bonding between Phosphorus, Carbon Nanotube, and Cross-Linked Polymer Binder.

    PubMed

    Song, Jiangxuan; Yu, Zhaoxin; Gordin, Mikhail L; Li, Xiaolin; Peng, Huisheng; Wang, Donghai

    2015-12-22

    Maintaining structural stability is a great challenge for high-capacity conversion electrodes with large volume change but is necessary for the development of high-energy-density, long-cycling batteries. Here, we report a stable phosphorus anode for sodium ion batteries by the synergistic use of chemically bonded phosphorus-carbon nanotube (P-CNT) hybrid and cross-linked polymer binder. The P-CNT hybrid was synthesized through ball-milling of red phosphorus and carboxylic group functionalized carbon nanotubes. The P-O-C bonds formed in this process help maintain contact between phosphorus and CNTs, leading to a durable hybrid. In addition, cross-linked carboxymethyl cellulose-citric acid binder was used to form a robust electrode. As a result, this anode delivers a stable cycling capacity of 1586.2 mAh/g after 100 cycles, along with high initial Coulombic efficiency of 84.7% and subsequent cycling efficiency of ∼99%. The unique electrode framework through chemical bonding strategy reported here is potentially inspirable for other electrode materials with large volume change in use.

  10. Electrically driven biofouling release of a poly(tetrafluoroethylene) membrane modified with an electrically induced reversibly cross-linked polymer.

    PubMed

    Chuo, Tsai-Wei; Wei, Ta-Chin; Chang, Yung; Liu, Ying-Ling

    2013-10-23

    Electrically induced reversible reactions between ferrocene (Fc) and β-cyclodextrin (β-CD) groups have been utilized for preparation of poly(tetrafluoroethylene) (PTFE) membranes exhibiting electrically driven biofouling release properties. PTFE membrane is surface-modified with polymer chains possessing Fc pendant groups. The surface layer is then cross-linked with a difunctional β-CD compound by means of the Fc/β-CD complexation reaction. The electrically induced reversibly cross-linking and de-cross-linking behaviors of the surface layer of the modified PTFE membrane have been characterized with Fourier transform Infrared, X-ray photoelectron spectroscopy, and scanning electron microscopy. The surface-modified PTFE membrane has been fouled with protein absorption. Electrical treatment of the fouled membrane results in a protein detachment from the membrane surface driven by the surface structure change accompanied with the electrically induced de-cross-linking reaction of the Fc/β-CD linkages. A smart membrane exhibiting a novel cleaning technology for membrane fouling has been developed.

  11. Enhancement in dose sensitivity of polymer gel dosimeters composed of radiation-crosslinked gel matrix and less toxic monomers

    NASA Astrophysics Data System (ADS)

    Hiroki, A.; Yamashita, S.; Taguchi, M.

    2015-01-01

    Polymer gel dosimeters based on radiation-crosslinked hydroxypropyl cellulose gel were prepared, which comprised 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol #400 dimethacrylate (9G) as less toxic monomers and tetrakis (hydroxymethyl) phosphonium chloride (THPC) as an antioxidant. The dosimeters exposed to 60Co γ-rays became cloudy at only 1 Gy. The irradiated dosimeters were optically analyzed by using a UV- vis spectrophotometer to evaluate dose response. Absorbance of the dosimeters linearly increased in the dose range from 0 to 10 Gy, in which dose sensitivity increased with increasing 9G concentration. The dose sensitivity of the dosimeters with 2 wt% HEMA and 3 wt% 9G was also enhanced by increment in THPC.

  12. Solid polymeric electrolytes obtained from modified natural polymers

    NASA Astrophysics Data System (ADS)

    Pawlicka, Agnieszka; Machado, G. O.; Guimaraes, K. V.; Dragunski, Douglas C.

    2003-10-01

    Polysaccharides like starch and cellulose derivatives, hydroxyethylcellulose (HEC) or hydroxypropylcellulose (HPC) were modified to obtain solid polymeric electrolytes. The chemical modifications were performed by the grafting of polymers with poly(ethylene oxide) mono and diisocyanates or JEFFAMINE (Shiff base). The physical modifications were made by the plasticization process of starch and cellulose derivatives with glycerol and ethylene glycol. All the samples obtained from polysaccharides were characterized by X-ray, thermal analysis (DSC) and impedance spectroscopy. The plasticized samples showed low glass transition temperatures (Tg); for HEC the value was about -60°C and for starch it was about -30°C. Tg values for grafted samples were of about -58°C for starch and -7°C for HPC. The low Tg values obtained are important to ensure good ionic conductivity that reached the values of about 10-5 Scm-1 for plasticized samples and 10-6 Scm-1 for grafted ones at room temperature. The good film forming and ionic conductivity properties of the samples of HEC, HPC and starch are very interesting candidates to be used as solid polymer electrolytes.

  13. Improved performance of Li hybrid solid polymer electrolyte cells

    NASA Astrophysics Data System (ADS)

    Nagasubramanian, G.; Bronstein, Lyudmila; Carini, John

    The seminal research by Wright et al. on polyethylene oxide (PEO) solid polymer electrolyte (SPE) generated intense interest in all solid-state rechargeable lithium batteries. Following this a number of researchers have studied the physical, electrical and transport properties of thin film PEO electrolyte containing Li salt. These studies have clearly identified the limitations of the PEO electrolyte. Chief among the limitations are a low cation transport number (t +), high crystallinity and segmental motion of the polymer chain, which carries the cation through the bulk electrolyte. While low t + leads to cell polarization and increase in cell resistance high T g reduces conductivity at and around room temperatures. For example, the conductivity of PEO electrolyte containing lithium salt is <10 -7 S cm -1 at room temperature. Although modified PEO electrolytes with lower T g exhibited higher conductivity (∼10 -5 S cm -1 at RT) the t + is still very low ∼0.25 for lithium ion. Numerous other attempts to improving t + have met with limited success. The latest approach involves integrating nano domains of inorganic moieties, such as silcate, alumosilicate, etc. within the polymer component. This approach yields an inorganic-organic component (OIC) based polymer electrolyte with higher conductivity and t + for Li + . This paper describes the improved electrical and electrochemical properties of OIC-based polymer electrolyte and cells containing Li anode with either a TiS 2 cathode or Mag-10 carbon electrode. Several solid polymer electrolytes derived from silicate OIC and salt-in-polymer constituent based on Li triflate (LiTf) and PEO are studied. A typical composition of the SPE investigated in this work consists of 600 kDa PEO, lithium triflate (LiTf, LiSO 3CF 3) and 55% of silicate based on (3-glycidoxypropyl)trimethoxysilane and tetramethoxysilane at molar ratio 4:1 and 0.65 mol% of aluminum(tri- sec-butoxide) (GTMOS-Al1-900k-55%). Several pouch cells

  14. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    SciTech Connect

    Liao, Chen; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  15. Preparation of a collagen/polymer hybrid gel designed for tissue membranes. Part I: controlling the polymer-collagen cross-linking process using an ethanol/water co-solvent.

    PubMed

    Nam, Kwangwoo; Kimura, Tsuyoshi; Funamoto, Seiichi; Kishida, Akio

    2010-02-01

    The drawback with collagen/2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hybrid gels (collagen/phospholipid polymer hybrid gels) prepared in alkaline morpholinoethane sulfonic acid (MES) aqueous solution is that the cross-linking rate between the polymer and the collagen is low. To solve this problem, ethanol has been adopted as the reaction solvent, to prevent 1-ethyl-3-(3-dimethylaminopropyl)-1-carbodiimide hydrochloride (EDC) hydrolysis. Alterations in the ethanol mole concentration changed the cross-linking rate between the MPC polymer and the collagen gel. Prevention of EDC hydrolysis is clearly observed; protonation of carboxyl groups implies that the ratio of ethanol to water should be controlled. The polymer shows signs of penetration into the collagen gel layer, thus forming a totally homogeneous phase gel. This affects the mechanical strength of the collagen gel, making the gel much stiffer and brittle with an increase in the swelling ratio, as compared with that prepared in MES buffer. However, it is possible to obtain a collagen/phospholipid polymer hybrid gel with a high polymer portion and the cross-linking rate can be successfully controlled.

  16. [The advance in researches for biomedical intelligent polymer materials].

    PubMed

    Zhang, Zhibin; Tang, Changwei; Qiu, Kai; Chen, Yuanwei; Xiong, Yanfang; Wan, Changxiu

    2004-10-01

    The properties of biomedical intelligent polymer materials can be changed obviously when there is a little physical or chemical change in external condition. They are in the forms of solids, solutions and polymers on the surface of carrier, including aqueous solution of hydrophilic polymers, cross-linking hydrophilic polymers (i.e. hydrogels) and the polymers on the surface of carrier. In this paper are reviewed the progress in researches and the application of biomedical intelligent polymer materials.

  17. Folic acid conjugated cross-linked acrylic polymer (FA-CLAP) hydrogel for site specific delivery of hydrophobic drugs to cancer cells

    PubMed Central

    2014-01-01

    Background The hydrogel based system is found to be rarely reported for the delivery of hydrophobic drug due to the incompatibility of hydrophilicity of the polymer network and the hydrophobicity of drug. This problem can be solved by preparing semi-interpenetrating network of cross-linked polymer for tuning the hydrophilicity so as to entrap the hydrophobic drugs. The current study is to develop a folic acid conjugated cross-linked pH sensitive, biocompatible polymeric hydrogel to achieve a site specific drug delivery. For that, we have synthesized a folic acid conjugated PEG cross-linked acrylic polymer (FA-CLAP) hydrogel and investigated its loading and release of curcumin. The formed polymer hydrogel was then conjugated with folic acid for the site specific delivery of curcumin to cancer cells and then further characterized and conducted the cell uptake and cytotoxicity studies on human cervical cancer cell lines (HeLa). Results In this study, we synthesized folic acid conjugated cross-linked acrylic hydrogel for the delivery of hydrophobic drugs to the cancer site. Poly (ethyleneglycol) (PEG) diacrylate cross-linked acrylic polymer (PAA) was prepared via inverse emulsion polymerization technique and later conjugated it with folic acid (FA-CLAP). Hydrophobic drug curcumin is entrapped into it and investigated the entrapment efficiency. Characterization of synthesized hydogel was done by using Fourier Transform-Infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC). Polymerization and folate conjugation was confirmed by FT-IR spectroscopy. The release kinetics of drug from the entrapped form was studied which showed initial burst release followed by sustained release due to swelling and increased cross-linking. In vitro cytotoxicity and cell uptake studies were conducted in human cervical cancer (HeLa) cell lines. Conclusions Results showed that curcumin entrapped folate conjugated cross-linked acrylic

  18. Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

    DOEpatents

    Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

    2015-02-24

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

  19. Fluorescence spectrophotometer analysis of polycyclic aromatic hydrocarbons in environmental samples based on solid phase extraction using molecularly imprinted polymer.

    PubMed

    Krupadam, Reddithota J; Bhagat, Bhagyashree; Wate, Satish R; Bodhe, Ghanshyam L; Sellergren, Borje; Anjaneyulu, Yerramilli

    2009-04-15

    A molecularly imprinted polymer (MIP) was synthesized using a polycyclic aromatic hydrocarbon (PAH) standard as a template, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and acetonitrile as a porogen. This polymer was used as a solid phase adsorbent for the quantitative enrichment of PAHs in coastal sediments, atmospheric particulates, and industrial effluents. The MIP selective adsorption capacity for PAHs started reducing when the chemical oxygen demand (COD) and total dissolved solids (TDS) was more than 800 mg L(-1) in the targeted environmental samples. The adsorption stability of the MIP was tested by the consecutive contact of environmental samples, and it was shown that the performance of the MIP did not vary after 10 enrichments and desorption cycles. Recoveries of eight PAH compounds, extracted from 10 g of coastal sediments and 1 L of industrial effluent spiked with 10 microL of standard PAHs, showed recoveries between 85 and 96%. The fluorescence spectrophotometer limit of detection of PAHs varied from 10 to 30 etag L(-1) in industrial effluent and from 0.1 to 2.9 etag kg(-1) in solid samples (coastal sediment and atmospheric particulates), and this indicates that the environmental analytical method is significantly sensitive, when compared with other commonly used methods such as gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

  20. Unusual, promoted release of guests from amphiphilic cross-linked polymer networks.

    PubMed

    Brown, Gerald O; Bergquist, Catherine; Ferm, Paul; Wooley, Karen L

    2005-08-17

    Hyperbranched fluoropolymer-poly(ethylene glycol) (HBFP-PEG) cross-linked networks have been found to exhibit capabilities for the encapsulation of high levels of geraniol guest molecules coupled with unusually rapid release of the volatile compound. The promotion of the release of the volatile fragrance geraniol, observed as decreasing volatilization temperatures and increasing volatilization rates by thermogravimetric analyses, was found to be dependent upon the HBFP-PEG network composition, with increasing effects from decreasing wt % PEG and a maximum effect occurring at 5 wt % PEG.

  1. Polymer-Induced Swelling of Solid-Supported Lipid Membranes

    PubMed Central

    Kreuzer, Martin; Trapp, Marcus; Dahint, Reiner; Steitz, Roland

    2015-01-01

    In this paper, we study the interaction of charged polymers with solid-supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes by in-situ neutron reflectivity. We observe an enormous swelling of the oligolamellar lipid bilayer stacks after incubation in solutions of poly(allylamine hydrochloride) (PAH) in D2O. The positively charged polyelectrolyte molecules interact with the lipid bilayers and induce a drastic increase in their d-spacing by a factor of ~4. Temperature, time, and pH influence the swollen interfacial lipid linings. From our study, we conclude that electrostatic interactions introduced by the adsorbed PAH are the main cause for the drastic swelling of the lipid coatings. The DMPC membrane stacks do not detach from their solid support at T > Tm. Steric interactions, also introduced by the PAH molecules, are held responsible for the stabilizing effect. We believe that this novel system offers great potential for fundamental studies of biomembrane properties, keeping the membrane’s natural fluidity and freedom, decoupled from a solid support at physiological conditions. PMID:26703746

  2. Effect of Molecular Weight on Mechanical and Electrochemical Performance of All Solid-State Polymer Electrolyte Membranes

    NASA Astrophysics Data System (ADS)

    He, Ruixuan; Ward, Daniel; Echeverri, Mauricio; Kyu, Thein

    2015-03-01

    Guided by ternary phase diagrams of polyethylene glycol diacrylate (PEGDA), succinonitrile plasticizer, and LiTFSI salt, completely amorphous solid-state transparent polymer electrolyte membranes (ss-PEM) were fabricated by UV irradiation in the isotropic melt state. Effects of PEGDA molecular weight (700 vs 6000 g/mol) on ss-PEM performance were investigated. These amorphous PEMs have superionic room temperature ionic conductivity of ~10-3 S/cm, whereby PEGDA6000-PEM outperforms its PEGDA700 counterpart, which may be ascribed to lower crosslinking density and greater segmental mobility. The longer chain between crosslinked points of PEGDA6000-PEM is responsible for greater extensibility of ~80% versus ~7% of PEGDA700-PEM. Besides, both PEMs exhibited thermal stability up to 120 °C and electrochemical stability versus Li+/Li up to 4.7V. LiFePO4/PEM/Li and Li4Ti5O12 /PEM/Li half-cells exhibited stable cyclic behavior up to 50 cycles tested with a capacity of ~140mAh/g, suggesting that LiFePO4/PEM/Li4Ti5O12 may be a promising full-cell for all solid-state lithium battery. We thank NSF-DMR 1161070 for providing funding of this project.

  3. Crosslinked redox polymer enzyme electrodes containing carbon nanotubes for high and stable glucose oxidation current.

    PubMed

    MacAodha, Domhnall; Ferrer, Maria Luisa; Conghaile, Peter Ó; Kavanagh, Paul; Leech, Dónal

    2012-11-14

    Co-immobilisation approaches for preparation of glucose-oxidising films of [Os(2,2'-bipyridine)(2)(poly-vinylimidazole)(10)Cl] and glucose oxidase on glassy carbon electrodes are compared. Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH(4) reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method. Addition of multi walled carbon nanotubes to the film deposition solutions produces an enhanced glucose oxidation current density of 5 mA cm(-2) at 0.35 V vs. Ag/AgCl, whilst improving the operational stability of the current signal. Carbon nanotube, glutaraldehyde vapour crosslinked, films on electrodes, reduced by NaBH(4), retain 77% of initial catalytic current over 24 hours of continuous amperometric testing in a 37 °C, 50 mM phosphate buffer solution containing 150 mM NaCl and 100 mM glucose. Potential application of this approach to implantable enzymatic biofuel cells is demonstrated by production of glucose oxidation currents, under pseudo-physiological conditions, using mediating films with lower redox potentials.

  4. Cross-linked polyvinyl polymers versus polyureas as designed supports for catalytically active M(0) nanoclusters. Part III. Nanometer scale structure of the cross-linked polyurea support EnCat 30 and of the Pd(II)/EnCat 30 and Pd(0)/EnCat 30NP catalysts.

    PubMed

    Centomo, P; Zecca, M; Zoleo, A; Maniero, A L; Canton, P; Jerábek, K; Corain, B

    2009-05-28

    The cross-linked polyurea support EnCat 30, its related macromolecular complex Pd(II)/EnCat 30 and its related Pd(0)/EnCat 30NP nanocomposite are thoroughly investigated with SEM, TEM, ISEC and ESR in the solid state (SEM and TEM) and swollen state in THF (ISEC and ESR). Pd(II)/EnCat 30 and its related Pd(0)/EnCat 30NP are obtained by microencapsulation of palladium acetate in a polyurea framework, which is formed upon hydrolysis/condensation of mixtures of multi-functional oligo-arylisocyanates in dichloroethane. Most remarkably, both Pd(II)/EnCat and Pd(0)/EnCat 30NP turn out to be far more (nano)porous and swellable materials than the blank polyurea matrix (EnCat 30). It is proposed that there is a strong nanostructural effect exerted by Pd(II) species due to its interaction with functional groups (amines stemming from the hydrolysis of the isocyanato groups or ureido groups belonging to the polymer chains) during the growth of the cross-linked polymer framework. As a consequence, the catalytic species in both Pd(II)/EnCat 30 and Pd(0)/EnCat 30NP are much more accessible to molecules diffusing from liquid phases in contact with the materials and, hence, are better catalysts than expected from the morphology of blank polyurea EnCat 30.

  5. Tritium Separation by Electrolysis Using Solid Polymer Electrolyte

    SciTech Connect

    Ogata, Y.; Sakuma, Y.; Ohtani, N.; Kotaka, M.

    2005-07-15

    Hydrogen isotope separation effect by electrolysis of water was theoretically investigated and was compared with experimental results. The separation mechanism was analyzed as the hydrogen isotope exchange reaction between water and diatomic hydride that consists of hydrogen and cathode material. The equilibrium constants of the isotope exchange reaction were calculated from reduced partition function ratio. Using the constants, the separation factor (SF) of the isotopes was calculated according to the two-phase distribution theory for isotopes. Experimentally, light or heavy water spiked with tritiated water was electrolyzed by a device with a solid polymer electrolyte, which equipped with SUS, Ni, or carbon cathode. Thus, the SFs were experimentally obtained. Calculated SFs were well agreed with the experimentally values for SUS and Ni cathodes, and that for carbon cathode was somewhat small then the experimental value.

  6. Microencapsulation of liquid and solid substances by reactive polymers.

    PubMed

    Shevchuk, O; Serdiuk, V; Bukartyk, N; Moncibovich, R; Tokarev, V

    2014-01-01

    This study is devoted to the development of techniques for the formation of polymeric microcapsules (MC) with either liquid or solid core and with the polymer shell containing diverse functional groups on the basis of new reactive functional copolymers (FC). Two approaches to the formation of MC containing FC shell that included the stages of "oil-in-water" or "water-in-oil" dispersion preparation followed by slow extraction of solvents from dispersed phase by dispersive media were examined. FC with the same structure was successfully applied for both "oil-in-water" and "water-in-oil" systems. Spherical MC with the liquid hydrocarbon core demonstrated essential increase in their volume after heating at the temperature exceeding a boiling point of hydrocarbon encapsulated. Presence of reactive groups in the MC shell opens up new opportunity for further tuning the MC properties via their interaction with proper compounds, particularly via graft-polymerisation of diverse vinyl monomers initiated from the MC surface.

  7. High discharge capacity solid composite polymer electrolyte lithium battery

    NASA Astrophysics Data System (ADS)

    Chen, Y. T.; Chuang, Y. C.; Su, J. H.; Yu, H. C.; Chen-Yang, Y. W.

    2011-03-01

    In this study, a series of nanocomposite polymer electrolytes (CPEs), PAN/LiClO4/SAP, with high conductivity are prepared based on polyacrylonitrile (PAN), LiClO4 and low content of the silica aerogel powder (SAP) prepared by the sol-gel method with ionic liquid (IL) as the template. The effect of addition of SAP on the properties of the CPEs is investigated by FTIR, AC impedance, linear sweep voltagrams and cyclic voltammetry measurements as well as the charge-discharge performance. It is found that the ionic conductivity of the CPE is significantly improved by addition of SAP. The maximum ambient ionic conductivity of CPEs is about 12.5 times higher than that without addition of SAP. The results of the voltammetry measurements of CPE-3, which contained 3 wt% of SAP, show that the anodic and cathodic peaks are well maintained after 100 cycles, showing excellent electrochemical stability and cyclability over the potential range between 0 V and 4 V vs. Li/Li+. Besides, the room temperature discharge capacity measured at 0.5C for the coin cell based on CPE-3 is 120 mAh g-1 and the capacity is retained after 20 cycles discharge, indicating the potential for practical use. This is perhaps the first report of the room temperature charge-discharge performance on the solid composite polymer electrolyte to the best of our knowledge.

  8. Epichlorohydrin crosslinked carboxymethyl cellulose-ethylenediamine imprinted polymer for the selective uptake of Cr(VI).

    PubMed

    Velempini, Tarisai; Pillay, Kriveshini; Mbianda, Xavier Y; Arotiba, Omotayo A

    2017-03-11

    A new ion-imprinted polymer (IIP) was synthesized from sodium carboxymethyl cellulose and used for the adsorption of hexavalent chromium from aqueous solution. Epichlorohydrin was used to stabilize the polymer before ethylenediamine (EDA) ligand and Cr(VI) were introduced. The obtained IIP was characterized with FTIR, XPS, TGA,(13)C NMR, SEM, EDX, BET and zeta sizer. The kinetics of adsorption followed a pseudo-second-order model while the Langmuir adsorption isotherm provided the best fit with a maximum adsorption capacity of 177.62mg/g at 25°C. The Langmuir adsorption capacity for the non-imprinted polymer (NIP) at 25°C was 149.93mg/g. Thermodynamic parameters indicated an endothermic process and spontaneous adsorption of Cr (VI) on the polymers. IIP adsorbent was successfully recycled 5 times using 0.1M NaOH as a leachate; 98% Cr(VI) was desorbed during the last adsorption-desorption cycle.

  9. Cross-Linking Cellulosic Fibers with Photoreactive Polymers: Visualization with Confocal Raman and Fluorescence Microscopy.

    PubMed

    Janko, Marek; Jocher, Michael; Boehm, Alexander; Babel, Laura; Bump, Steven; Biesalski, Markus; Meckel, Tobias; Stark, Robert W

    2015-07-13

    The properties of paper sheets can be tuned by adjusting the surface or bulk chemistry using functional polymers that are applied during (online) or after (offline) papermaking processes. In particular, polymers are widely used to enhance the mechanical strength of the wet state of paper sheets. However, the mechanical strength depends not only on the chemical nature of the polymeric additives but also on the distribution of the polymer on and in the lignocellulosic paper. Here, we analyze the photochemical attachment and distribution of hydrophilic polydimethylacrylamide-co-methacrylate-benzophenone P(DMAA-co-MABP) copolymers with defined amounts of photoreactive benzophenone moieties in model paper sheets. Raman microscopy was used for the unambiguous identification of P(DMAA-co-MABP) and cellulose specific bands and thus the copolymer distribution within the cellulose matrix. Two-dimensional Raman spectral maps at the intersections of overlapping cellulose fibers document that the macromolecules only partially surround the cellulose fibers, favor to attach to the fiber surface, and connect the cellulose fibers at crossings. Moreover, the copolymer appears to accumulate preferentially in holes, vacancies, and dips on the cellulose fiber surface. Correlative brightfield, Raman, and confocal laser scanning microscopy finally reveal a reticular three-dimensional distribution of the polymer and show that the polymer is predominately deposited in regions of high capillarity (i.e., in proximity to fine cellulose fibrils). These data provide deeper insights into the effects of paper functionalization with a copolymer and aid in understanding how these agents ultimately influence the local and overall properties of paper.

  10. Effect of Network Structure/Topology on Mechanical Properties of Crosslinked Polymers

    NASA Astrophysics Data System (ADS)

    Sharifi, Majid

    The interest in epoxy thermosetting polymers is widespread (e.g. Boeing 787 Dreamliner, windmill blades, automobiles, coatings, adhesives, etc.), and a demand still exists for improving toughness of these materials without degrading advantageous properties such as strength, modulus, and Tg. This study introduces novel approaches for improving the intrinsic mechanical characteristics of these polymers. The designed synthetic techniques focus on developing polymer materials with the same overall compositions but varying in network topologies, with distinct topological features in the size range of 5-50 nm, measured by SAXS and SEM. It was found that without altering chemical structure, the network topology of a dense thermoset can be engineered such that, under mechanical deformation, nano-cavities open and dissipate energy before rupturing covalent bonds, producing a tougher material without sacrificing strength, modulus, and even glass transition temperature. Modified structures also revealed higher resistance to fracture than the corresponding control structures. The major fracture mechanism responsible for the increased energy dissipation was found to be nano-cavitation. SEM images from the fracture surfaces showed clear cavities on the modified samples whereas none were seen on the fracture surface of the control samples. Overall, it was demonstrated that network topology can be used to tailor thermal and mechanical properties of thermosetting polymers. The experimental methodologies in this dissertation can directly and economically be applied to design polymeric materials with improved properties for desired applications. Although topology-based toughening was investigated on epoxy-amine polymers, the concept can be extended to most thermoset chemistries and perhaps to other brittle network forming materials.

  11. Synthesis of a molecularly imprinted polymer for the solid-phase extraction of betulin and betulinic acid from plane bark.

    PubMed

    Claude, Berengere; Viron-Lamy, Cecile; Haupt, Karsten; Morin, Philippe

    2010-01-01

    Plant extracts are usually complex mixtures of various polarity compounds and their study often includes a purification step, such as solid-phase extraction (SPE), to isolate interest compounds prior analytical investigations. Molecularly imprinted polymers (MIPs) are a new promising type of SPE material which offer tailor-made selectivity for the extraction of trace active components in complex matrices. Numerous specific cavities that are sterically and chemically complementary of the target molecules, are formed in imprinted polymers. A molecularly imprinted polymer (MIP) was synthesised in order to trap a specific class of triterpene, including betulin and betulinic acid from a methanolic extract of plane bark. Imprinted polymers were synthesised by thermal polymerisation of betulin as template, methacrylic acid (MAA) or acrylamide (AA) as functional monomer, ethylene glycol dimethacrylate as crosslinking agent and chloroform as porogen. Afterwards, MAA- and AA-MIPs were compared with their non-imprinted polymers (NIPs) in order to assess the selectivity vs betulin and its derivatives. Recovered triterpenes were analysed by HPLC during MIP-SPE protocol. After SPE optimisation, the MAA-imprinted polymer exhibited highest selectivity and recovery (better than 70%) for betulin and best affinity for its structural analogues. Thus, a selective washing step (chloroform, acetonitrile) removed unwanted matrix compounds (fatty acids) from the SPE cartridge. The elution solvent was methanol. Finally, the MAA-MIP was applied to fractionate a plane bark methanolic extract containing betulin and betulinic acid. This study demonstrated the possibility of direct extraction of betulin and its structural analogues from plant extracts by MIP technology.

  12. Deformation-strength properties in the tension of cross-linked polymers based on mixtures of epoxide and epoxy-oligoether oligomers

    SciTech Connect

    Markevich, M.A.

    1992-05-01

    Epoxy network polymers are finding increasing use as adhesives, sealing and impregnating compounds, binders in composites and filled materials, protective and insulating coatings in the radio and electronics industries, and other applications. Broad use reflects their high strength and ductility properties, good electric and dielectic properties, elasticity, ability to adhere to a wide range of materials, chemical stability, etc. However, one of the main shortcomings of epoxide cross-linked polymers is their low fracture strain in tension. Their low impact strength is also a problem. To improve the strength and ductility properties of cross-linked epoxides, use is made of mixtures of oligomers of adherent molecular weights. The oligomers may be either of the same chemical nature or may have different molecular structures and functionalities. In the present article, the author reports the results of a study of the strength and ductility properties of mixtures of epoxide polygomers based on diphenylolpropane (E-40, molecular weight 600) and epichlorohydrin (Oksilin-5, molecular weight 2200) coated with diethylenetriamine. The composition of the mixtures is varied broadly in the study. The choice of an epoxidized oligoether was dictated by the fact that cross-linked polymers based on it should exhibit greater elongation. Moreover, the use of mixtures of epoxide oligomers of different types makes it possible to modify both the microscopic (density, free volume, temperature transitions, etc.) and macroscopic properties (Young`s modulus elongation, short- and long-term strength, impact strength) of cross linked polymers.

  13. Reciprocated suppression of polymer crystallization toward improved solid polymer electrolytes: Higher ion conductivity and tunable mechanical properties

    DOE PAGES

    Bi, Sheng; Sun, Che-Nan; Zawodzinski, Thomas A.; ...

    2015-08-06

    Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl) imide and polymer matrix were extensively studied in the past due to their excellent potential in a broad range of energy related applications. Poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) are among the most examined polymer candidates as solid polymer electrolyte matrix. In this paper, we study the effect of reciprocated suppression of polymer crystallization in PVDF/PEO binary matrix on ion transport and mechanical properties of the resultant solid polymer electrolytes. With electron and X-ray diffractions as well as energy filtered transmission electron microscopy, we identify and examine the appropriate blending composition thatmore » is responsible for the diminishment of both PVDF and PEO crystallites. Laslty, a three-fold conductivity enhancement is achieved along with a highly tunable elastic modulus ranging from 20 to 200 MPa, which is expected to contribute toward future designs of solid polymer electrolytes with high room-temperature ion conductivities and mechanical flexibility.« less

  14. Safety of solid-state Li metal battery: Solid polymer versus liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Perea, Alexis; Dontigny, Martin; Zaghib, Karim

    2017-08-01

    In this article we present the difference in thermal stability of Li/LiFePO4| half cells with liquid and solid polymer electrolytes. After two initial cycles, the cells were charged to two different state of charge (SOC) of 50 and 100%. The thermal stability of the half cells is assessed with an accelerating rate calorimeter, and the thermal runaway parameters are discussed for each experiment: dependence of self-heating rate on temperature, temperature of a first-detected exothermic reaction, and maximum cell temperature. The dependence of those parameters with respect to the SOC is also presented.

  15. Retention of aroma compounds from Mentha piperita essential oil by cyclodextrins and crosslinked cyclodextrin polymers.

    PubMed

    Ciobanu, A; Mallard, I; Landy, D; Brabie, G; Nistor, D; Fourmentin, S

    2013-05-01

    In this paper, the controlled release of aroma compounds from cyclodextrins (CDs) and CD polymers was studied by multiple headspace extraction (MHE) experiments. Mentha piperita essential oil was obtained by Soxhlet extraction and identification of the major compounds was performed by GC-MS analysis. Menthol, menthone, pulegone and eucalyptol were identified as the major components. Retention of standard compounds in the presence of different CDs and CD polymers has been realised by static headspace gas chromatography (SH-GC) at 25 °C in the aqueous or gaseous phase. Stability constants for standard compounds and for compounds in essential oil have been also determined with monomeric CD derivatives. The obtained results indicated the formation of a 1:1 inclusion complex for all the studied compounds. Molecular modelling was used to investigate the complementarities between host and guest. This study showed that β-CDs were the most versatile CDs and that β-CD polymers could perform the controlled release of aroma compounds. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. The Effect of Filler-Polymer Interactions on Cold-Crystallization Kinetics in Crosslinked, Silica Filled PDMS/PDPS Copolymer Melts.

    SciTech Connect

    Chien, A; DeTeresa, S; Thompson, L; Cohenour, R; Balazs, B; Maxwell, R S

    2006-04-21

    Crystallization in a series of variable crosslink density poly(dimethyl-diphenyl) siloxanes random block copolymers reinforced through a mixture of precipitated and fumed silica fillers has been studied by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and X-ray Diffraction (XRD). The silicone composite studied was composed of 94.6 mol% Dimethoylsiloxane, 5.1 mol% diphenylsiloxane, and 0.3 mol% methyl-vinyl siloxane (which formed crosslinking after a peroxide cure). The polymer was filled with a mixture of 21.6 wt. % fumed silica and 4.0 wt. % precipitated silica previously treated with 6.8 wt. % ethoxy-endblocked siloxane processing aid. The base composite was characterized by a molecular weight between crosslinks in the polymer network of {approx}24 kDa and an overall molecular weight (including the influence of the silica fillers) between crosslinks of {approx}11 kDa. Molecular weight between crosslinks and filler-polymer interaction strength were then modified by exposure to {gamma}-irradiation in either air or vacuum. The unirradiated material exhibited crystallization at -80 C as measured by DSC with a 16% crystallization as measured by XRD. Isothermal DMA experiments illustrated that crystallization at -85 C occurred over a 1.8 hour period in silica-filled systems and 2.2-2.6 hours in unfilled systems. The onset of crystallization typically occurred after a 30-minute incubation/nucleation period. The crystallization kinetics were dependent on crosslink density. Changes in molecular weight of a factor of two did not, however, change the amount of crystallization. Irradiation in vacuum resulted in faster overall crystallization rates compared to air irradiation for the same crosslink density, likely due to a reduction in the interaction between the polymer chains and the silica filler surface. Modulated differential scanning calorimetry contrasted the crystallization and melting behavior of pure PDMS versus the PDMS/PDPS base

  17. Semiconductor/Solid Electrolyte Junctions for Optical Information Storage. Electrochromic Effects on Heptylviologen Incorporated within a Solid Polymer Electrolyte Cell.

    DTIC Science & Technology

    1986-05-15

    cathode5 . Electrochromic devices based upon these electrochemically reversible viologen redox couples would greatly benefit by their incorporation...electrolyte analogs. Here we wish to discuss some recent work from our laboratory on solid- state electrochromic cells in which heptyl viologen (HV2+) was...OPTICAL INFORMATION STORAGE. ELECTROCHROMIC EFFECTS QN HEPTYLVIOLOGEN INCORPORATED WITHIN A SOLID POLYMER ELECTROLYTE CELL By Anthony F. Sammells and

  18. A new molecularly imprinted polymer for selective extraction of cotinine from urine samples by solid-phase extraction.

    PubMed

    Yang, Jun; Hu, Yan; Cai, Ji-Bao; Zhu, Xiao-Lan; Su, Qing-De

    2006-02-01

    Cotinine, the main metabolite of nicotine in human body, is widely used as a biomarker for assessment of direct or passive exposure to tobacco smoke. A method for molecularly imprinted solid-phase extraction (MISPE) of cotinine from human urine has been investigated. The molecularly imprinted polymer (MIP) with good selectivity and affinity for cotinine was synthesized using cotinine as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The imprinted polymer was evaluated for use as a SPE sorbent, in tests with aqueous standards, by comparing recovery data obtained using the imprinted form of the polymer and a non-imprinted form (NIP). Extraction from the aqueous solutions resulted in more than 80% recovery. A range of linearity for cotinine between 0.05 and 5 microg mL-1 was obtained by loading 1 mL blank urine samples spiked with cotinine at different concentrations in acetate buffer of pH 9.0, and by using double basic washing and acidic elution. The intra-day coefficient of variation (CV) was below 7% and inter-day CV was below 10%. This investigation has provided a reliable MISPE-HPLC method for determination of cotinine in human urine from both active smokers and passive smokers.

  19. Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

    PubMed

    Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

    2016-03-14

    Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

  20. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device.

    PubMed

    Muschenborn, Andrea D; Hearon, Keith; Volk, Brent L; Conway, Jordan W; Maitland, Duncan J

    2014-02-25

    To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Four thermoset acrylic copolymers containing benzylmethacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn~512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole % BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

  1. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

    PubMed Central

    Muschenborn, Andrea D.; Hearon, Keith; Volk, Brent L.; Conway, Jordan W.; Maitland, Duncan J.

    2014-01-01

    Purpose To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods Four thermoset acrylic copolymers containing benzylmethacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn~512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole % BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application. PMID:25414549

  2. Jacket-free stir bar sorptive extraction with bio-inspired polydopamine-functionalized immobilization of cross-linked polymer on stainless steel wire.

    PubMed

    Zhang, Zixin; Zhang, Wenpeng; Bao, Tao; Chen, Zilin

    2015-08-14

    Stainless steel wire (SSW) is a good substrate for stir bar sorptive extraction (SBSE). However, it is still a challenge to immobilize commonly used cross-linked polymers onto SSW. In this work, we present a new approach for immobilization of the cross-linked organic polymer onto SSW for jacket-free SBSE. A dopamine derivative was firstly synthesized; by introducing a mussel-inspired polydopamine process, a stable coating layer was finally generated on the surface of SSW. Secondly, the cross-linked polymer was synthesized on the polydopamine-modified SSW by using acetonitrile as the porogen, acrylamide (AA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2'-azobis (2-methylpropionitrile) as the initiator. A diluted pre-polymerization solution was carefully prepared to generate a thin layer of the polymer. The prepared poly(EGDMA-AA)-modified stir bar showed high stability and good tolerance toward stirring, ultrasonication, organic solvents, and strong acidic and basic conditions. Morphology and structure characterization of coatings were performed by scanning electron microscopy and Fourier transform infrared spectra, respectively. The prepared poly(EGDMA-AA)-modified stir bar showed great extraction efficiency toward protoberberines, with enrichment factors of 19-42. An SBSE-HPLC method was also developed for quantitative analysis of protoberberines. The method showed low limits of detection (0.06-0.15 ng mL(-1)), wide linear range (0.5-400 ng mL(-1)), good linearity (R≥0.9980) and good reproducibility (RSD≤3.60% for intra-day, RSD≤4.73% for inter-day). The developed method has been successfully applied to determine protoberberines in herb and rat plasma samples, with recoveries of 88.53-114.61%. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. A crosslinked β-cyclodextrin polymer used for rapid removal of a broad-spectrum of organic micropollutants from water.

    PubMed

    Wang, Zhanghui; Zhang, Peibin; Hu, Fan; Zhao, Yifan; Zhu, Liping

    2017-12-01

    Organic micropollutants in aquatic environment such as plasticizer, pesticide and pharmaceuticals, have posed a serious threat to human health and are emerging as a great challenge to humanity. Traditional water treatment techniques fail to achieve high removal efficiency for low concentration of organic micropollutants. Here we demonstrate a water-insoluble crosslinked β-cyclodextrin (β-CD) polymer able to remove a broad-spectrum of organic micropollutants from water by rapid adsorption. A family of β-CD polymers (β-CDPs) were synthesized by nucleophilic aromatic substitution of β-CD hydroxyl groups and 4,4'-difluorodiphenylsulfone. The β-CDPs were used to adsorb various organic micropollutants in water by static or dynamic adsorption process. It was found that more than 99% micropollutants in water were removed by flowing the feed water through the column of β-CDPs. The results of static adsorption experiments indicated the adsorption process was fast and the adsorption capacity was very high (the maximal value was 113.0mg of bisphenol A per gram of β-CDP). The adsorption process was fitted well with the quasi-second-order kinetics and the Langmuir isothermal adsorption model, suggesting that it is mainly a chemical adsorption of monolayer. The water-insoluble characteristic of the β-CDPs is convenient for their separation from the treated solution after adsorption saturation for regeneration and reuse. The adsorption ability of β-CDPs was kept nearly unchanged after five filtration-regeneration cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Novel cross-linked alcohol-insoluble solid (CL-AIS) affinity gel from pea pod for pectinesterase purification.

    PubMed

    Wu, Ming-Chang; Lin, Guan-Hui; Wang, Yuh-Tai; Jiang, Chii-Ming; Chang, Hung-Min

    2005-10-05

    Alcohol-insoluble solids (AIS) from pea pod were cross-linked (CL-AIS) and used as an affinity gel matrix to isolate pectin esterases (PEs) from tendril shoots of chayote (TSC) and jelly fig achenes (JFA), and the results were compared with those isolated by ion-exchange chromatography with a commercial resin. CL-AIS gel matrix in a column displayed poor absorption and purification fold of PE; however, highly methoxylated CL-AIS (HM-CL-AIS), by exposing CL-AIS to methanolic sulfuric acid to increase the degree of esterification (DE) to 92%, facilitated the enzyme purification. The purified TSC PE and JFA PE by the HM-CL-AIS column were proofed as a single band on an SDS-PAGE gel, showing that the HM-CL-AIS column was a good matrix for purification of PE, either with alkaline isoelectric point (pI) (TSC PE) or with acidic pI (JFA PE).

  5. Cross-linked carbon network with hierarchical porous structure for high performance solid-state electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Cheng, Yongliang; Huang, Liang; Xiao, Xu; Yao, Bin; Hu, Zhimi; Li, Tianqi; Liu, Kang; Zhou, Jun

    2016-09-01

    The development of portable electronics strongly requires flexible, lightweight, and inexpensive energy-storage devices with high power density, long cycling stability, and high reliability. In this work, we prepare a flexible solid-state electrochemical capacitor using cross-linked hierarchical porous carbon network as electrode material via electrospinning and carbonization process. This device can reversibly deliver a maximum energy density of 10.18 W h/kg with excellent cycling stability which achieves 95% capacitance retention after 20000 charge/discharge cycles. Moreover, it also demonstrates outstanding mechanical flexibility and excellent capacitance retention even when the device is repeatedly bended 10000 cycles under 90°. All of these results suggest its promising perspective in flexible energy storage device.

  6. Fabrication of Redox-Responsive Degradable Capsule Particles by a Shell-Selective Photoinduced Cross-Linking Approach from Spherical Polymer Particles.

    PubMed

    Kitayama, Yukiya; Takeuchi, Toshifumi

    2017-09-18

    In this study, a fabrication route towards functional capsule particles was successfully developed by means of a self-templating shell-selective cross-linking strategy that enables us to prepare shell-cross-linked hollow polymer particles directly from homogeneous spherical polymer particles. To prepare redox-responsive degradable capsule particles, a newly designed monomer bearing a photoinduced post-cross-linking group (cinnamoyl group) and a redox-environment-responsive cleavable group (disulfide group), N-cinnamoyl-N'-methyacryloylcystamine (MCC), was synthesized. Redox-responsive degradable capsule particles were successfully prepared from homogeneous spherical poly(MCC)-based particles by a self-templating shell-selective photoinduced cross-linking approach. Moreover, the cargo loading capability of the shell-cross-linked hollow particles was confirmed through a solvent exchange procedure using dyes, polymer precursors and anticancer reagents. Furthermore, redox-responsive degradability of the capsule polymer particles was also confirmed by adding a reducing agent for cleavage of the disulfide linkage. We hope that the efficient fabrication route of functional capsule particles directly from spherical polymer particles opens efficient routes for the fabrication of a wide range of capsule particles; in particular, this technique is robust, productive, and facile because neither additional sacrificial template particles nor toxic solvents are required. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Effect of degree of crosslinking and polymerization of 3D printable polymer/ionic liquid composites on performance of stretchable piezoresistive sensors

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwoo; Faruk Emon, Md Omar; Vatani, Morteza; Choi, Jae-Won

    2017-03-01

    Ionic liquid (IL)/polymer composites (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF4)/2-[[(butylamino)carbonyl]oxy]ethyl acrylate (BACOEA)) were fabricated to use as sensing materials for stretchable piezoresistive tactile sensors. The detectability of the IL/polymer composites was enhanced because the ionic transport properties of EMIMBF4 in the composites were improved by the synergic actions between the coordinate sites generated by the local motion of BACOEA chain segments under enough activation energy. The performance of the piezoresistive sensors was investigated with the degree of crosslinking and polymerization of the IL/polymer composites. As the compressive strain was increased, the distance between two electrodes decreased, and the motion of polymer chains and IL occurred, resulting in a decrease in the electrical resistance of the sensors. We have confirmed that the sensitivity of the sensors are affected by the degree of crosslink and polymerization of the IL/polymer composites. In addition, all of the materials (skins, sensing material, and electrode) used in this study are photo-curable, and thus the stretchable piezoresistive tactile sensors can be successfully fabricated by 3D printing.

  8. Molecular dynamics simulation of cross-linked urea-formaldehyde polymers for self-healing nanocomposites: prediction of mechanical properties and glass transition temperature.

    PubMed

    Arab, Behrouz; Shokuhfar, Ali

    2013-11-01

    Urea-formaldehyde polymers, which are utilized in the adhesives industry, have recently been shown to be suitable materials for synthesizing micro/nanocapsules for use in self-healing (nano)composites. In this study, molecular dynamics was employed to simulate the process in which urea and formaldehyde are cross-linked via methylene and ether cross linkers, and to study the structure and mechanical/thermal properties of simulated poly(urea-formaldehyde)s (PUFs). The elastic stiffness constants of the simulated materials were calculated using the constant-strain (static) method. A temperature cycle was applied to the cross-linked PUFs, and the glass transition behavior of each material was investigated through the mean squared displacement (MSD) and temperature evolution of the energy and the specific volume of the polymer. The simulation results confirmed that there was considerable improvement in the properties of the poly(UF) materials upon cross linking. The radial distribution function was also used to study the local structures of the polymers, and this revealed that increasing the temperature and cross linking density results in a significant drop in hydrogen bonding intensity in the cross-linked PUF systems.

  9. Low-voltage organic field-effect transistors and inverters enabled by ultrathin cross-linked polymers as gate dielectrics.

    PubMed

    Yoon, Myung-Han; Yan, He; Facchetti, Antonio; Marks, Tobin J

    2005-07-27

    The quest for high-performance organic thin-film transistor (OTFT) gate dielectrics is of intense current interest. Beyond having excellent insulating properties, such materials must meet other stringent requirements for optimum OTFT function: efficient low-temperature solution fabrication, mechanical flexibility, and compatibility with diverse gate materials and organic semiconductors. The OTFTs should function at low biases to minimize power consumption, hence the dielectric must exhibit large gate capacitance. We report the realization of new spin-coatable, ultrathin (<20 nm) cross-linked polymer blends exhibiting excellent insulating properties (leakage current densities approximately 10(-)(8) Acm(-)(2)), large capacitances (up to approximately 300 nF cm(-)(2)), and enabling low-voltage OTFT functions. These dielectrics exhibit good uniformity over areas approximately 150 cm(2), are insoluble in common solvents, can be patterned using standard microelectronic etching methodologies, and adhere to/are compatible with n(+)-Si, ITO, and Al gates, and with a wide range of p- and n-type semiconductors. Using these dielectrics, complementary invertors have been fabricated which function at 2 V.

  10. Dually actuated triple shape memory polymers of cross-linked polycyclooctene-carbon nanotube/polyethylene nanocomposites.

    PubMed

    Wang, Zhenwen; Zhao, Jun; Chen, Min; Yang, Minhao; Tang, Luyang; Dang, Zhi-Min; Chen, Fenghua; Huang, Miaoming; Dong, Xia

    2014-11-26

    In this work, electrically and thermally actuated triple shape memory polymers (SMPs) of chemically cross-linked polycyclooctene (PCO)-multiwalled carbon nanotube (MWCNT)/polyethylene (PE) nanocomposites with co-continuous structure and selective distribution of fillers in PCO phase are prepared. We systematically studied not only the microstructure including morphology and fillers' selective distribution in one phase of the PCO/PE blends, but also the macroscopic properties including thermal, mechanical, and electrical properties. The co-continuous window of the immiscible PCO/PE blends is found to be the volume fraction of PCO (vPCO) of ca. 40-70 vol %. The selective distribution of fillers in one phase of co-continuous blends is obtained by a masterbatch technique. The prepared triple SMP materials show pronounced triple shape memory effects (SMEs) on the dynamic mechanical thermal analysis (DMTA) and the visual observation by both thermal and electric actuations. Such polyolefin samples with well-defined microstructure, electrical actuation, and triple SMEs might have potential applications as, for example, multiple autochoke elements for engines, self-adjusting orthodontic wires, and ophthalmic devices.

  11. Influences of dehydration and rehydration on the lubrication properties of phospholipid polymer-grafted cross-linked polyethylene.

    PubMed

    Yarimitsu, Seido; Moro, Toru; Kyomoto, Masayuki; Watanabe, Kenichi; Tanaka, Sakae; Ishihara, Kazuhiko; Murakami, Teruo

    2015-07-01

    Surface modification by grafting of biocompatible phospholipid polymer onto the surface of artificial joint material has been proposed to reduce the risk of aseptic loosening and improve the durability. Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted cross-linked polyethylene (CLPE) has shown promising results for reducing wear of CLPE. The main lubrication mechanism for the PMPC layer is considered to be the hydration lubrication. In this study, the lubrication properties of PMPC-grafted CLPE were evaluated in reciprocating friction test with rehydration process by unloading in various lubricants. The start-up friction of PMPC-grafted CLPE was reduced, and the damage of PMPC layer was suppressed by rehydration in water or hyaluronic acid solutions. In contrast, the start-up friction of PMPC-grafted CLPE increased in fetal bovine serum solution, and the damage for PMPC layer was quite noticeable. Interestingly, the start-up friction of PMPC-grafted CLPE was reduced in fetal bovine serum solution containing hyaluronic acid, and the damage of the PMPC layer was suppressed. These results indicate that the rehydration by unloading and hyaluronic acid are elemental in maximizing the lubrication effect of hydrated PMPC layer.

  12. Anhydrous state proton and lithium ion conducting solid polymer electrolytes based on sulfonated bisphenol-A-poly(arylene ethers)

    NASA Astrophysics Data System (ADS)

    Guha Thakurta, Soma

    Sulfonated polymer based solid polymer electrolytes (SPEs) have received considerable interest in recent years because of their wide variety of applications particularly in fuel cells, batteries, supercapacitors, and electrochromic devices. The present research was focused on three interrelated subtopics. First, two different bisphenol-A-poly(arylene ethers), polyetherimide (PEI) and polysulfone (PSU) were sulfonated by a post sulfonation method to various degrees of sulfonation, and their thermal and mechanical properties were examined. The effects of poly(arylene ether) chemical structure, reaction time, concentration, and types of sulfonating agents on sulfonation reaction were investigated. It was found that deactivation of bisphenol A unit caused by the electron withdrawing imide, retarded the sulfonation of PEI compared to PSU. Sulfonation conducted with a high concentration of sulfonating agent and/or prolonged reaction time exhibited evidence of degradation at the isopropylidene unit. The degradation occurred through the same mechanistic pathway with the two different sulfonating agents, chlorosulfonic acid (CSA) and trimethylsilyl chlorosulfonate (TMSCS). The degradation was faster with CSA than its silyl ester, TMSCS, and was evident even at low acid concentration. Second, novel anhydrous proton conducting solid polymer electrolytes (SPEs) were prepared by the incorporation of 1H-1,2,4-triazole (Taz) as a proton solvent in sulfonated polyetherimide (SPEI) matrix. The size, shape, and state of dispersion (crystal morphology) of triazole crystals in SPEI were examined as a function of degree of sulfonation and triazole concentration. Increasing sulfonic acid content caused reduction of triazole crystallite size, hence the depression of melting temperature and their uniform distribution throughout the sulfonated polymer matrix. The increased rate of structure diffusion within the smaller size crystals due to the improved molecular mobility contributed

  13. Preparation and application of sulfaguanidine-imprinted polymer on solid-phase extraction of pharmaceuticals from water.

    PubMed

    Mutavdžić Pavlović, Dragana; Nikšić, Korana; Livazović, Sara; Brnardić, Ivan; Anžlovar, Alojz

    2015-01-01

    The molecularly imprinted polymers (MIPs) with sulfaguanidine as a template, methacrylic acid, 4-vinylpyridine, and 2-hydroxyethyl methacrylate as functional monomers, ethylene glycol dimethacrylate as a cross-linker and 2,2'-azobis-isobutyronitrile as an initiator have been prepared through the cross-link reaction of polymerization. Solid-phase extraction (SPE) procedure for the extraction of sulfaguanidine from water samples using the prepared MIPs and non-imprinted (NIPs) was evaluated. The best MIP in combination with commercial sorbents was applied for simultaneous extraction of eight pharmaceuticals. New SPE cartridges were prepared by combination of optimal produced MIP and Oasis HLB in 6 mL of polypropilene SPE reservoir. The developed method which includes new SPE cartridge (MIPMAA-Oasis HLB, 400mg/6 mL) and thin-layer chromatography was validated. The method provides a linear response over the concentration range of 0.5-150 μg/L, depending on the pharmaceutical with the correlation coefficients>0.9843 in all cases except for norfloxacin (0.9770) and penicillin G procaine (0.9801). Also, the method has revealed low limits of detection (0.25-20 μg/L), good precision (intra and inter-day), a relative standard deviation below 15% and recoveries above 95% for all eight pharmaceuticals. The developed method by using newly prepared SPE cartridge has been successfully applied to the analysis of production wastewater samples from pharmaceutical industry.

  14. Hemostatic potential of natural/synthetic polymer based hydrogels crosslinked by gamma radiation

    NASA Astrophysics Data System (ADS)

    Barba, Bin Jeremiah D.; Tranquilan-Aranilla, Charito; Abad, Lucille V.

    2016-01-01

    Various raw materials and hydrogels prepared from their combination were assessed for hemostatic capability using swine whole blood clotting analysis. Initial screening showed efficient coagulative properties from κ-carrageenan and its carboxymethylated form, and α-chitosan, even compared to commercial products like QuikClot Zeolite Powder. Blending natural and synthetic polymers formed into hydrogels using gamma radiation produced materials with improved properties. KC and CMKC hydrogels were found to have the lowest blood clotting index in granulated form and had the higher capacity for platelet adhesion in foamed form compared to GelFoam. Possible mechanisms involved in the evident thrombogenicity of the materials include adsorption of platelets and related proteins that aid in platelet activation (primary hemostasis), absorption of water to concentrate protein factors that control the coagulation cascade, contact activation by its negatively charged surface and the formation of gel-blood clots.

  15. Long-lasting solid-polymer electrolytic hygrometer

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1978-01-01

    Device consists of hollow tube node of oxidation-resistant sulfonated fluorocarbon polymer. Tube absorbs moisture from air passing across inner and outer surfaces, causing change in polymer conductance. Change is related to change in water content in gas sample.

  16. Physical stability of l-ascorbic acid amorphous solid dispersions in different polymers: A study of polymer crystallization inhibitor properties.

    PubMed

    Christina, Belinda; Taylor, Lynne S; Mauer, Lisa J

    2015-10-01

    The effects of different polymer types on inhibiting the crystallization of ascorbic acid (VitC) from amorphous solid dispersions at various temperatures and relative humidities (RHs) were studied. Polymer properties (ability to form hydrogen bonds with VitC, hygroscopicity, and glass transition temperature (Tg)) were correlated to their crystallization inhibitor performance. Solid dispersions of VitC with different pectins, polyvinylpyrrolidone (PVP), and polyacrylic acid (PAA) were formed from lyophilized solutions. Crystallinity, VitC-polymer interactions, hygroscopicity, and Tg were determined using X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), moisture sorption isotherm, and differential scanning calorimetry (DSC) methods, respectively. XRPD amorphous VitC could not be formed by lyophilization in the absence of a polymer, nor in PAA dispersions, but could be formed in pectin and PVP dispersions. The VitC-pectin and PVP dispersions remained amorphous when stored at low RHs, but some crystallization occurred within one week at high RHs. Evidence of hydrogen bonding between VitC and both pectins and PVP, but not PAA, was found in FTIR spectra, and correlated better with physical stability than the Tg. The hygroscopicity of the polymer also influenced the stability of the amorphous VitC solid dispersions. A ranking of the polymer crystallization inhibitor properties was: PVP>pectin with lower degree of esterification (DE)>pectin with higher DE >PAA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Parabolic dependence of material properties and cell behavior on the composition of polymer networks via simultaneously controlling crosslinking density and crystallinity.

    PubMed

    Cai, Lei; Wang, Shanfeng

    2010-10-01

    A systematic investigation was performed on regulating materials properties and cell behavior using hybrid networks composed of amorphous poly(propylene fumarate) (PPF) and three poly(epsilon-caprolactone) diacrylates (PCLDAs) with variance in crystallinity and melting temperature. Through controlling both crosslinking density and crystallinity in the photo-crosslinked PPF/PCLDA blends, mechanical properties could be tuned efficiently in a wide range. For PCLDA synthesized from a low-molecular weight PCL diol precursor with a low crystallinity and a low melting point, crosslinks could completely suppress crystalline domains over the composition range in the PPF/PCLDA networks. Consequently, tensile, shear, torsional, and compression moduli all increased with the composition of PPF or the crosslinking density continuously for amorphous PPF/PCLDA networks. For PCLDAs synthesized using two PCL diols with higher molecular weights, crystallinity remained for the PCLDA compositions between approximately 80% and 100%. Minimum moduli and tensile stress at break were found at the lowest required composition of PPF for suppressing crystallinity. Surface physicochemical properties and morphology of the crosslinked blend disks have been characterized and their capabilities of adsorbing proteins from cell culture medium have been determined. Using both mouse MC3T3-E1 cells and rat Schwann cell precursor line (SpL201) cells, cell responses to these polymer networks such as cell adhesion, spreading, and proliferation were found to be dramatically distinct on different polymer networks and demonstrated non-monotonic or parabolic dependence on the network composition, coincident with the composition dependence of the mechanical properties.

  18. Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

    NASA Technical Reports Server (NTRS)

    Herring, Helen M.

    2008-01-01

    Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

  19. Improved properties of LiBOB-based solid polymer electrolyte by additive incorporation

    NASA Astrophysics Data System (ADS)

    Ratri, C.; Sabrina, Q.; Lestariningsih, T.; Wigayati, E.

    2017-04-01

    Solid polymer electrolytes comprising of poly(vinylidene fluoride) (PVdF) and lithium bis (oxalato) borate (LiBOB) have been prepared using solution casting technique. Having an important role in lithium-ion battery system, electrolyte is required to have high ability to transfer lithium ions between electrodes. Safety aspect is the main reason for the development of solid polymer electrolyte as advancement from conventional liquid electrolyte. Nevertheless, solid polymer electrolyte generally has lower conductivities compared to liquid electrolyte. In this research, ceramic additives, as well as plasticiser materials, have been incorporated within the solid polymer electrolyte system to improve its conductivity. Addition of TiO2 filler has proven to increase ionic conductivity by two orders of magnitude. Further improvement was seen in the incorporation of PEG plasticiser, where ionic conductivity was enhanced by three orders of magnitude.

  20. Molecularly imprinted polymer on a SiO2 -coated graphene oxide surface for the fast and selective dispersive solid-phase extraction of Carbamazepine from biological samples.

    PubMed

    Khalilian, Faezeh; Ahmadian, Setareh

    2016-04-01

    A surface carbamazepine-imprinted polymer was grafted and synthesized on the SiO2 /graphene oxide surface. Firstly SiO2 was coated on synthesized graphene oxide sheet using the sol-gel technique. Prior to polymerization, the vinyl group was incorporated on to the surface of SiO2 /graphene oxide to direct selective polymerization on the surface. Methacrylic acid, ethylene glycol dimethacrylate and ethanol were used as monomer, cross-linker and porogen, respectively. Nonimprinted polymer was also prepared for comparison. The properties of the molecularly imprinted polymer were characterized using field-emission scanning electron microscopy and Fourier-transform infrared spectroscopy. The surface molecularly imprinted polymer was utilized as an adsorbent of dispersive solid-phase extraction for separation and preconcentration of carbamazepine. The effects of the different parameters influencing the extraction efficiency, such as sample pH were investigated and optimized. The specificity of the molecular imprinted polymer over the nonimprinted polymer was examined in absence and presence of competitive drugs. The carbamazepine calibration curve showed linearity in the ranges 0.5-500 μg/L. The limits of detection and quantification under the optimized conditions were 0.1 and 0.3 μg/L, respectively. The within-day and between-day relative standard deviations (n = 3) were 3.6 and 4.3%, respectively. Furthermore, the relative recoveries for spiked biological samples were above 85%.

  1. Molecular implications of drug-polymer solubility in understanding the destabilization of solid dispersions by milling.

    PubMed

    Yang, Ziyi; Nollenberger, Kathrin; Albers, Jessica; Qi, Sheng

    2014-07-07

    The solubility of drugs in polymer matrixes has been recognized as one of the key factors governing the physical stability of solid dispersions. This study has explored the implications of drug solubility on the destabilization that occurs on milling, which is often used as an additional process for hot melt extruded (HME) solid dispersions. The theoretical drug solubility in the polymer was first predicted using various theoretical and experimental approaches. The destabilization effects of high-energy mechanical milling on the solid dispersions with drug loadings below and above the predicted solubility were then investigated using a range of thermal, microscopic, and spectroscopic techniques. Four model drug-polymer combinations were studied. The HME formulations with drug loading below the predicted solid solubility (undersaturated and true molecular dispersion) showed good stability against milling. In contrast, milling destabilized supersaturated HME dispersions via increasing molecular mobility and creating phase-separated, amorphous, drug-rich domains. However, these additional amorphous drug-rich domains created by milling show good stability under ambient conditions, though crystallization can be accelerated by additional heating. These results highlighted that the processing method used to prepare the solid dispersions may play a role in facilitating the stabilization of amorphous drug in supersaturated solid dispersions. The degree of supersaturation of the drug in the polymer showed significant impact on the destabilization behavior of milling on solid dispersions. An improved understanding of the destabilization behavior of solid dispersions upon milling can provide new insights into the processing related apparent solubility of drugs in polymers.

  2. A semi-empirical model to simplify the synthesis of homogeneous and transparent cross-linked polymers and their application in the preparation of optical sensing films.

    PubMed

    Medina-Castillo, Antonio L; Fernandez-Sanchez, Jorge F; Segura-Carretero, Antonio; Fernandez-Gutierrez, Alberto

    2009-10-15

    We propose a simple, semi-empirical model based on Hansen's solubility parameters for simplifying the synthesis and the optimization of homogeneous and transparent cross-linked polymers in order to obtain optical sensing films. More than 740 experiments were undertaken to demonstrate the reliability of the model and several applications are proposed. We have demonstrated that our model can help in the synthesis and optimization (percentage of cross-linker, changes in hydrophilicity, selection of porogens, quantity of template etc.) of homogeneous and transparent MIPs and NIPs (molecularly imprinted polymers) with VOCs; after the synthesis of 440 polymers in the homogeneity zone only 4.32% of them (19 samples out of 440) were heterogeneous. We suggest a role for its use in the development of novel polymeric resins for detecting volatile organic compounds in water by measuring intrinsic fluorescence, in simplifying the synthesis of imprinted polymers and in decreasing the number of experiments required to optimize optical sensing membranes. In addition, it might also be used for synthesizing and optimizing MIPs with a non-volatile template.

  3. Development of Multi-Adaptive Simulation Technologies for Nonlinear Solid Polymer Viscoelasticity

    DTIC Science & Technology

    2007-10-31

    2007 4. TITLE AND SUBTITLE Development of multi-adaptive simulation technologies for nonlinear solid polymer viscoelasticity 6. AUTHOR(S) J.R. Whiteman...Close out report (funding period 1 April 2007 – 31 July 2007) Development of multi-adaptive simulation technologies for nonlinear solid polymer ...equations describing the inflation of a hyperelastic membrane. With U denoting the exact displacement and V denoting the exact velocity the weak forms

  4. Controlled release from solid dispersion composed of poly(ethylene oxide)-Carbopol interpolymer complex with various cross-linking degrees of Carbopol.

    PubMed

    Ozeki, T; Yuasa, H; Kanaya, Y

    2000-02-03

    Solid dispersion composed of the poly(ethylene oxide) (PEO)-Carbopol((R)) (CP) interpolymer complex containing phenacetin (PHE) was prepared by using six grades of CP having various cross-linking degrees. We attempted to control the medicine release from the PEO-CP solid dispersion by varying the CP grade. The powder X-ray diffraction pattern and differential scanning calorimetry curves suggested that PHE existed in the amorphous state, and PEO in the crystalline state disappeared in the solid dispersions. The release profile of PHE varied depending on the CP grade. A small release rate was observed at CP910 and CP971P that are cross-linked at low and middle degrees, respectively. The Fourier transform-infrared (FT-IR) spectra showed that the amount of the PEO-CP complex formed by hydrogen bonding changed depending on the CP grade. With the cross-linked CP, a good correlation was observed between the hydrogen bonding percent and the percent released of the PHE after 60 min (D(60 min)), indicating that PHE release was controlled by the amount of PEO-CP complex formation in the solid dispersion. These results show that it is feasible to control the medicine release from PEO-CP solid dispersion by varying the CP grade.

  5. Solid state, transparent, cadmium sulfide-polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Kothurkar, Nikhil K.

    This dissertation deals with the preparation and characterization of solid state, transparent CdS-polymer nanocomposites for potential applications in optical limiting, lenses and photovoltaics. The focus of this research was controlling CdS aggregation to obtain 1 mm thick, films with a transmittance >85%. CdS-polysulfone nanocomposites gave transparent sols using thiol-capping agents however solid films obtained, were translucent to opaque. CdS-epoxy nanocomposites gave 1 mm thick films with >85% transmittance. Oligomeric polyoxypropylene diamine stabilizers were used to shield the inter particle forces and increase the viscosity of the medium to give air stable sols. Films were obtained by curing the CdS sols with an epoxy resin system. The band edge of the nanocomposites showed a shoulder corresponding to the absorption from the CdS particles. A majority of small amorphous and non-stoichiometric (richer in Cd) particles <5 nm were observed in TEM micrographs. Relatively fewer CdS aggregates in the range of tens to hundreds of nanometers were also detected. Aggregates were generally more numerous in films as compared to sols. The two-photon absorption coefficient of the CdS particles in the films showed a 30-fold reduction compared to bulk CdS. This was attributed to the lack of crystallinity of particles. The films were stable up to 300°C. CdS aggregation in the CdS-epoxy system depends on a number of factors including temperature, stabilizer concentration, stabilizer molar mass and US concentration. Effective aggregation control yields transparent films. Factors affecting the band edge and transparency of the films were detected and regression models were fitted to the data. Temperature, stabilizer concentration and CdS concentration had significant effects on the band edge and transparency. Interactions between temperature-stabilizer concentration and temperature-CdS concentration had significant effects on the band edge. Band edge tunability with

  6. Thiolated polymers: self-crosslinking properties of thiolated 450 kDa poly(acrylic acid) and their influence on mucoadhesion.

    PubMed

    Marschütz, Michaela K; Bernkop-Schnürch, Andreas

    2002-05-01

    This study examined the rheological and mucoadhesive properties of a self-crosslinking anionic thiolated polymer in vitro. Mediated by a carbodiimide, L-cysteine was covalently bound to poly(acrylic acid) of 450 kDa molecular mass. The resulting thiolated polymers (conjugates I and II) contained 90.5+/-15.8 and 511.6+/-52 micromol thiol groups per gram polymer, respectively (mean+/-S.D., n=3). The amount of covalently attached cysteine was therefore dependent on the concentration of carbodiimide used for the coupling reaction. Both conjugates (3%, m/v) were capable of forming inter- and/or intramolecular disulfide bonds in 100 mM phosphate buffer pH 6.8. Consequently, the apparent viscosity of conjugates I and II increased 12- and 10-fold, respectively, within 24 h of incubation at 37 degrees C. Further, rheological synergy was observed by mixing equal volumes of polymer (unmodified as well as modified) with a mucin solution. A six-fold increase in viscosity immediately after mixing could be observed for the conjugate II/mucin mixture. This clearly indicates the high interaction potential of self-crosslinking thiomers with the mucus gel layer. Mucoadhesion studies confirmed the rheological results. Tablets based on conjugate II remained attached on freshly excised porcine mucosa for about 25 times longer than the corresponding controls, which is the longest time of mucoadhesion ever found among anionic thiomers. Due to the results of the present study, self-crosslinking thiolated poly(acrylates) of 450 kDa represent very promising excipients for the development of various mucoadhesive drug delivery systems.

  7. Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.

    PubMed

    Ishiwata, Takumi; Furukawa, Yuki; Sugikawa, Kouta; Kokado, Kenta; Sada, Kazuki

    2013-04-10

    Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.

  8. Conducting Polymers Crosslinked with Sulfur as Cathode Materials for High-Rate, Ultralong-Life Lithium-Sulfur Batteries.

    PubMed

    Zeng, Shuaibo; Li, Ligui; Xie, Lihong; Zhao, Dengke; Wang, Nan; Chen, Shaowei

    2017-09-11

    Low electrical conductivity and a lack of chemical confinement are two major factors that limit the rate performances and cycling stabilities of cathode materials in lithium-sulfur (Li-S) batteries. Herein, sulfur is copolymerized with poly(m-aminothiophenol) (PMAT) nanoplates through inverse vulcanization to form the highly crosslinked copolymer cp(S-PMAT) in which approximately 80 wt % of the feed sulfur is bonded chemically to the thiol groups of PMAT. A cp(S-PMAT)/C-based cathode exhibits a high discharge capacity of 1240 mAh g(-1) at 0.1 C and remarkable rate capacities of 880 mAh g(-1) at 1 C and 600 mAh g(-1) at 5 C. Moreover, it can retain a capacity of 495 mAh g(-1) after 1000 deep discharge-charge cycles at 2 C; this corresponds to a retention of 66.9 % and a decay rate of only 0.040 % per cycle. Such a remarkable rate performance is attributed to the highly conductive pathways of PMAT nanoplates, and the excellent cycling stability is ascribed mainly to the chemical confinement of sulfur through a large number of stable covalent bonds between sulfur and the thiol groups of PMAT. The results suggest that this strategy is a viable paradigm for the design and engineering of conducting polymers with reactive functional groups as effective electrode materials for high-performance Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. A Hyper-Crosslinked Carbohydrate Polymer Scaffold Facilitates Lineage Commitment and Maintains a Reserve Pool of Proliferating Cardiovascular Progenitors.

    PubMed

    Baio, Jonathan M; Walden, Ryan C; Fuentes, Tania I; Lee, Charles C; Hasaniya, Nahidh W; Bailey, Leonard L; Kearns-Jonker, Mary K

    2017-05-01

    Cardiovascular progenitor cells (CPCs) have been cultured on various scaffolds to resolve the challenge of cell retention after transplantation and to improve functional outcome after cell-based cardiac therapy. Previous studies have reported successful culture of fully differentiated cardiomyocytes on scaffolds of various types, and ongoing efforts are focused on optimizing the mix of cardiomyocytes and endothelial cells as well as on the identification of a source of progenitors capable of reversing cardiovascular damage. A scaffold culture that fosters cell differentiation into cardiomyocytes and endothelial cells while maintaining a progenitor reserve would benefit allogeneic cell transplantation. Isl-1 + c-Kit + CPCs were isolated as clonal populations from human and sheep heart tissue. After hyper-crosslinked carbohydrate polymer scaffold culture, cells were assessed for differentiation, intracellular signaling, cell cycling, and growth factor/chemokine expression using real time polymerase chain reaction, flow cytometry, immunohistochemistry, and calcium staining. Insulin-like growth factor 1, hepatocyte growth factor, and stromal cell derived factor 1α paracrine factors were induced, protein kinase B signaling was activated, extracellular signal-regulated kinase phosphorylation was reduced and differentiation into both cardiomyocytes and endothelial cells was induced by scaffold-based cell culture. Interestingly, movement of CPCs out of the G1 phase of the cell cycle and increased expression of pluripotency genes PLOU5F1 (Oct4) and T (Brachyury) within a portion of the cultured population occurred, which suggests the maintenance of a progenitor population. Two-color immunostaining and 3-color fluorescence-activated cell sorting analysis confirmed the presence of both Isl-1 expressing undifferentiated cells and differentiated cells identified by troponin T and von Willebrand factor expression. Ki-67 labeling verified the presence of proliferating cells that

  10. Solvent activities of the fluorinated solid polymer electrolyte/water system in fuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hwan; Bae, Young Chan

    We modified the lattice fluid equation-of-state by the introducing Debye-Hückel equation. A thermodynamic model taking into account the specific interaction and ionic strength between the polymer and the solvent is proposed. The proposed model successfully predicts the vapor/liquid equilibria (VLE) of solvents and the solid polymer electrolyte (SPE). A generalized lattice fluid model is modified to describe the change of water activity in solid polymer electrolyte (SPE)/water systems. The calculated activity curves using the proposed model agree remarkably well with the experimental data.

  11. Selective solid-phase extraction using molecularly imprinted polymer as a sorbent for the analysis of fenarimol in food samples.

    PubMed

    Khan, Shagufta; Bhatia, Tejasvi; Trivedi, Purushottam; Satyanarayana, G N V; Mandrah, Kapil; Saxena, Prem Narayan; Mudiam, Mohana Krishna Reddy; Roy, Somendu Kumar

    2016-05-15

    In the present communication, a non-covalent fenarimol-imprinted polymer was synthesized by precipitation polymerization technique using methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, and azobisisobutyronitrile (AIBN) as an initiator in different porogenic solvent. Binding study of molecularly imprinted and non-imprinted polymer (MIP and NIP) showed that MIP possesses a higher affinity towards this analyte compared to NIP. The binding affinity of MIP was calculated by static and kinetic adsorption study. Further, a MIP based cartridge was designed to use in extraction process, necessary for specific determination and quantification of the fungicide in food matrices. Under the optimum conditions, developed method was found to be linear (R(2)=0.9999-0.9994). Limit of detection (LOD) and limit of quantitation (LOQ) in samples were 0.03-0.06 and 0.12-0.21 μg mL(-1), respectively. The rate of recovery of fenarimol was 91.16-99.52% on MIPs. The validated method of molecularly imprinted solid-phase extraction (MISPE) cartridge was successfully applied to the food matrices and compared with commercial sorbent (RP18 and Oasis HLB). However we feel, this method has promising applications in the routine analysis of food samples in industry.

  12. Selective solid-phase extraction of a triterpene acid from a plant extract by molecularly imprinted polymer.

    PubMed

    Claude, Bérengère; Morin, Philippe; Lafosse, Michel; Belmont, Anne-Sophie; Haupt, Karsten

    2008-04-15

    A molecularly imprinted polymer (MIP) has been prepared by a thermal polymerisation method using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent, chloroform as porogenic solvent and an oleanane triterpene compound (18-beta-glycyrrhetinic acid) as imprinted molecule (template). Equilibrium ligand binding experiments were done to assess the performance of the MIP relative to non-imprinted polymer (NIP). After optimisation of SPE protocol (CHCl3 as washing solvent and MeOH as elution solvent), successful imprinting was confirmed by comparison of the recoveries between NIP (5%) and MIP (97%) cartridges. The binding capacity of the MIP for 18-beta-glycyrrhetinic acid was determined to be 0.94 mg g(-1). Four structurally related oleanane triterpenes (18-alpha-glycyrrhetinic acid, oleanolic acid, echinocystic acid, erythrodiol) were selected to assess the MIP selectivity. Experimental data illustrated the influence of functional groups on the triterpene skeleton. The MIP was applied to the solid-phase extraction of triterpenoids from a plant extract prior HPLC analysis. However, CHCl3 was replaced by ACN during the washing step in order to suppress non-specific interactions due to polar matrix components. A selective extraction of 18-beta-glycyrrhetinic acid from hydrolyzed extract of liquorice roots was achieved with a good extraction yield (98%).

  13. Influence of molecular weight of polymethyl(methacrylate) beads on the properties and structure of cross-linked denture base polymer.

    PubMed

    Kawaguchi, Tomohiro; Lassila, Lippo V J; Tokue, Ai; Takahashi, Yutaka; Vallittu, Pekka K

    2011-11-01

    Denture base polymers are multiphase polymers made of polymethyl(methacrylate) (PMMA) beads and monomers containing methylmethacrylate and cross-linking agent. The cross-linking agent is typically dimethacrylate but methacrylated dendrimers have been tested. The aim of this study was to investigate the influence of the molecular weight of the PMMA beads on the mechanical properties of cross-linked denture base polymers. Resin powder with three different molecular weights (Mw 120,000, 350,000, and 996,000) and a commercial autopolymerizing denture base resin (Palapress, Mw 220,000) were tested. The resin monomer liquid was applied with a methylmethacrylate mixture containing 4.6 vol% dendrimer (DD1, VTT Processes). To investigate the flexural properties, the surface microhardness of the PMMA beads, and the thickness of the swollen interpenetrating polymer network (IPN) layer on the PMMA beads, test specimens (3.3×10×65 mm) were fabricated from autopolymerizing resin using a powder/liquid ratio of 10 g/7 ml. The specimens were polymerized in distilled water maintained at 55 °C under 0.4 MPa pressure for 20 min. The flexural strength and flexural modulus (n=8/group) were measured with a three-point bending test at a crosshead speed of 5 mm/min. The Vickers hardness of the area of the polymer with PMMA beads (n=10/group) was tested using a load of 98.12 mN for 5 s. In addition, the thickness of the swollen layer on the PMMA beads was measured (n=10/group). Statistical analysis was performed using a one-way ANOVA and Tukey's test. The flexural strength of the specimens with Mw 220,000 and 350,000 PMMA beads was significantly higher than the strength of specimens with beads having other molecular weights. The flexural modulus of specimens with Mw 120,000 PMMA beads was the lowest. There was no difference in the surface microhardness among all groups. The thickness of the swollen IPN layer on specimens with 120,000 Mw PMMA beads was significantly higher than in the

  14. Superior Blends Solid Polymer Electrolyte with Integrated Hierarchical Architectures for All-Solid-State Lithium Ion Batteries.

    PubMed

    Zhang, Dechao; Zhang, Long; Yang, Kun; Wang, Hongqiang; Yu, Chuang; Xu, Di; Xu, Bo; Wang, Li-Min

    2017-10-06

    Exploration of advanced solid electrolytes with good interfacial stability toward electrodes is a highly relevant research topic for all-solid-state batteries. Here, we report PCL/SN blends integrating with PAN-skeleton as solid polymer electrolyte prepared by a facile method. This polymer electrolyte with hierarchical architectures exhibits high ionic conductivity, large electrochemical windows, high degree flexibility, good flame-retardance ability, and thermal stability (workable at 80 °C). Additionally, it demonstrates superior compatibility and electrochemical stability toward metallic Li as well as LiFePO4 cathode. The electrolyte/electrode interfaces are very stable even subjected to 4.5 V at charging state for long time. The LiFePO4/Li all-solid-state cells based on this electrolyte deliver high capacity, outstanding cycling stability, and superior rate capability better than those based on liquid electrolyte. This solid polymer electrolyte is eligible for next generation high energy density all-solid-state batteries.

  15. Thermally crosslinked polymeric compositions and methods of making the same

    DOEpatents

    Koros, William John; Kratochvil, Adam Michal

    2014-03-04

    The various embodiments of the present disclosure relate generally to thermally crosslinked polymeric compositions and methods of making thermally crosslinked polymeric compositions. An embodiment of the present invention comprises a composition comprising: a first polymer comprising a first repeat unit, the first repeat unit comprising a carboxyl group, wherein the first polymer crosslinks to a second polymer formed from a second repeat unit, and wherein the first polymer crosslinks to the second polymer without formation of an ester group.

  16. One-Step Synthesis of Cross-Linked Ionic Polymer Thin Films in Vapor Phase and Its Application to an Oil/Water Separation Membrane.

    PubMed

    Joo, Munkyu; Shin, Jihye; Kim, Jiyeon; You, Jae Bem; Yoo, Youngmin; Kwak, Moo Jin; Oh, Myung Seok; Im, Sung Gap

    2017-02-15

    In spite of the huge research interest, ionic polymers could not have been synthesized in the vapor phase because the monomers of ionic polymers contain nonvolatile ionic salts, preventing the monomers from vaporization. Here, we suggest a new, one-step synthetic pathway to form a series of cross-linked ionic polymers (CIPs) in the vapor phase via initiated chemical vapor deposition (iCVD). 2-(Dimethylamino)ethyl methacrylate (DMAEMA) and 4-vinylbenzyl chloride (VBC) monomers are introduced into the iCVD reactor in the vapor phase to form a copolymer film. Simultaneously in the course of the deposition process, the tertiary amine in DMAEMA and benzylic chloride in VBC undergo a Menshutkin nucleophilic substitution reaction to form an ionic ammonium-chloride complex, forming a highly cross-linked ionic copolymer film of p(DMAEMA-co-VBC). To the best of our knowledge, this is the first report on the synthesis of CIP films in the vapor phase. The newly developed CIP thin film is further applied to the surface modification of the membrane for oil/water separation. With the hydrophilic and underwater oleophobic membrane whose surface is modified with the CIP film, excellent separation efficiency (>99%) and unprecedentedly high permeation flux (average 2.32 × 10(5) L m(-2) h(-1)) are achieved.

  17. Effect of polyacrylonitrile on triethylene glycol diacetate-2-propenoic acid butyl ester gel polymer electrolytes with interpenetrating crosslinked network for flexible lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Qiujun; Song, Wei-Li; Fan, Li-Zhen; Shi, Qiao

    2015-11-01

    A new flexible gel polymer electrolytes (GPE) with interpenetrating cross-linked network is fabricated by blending long-chain polyacrylonitrile (PAN) polymer matrix and short-chain triethylene glycol diacetate-2-propenoic acid butyl ester (TEGDA-BA) framework, with the purpose of enhancing the mechanical stability of the GPE frameworks via synergistic effects of the linear polymers and crosslinked monomers. The as fabricated frameworks enable the liquid electrolytes to be firmly entrapped in the polymeric matrices, which significantly improves the mechanical bendability and interface stability of the resultant GPE. The GPE with 5 wt% PAN exhibits high ionic conductivity up to 5.9 × 10-3 S cm-1 at 25 °C with a stable electrochemical window observed (>5.0 V vs. Li/Li+). The Li|GPE|LiFePO4 half cells demonstrate remarkably stable capacity retention and rate ability during cycling tests. As expected, the LiFePO4|GPE|Li4Ti5O12 full cells also exhibit discharge capacity of 125.2 mAh g-1 coupled with high columbic efficiency greater than 98% after 100 cycles. The excellent mechanical flexibility and charge/discharge performance suggest that the GPE holds great application potential in flexible LIBs.

  18. Photoswitching of glass transition temperatures of azobenzene-containing polymers induces reversible solid-to-liquid transitions

    NASA Astrophysics Data System (ADS)

    Zhou, Hongwei; Xue, Changguo; Weis, Philipp; Suzuki, Yasuhito; Huang, Shilin; Koynov, Kaloian; Auernhammer, Günter K.; Berger, Rüdiger; Butt, Hans-Jürgen; Wu, Si

    2016-10-01

    The development of polymers with switchable glass transition temperatures (Tg) can address scientific challenges such as the healing of cracks in high-Tg polymers and the processing of hard polymers at room temperature without using plasticizing solvents. Here, we demonstrate that light can switch the Tg of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization abilities. Trans azopolymers are solids with Tg above room temperature, whereas cis azopolymers are liquids with Tg below room temperature. Because of the photoinduced solid-to-liquid transitions of these polymers, light can reduce the surface roughness of azopolymer films by almost 600%, repeatedly heal cracks in azopolymers, and control the adhesion of azopolymers for transfer printing. The photoswitching of Tg provides a new strategy for designing healable polymers with high Tg and allows for control over the mechanical properties of polymers with high spatiotemporal resolution.

  19. Solid Tumor-Targeting Theranostic Polymer Nanoparticle in Nuclear Medicinal Fields

    PubMed Central

    Makino, Akira; Kimura, Shunsaku

    2014-01-01

    Polymer nanoparticles can be prepared by self-assembling of amphiphilic polymers, and various types of molecular assemblies have been reported. In particular, in medicinal fields, utilization of these polymer nanoparticles as carriers for drug delivery system (DDS) has been actively tried, and some nanoparticulate drugs are currently under preclinical evaluations. A radionuclide is an unstable nucleus and decays with emission of radioactive rays, which can be utilized as a tracer in the diagnostic imaging systems of PET and SPECT and also in therapeutic purposes. Since polymer nanoparticles can encapsulate most of diagnostic and therapeutic agents with a proper design of amphiphilic polymers, they should be effective DDS carriers of radionuclides in the nuclear medicinal field. Indeed, nanoparticles have been recently attracting much attention as common platform carriers for diagnostic and therapeutic drugs and contribute to the development of nanotheranostics. In this paper, recent developments of solid tumor-targeting polymer nanoparticles in nuclear medicinal fields are reviewed. PMID:25379530

  20. Peripherally cross-linking the shell of core-shell polymer micelles decreases premature release of physically loaded combretastatin A4 in whole blood and increases its mean residence time and subsequent potency against primary murine breast tumors after IV administration

    PubMed Central

    Wakaskar, Rajesh R.; Bathena, Sai Praneeth R.; Tallapaka, Shailendra; Ambardekar, Vishakha V.; Gautum, Nagsen; Thakare, Rhishikesh N.; Simet, Samantha M.; Curran, Stephen M.; Singh, Rakesh K.; Dong, Yuxiang

    2014-01-01

    Purpose Determine the feasibility and potential benefit of peripherally cross-linking the shell of core-shell polymer micelles on the premature release of physically loaded hydrophobic drug in whole blood and subsequent potency against solid tumors. Methods Individual Pluronic F127 polymer micelles (F127 PM) peripherally cross-linked with ethylenediamine at 76% of total PEO blocks (X-F127 PM) were physically loaded with combretastatin A4 (CA4) by the solid dispersion method and compared to CA4 physically loaded in uncross-linked F127 PM, CA4 in DMSO in vitro, or water-soluble CA4 phosphate (CA4P) in vivo. Results X-F127 PM had similar CA4 loading and aqueous solubility as F127 PM up to 10 mg CA4 / mL at 22.9 wt% and did not aggregate in PBS or 90% (v/v) human serum at 37°C for at least 24 h. In contrast, X-F127 PM decreased the unbound fraction of CA4 in whole blood (fu) and increased the mean plasma residence time and subsequent potency of CA4 against the vascular function and growth of primary murine 4T1 breast tumors over CA4 in F127 PM and water-soluble CA4P after IV administration. Conclusions Given that decreasing the fu is an indication of decreased drug release, peripherally cross-linking the shell of core-shell polymer micelles may be a simple approach to decrease premature release of physically loaded hydrophobic drug in the blood and increase subsequent potency in solid tumors. PMID:25223962

  1. [Enrichment of triphenyltin in water samples by beta-cyclodextrin cross-linking polymer and determination by hydride-generation atomic fluorescence spectrometry].

    PubMed

    Qiu, Hai-Ou; Yang, Xiao-Qiu; Yang, Ming; Xi, Yong-Qing; Tang, Zhi-Yong

    2007-04-01

    A new method was proposed for the enrichment of triphenyltin in water samples by beta-cyclodextrin cross-linking polymer and the quantitative determination of tin in triphenyltin by hydride-generation atomic fluorescence spectrometry. The chemical conditions and instrumental conditions were investigated and optimized. The method is sensitive and precise. The detection limit is 0.1 ng x mL(-1) and the RSD 2.64% (for 0.04 microg x mL(-1)). The proposed method has been successfully applied to the determination of triphenyltin in various water samples.

  2. Semiconducting polymers: Probing the solid-liquid interface

    NASA Astrophysics Data System (ADS)

    Crispin, Xavier; Kalinin, Sergei V.

    2017-07-01

    Exploring the minute mechanical deformations induced by electrical bias at the interface with electrolytes allows the identification of local crystallinity and distinguishing adsorption and intercalation of ions in electroactive polymers.

  3. All-Solid-State Lithium-Ion Batteries with Grafted Ceramic Nanoparticles Dispersed in Solid Polymer Electrolytes.

    PubMed

    Lago, Nerea; Garcia-Calvo, Oihane; Lopez del Amo, Juan Miguel; Rojo, Teofilo; Armand, Michel

    2015-09-21

    Lithium-based rechargeable batteries offer superior specific energy and power, and have enabled exponential growth in industries focused on small electronic devices. However, further increases in energy density, for example for electric transportation, face the challenge of harnessing the lithium metal as negative electrode instead of limited-capacity graphite and its heavy copper current collector. All-solid-state batteries utilize solid polymer electrolytes (SPEs) to overcome the safety issues of liquid electrolytes. We demonstrate an all-solid-state lithium-ion battery by using plasticized poly(ethylene oxide)-based SPEs comprising anions grafted or co-grafted onto ceramic nanoparticles. This new approach using grafted ceramic nanoparticles enables the development of a new generation of nanohybrid polymer electrolytes with high ionic conductivity as well as high electrochemical and mechanical stability, enabling Li-ion batteries with long cycle life.

  4. Cross-linking characterization of polymers based on their optical dispersion utilizing a white-light interferometer

    NASA Astrophysics Data System (ADS)

    Taudt, Ch.; Baselt, T.; Oreski, G.; Hirschl, Ch.; Koch, E.; Hartmann, P.

    2015-05-01

    This work analyses samples of the widely used encapsulant of photovoltaics modules, ethylene vinyl acetate (EVA). The samples were cross-linked using a lamination technique for different curing times (0 - 20 minutes). The cross-linking characterization is done by determinating the material dispersion with the aid of a combined temporal- and spectral domain white-light interferometer. With the proposed technique it was possible to discriminate the differences in crosslinking for the given curing times. One important feature of this approach is the possibility to perform space resolved measurements of the crosslinking state with μm-resolution. Furthermore the paper discusses the mathematical analysis and processing of measurement data and shows a prototype solution for the fast and automated data acquisition for industrial application.

  5. Solid state drug-polymer miscibility studies using the model drug ABT-102.

    PubMed

    Jog, Rajan; Gokhale, Rajeev; Burgess, Diane J

    2016-07-25

    Amorphous solid dispersions typically suffer storage stability issues due to: their amorphous nature, high drug loading, uneven drug:stabilizer ratio and plasticization effects as a result of hygroscopic excipients. An extensive solid state miscibility study was conducted to aid in understanding the mechanisms involved in drug/stabilizer interactions. ABT-102 (model drug) and nine different polymers with different molecular weights and viscosities were selected to investigate drug/polymer miscibility. Three different polymer:drug ratios (1:3, 1:1 and 3:1, w/w) were analyzed using: DSC, FTIR and PXRD. Three different techniques were used to prepare the amorphous solid dispersions: serial dilution, solvent evaporation and spray drying. Spray drying was the best method to obtain amorphous solid dispersions. However, under certain conditions amorphous formulations could be obtained using solvent evaporation. Melting point depression was used to calculate interaction parameters and free energy of mixing for the various drug polymer mixtures. The spray dried solid dispersions yielded a negative free energy of mixing which indicated strong drug-polymer miscibility compared to the solvent evaporation and serial dilution method. Soluplus was the best stabilizer compared to PVP and HPMC, which is probably a consequence of strong hydrogen bonding between the two CO moieties of soluplus and the drug NH moieities. Copyright © 2016. Published by Elsevier B.V.

  6. Crosslinking of Perfluorocarbon Polymers

    DTIC Science & Technology

    1978-05-01

    Preparation of 5-Chlorooctafluoro- sodium- pentanoate .... .......... ... 23 c. Preparation of 4-Chloroperfluoro- butene-1 . . . . . . . . . . . . 24 d... pentanoate Sodium hydroxide (5.17 g, 129.25 mmol) was dissolved in water (25 ml). To the warm solution was added dropwise CI(CF 2 )4 CO2 CH3 (25.00 g, 84.88

  7. Crosslinking of Perfluorocarbon Polymers

    DTIC Science & Technology

    1977-04-01

    the pyrolysis and in particular for the epoxidation process 3 were determined employing perfluorooctanoic acid as a readily available substitute. The...sodium salt of perfluorooctanoic acid was obtained from the acid in essentially quantitative yield and, varying the pyrolysis conditions, yields of 68...to a purer product. 35 d. Preparation of n-Perfluoroheptene-l The sodium salt of n- perfluorooctanoic acid was obtained in 96% yield from the acid

  8. Hyper-crosslinked β-cyclodextrin porous polymer: an adsorption-facilitated molecular catalyst support for transformation of water-soluble aromatic molecules.

    PubMed

    Li, Haiying; Meng, Bo; Chai, Song-Hai; Liu, Honglai; Dai, Sheng

    2016-02-01

    A hyper-crosslinked β-cyclodextrin porous polymer (BnCD-HCPP) was designed and synthesized facilely by β-cyclodextrin benzylation and subsequent crosslinking via a Friedel-Crafts alkylation route. The BnCD-HCPP shows an extremely high BET surface area, large pore volume, and high thermal stability, making it a highly efficient adsorbent for removal of aromatic pollutants from water. The adsorption efficiency in terms of distribution coefficient, defined as the ratio of adsorption capacity to equilibrium adsorbate concentration, ranged from 10(3) to 10(6) mL g(-1) within a concentration of 0-100 ppm, one order of magnitude higher than that of other β-cyclodextrin-based adsorbents reported previously. The molar percentage of adsorbate to β-cyclodextrin exceeded 300%, suggesting that the adsorption occurred not only in the cyclodextrin cavities via a 1 : 1 complexation, but also in the nanopores of the BnCD-HCPP created during the hyper-crosslinking. The BnCD-HCPP can be further functionalized by incorporation of gold nanoparticles for catalytic transformation of adsorbed phenolic compounds such as 4-nitrophenol to 4-aminophenol.

  9. pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli.

    PubMed

    Holten-Andersen, Niels; Harrington, Matthew J; Birkedal, Henrik; Lee, Bruce P; Messersmith, Phillip B; Lee, Ka Yee C; Waite, J Herbert

    2011-02-15

    Growing evidence supports a critical role of metal-ligand coordination in many attributes of biological materials including adhesion, self-assembly, toughness, and hardness without mineralization [Rubin DJ, Miserez A, Waite JH (2010) Advances in Insect Physiology: Insect Integument and Color, eds Jérôme C, Stephen JS (Academic Press, London), pp 75-133]. Coordination between Fe and catechol ligands has recently been correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and proposed to endow self-healing properties [Harrington MJ, Masic A, Holten-Andersen N, Waite JH, Fratzl P (2010) Science 328:216-220]. Inspired by the pH jump experienced by proteins during maturation of a mussel byssus secretion, we have developed a simple method to control catechol-Fe(3+) interpolymer cross-linking via pH. The resonance Raman signature of catechol-Fe(3+) cross-linked polymer gels at high pH was similar to that from native mussel thread cuticle and the gels displayed elastic moduli (G') that approach covalently cross-linked gels as well as self-healing properties.

  10. pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

    PubMed Central

    Holten-Andersen, Niels; Harrington, Matthew J.; Birkedal, Henrik; Lee, Bruce P.; Messersmith, Phillip B.; Lee, Ka Yee C.; Waite, J. Herbert

    2011-01-01

    Growing evidence supports a critical role of metal-ligand coordination in many attributes of biological materials including adhesion, self-assembly, toughness, and hardness without mineralization [Rubin DJ, Miserez A, Waite JH (2010) Advances in Insect Physiology: Insect Integument and Color, eds Jérôme C, Stephen JS (Academic Press, London), pp 75–133]. Coordination between Fe and catechol ligands has recently been correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and proposed to endow self-healing properties [Harrington MJ, Masic A, Holten-Andersen N, Waite JH, Fratzl P (2010) Science 328:216–220]. Inspired by the pH jump experienced by proteins during maturation of a mussel byssus secretion, we have developed a simple method to control catechol-Fe3+ interpolymer cross-linking via pH. The resonance Raman signature of catechol-Fe3+ cross-linked polymer gels at high pH was similar to that from native mussel thread cuticle and the gels displayed elastic moduli (G′) that approach covalently cross-linked gels as well as self-healing properties. PMID:21278337

  11. Drug-polymer solubility and miscibility: Stability consideration and practical challenges in amorphous solid dispersion development.

    PubMed

    Qian, Feng; Huang, Jun; Hussain, Munir A

    2010-07-01

    Drug-polymer solid dispersion has been demonstrated as a feasible approach to formulate poorly water-soluble drugs in the amorphous form, for the enhancement of dissolution rate and bioperformance. The solubility (for crystalline drug) and miscibility (for amorphous drug) in the polymer are directly related to the stabilization of amorphous drug against crystallization. Therefore, it is important for pharmaceutical scientists to rationally assess solubility and miscibility in order to select the optimal formulation (e.g., polymer type, drug loading, etc.) and recommend storage conditions, with respect to maximizing the physical stability. This commentary attempts to discuss the concepts and implications of the drug-polymer solubility and miscibility on the stabilization of solid dispersions, review recent literatures, and propose some practical strategies for the evaluation and development of such systems utilizing a working diagram.

  12. A Cross-Linking Succinonitrile-Based Composite Polymer Electrolyte with Uniformly Dispersed Vinyl-Functionalized SiO2 Particles for Li-Ion Batteries.

    PubMed

    Liu, Kai; Ding, Fei; Liu, Jiaquan; Zhang, Qingqing; Liu, Xingjiang; Zhang, Jinli; Xu, Qiang

    2016-09-14

    A cross-linking succinonitrile (SN)-based composite polymer electrolyte (referred to as "CLPC-CPE"), in which vinyl-functionalized SiO2 particles connect with trimethylolpropane propoxylate triacrylate (TPPTA) monomers by covalent bonds, was prepared by an ultraviolet irradiation (UV-curing) process successfully. Vinyl-functionalized SiO2 particles may react with TPPTA monomers to form a cross-linking network within the SN-based composite polymer electrolyte under ultraviolet irradiation. Vinyl-functionalized SiO2 particles as the fillers of polymer electrolyte may improve both the thermal stability of CLPC-CPE and interfacial compatibility between CLPC-CPE and electrodes effectively. There is no weight loss for CLPC-CPE until above 230 °C. The ionic conductivity of CLPC-CPE may reach 7.02 × 10(-4) S cm(-1) at 25 °C. CLPC-CPE has no significant oxidation current until up to 4.6 V (vs Li/Li(+)). The cell of LiFePO4/CLPC-CPE/Li has presented superior cycle performance and rate capability. The cell of LiFePO4/CLPC-CPE/Li may deliver a high discharge capacity of 154.4 mAh g(-1) at a rate of 0.1 C after 100 charge-discharge cycles, which is similar than that of the control cell of LiFePO4/liquid electrolyte/Li. Furthermore, the cell of LiFePO4/CLPC-CPE/Li can display a high discharge capacity of 112.7 mAh g(-1) at a rate of 2 C, which is higher than that of the cells assembled with other plastic crystal polymer electrolyte reported before obviously.

  13. Coarse-Grained Molecular Dynamics Study of the Curing and Properties of Highly Cross-Linked Epoxy Polymers.

    PubMed

    Aramoon, Amin; Breitzman, Timothy D; Woodward, Christopher; El-Awady, Jaafar A

    2016-09-08

    In this work, a coarse-grained model is developed for highly cross-linked bisphenol A diglycidyl ether epoxy resin with diaminobutane hardener. In this model, all conformationally relevant coarse-grained degrees of freedom are accounted for by sampling over the free-energy surfaces of the atomic structures using quantum mechanical simulations. The interaction potentials between nonbonded coarse-grained particles are optimized to accurately predict the experimentally measured density and glass-transition temperature of the system. In addition, a new curing algorithm is also developed to model the creation of highly cross-linked epoxy networks. In this algorithm, to create a highly cross-linked network, the reactants are redistributed from regions with an excessive number of reactive molecules to regions with a lower number of reactants to increase the chances of cross-linking. This new algorithm also dynamically controls the rate of cross-linking at each local region to ensure uniformity of the resulting network. The curing simulation conducted using this algorithm is able to develop polymeric networks having a higher average degree of cross-linking, which is more uniform throughout the simulation cell as compared to that in the networks cured using other curing algorithms. The predicted gel point from the current curing algorithm is in the acceptable theoretical and experimental range of measured values. Also, the resulting cross-linked microstructure shows a volume shrinkage of 5%, which is close to the experimentally measured volume shrinkage of the cured epoxy. Finally, the thermal expansion coefficients of materials in the glassy and rubbery states show good agreement with the experimental values.

  14. Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Manko, David J.; Koch, Hermann; Enayetullah, Mohammad A.; Appleby, A. John

    1989-01-01

    Of all the fuel cell systems only alkaline and solid polymer electrolyte fuel cells are capable of achieving high power densities (greater than 1 W/sq cm) required for terrestrial and extraterrestrial applications. Electrode kinetic criteria for attaining such high power densities are discussed. Attainment of high power densities in solid polymer electrolyte fuel cells has been demonstrated earlier by different groups using high platinum loading electrodes (4 mg/sq cm). Recent works at Los Alamos National Laboratory and at Texas A and M University (TAMU) demonstrated similar performance for solid polymer electrolyte fuel cells with ten times lower platinum loading (0.45 mg/sq cm) in the electrodes. Some of the results obtained are discussed in terms of the effects of type and thickness of membrane and of the methods platinum localization in the electrodes on the performance of a single cell.

  15. Pressure-controlled motion of single polymers through solid-state nanopores

    PubMed Central

    Lu, Bo; Hoogerheide, David P.; Zhao, Qing; Zhang, Hengbin; Tang, Zhipeng; Yu, Dapeng; Golovchenko, Jene A.

    2013-01-01

    Voltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second molecular driving force that provides new freedom for studying molecules in nanopores. In this work, we show that opposing pressure and voltage bias enables nanopores to detect and resolve very short DNA molecules, as well as to detect near-neutral polymers. PMID:23802688

  16. Self-replenishing ability of cross-linked low surface energy polymer films investigated by a complementary experimental-simulation approach

    SciTech Connect

    Esteves, A. C. C. E-mail: g.dewith@tue.nl; Lyakhova, K.; Riel, J. M. van; With, G. de E-mail: g.dewith@tue.nl; Ven, L. G. J. van der; Benthem, R. A. T. M. van

    2014-03-28

    Nowadays, many self-healing strategies are available for recovering mechanical damage of bulk polymeric materials. The recovery of surface-dependent functionalities on polymer films is, however, equally important and has been less investigated. In this work we study the ability of low surface energy cross-linked poly(ester urethane) networks containing perfluorinated dangling chains to self-replenish their surface, after being submitted to repeated surface damage. For this purpose we used a combined experimental-simulation approach. Experimentally, the cross-linked films were intentionally damaged by cryo-microtoming to remove top layers and create new surfaces which were characterized by water Contact Angle measurements and X-Ray Photoelectron Spectroscopy. The same systems were simultaneously represented by a Dissipative Particles Dynamics simulation method, where the damage was modeled by removing the top film layers in the simulation box and replacing it by new “air” beads. The influence of different experimental parameters, such as the concentration of the low surface energy component and the molecular mobility span of the dangling chains, on the surface recovery is discussed. The combined approach reveals important details of the self-replenishing ability of damaged polymer films such as the occurrence of multiple-healing events, the self-replenishing efficiency, and the minimum “healing agent” concentration for a maximum recovery.

  17. Self-replenishing ability of cross-linked low surface energy polymer films investigated by a complementary experimental-simulation approach

    NASA Astrophysics Data System (ADS)

    Esteves, A. C. C.; Lyakhova, K.; van Riel, J. M.; van der Ven, L. G. J.; van Benthem, R. A. T. M.; de With, G.

    2014-03-01

    Nowadays, many self-healing strategies are available for recovering mechanical damage of bulk polymeric materials. The recovery of surface-dependent functionalities on polymer films is, however, equally important and has been less investigated. In this work we study the ability of low surface energy cross-linked poly(ester urethane) networks containing perfluorinated dangling chains to self-replenish their surface, after being submitted to repeated surface damage. For this purpose we used a combined experimental-simulation approach. Experimentally, the cross-linked films were intentionally damaged by cryo-microtoming to remove top layers and create new surfaces which were characterized by water Contact Angle measurements and X-Ray Photoelectron Spectroscopy. The same systems were simultaneously represented by a Dissipative Particles Dynamics simulation method, where the damage was modeled by removing the top film layers in the simulation box and replacing it by new "air" beads. The influence of different experimental parameters, such as the concentration of the low surface energy component and the molecular mobility span of the dangling chains, on the surface recovery is discussed. The combined approach reveals important details of the self-replenishing ability of damaged polymer films such as the occurrence of multiple-healing events, the self-replenishing efficiency, and the minimum "healing agent" concentration for a maximum recovery.

  18. Self-replenishing ability of cross-linked low surface energy polymer films investigated by a complementary experimental-simulation approach.

    PubMed

    Esteves, A C C; Lyakhova, K; van Riel, J M; van der Ven, L G J; van Benthem, R A T M; de With, G

    2014-03-28

    Nowadays, many self-healing strategies are available for recovering mechanical damage of bulk polymeric materials. The recovery of surface-dependent functionalities on polymer films is, however, equally important and has been less investigated. In this work we study the ability of low surface energy cross-linked poly(ester urethane) networks containing perfluorinated dangling chains to self-replenish their surface, after being submitted to repeated surface damage. For this purpose we used a combined experimental-simulation approach. Experimentally, the cross-linked films were intentionally damaged by cryo-microtoming to remove top layers and create new surfaces which were characterized by water Contact Angle measurements and X-Ray Photoelectron Spectroscopy. The same systems were simultaneously represented by a Dissipative Particles Dynamics simulation method, where the damage was modeled by removing the top film layers in the simulation box and replacing it by new "air" beads. The influence of different experimental parameters, such as the concentration of the low surface energy component and the molecular mobility span of the dangling chains, on the surface recovery is discussed. The combined approach reveals important details of the self-replenishing ability of damaged polymer films such as the occurrence of multiple-healing events, the self-replenishing efficiency, and the minimum "healing agent" concentration for a maximum recovery.

  19. High temperature lithium cells with solid polymer electrolytes

    DOEpatents

    Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

    2017-03-07

    Electrochemical cells that use electrolytes made from new polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers. Such electrochemical cells can operate safely at higher temperatures than have been possible before, especially in lithium cells. The ionic conductivity of the electrolytes increases with increasing temperature.

  20. Influence of carbon nanotubes on the optical properties of plasticized solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Ibrahim, Suriani; Yasin, Siti Mariah Mohd; Johan, Mohd Rafie

    2013-07-01

    Polyethylene oxide (PEO) based solid polymer electrolyte films complexed with lithium hexafluorophosphate (LiPF6), ethylene carbonate (EC) and carbon nanotubes (CNTs) are prepared by solution-casting technique. The complexation of doping materials with polymer is confirmed by X-ray diffraction and infrared studies. The incorporation of LiPF6, EC and CNTs into the host polymer shows a significant increase in conductivity of 10-10 and 10-3 S cm-1. The optical properties such as direct and indirect band gaps are investigated for pure and doped polymer films within a wavelength range of 200-400 nm. It is found that the energy gaps and band edge values shift towards lower energies upon doping. It is shown that LiPF6, EC and CNTs are responsible for the formation of defects in polymer electrolytes, which increases the degree of disorder in the films.

  1. Enhanced ionic conductivity and optical studies of plasticized (PEO-KCl) solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Chapi, Sharanappa; H, Devendrappa

    2015-06-01

    Solid polymer electrolytes (SPEs) based on Polyethylene oxide (PEO) doped with potassium chloride (KCl) were prepared by the solution cast technique. The conductivity increases from 10-10 to 10-6 Scm-1 at 303K with dopant. Optical absorption study shows that the direct & indirect optical band gaps were found decreased from 5.45-4.46eV and 4.96-3.86eV respectively with increasing the KCl. The XRD patterns reveal increasing the amorphous with increasing the dopent. The obtained results suggest that, these polymer systems are suitable candidates for solid state battery, electro chromic devices & optoelectronics display etc.

  2. Cross-linked branching nanohybrid polymer electrolyte with monodispersed TiO2 nanoparticles for high performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ma, Cheng; Zhang, Jinfang; Xu, Mingquan; Xia, Qingbing; Liu, Jiatu; Zhao, Shuai; Chen, Libao; Pan, Anqiang; Ivey, Douglas G.; Wei, Weifeng

    2016-06-01

    Nanohybrid polymer electrolytes (NHPE) with ceramic particles have attracted significant attention owing to their improvement in electrochemical performance. However, particle aggregation and weak nanoparticle/polymer matrix interaction restrict their further application in lithium-ion batteries (LIBs). We demonstrate a facile in-situ polymerization/crystallization method to synthesize a homogeneous TiO2-grafted NHPE with a cross-linked branching structure, comprised of ion-conducting poly(ethylene glycol) methyl ether methacrylate (PEGMEM) and non-polar stearyl methacrylate (SMA). This technique is different from existing methods of blending functionalized ceramic particles into the polymer matrix. Highly monodispersed TiO2 nanocrystals enhance the effective interfacial interactions between particles and polymer matrix, which suppress the crystallization of ethylene oxide (EO) groups and facilitate forming continuously interconnected ion-conducting channels. Moreover, an increased dissociation degree of Li salt can also be achieved. The TiO2-grafted NHPE exhibits superior electrochemical properties with an ionic conductivity of 1.1 × 10-4 S cm-1 at 30 °C, a high lithium ion transference number and excellent interfacial compatibility with the lithium electrode. In particular, a lithium-ion battery based on TiO2-grafted NHPE demonstrates good C-rate performance, as well as excellent cycling stability with an initial discharge capacity of 153.5 mAh g-1 and a capacity retention of 96% after 300 cycles at 1 C (80 °C).

  3. Impact of in situ polymer coating on particle dispersion into solid laser-generated nanocomposites.

    PubMed

    Wagener, Philipp; Brandes, Gudrun; Schwenke, Andreas; Barcikowski, Stephan

    2011-03-21

    The crucial step in the production of solid nanocomposites is the uniform embedding of nanoparticles into the polymer matrix, since the colloidal properties or specific physical properties are very sensitive to particle dispersion within the nanocomposite. Therefore, we studied a laser-based generation method of a nanocomposite which enables us to control the agglomeration of nanoparticles and to increase the single particle dispersion within polyurethane. For this purpose, we ablated targets of silver and copper inside a polymer-doped solution of tetrahydrofuran by a picosecond laser (using a pulse energy of 125 μJ at 33.3 kHz repetition rate) and hardened the resulting colloids into solid polymers. Electron microscopy of these nanocomposites revealed that primary particle size, agglomerate size and particle dispersion strongly depend on concentration of the polyurethane added before laser ablation. 0.3 wt% polyurethane is the optimal polymer concentration to produce nanocomposites with improved particle dispersion and adequate productivity. Lower polyurethane concentration results in agglomeration whereas higher concentration reduces the production rate significantly. The following evaporation step did not change the distribution of the nanocomposite inside the polyurethane matrix. Hence, the in situ coating of nanoparticles with polyurethane during laser ablation enables simple integration into the structural analogue polymer matrix without additives. Furthermore, it was possible to injection mold these in situ-stabilized nanocomposites without affecting particle dispersion. This clarifies that sufficient in situ stabilization during laser ablation in polymer solution is able to prevent agglomeration even in a hot polymer melt.

  4. Crystallization of amorphous solid dispersions of resveratrol during preparation and storage-Impact of different polymers.

    PubMed

    Wegiel, Lindsay A; Mauer, Lisa J; Edgar, Kevin J; Taylor, Lynne S

    2013-01-01

    The objective of this study was to investigate intermolecular interactions between resveratrol and polymers in amorphous blends and to study the potential correlations between compound-polymer interactions, manufacturability, and stability of the amorphous system to crystallization during storage. Polymers included two grades of poly (vinylpyrrolidone) (PVP), Eudragit E100 (E100), hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS), carboxymethyl cellulose acetate butyrate, and poly (acrylic acid) (PAA). Amorphous blends ("solid dispersions") were prepared by dissolving both resveratrol and polymer in a solvent followed by rotary evaporation. Crystallinity was evaluated using X-ray powder diffraction and was studied as a function of time. Mid-infrared (IR) spectroscopy was used to investigate resveratrol-polymer interactions. Polymer influence on the crystallization behavior of resveratrol varied and could be correlated to the polymer structure, whereby polymers with good hydrogen bond acceptor groups performed better as crystallization inhibitors. Resveratrol-polymer hydrogen bonding interactions could be inferred from the IR spectra. Somewhat surprisingly, E100 and resveratrol showed evidence of an acid-base reaction, in addition to intermolecular hydrogen bonding interactions. PVP K29/32 appeared to form stronger hydrogen bond interactions with resveratrol relative to HPMC, HPMCAS, and PAA, consistent with acceptor group chemistry. Long-term stability of the systems against crystallization suggested that stability is linked to the type and strength of intermolecular interactions present. whereby resveratrol blended with E100 and PVP K29/32 showed the greatest stability to crystallization. In conclusion, amorphous resveratrol is unstable and difficult to form, requiring the assistance of a polymeric crystallization inhibitor to facilitate the formation of an amorphous solid dispersion. Polymers effective at inhibiting

  5. 'All-solid-state' electrochemistry of a protein-confined polymer electrolyte film

    SciTech Connect

    Parthasarathy, Meera; Pillai, Vijayamohanan K. Mulla, Imtiaz S.; Shabab, Mohammed; Khan, M.I.

    2007-12-07

    Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique 'all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe{sup 2+}-form of the entrapped protein is found to bind molecular oxygen more strongly than the native protein. In the 'all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry.

  6. 'All-solid-state' electrochemistry of a protein-confined polymer electrolyte film.

    PubMed

    Parthasarathy, Meera; Pillai, Vijayamohanan K; Mulla, Imtiaz S; Shabab, Mohammed; Khan, M I

    2007-12-07

    Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique 'all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe2+-form of the entrapped protein is found to bind molecular oxygen more strongly than the native protein. In the 'all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry.

  7. High ionic conductivity P(VDF-TrFE)/PEO blended polymer electrolytes for solid electrochromic devices.

    PubMed

    Nguyen, Chien A; Xiong, Shanxin; Ma, Jan; Lu, Xuehong; Lee, Pooi See

    2011-08-07

    Solid polymer electrolytes with excellent ionic conductivity (above 10(-4) S cm(-1)), which result in high optical modulation for solid electrochromic (EC) devices are presented. The combination of a polar host matrix poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and a solid plasticized of a low molecular weight poly(ethylene oxide) (PEO) (M(w)≤ 20,000) blended polymer electrolyte serves to enhance both the dissolution of lithium salt and the ionic transport. Calorimetric measurement shows a reduced crystallization due to a better intermixing of the polymers with small molecular weight PEO. Vibrational spectroscopy identifies the presence of free ions and ion pairs in the electrolytes with PEO of M(w)≤ 8000. The ionic dissolution is improved using PEO as a plasticizer when compared to liquid propylene carbonate, evidently shown in the transference number analysis. Ionic transport follows the Arrhenius equation with a low activation energy (0.16-0.2 eV), leading to high ionic conductivities. Solid electrochromic devices fabricated with the blended P(VDF-TrFE)/PEO electrolytes and polyaniline show good spectroelectrochemical performance in the visible (300-800 nm) and near-infrared (0.9-2.4 μm) regions with a modulation up to 60% and fast switching speed of below 20 seconds. The successful introduction of the solid polymer electrolytes with its best harnessed qualities helps to expedite the application of various electrochemical devices. This journal is © the Owner Societies 2011

  8. In situ micro-FTIR study of the solid-solid interface between lithium electrode and polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Cheng, H.; Zhu, C. B.; Lu, M.; Yang, Y.

    In situ micro-FTIR spectroscopy was explored to characterize the solid-solid interface between lithium electrode and polymer electrolytes. The cyclic voltammetric (CV) results indicated that the reduction reactions of oxygen and water as well as the formation of underpotential deposition (UPD) Li occur in the Li/PEO 20-LiN(CF 3SO 2) 2 electrolyte interface in the different potential region. The infrared spectral changes observed during the CV process revealed that there is a direct correlation between the CV peaks and the magnitude of the infrared peaks. It is shown that the infrared reflectivity from the solid-solid interface is very sensitive to the formation of the passive layer on the lithium electrodes. The results obtained from optical micrographs also displayed directly the formation of the passive layer along with lithium deposition and dissolution process. It is correlated well with in situ FTIR and electrochemical experiments.

  9. Polymer-encapsulated carbon capture liquids that tolerate precipitation of solids for increased capacity

    SciTech Connect

    Aines, Roger D; Bourcier, William L; Spadaccini, Christopher M; Stolaroff, Joshuah K

    2015-02-03

    A system for carbon dioxide capture from flue gas and other industrial gas sources utilizes microcapsules with very thin polymer shells. The contents of the microcapsules can be liquids or mixtures of liquids and solids. The microcapsules are exposed to the flue gas and other industrial gas and take up carbon dioxide from the flue gas and other industrial gas and eventual precipitate solids in the capsule.

  10. Nano-Sponge Ionic Liquid-Polymer Composite Electrolytes for Solid-State Lithium Power Sources

    DTIC Science & Technology

    2010-01-01

    images of these solid thin films indicate that these polymer gel electrolytes have the structure of nano-sponges, with a sub-micron pore size. For these... thin film batteries, 150 charge–discharge cycles are run for LixCoO2 where x is cycled between 0.95 down to 0.55. Minimal internal resistance effects...9702;C; exhibiting a significant advancement in the safety of lithium batteries. Atomic force microscopy images of these solid thin films indicate

  11. Preparation of new crosslinking agents and additives for use in polymer electrolyte membranes (PEMs) for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Zhou, Yangliu

    The most commonly used proton conductive membrane in polymer electrolyte membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC) studies to date is DuPont's NafionRTM, which is a perfluorinated copolymer of tetrafluoroethylene (TFE) and perfluorovinyl ether with a pendant sulfonic acid group. A focus of this work is to find ways to improve the performance of NafionRTM membranes. Crosslinking the TFE chains of fluorinated ionomeric copolymers to improve their thermal and mechanical stability is a proven route to this goal. A straightforward synthetic route to perfluorinated divinyl ethers of the formula CF2=CFO(CF 2)3[OCF(CF3)CF2]mOCF=CF 2 (m = 0-1) has been demonstrated. The compounds CF2=CFO(CF 2)3OCF=CF2 and CF2=CFO(CF2) 3OCF(CF3)CF2OCF=CF2 were prepared and characterized by GC-MS, 13C and 19F NMR, and gas-IR spectroscopy. Synthetic routes to fluorosulfato-tetrafluoropropionyl fluoride [FSO3CF2CF2C(O)F] and difluoromalonyl difluoride [F(O)CCF2C(O)F] with improved yields were found. The second focus of the dissertation was the development of fluorous triarylphosphines for use as new doping materials for the modification of NafionRTM membranes and for use as ligands in catalysts for biphasic catalysis. The synthesis and characterization of a series of new polyhexafluoropropylene oxide derivatives for preparation of fluorous triarylphosphines and phosphonium salts was studied, such as F[CF(CF3)CF2O] 4CF(CF3)CH2CH2I, F[CF(CF3)CF 2O]4CF(CF3)CH=CH2, F[CF(CF3)CF 2O]4CF(CF3) CH2CH2C6H5, and F[CF(CF 3)CF2O]4CF(CF3)CH2CH 2C6H4Br. In a separate study, the photochlorination of 2,2,3,3-tetrafluoro-1-propanol (HCF2CF2CH2OH) and 2,2,3,3-tetrafluoropropyl 2,2,3,3-tetrafluoropropionate [HCF2CF2C(O)OCH2 CF2CF2H] with super diazo blue light (lambda max = 420 nm) were investigated. The photochemical products are different from those obtained under mercury light (lambda = 253.7nm). A new compound ClCF2CF2C(O)OC(H)ClCF2CF2Cl was prepared and characterized by GC-MS, elemental

  12. Influence of unmodified and β-glycerophosphate cross-linked chitosan on anti-Candida activity of clotrimazole in semi-solid delivery systems.

    PubMed

    Szymańska, Emilia; Winnicka, Katarzyna; Wieczorek, Piotr; Sacha, Paweł Tomasz; Tryniszewska, Elżbieta Anna

    2014-09-30

    The combination of an antifungal agent and drug carrier with adjunctive antimicrobial properties represents novel strategy of complex therapy in pharmaceutical technology. The goal of this study was to investigate the unmodified and ion cross-linked chitosan's influence on anti-Candida activity of clotrimazole used as a model drug in hydrogels. It was particularly crucial to explore whether the chitosans' structure modification by β-glycerophosphate altered its antifungal properties. Antifungal studies (performed by plate diffusion method according to CLSI reference protocol) revealed that hydrogels obtained with chitosan/β-glycerophosphate displayed lower anti-Candida effect, probably as a result of weakened polycationic properties of chitosan in the presence of ion cross-linker. Designed chitosan hydrogels with clotrimazole were found to be more efficient against tested Candida strains and showed more favorable drug release profile compared to commercially available product. These observations indicate that novel chitosan formulations may be considered as promising semi-solid delivery system of clotrimazole.

  13. Rubber Elasticity in Highly Crosslinked Polyesters.

    DTIC Science & Technology

    Esters, *Polymers, *Elastic properties, Rubber, Propylene glycol , Maleic acid, Anhydrides, Phthalic acids, Mechanical properties, Molecular structure, Crosslinking(Chemistry), Polymerization, Styrenes, Temperature, Transition temperature, Molecular weight

  14. Continuous preparation of polymer coated drug crystals by solid hollow fiber membrane-based cooling crystallization.

    PubMed

    Chen, Dengyue; Singh, Dhananjay; Sirkar, Kamalesh K; Pfeffer, Robert

    2016-02-29

    A facile way to continuously coat drug crystals with a polymer is needed in controlled drug release. Conventional polymer coating methods have disadvantages: high energy consumption, low productivity, batch processing. A novel method for continuous polymer coating of drug crystals based on solid hollow fiber cooling crystallization (SHFCC) is introduced here. The drug acting as the host particle and the polymer for coating are Griseofulvin (GF) and Eudragit RL100, respectively. The polymer's cloud point temperature in its acetone solution was determined by UV spectrophotometry. An acetone solution of the polymer containing the drug in solution as well as undissolved drug crystals in suspension were pumped through the tube side of the SHFCC device; a cold liquid was circulated in the shell side to rapidly cool down the feed solution-suspension in the hollow-fiber lumen. The polymer precipitated from the solution and coated the suspended crystals due to rapid temperature reduction and heterogeneous nucleation; crystals formed from the solution were also coated by the polymer. Characterizations by scanning electron microscopy, thermogravimetric analysis, laser diffraction spectroscopy, X-ray diffraction, Raman spectroscopy, and dissolution tests show that a uniformly coated, free-flowing drug/product can be obtained under appropriate operating conditions without losing the drug's pharmaceutical properties and controlled release characteristics. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Structure, morphology and ionic conductivity of solid polymer electrolyte

    SciTech Connect

    Dey, Arup; Karan, S.; Dey, Ashis; De, S.K.

    2011-11-15

    Graphical abstract: Two-dimensional atomic force image of pure polyethylene oxide presents a crystallized network of regular spherulites developing spirals and branches of well distributed surface contours. Highlights: {yields} The incorporation of ceria significantly modifies the morphology of polyethylene oxide (PEO)-KI complex. {yields} The ionic conductivity increases by about two orders of magnitude by the addition of ceria nanoparticles. {yields} Ionic conductivity as a function of ceria concentration reveals two maxima. {yields} Grain boundary effect of nanofiller, strong Lewis acid-base interaction between PEO and nanosized ceria, change of conformation of PEO molecule and epitaxial effect of ceria nanoparticles control the ionic conductivity of composite polymer electrolyte. -- Abstract: Polyethylene oxide (PEO) complexed with potassium iodide (KI) is synthesized to investigate the ionic conductivity of alkaline based polymer electrolytes. The structural and morphological characterizations of the nanocomposite polymer electrolytes are performed by X-ray diffractometry (XRD), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) measurements. The ionic conductivity increases with the increase of KI concentration up to about 20 wt.%. The effect of nanosized ceria (CeO{sub 2} {approx} 10 nm) fillers on ionic conductivity in PEO-KI polymer electrolyte is also carried out, keeping PEO to KI wt.% ratio 80:20 and 85:15. The result reveals that the addition of ceria nanoparticles enhances the conductivity by two orders of magnitude. The presence of ceria at the highest concentration induces the same molecular environment within PEO chain as that of undoped PEO. Temperature dependence of ionic conductivity follows Arrhenius mechanism.

  16. Semi-Interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

    Treesearch

    Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Gisela. Buschle-Diller

    2012-01-01

    Semi-interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that...

  17. Theoretical simulation of the infrared signature of mechanically stressed polymer solids

    PubMed Central

    Sammon, Matthew S

    2017-01-01

    Mechanical stress leads to deformation of strands in polymer solids, including elongation of covalent bonds and widening of bond angles, which changes the infrared spectrum. Here, the infrared spectrum of solid polymer samples exposed to mechanical stress is simulated by density functional theory calculations. Mechanical stress is described with the external force explicitly included (EFEI) method. The uneven distribution of the external stress on individual polymer strands is accounted for by a convolution of simulated spectra with a realistic force distribution. N-Propylpropanamide and propyl propanoate are chosen as model molecules for polyamide and polyester, respectively. The effect of a specific force on the polymer backbone is a redshift of vibrational modes involving the C–N and C–O bonds in the backbone, while the free C–O stretching mode perpendicular to the backbone is largely unaffected. The convolution with a realistic force distribution shows that the dominant effect on the strongest infrared bands is not a shift of the peak position, but rather peak broadening and a characteristic change in the relative intensities of the strongest bands, which may serve for the identification and quantification of mechanical stress in polymer solids. PMID:28904614

  18. Theoretical simulation of the infrared signature of mechanically stressed polymer solids.

    PubMed

    Sammon, Matthew S; Ončák, Milan; Beyer, Martin K

    2017-01-01

    Mechanical stress leads to deformation of strands in polymer solids, including elongation of covalent bonds and widening of bond angles, which changes the infrared spectrum. Here, the infrared spectrum of solid polymer samples exposed to mechanical stress is simulated by density functional theory calculations. Mechanical stress is described with the external force explicitly included (EFEI) method. The uneven distribution of the external stress on individual polymer strands is accounted for by a convolution of simulated spectra with a realistic force distribution. N-Propylpropanamide and propyl propanoate are chosen as model molecules for polyamide and polyester, respectively. The effect of a specific force on the polymer backbone is a redshift of vibrational modes involving the C-N and C-O bonds in the backbone, while the free C-O stretching mode perpendicular to the backbone is largely unaffected. The convolution with a realistic force distribution shows that the dominant effect on the strongest infrared bands is not a shift of the peak position, but rather peak broadening and a characteristic change in the relative intensities of the strongest bands, which may serve for the identification and quantification of mechanical stress in polymer solids.

  19. Applications of Polymers as Pharmaceutical Excipients in Solid Oral Dosage Forms.

    PubMed

    Debotton, Nir; Dahan, Arik

    2017-01-01

    Over the last few decades, polymers have been extensively used as pharmaceutical excipients in drug delivery systems. Pharmaceutical polymers evolved from being simply used as gelatin shells comprising capsule to offering great formulation advantages including enabling controlled/slow release and specific targeting of drugs to the site(s) of action (the "magic bullets" concept), hence hold a significant clinical promise. Oral administration of solid dosage forms (e.g., tablets and capsules) is the most common and convenient route of drug administration. When formulating challenging molecules into solid oral dosage forms, polymeric pharmaceutical excipients permit masking undesired physicochemical properties of drugs and consequently, altering their pharmacokinetic profiles to improve the therapeutic effect. As a result, the number of synthetic and natural polymers available commercially as pharmaceutical excipients has increased dramatically, offering potential solutions to various difficulties. For instance, the different polymers may allow increased solubility, swellability, viscosity, biodegradability, advanced coatings, pH dependency, mucodhesion, and inhibition of crystallization. The aim of this article is to provide a wide angle prospect of the different uses of pharmaceutical polymers in solid oral dosage forms. The various types of polymeric excipients are presented, and their distinctive role in oral drug delivery is emphasized. The comprehensive know-how provided in this article may allow scientists to use these polymeric excipients rationally, to fully exploit their different features and potential influence on drug delivery, with the overall aim of making better drug products. © 2016 Wiley Periodicals, Inc.

  20. Porous polymers bearing functional quaternary ammonium salts as efficient solid catalysts for the fixation of CO2 into cyclic carbonates.

    PubMed

    Cai, Sheng; Zhu, Dongliang; Zou, Yan; Zhao, Jing

    2016-12-01

    A series of porous polymers bearing functional quaternary ammonium salts were solvothermally synthesized through the free radical copolymerization of divinylbenzene (DVB) and functionalized quaternary ammonium salts. The obtained polymers feature highly cross-linked matrices, large surface areas, and abundant halogen anions. These polymers were evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from epoxides and CO2 in the absence of co-catalysts and solvents. The results revealed that the synergistic effect between the functional hydroxyl groups and the halide anion Br(-) afforded excellent catalytic activity to cyclic carbonates. In addition, the catalyst can be easily recovered and reused for at least five cycles without significant loss in activity.

  1. Porous polymers bearing functional quaternary ammonium salts as efficient solid catalysts for the fixation of CO2 into cyclic carbonates

    NASA Astrophysics Data System (ADS)

    Cai, Sheng; Zhu, Dongliang; Zou, Yan; Zhao, Jing

    2016-07-01

    A series of porous polymers bearing functional quaternary ammonium salts were solvothermally synthesized through the free radical copolymerization of divinylbenzene (DVB) and functionalized quaternary ammonium salts. The obtained polymers feature highly cross-linked matrices, large surface areas, and abundant halogen anions. These polymers were evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from epoxides and CO2 in the absence of co-catalysts and solvents. The results revealed that the synergistic effect between the functional hydroxyl groups and the halide anion Br- afforded excellent catalytic activity to cyclic carbonates. In addition, the catalyst can be easily recovered and reused for at least five cycles without significant loss in activity.

  2. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    PubMed Central

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm−1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions. PMID:26791572

  3. Solid mesostructured polymer-surfactant films at the air-liquid interface.

    PubMed

    Pegg, Jonathan C; Eastoe, Julian

    2015-08-01

    Pioneering work by Edler et al. has spawned a new sub-set of mesostructured materials. These are solid, self-supporting films comprising surfactant micelles encased within polymer hydrogel; composite polymer-surfactant films can be grown spontaneously at the air-liquid interface and have defined and controllable mesostructures. Addition of siliconalkoxide to polymer-surfactant mixtures allows for the growth of mesostructured hybrid polymer-surfactant silica films that retain film geometry after calcinations and exhibit superior mechanical properties to typically brittle inorganic films. Growing films at the air-liquid interface provides a rapid and simple means to prepare ordered solid inorganic films, and to date the only method for generating mesostructured films thick enough (up to several hundred microns) to be removed from the interface. Applications of these films could range from catalysis to encapsulation of hydrophobic species and drug delivery. Film properties and mesostructures are sensitive to surfactant structure, polymer properties and polymer-surfactant phase behaviour: herein it will be shown how film mesostructure can be tailored by directing these parameters, and some interesting analogies will be drawn with more familiar mesostructured silica materials.

  4. Hydrophilic-hydrophobic polymer blend for modulation of crystalline changes and molecular interactions in solid dispersion.

    PubMed

    Van Ngo, Hai; Nguyen, Phuc Kien; Van Vo, Toi; Duan, Wei; Tran, Van-Thanh; Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh

    2016-11-20

    This research study aimed to develop a new strategy for using a polymer blend in solid dispersion (SD) for dissolution enhancement of poorly water-soluble drugs. SDs with different blends of hydrophilic-hydrophobic polymers (zein/hydroxypropyl methylcellulose - zein/HPMC) were prepared using spray drying to modulate the drug crystal and polymer-drug interactions in SDs. Physicochemical characterizations, including power X-ray diffraction and Fourier transform infrared spectroscopy, were performed to elucidate the roles of the blends in SDs. Although hydrophobic polymers played a key role in changing the model drug from a crystal to an amorphous state, the dissolution rate was limited due to the wetting property. Fortunately, the hydrophilic-hydrophobic blend not only reduced the drug crystallinity but also resulted in a hydrogen bonding interaction between the drugs and the polymer for a dissolution rate improvement. This work may contribute to a new generation of solid dispersion using a blend of hydrophilic-hydrophobic polymers for an effective dissolution enhancement of poorly water-soluble drugs.

  5. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    NASA Astrophysics Data System (ADS)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic ‑EO‑ based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm‑1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  6. Ion transport in polycarbonate based solid polymer electrolytes: experimental and computational investigations.

    PubMed

    Sun, Bing; Mindemark, Jonas; Morozov, Evgeny V; Costa, Luciano T; Bergman, Martin; Johansson, Patrik; Fang, Yuan; Furó, István; Brandell, Daniel

    2016-04-14

    Among the alternative host materials for solid polymer electrolytes (SPEs), polycarbonates have recently shown promising functionality in all-solid-state lithium batteries from ambient to elevated temperatures. While the computational and experimental investigations of ion conduction in conventional polyethers have been extensive, the ion transport in polycarbonates has been much less studied. The present work investigates the ionic transport behavior in SPEs based on poly(trimethylene carbonate) (PTMC) and its co-polymer with ε-caprolactone (CL) via both experimental and computational approaches. FTIR spectra indicated a preferential local coordination between Li(+) and ester carbonyl oxygen atoms in the P(TMC20CL80) co-polymer SPE. Diffusion NMR revealed that the co-polymer SPE also displays higher ion mobilities than PTMC. For both systems, locally oriented polymer domains, a few hundred nanometers in size and with limited connections between them, were inferred from the NMR spin relaxation and diffusion data. Potentiostatic polarization experiments revealed notably higher cationic transference numbers in the polycarbonate based SPEs as compared to conventional polyether based SPEs. In addition, MD simulations provided atomic-scale insight into the structure-dynamics properties, including confirmation of a preferential Li(+)-carbonyl oxygen atom coordination, with a preference in coordination to the ester based monomers. A coupling of the Li-ion dynamics to the polymer chain dynamics was indicated by both simulations and experiments.

  7. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries.

    PubMed

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-21

    Here we demonstrate that by regulating the mobility of classic -EO- based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm(-1) are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li(+)), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  8. Status and applicability of solid polymer electrolyte technology to electrolytic hydrogen and oxygen production

    NASA Technical Reports Server (NTRS)

    Titterington, W. A.

    1973-01-01

    The solid polymer electrolyte (SPE) water electrolysis technology is presented as a potential energy conversion method for wind driven generator systems. Electrolysis life and performance data are presented from laboratory sized single cells (7.2 sq in active area) with high cell current density selected (1000 ASF) for normal operation.

  9. Solid Polymer Electrolyte (SPE) fuel cell technology, program review, phase 2

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The purpose of the solid polymer electrolyte (SPE) fuel cell program is to advance the SPE fuel cell technology in four target areas. These areas are: (1) reduced fuel cell costs; (2) reduced fuel cell weight; (3) improved fuel cell efficiency; and (4) increased systems compatibility.

  10. [Some aspects of water electrolysis with the use of a solid polymer electrolyte].

    PubMed

    Zorina, N G

    2006-01-01

    Electrochemical process in cells with a solid polymer electrolyte is dependent on catalyst durability in harsh environments and catalyst sputtering technology to ensure efficient power consumption. Active polymer electrolytes will permit to reduce substantially non-productive layouts and design a cost-effective, compact and safe system generator of high-purity oxygen and hydrogen. The existing designs of combined oxide systems integrating rear-earth and earth metals with a structure of Ln3+x Me2+1-x CoO3 containing perofskites were shown to be active catalysts in cells with a solid polymer electrolyte, and the sputtering technology was proven to reduce non-productive layouts in 2 or 2.5 times.

  11. Solid-state synthesis of ordered mesoporous carbon catalysts via a mechanochemical assembly through coordination cross-linking

    NASA Astrophysics Data System (ADS)

    Zhang, Pengfei; Wang, Li; Yang, Shize; Schott, Jennifer A.; Liu, Xiaofei; Mahurin, Shannon M.; Huang, Caili; Zhang, Yu; Fulvio, Pasquale F.; Chisholm, Matthew F.; Dai, Sheng

    2017-04-01

    Ordered mesoporous carbons (OMCs) have demonstrated great potential in catalysis, and as supercapacitors and adsorbents. Since the introduction of the organic-organic self-assembly approach in 2004/2005 until now, the direct synthesis of OMCs is still limited to the wet processing of phenol-formaldehyde polycondensation, which involves soluble toxic precursors, and acid or alkali catalysts, and requires multiple synthesis steps, thus restricting the widespread application of OMCs. Herein, we report a simple, general, scalable and sustainable solid-state synthesis of OMCs and nickel OMCs with uniform and tunable mesopores (~4-10 nm), large pore volumes (up to 0.96 cm3 g-1) and high-surface areas exceeding 1,000 m2 g-1, based on a mechanochemical assembly between polyphenol-metal complexes and triblock co-polymers. Nickel nanoparticles (~5.40 nm) confined in the cylindrical nanochannels show great thermal stability at 600 °C. Moreover, the nickel OMCs offer exceptional activity in the hydrogenation of bulky molecules (~2 nm).

  12. The Role of Inclusion Binding Contributions for β-Cyclodextrin Polymers Cross-Linked with Divinyl Sulfone?--A Comment on Morales-Sanfrutos et al. Entitled "Divinyl Sulfone Cross-Linked Cyclodextrin-Based Polymeric Materials: Synthesis and Applications as Sorbents and Encapsulating Agents", Molecules, 2015, 20, 3565-3581.

    PubMed

    Wilson, Lee D; Mohamed, Mohamed H; McMartin, Dena W

    2016-01-14

    This commentary reports on a recent scientific study reported in this journal (cf. Molecules 2015, 20(3), 3565-3581). Some key scientific issues that require further explanation and clarification in the former article are as follows: (i) the relationship between the inclusion site accessibility and the level of cross-linking employed are brought into question for the case of α-CD and β-CD cross-linked adsorbent materials; (ii) the binding affinity of the CD/guest complexes were not related to the isotherm parameters for the CD-polymer/guest systems; (iii) the limited molecular level structural characterization of the cross-linked polymer materials; and (iv) the interpretation of the adsorption isotherm results by the authors.

  13. Development of an in-process UV-crosslinked, electrospun PCL/aPLA-co-TMC composite polymer for tubular tissue engineering applications.

    PubMed

    Stefani, I; Cooper-White, J J

    2016-05-01

    Cardiovascular diseases remain the largest cause of death worldwide, and half of these deaths are the result of failure of the vascular system. Tissue engineering promises to provide new, and potentially more effective therapeutic strategies to replace damaged or degenerated vessels with functional vessels. However, these engineered vessels have substantial performance criteria, including vessel-like tubular shape, structure and mechanical property slate. Further, whether implanted without or with prior in vitro culture, such tubular scaffolds must provide a suitable environment for cell adhesion and growth and be of sufficient porosity to permit cell colonization. This study investigates the fabrication of slowly degradable, composite tubular polymer scaffolds made from polycaprolactone (PCL) and acrylated l-lactide-co-trimethylene carbonate (aPLA-co-TMC). The addition of acrylate groups permits the 'in-process' formation of crosslinks between aPLA-co-TMC chains during electrospinning of the composite system, exemplifying a novel process to produce multicomponent, elastomeric electrospun polymer scaffolds. Although PCL and aPLA-co-TMC were miscible in a co-solvent, a criteria for electrospinning, due to thermodynamic incompatibility of the two polymers as melts, solvent evaporation during electrospinning drove phase separation of these two systems, producing 'core-shell' fibres, with the core being composed of PCL, and the shell of crosslinked elastomeric aPLA-co-TMC. The resulting elastic fibrous scaffolds displayed burst pressures and suture retention strengths comparable with human arteries. Cytocompatibility testing with human mesenchymal stem cells confirmed adhesion to, and proliferation on the three-dimensional fibrous network, as well as alignment with highly-organized fibres. This new processing methodology and resulting mechanically-robust composite scaffolds hold significant promise for tubular tissue engineering applications. Autologous small diameter

  14. Correlation of inhibitory effects of polymers on indomethacin precipitation in solution and amorphous solid crystallization based on molecular interaction.

    PubMed

    Chauhan, Harsh; Kuldipkumar, Anuj; Barder, Timothy; Medek, Ales; Gu, Chong-Hui; Atef, Eman

    2014-02-01

    To correlate the polymer's degree of precipitation inhibition of indomethacin in solution to the amorphous stabilization in solid state. Precipitation of indomethacin (IMC) in presence of polymers was continuously monitored by a UV spectrophotometer. Precipitates were characterized by PXRD, IR and SEM. Solid dispersions with different polymer to drug ratios were prepared using solvent evaporation. Crystallization of the solid dispersion was monitored using PXRD. Modulated differential scanning calorimetry (MDSC), IR, Raman and solid state NMR were used to explore the possible interactions between IMC and polymers. PVP K90, HPMC and Eudragit E100 showed precipitation inhibitory effects in solution whereas Eudragit L100, Eudragit S100 and PEG 8000 showed no effect on IMC precipitation. The rank order of precipitation inhibitory effect on IMC was found to be PVP K90 > Eudragit E100 > HPMC. In the solid state, polymers showing precipitation inhibitory effect also exhibited amorphous stabilization of IMC with the same rank order of effectiveness. IR, Raman and solid state NMR studies showed that rank order of crystallization inhibition correlates with strength of molecular interaction between IMC and polymers. Correlation is observed in the polymers ability to inhibit precipitation in solution and amorphous stabilization in the solid state for IMC and can be explained by the strength of drug polymer interactions.

  15. Spontaneous, Solvent-Free, Polymer-Templated, Solid-Solid Transformation of Thin Metal Films into Nanoparticles.

    PubMed

    Hernández-Cruz, Olivia; Avila-Gutierrez, Lizeth; Zolotukhin, Mikhail G; Gonzalez, Gonzalo; Monroy, B Marel; Montiel, Raúl; Vera-Graziano, Ricardo; Romero-Ibarra, Josue E; Novelo-Peralta, Omar; Massó Rojas, Felipe Alonso

    2016-09-14

    Metal nanoparticles have unusual optical, electronic, sensing, recognition, catalytic, and therapeutic properties. They are expected to form the basis of many of the technological and biological innovations of this century. A prerequisite for future applications using nanoparticles as functional entities is control of the shape, size, and homogeneity of these nanoparticles and of their interparticle spacing and arrangement on surfaces, between electrodes, or in devices. Here, we demonstrate that thin films of gold, silver, and copper sputter-deposited onto the surface of an organic polymer poly[[1,1':4',1″-terphenyl]-4,4″-diyl(2-bromo-1-carboxyethylidene)] (PTBC) undergo spontaneous solid-solid transformation into nanoparticles. Furthermore, we show that, by varying the thickness of the films, the volume-to-surface ratio of the polymer substrate, and the amount of plasticizer, it is possible to control the rate of transformation and the morphology of the nanoparticles formed. PTBC containing Au nanoparticles was found to enhance the cell adhesion and proliferation. To the best of our knowledge, our findings constitute the first experimental evidence of spontaneous, room-temperature, solid-solid transformation of metal films sputtered onto the surface of an organic polymeric substrate into nanoparticles (crystals).

  16. Unusual Transformation from a Solvent-Stabilized 1D Coordination Polymer to a Metal-Organic Framework (MOF)-Like Cross-Linked 3D Coordination Polymer.

    PubMed

    Lee, Seung-Chul; Choi, Eun-Young; Lee, Sang-Beom; Kim, Sang-Wook; Kwon, O-Pil

    2015-10-26

    An unusual 1D-to-3D transformation of a coordination polymer based on organic linkers containing highly polar push-pull π-conjugated side chains is reported. The coordination polymers are synthesized from zinc nitrate and an organic linker, namely, 2,5-bis{4-[1-(4-nitrophenyl)pyrrolidin-2-yl]butoxy}terephthalic acid, which possesses highly polar (4-nitrophenyl)pyrrolidine groups, with high dipole moments of about 7 D. The coordination polymers exhibit an unusual transformation from a soluble, solvent-stabilized 1D coordination polymer into an insoluble, metal-organic framework (MOF)-like 3D coordination polymer. The coordination polymer exhibits good film-forming ability, and the MOF-like films are insoluble in conventional organic solvents. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. All-solid-state proton battery using gel polymer electrolyte

    SciTech Connect

    Mishra, Kuldeep; Pundir, S. S.; Rai, D. K.

    2014-04-24

    A proton conducting gel polymer electrolyte system; PMMA+NH{sub 4}SCN+EC/PC, has been prepared. The highest ionic conductivity obtained from the system is 2.5 × 10−4 S cm{sup −1}. The optimized composition of the gel electrolyte has been used to fabricate a proton battery with Zn/ZnSO{sub 4}⋅7H{sub 2}O anode and MnO{sub 2} cathode. The open circuit voltage of the battery is 1.4 V and the highest energy density is 5.7 W h kg−1 for low current drain.

  18. Efficient ibuprofen delivery from anhydrous semisolid formulation based on a novel cross-linked silicone polymer network: an in vitro and in vivo study.

    PubMed

    Aliyar, Hyder; Huber, Robert; Loubert, Gary; Schalau, Gerald

    2014-07-01

    The use of silicone as a primary polymer in topical semisolid pharmaceutical formulations is infrequent. Recent development of novel silicone materials provides an opportunity to investigate their drug delivery efficiencies. In this study, an anhydrous semisolid formulation was prepared using a novel cross-linked silicone polymer network swollen in isododecane. Similar formulations were prepared using petrolatum, an acrylic, or a cellulose polymer. All formulations contained 5% ibuprofen (IBP). In vitro permeability was evaluated for all formulations and a commercial product using human cadaver epidermis. The silicone formulation delivered IBP more efficiently than all other formulations in terms of flux, cumulative amount, and percent drug release. The silicone formulation showed the maximum flux of 85.9 μg . cm(-2) . h(-1) and a cumulative IBP release of 261.6 μg in 8 h, whereas the benchmark showed 20.1 μg . cm(-2) . h(-1) and 30.9 μg, respectively. An in vivo study conducted on rats showed calculated blood AUCs of 59.2 and 17.6 μg . h/g (p < 0.003) for the silicone formulation and the benchmark, respectively. The IBP in excised rat skin was 264 ± 59 μg/g for the silicone formulation and 102 ± 5 μg/g for the benchmark. The results obtained from the in vitro and in vivo studies demonstrate efficient topical IBP delivery by the silicone formulation.

  19. Polymers used to absorb fats and oils: A concept

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.

    1974-01-01

    One approach to problem of excessive oils and fats is to develop method by which oil is absorbed into solid mixture for elimination as solid waste. Materials proposed for these purposes are cross-linked (network) polymers that have high affinity for aliphatic substances, i. e., petroleum, animal, and vegetable oils.

  20. Optimization of a quasi-solid-state dye-sensitized solar cell employing a nanocrystal-polymer composite electrolyte modified with water and ethanol.

    PubMed

    Yang, Ying; Zhou, Cong-Hua; Xu, Sheng; Zhang, Jing; Wu, Su-Juan; Hu, Hao; Chen, Bo-Lei; Tai, Qi-Dong; Sun, Zheng-Hua; Liu, Wei; Zhao, Xing-Zhong

    2009-03-11

    A quasi-solid-state dye-sensitized solar cell employing a poly(ethylene oxide)-poly(vinylidene fluoride) (PEO-PVDF)/TiO2 gel electrolyte modified by various concentrations of water and ethanol is described. It is shown that the introduction of water and ethanol prevents the crystallization of the polymer matrix, and enhances the free I(-)/I(3)(-) concentration and the networks for ion transportation in the electrolyte, thus leading to an improvement in conductivity. A high energy conversion efficiency of about 5.8% is achieved by controlling the additive concentration in the electrolyte. Optimization of the additive-modified electrolyte performance has been obtained by studying the cross-linking behavior of water and ethanol with Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and viscosity measurements, and the electrical conduction behavior of the electrolyte with impedance spectra measurements.

  1. All solid-state electric double-layer capacitors based on alkaline polyvinyl alcohol polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Hsu, Sung-Ting; Chien, Wen-Chen

    Solid-state electrochemical double-layer capacitors (ELDCs) based on alkaline polyvinyl alcohol (PVA) solid polymer electrolytes (SPEs) are prepared. Electrochemical capacitance performance of these capacitors is studied by cyclic voltammetry, galvanostatic charge-discharge testing, and ac impedance spectroscopy. For comparison, two types of EDLC cells are constructed and tested. It is found that an EDLC with a PVA polymer electrolyte exhibits much higher capacitance and longer cycle-life than one with the PP/PE separator. The specific capacitance for the EDLC with the PVA-based SPE is in the range of 100-112 F g -1, and depends on the scan rate or the charge-discharge current rates. The results also indicate that the solid-state EDLC shows a relatively stable specific capacitance of 100 F g -1 after 1000 cycles. The findings suggest that the PVA-based SPE is a promising material for use in EDLCs.

  2. Nanocomposite polymer electrolyte based on Poly(ethylene oxide) and solid super acid for lithium polymer battery

    NASA Astrophysics Data System (ADS)

    Xi, Jingyu; Tang, Xiaozhen

    2004-07-01

    This Letter reports a novel PEO-based nanocomposite polymer electrolyte by using solid super acid SO 42-/ZrO 2 as filler. XRD, DSC, and FT-IR results prove the strong Lewis acid-base interactions between SO 42-/ZrO 2 and PEO chains. The addition of SO 42-/ZrO 2 can enhance the ionic conductivity and the lithium ion transference number of the electrolyte. The highest room temperature ionic conductivity of 2.1 × 10 -5 S cm -1 is obtained for the sample PEO 12-LiClO 4-7%SO 42-/ZrO 2. The excellent performances such as good compatibility with lithium electrode, and broad electrochemical stability window suggest that PEO-LiClO 4-SO 42-/ZrO 2 nanocomposite electrolyte can be used as electrolyte materials for lithium polymer batteries.

  3. Amorphous stabilization and dissolution enhancement of amorphous ternary solid dispersions: combination of polymers showing drug-polymer interaction for synergistic effects.

    PubMed

    Prasad, Dev; Chauhan, Harsh; Atef, Eman

    2014-11-01

    The purpose of this study was to understand the combined effect of two polymers showing drug-polymer interactions on amorphous stabilization and dissolution enhancement of indomethacin (IND) in amorphous ternary solid dispersions. The mechanism responsible for the enhanced stability and dissolution of IND in amorphous ternary systems was studied by exploring the miscibility and intermolecular interactions between IND and polymers through thermal and spectroscopic analysis. Eudragit E100 and PVP K90 at low concentrations (2.5%-40%, w/w) were used to prepare amorphous binary and ternary solid dispersions by solvent evaporation. Stability results showed that amorphous ternary solid dispersions have better stability compared with amorphous binary solid dispersions. The dissolution of IND from the ternary dispersion was substantially higher than the binary dispersions as well as amorphous drug. Melting point depression of physical mixtures reveals that the drug was miscible in both the polymers; however, greater miscibility was observed in ternary physical mixtures. The IR analysis confirmed intermolecular interactions between IND and individual polymers. These interactions were found to be intact in ternary systems. These results suggest that the combination of two polymers showing drug-polymer interaction offers synergistic enhancement in amorphous stability and dissolution in ternary solid dispersions.

  4. Highly durable polymer electrolyte membranes at elevated temperature: Cross-linked copolymer structure consisting of poly(benzoxazine) and poly(benzimidazole)

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Kon; Kim, Ki-Hyun; Park, Jung Ock; Kim, Kihyun; Ko, Taeyun; Choi, Seong-Woo; Pak, Chanho; Chang, Hyuk; Lee, Jong-Chan

    2013-03-01

    For polymer electrolyte membrane fuel cell (PEMFC) applications at elevated temperature (>100 °C), a series of cross-linked benzoxazine-benzimidazole copolymer, P(HFa-co-BI), membranes are prepared by casting a solution of poly[2,2‧-(m-phenylene)-5,5‧-bibenzimidazole] (PBI) and di-functional benzoxazine monomer, 6,6‧-(hexafluoroisopropylidene)bis(3-phenyl-3,4-dihydro-2H-benzoxazine) (HFa), in N,N-dimethylacetamide prior to stepwise heating to 250 °C. The films are also viable to manufacture to large quantities and area by roll-to-roll coating. The resulting cross-linked copolymer, P(HFa-co-BI), membranes are found to be thermally and mechanically stable. Although the proton conductivity values of P(HFa-co-BI) membranes are smaller than that of the PBI membrane, their cell performance (0.68 V at 0.2 A cm-2 at 150 °C) is close to that of PBI membrane and their long-term durability (ca. 3116 cycles on in situ accelerated lifetime mode of load cycling testing) is found to be far superior to the PBI membrane.

  5. Initiated Chemical Vapor Deposition (iCVD) of Highly Cross-Linked Polymer Films for Advanced Lithium-Ion Battery Separators.

    PubMed

    Yoo, Youngmin; Kim, Byung Gon; Pak, Kwanyong; Han, Sung Jae; Song, Heon-Sik; Choi, Jang Wook; Im, Sung Gap

    2015-08-26

    We report an initiated chemical vapor deposition (iCVD) process to coat polyethylene (PE) separators in Li-ion batteries with a highly cross-linked, mechanically strong polymer, namely, polyhexavinyldisiloxane (pHVDS). The highly cross-linked but ultrathin pHVDS films can only be obtained by a vapor-phase process, because the pHVDS is insoluble in most solvents and thus infeasible with conventional solution-based methods. Moreover, even after the pHVDS coating, the initial porous structure of the separator is well preserved owing to the conformal vapor-phase deposition. The coating thickness is delicately controlled by deposition time to the level that the pore size decreases to below 7% compared to the original dimension. The pHVDS-coated PE shows substantially improved thermal stability and electrolyte wettability. After incubation at 140 °C for 30 min, the pHVDS-coated PE causes only a 12% areal shrinkage (versus 90% of the pristine separator). The superior wettability results in increased electrolyte uptake and ionic conductivity, leading to significantly improved rate performance. The current approach is applicable to a wide range of porous polymeric separators that suffer from thermal shrinkage and poor electrolyte wetting.

  6. Catalytic trimerization of aromatic nitriles and triaryl-s-triazine ring cross-linked high temperature resistant polymers and copolymers made thereby

    NASA Technical Reports Server (NTRS)

    Hsu, L. C. (Inventor)

    1979-01-01

    Triazine compounds and cross-linked polymer compositions are made by heating aromatic nitriles to a temperature in the range of from about 100 C to about 700 C, and preferably in the range of from about 200 C to about 350 C, in the presence of a catalyst or mixture of catalysts selected from one or more of the following groups: (1) organic sulfonic and sulfinic acids, (2) organic phosphonic and phosphinic acids, and (3)metallic acetylacetonates, at a pressure in the range of from about atmospheric pressure to about 10,000 psi and preferably in the range of from about 200 psi to about 750 psi. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers are made which are trimerized with or without a filler by the aforementioned catalytic trimerization process into triaryl-s-triazine ring containing or cross-linked polymeric or copolymeric products useful in applications requiring high thermal-oxidative stability and high performance structural properties at elevated temperatures.

  7. Chemical modification of wheat protein-based natural polymers: grafting and cross-linking reactions with poly(ethylene oxide) diglycidyl ether and ethyl diamine.

    PubMed

    Kurniawan, Lusiana; Qiao, Greg G; Zhang, Xiaoqing

    2007-09-01

    Mobile poly(ethylene oxide) diglycidyl ether (PEODGE) segments were chemically grafted onto a soluble wheat protein (WP), and different network structures were formed via coupling reactions with ethyl diamine (EDA) in different PEODGE/EDA (PE) ratios. When the PE ratio was 1:1, linear PEs were the predominant segments grafted onto WP chains and the whole WP-PEODGE-EDA (WPE) system was still soluble with an increased molecular weight. Reducing the amount of EDA in the systems produced insoluble cross-linked WPE networks. The broad distribution of network structures and chain mobility resulted in a broad glass transition for the WPE materials. However, the glass transition started at lower temperatures, and the materials became flexible at room temperature. The PE segments were present in all rigid, intermediate, and mobile phases in WPE networks, while the proportion of mobile WP chains was increased as a result of the plasticization effect from the mobile PE segments. The mobility of the most mobile component lipid was also restricted to some extent when forming the cross-linked WPE networks. The study demonstrated that the formation of different network structures with PE segments could significantly improve the flexibility of WP materials, vary the solubility, and modify the mechanical performance of WP-based natural polymer materials.

  8. Synthesis and In Vivo Pharmacokinetic Evaluation of Degradable Shell Crosslinked Polymer Nanoparticles with Poly(carboxybetaine) vs. Poly(ethylene glycol) Surface-grafted Coatings

    PubMed Central

    Li, Ang; Luehmann, Hannah P.; Sun, Guorong; Samarajeewa, Sandani; Zou, Jiong; Zhang, Shiyi; Zhang, Fuwu; Welch, Michael J.; Liu, Yongjian; Wooley, Karen L.

    2012-01-01

    Nanoparticles with tunable pharmacokinetics are desirable for various biomedical applications. Poly(ethylene glycol) (PEG) is well known to create “stealth” effects to stabilize and extend the blood circulation of nanoparticles. In this work, poly(carboxybetaine) (PCB), a new non-fouling polymer material, was incorporated as surface-grafted coatings, conjugated onto degradable shell crosslinked knedel-like nanoparticles (dSCKs) composed of poly(acrylic acid)- based shells and poly(lactic acid) (PLA) cores, to compare the in vivo pharmacokinetics to their PEG-functionalized analogs. A series of five dSCKs was prepared from amphiphilic block copolymers, having different numbers and lengths of either PEG or PCB grafts, by supramolecular assembly in water followed by shell crosslinking, and then studied by a lactate assay to confirm their core hydrolytic degradabilities. Each dSCK was also conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) macrocyclic chelators and tyramine moieties to provide for 64Cu and/or radiohalogen labeling. The high specific activity of 64Cu radiolabeling ensured nanogram administration of dSCKs for in vivo evaluation of their pharmacokinetics. Biodistribution studies demonstrated comparable in vivo pharmacokinetic profiles of PCB-grafted dSCKs to their PEG-conjugated counterparts. These results indicated that PCB-functionalized dSCKs have great potential as a theranostic platform for translational research. PMID:23043240

  9. Fluorescent Cross-Linked Supramolecular Polymer Constructed by Orthogonal Self-Assembly of Metal-Ligand Coordination and Host-Guest Interaction.

    PubMed

    Qian, Xiaomin; Gong, Weitao; Li, Xiaopeng; Fang, Le; Kuang, Xiaojun; Ning, Guiling

    2016-05-10

    A new host molecule consists of four terpyridine groups as the binding sites with zinc(II) ion and a copillar[5]arene incorporated in the center as a spacer to interact with guest molecule was designed and synthesized. Due to the 120 ° angle of the rigid aromatic segment, a cross-linked dimeric hexagonal supramolecular polymer was therefore generated as the result of the orthogonal self-assembly of metal-ligand coordination and host-guest interaction. UV/Vis spectroscopy, (1) H NMR spectroscopy, viscosity and dynamic light-scattering techniques were employed to characterize and understand the cross-linking process with the introduction of zinc(II) ion and guest molecule. More importantly, well-defined morphology of the self-assembled supramolecular structure can be tuned by altering the adding sequence of the two components, that is, the zinc(II) ion and the guest molecule. In addition, introduction of a competitive ligand suggested the dynamic nature of the supramolecular structure.

  10. Generation of Pretilt Angle for Nematic Liquid Crystal Using the Photodimerization Method on Various New Photo-Crosslinkable Polyimide Based Polymers

    NASA Astrophysics Data System (ADS)

    Hwang, Jeoung-Yeon; Seo, Dae-Shik; Son, Jong-Ho; Suh, Dong Hack

    2001-07-01

    We synthesized the various new photo-crosslinkable polyimide based polymers and generation of pretilt angle for a nematic liquid crystal (NLC) using a photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimatric analysis (TGA) measurement until 450°C. The NLC pretilt angle generated was about 2.5°-3.0° by polarized UV exposure on the photopolymers containing a biphenyl (BP), decyl (De), and cholesteryl(chol), chalcone(Chal) group, respectively. However, low pretilt angle of the NLC was measured by polarized UV exposure on the photopolymers containing the fluorine and chalcone group. The NLC pretilt angle generated is attributed to the biphenyl and alkyl moieties, and the photo-dimerized chalcone group of the photopolymer.

  11. Poly(ethyleneimine) cross-linked multilayers deposited onto solid surfaces and enzyme immobilization as a function of the film properties

    NASA Astrophysics Data System (ADS)

    Bucatariu, Florin; Ghiorghita, Claudiu-Augustin; Simon, Frank; Bellmann, Cornelia; Dragan, Ecaterina Stela

    2013-09-01

    Single polycation cross-linked multilayers, based on poly(ethyleneimine) (PEI), have been prepared using a method of 3,3‧,4,4‧-benzophenonetetracarboxylic-dianhydride (BTCDA)-mediated electrostatics and hydrogen bonds layer-by-layer assembly. Linear PEI [PEI(L)] and branched PEI [PEI(B)] were adsorbed from salt-free aqueous solutions, either onto silica microparticles with particle diameter of 40-60 μm (Daisogel type) and 9-11 μm (Davisil type) or silicon wafers. The BTCDA cross-linking of the polycation adsorbed onto the solid surface results in a surface covered with carboxylic groups. The cross-linked polycation layers, which are negatively charged over a wide range of pH, can adsorb a new positively charged polyelectrolyte layer. A regular increase of the single polycation multilayers onto silica microparticles was observed by zeta potential measurements and X-ray photoelectron spectroscopy. The immobilization of two enzymes (pepsin and lysozyme) onto the functionalized silica surface, via glutaraldehyde (GA), has been tested. The amount of the attached enzyme significantly depended on the isoelectric point of the enzyme. Surface characteristics, average height, ha, and average roughness, Ra, slightly increased after each modification step of the organic film.

  12. Gelation of Copolymers Photo-crosslinked by Pendant Benzophenones

    NASA Astrophysics Data System (ADS)

    Christensen, Scott; Hayward, Ryan C.

    2011-03-01

    Copolymers containing pendant benzophenone (BP) groups provide a simple and powerful route to crosslinkable polymer films. While the solution state photo-chemistry of BP is well established, and crosslinking of polymers blended with BP has been studied in detail, the process of crosslinking by covalently attached BP has received comparatively little attention. We have prepared copolymers of BP with several different monomers, and studied gelation as a function of BP content and degree of photochemical conversion. We seek to understand the influence of polymer chemistry on crosslinking efficiency, to guide choices of materials for photo- crosslinkable polymer films and to provide a route for tailoring morphology in polymer blends.

  13. Gelation of Copolymers Photo-crosslinked by Pendent Benzophenones

    NASA Astrophysics Data System (ADS)

    Christensen, Scott; Hayward, Ryan C.

    2012-02-01

    Copolymers containing pendent benzophenone (BP) groups provide a simple and powerful route to crosslinkable polymer films. While the solution state photo-chemistry of BP is well established, and crosslinking of polymers blended with BP has been studied in detail, the process of crosslinking by covalently attached BP has received comparatively little attention. We have prepared copolymers of BP with several different monomers, and studied gelation as a function of BP content and degree of photochemical conversion. Understanding the influence of polymer chemistry on crosslinking efficiency allows the appropriate choice of materials for nanostructured photo-crosslinkable polymer films and reactive polymer blends.

  14. Neural stem cell differentiation by electrical stimulation using a cross-linked PEDOT substrate: Expanding the use of biocompatible conjugated conductive polymers for neural tissue engineering.

    PubMed

    Pires, Filipa; Ferreira, Quirina; Rodrigues, Carlos A V; Morgado, Jorge; Ferreira, Frederico Castelo

    2015-06-01

    The use of conjugated polymers allows versatile interactions between cells and flexible processable materials, while providing a platform for electrical stimulation, which is particularly relevant when targeting differentiation of neural stem cells and further application for therapy or drug screening. Materials were tested for cytotoxicity following the ISO10993-5. PSS was cross-linked. ReNcellVM neural stem cells (NSC) were seeded in laminin coated surfaces, cultured for 4 days in the presence of EGF (20 ng/mL), FGF-2 (20 ng/mL) and B27 (20 μg/mL) and differentiated over eight additional days in the absence of those factors under 100Hz pulsed DC electrical stimulation, 1V with 10 ms pulses. NSC and neuron elongation aspect ratio as well as neurite length were assessed using ImageJ. Cells were immune-stained for Tuj1 and GFAP. F8T2, MEH-PPV, P3HT and cross-linked PSS (x PSS) were assessed as non-cytotoxic. L929 fibroblast population was 1.3 higher for x PSS than for glass control, while F8T2 presents moderate proliferation. The population of neurons (Tuj1) was 1.6 times higher with longer neurites (73 vs 108 μm) for cells cultured under electrical stimulus, with cultured NSC. Such stimulus led also to longer neurons. x PSS was, for the first time, used to elongate human NSC through the application of pulsed current, impacting on their differentiation towards neurons and contributing to longer neurites. The range of conductive conjugated polymers known as non-cytotoxic was expanded. x PSS was introduced as a stable material, easily processed from solution, to interface with biological systems, in particular NSC, without the need of in-situ polymerization. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Automated direct-immersion solid-phase microextraction using crosslinked polymeric ionic liquid sorbent coatings for the determination of water pollutants by gas chromatography.

    PubMed

    Cordero-Vaca, María; Trujillo-Rodríguez, María J; Zhang, Cheng; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

    2015-06-01

    Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.

  16. Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction.

    PubMed

    Shirvani-Arani, Simindokht; Ahmadi, Seyed Javad; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

    2008-08-08

    A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2'-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1 microg, present in 200 mL, could be preconcentrated into 25 mL of 1.0 M HCl.

  17. Thermal aging of interfacial polymer chains in ethylene-propylene-diene terpolymer/aluminum hydroxide composites: solid-state NMR study.

    PubMed

    Gabrielle, Brice; Lorthioir, Cédric; Lauprêtre, Françoise

    2011-11-03

    The possible influence of micrometric-size filler particles on the thermo-oxidative degradation behavior of the polymer chains at polymer/filler interfaces is still an open question. In this study, a cross-linked ethylene-propylene-diene (EPDM) terpolymer filled by aluminum trihydrate (ATH) particles is investigated using (1)H solid-state NMR. The time evolution of the EPDM network microstructure under thermal aging at 80 °C is monitored as a function of the exposure time and compared to that of an unfilled EPDM network displaying a similar initial structure. While nearly no variations of the topology are observed on the neat EPDM network over 5 days at 80 °C, a significant amount of chain scission phenomena are evidenced in EPDM/ATH. A specific surface effect induced by ATH on the thermodegradative properties of the polymer chains located in their vicinity is thus pointed out. Close to the filler particles, a higher amount of chain scissions are detected, and the characteristic length scale related to these interfacial regions displaying a significant thermo-oxidation process is determined as a function of the aging time.

  18. Ion beam irradiation as a tool to improve the ionic conductivity in solid polymer electrolyte systems

    SciTech Connect

    Manjunatha, H. Kumaraswamy, G. N.; Damle, R.

    2016-0