Science.gov

Sample records for porous polymer coatings

  1. Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides.

    PubMed

    Lamprou, Alexandros; Wang, Hongxia; Saeed, Adeela; Svec, Frantisek; Britt, David; Maya, Fernando

    2015-07-14

    We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process. The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

  2. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a...

  3. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a...

  4. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a...

  5. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a...

  6. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a...

  7. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors.

    PubMed

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-28

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl(2)) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.

  8. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors

    NASA Astrophysics Data System (ADS)

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-01

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm

  9. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a...

  10. 21 CFR 888.3535 - Knee joint femorotibial (uni-compartmental) metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .../polymer porous-coated uncemented prosthesis. 888.3535 Section 888.3535 Food and Drugs FOOD AND DRUG... Devices § 888.3535 Knee joint femorotibial (uni-compartmental) metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint femorotibial (uni-compartmental) metal/polymer...

  11. 21 CFR 888.3535 - Knee joint femorotibial (uni-compartmental) metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .../polymer porous-coated uncemented prosthesis. 888.3535 Section 888.3535 Food and Drugs FOOD AND DRUG... Devices § 888.3535 Knee joint femorotibial (uni-compartmental) metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint femorotibial (uni-compartmental) metal/polymer...

  12. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a...

  13. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a...

  14. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a...

  15. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a...

  16. "Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

    PubMed

    McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

    2016-02-01

    Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.

  17. Hydroxyapatite porous scaffold engineered with biological polymer hybrid coating for antibiotic Vancomycin release.

    PubMed

    Kim, Hae-Won; Knowles, Jonathan C; Kim, Hyoun-Ee

    2005-03-01

    The purpose of this study is to improve hydroxyapatite (HA) porous scaffolds via coating with biological polymer-HA hybrids for use as wound healing and tissue regeneration. Highly porous HA scaffolds, fabricated by a polyurethane foam reticulate method, were coated with hybrid coating solution, consisting of poly(epsilon-caprolactone) (PCL), HA powders, and the antibiotic Vancomycin. The PCL to HA ratio was fixed at 1.5 and the drug amounts were varied [drug/(PCL + HA) = 0.02 and 0.04]. For the purpose of comparison, bare HA scaffold without the hybrid coating layer was also loaded with Vancomycin via an immersion-adsorption method. The hybrid coating structure and morphology were observed with Fourier transformed infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The effects of the hybrid coating on the compressive mechanical properties and the in vitro drug release of the scaffolds were investigated in comparison with bare HA scaffold. The PCL-HA hybrid coating altered the scaffold pore structure slightly, resulting in thicker stems and reduced porosity. With the hybrid coating, the HA scaffold responded to an applied compressive stress more effectively without showing a brittle failure. This was attributed to the shielding and covering of the framework surface by the coating layer. The encapsulated drugs within the coated scaffold was released in a highly sustained manner as compared to the rapid release of drugs directly adsorbed on the pure HA scaffold. These findings suggest that the coated HA scaffolds expand their applicability in hard tissue regeneration and wound healing substitutes delivering bioactive molecules.

  18. Porous structures of polymer films prepared by spin coating with mixed solvents under humid condition.

    PubMed

    Park, Min Soo; Joo, Wonchul; Kim, Jin Kon

    2006-05-09

    We investigate the effects of interfacial energy between water and solvent as well as polymer concentration on the formation of porous structures of polymer films prepared by spin coating of cellulose acetate butyrate (CAB) in mixed solvent of tetrahydrofuran (THF) and chloroform under humid condition. The interfacial energy between water and the solvent was gradually changed by the addition of chloroform to the solvent. At a high polymer concentration (0.15 g/cm3 in THF), porous structures were limited only at the top surfaces of CAB films, regardless of interfacial energies, due to the high viscosity of the solution. At a medium concentration (approximately 0.08 g/cm3 in THF), CAB film had relatively uniform pores at the top surface and very small pores inside the film because of the mixing of the water droplets with THF solution. When chloroform was added to THF, pores at the inner CAB film had a comparable size with those at the top surface because of the reduced degree of the mixing between the water droplets and the mixed solvent. A further decrease in polymer concentration (0.05 g/cm3 in THF) caused the final films to have a two-layer porous structure, and the size of pores at each layer was almost the same.

  19. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint...

  20. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint...

  1. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint...

  2. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint...

  3. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint...

  4. Continuous synthesis of polymer-coated drug particles by porous hollow fiber membrane-based antisolvent crystallization.

    PubMed

    Chen, Dengyue; Singh, Dhananjay; Sirkar, Kamalesh K; Pfeffer, Robert

    2015-01-01

    Using porous hollow fiber membranes, this study illustrates a novel technique to continuously synthesize polymer-coated drug crystals by antisolvent crystallization. The synthesized polymer-coated drug crystals involve crystals of the drug Griseofulvin (GF) coated by a thin layer of the polymer Eudragit RL100. The process feed, an acetone solution of the drug GF containing the dissolved polymer, was passed through the shell side of a membrane module containing many porous hollow fibers of Nylon-6. Through the lumen of the hollow fibers, the antisolvent water was passed at a higher pressure to inject water jets through every pore in the fiber wall into the shell-side acetone feed solution, creating an extremely high level of supersaturation and immediate crystallization. It appears that the GF crystals are formed first and serve as nuclei for the precipitation of the polymer Eudragit, which forms a thin coating around the GF crystals. The polymer-coated drug crystals were collected by a filtration device at the shell-side outlet of the membrane module, and the surface morphology, particle size distribution, and the polymer coating thickness were then characterized by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), laser diffraction spectroscopy (LDS), and thermogravimetric analysis (TGA). To study the properties of the coated drug crystals, X-ray diffraction (XRD), Raman spectroscopy, and dissolution tests were implemented. These results indicate that a polymer-coated, free-flowing product was successfully developed under appropriate conditions in this novel porous hollow fiber antisolvent crystallization (PHFAC) method. The coated drug particles can be potentially used for controlled release. The molecular and the crystal structures of GF were not affected by the PHFAC method, which may be easily scaled up.

  5. Influence of natural organic matter on transport and retention of polymer coated silver nanoparticles in porous media.

    PubMed

    Yang, Xinyao; Lin, Shihong; Wiesner, Mark R

    2014-01-15

    Interactions between organic matter (OM) and engineered polymer coatings as they affect the retention of polyvinylpyrrolidone (PVP) polymer-coated silver nanoparticles (AgNPs) were studied. Two distinct types of OM-cysteine representing low molecular weight multivalent functional groups, and Suwannee River Humic Acid (HA) representing high molecular weight polymers, were investigated with respect to their effects on particle stability in aggregation and deposition. Aggregation of the PVP coated AgNPs (PVP-AgNPs) was enhanced by cysteine addition at high ionic strengths, which was attributed to cysteine binding to the AgNPs and replacing the otherwise steric stabilizing agent PVP. In contrast the addition of HA did not increase aggregation rates and decreased PVP-AgNP deposition to the silica porous medium, consistent with enhanced electrosteric stabilization by the HA. Although cysteine also reduced deposition in the porous medium, the mechanisms of reduced deposition appear to be enhanced electric double layer (EDL) interaction at low ionic strengths. At higher ionic strengths, aggregation was favored leading to lower deposition due to smaller diffusion coefficients and single collector efficiencies despite the reduced EDL interactions.

  6. Porous Shape Memory Polymers.

    PubMed

    Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C; Wilson, Thomas S; Maitland, Duncan J

    2013-02-04

    Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use.

  7. Porous Shape Memory Polymers

    PubMed Central

    Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-01-01

    Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

  8. Porous polymer media

    DOEpatents

    Shepodd, Timothy J.

    2002-01-01

    Highly crosslinked monolithic porous polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a porous polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.

  9. Knudsen effusion through polymer-coated three-layer porous graphene membranes.

    PubMed

    Boutilier, Michael S H; Hadjiconstantinou, Nicolas G; Karnik, Rohit

    2017-05-05

    Graphene membranes have the potential to exceed the permeance and selectivity limits of conventional gas separation membranes. Realizing this potential in practical systems relies on overcoming numerous scalability challenges, such as isolating or sealing permeable defects in macroscopic areas of graphene that can compromise performance and developing methods to create high densities of selective pores over large areas. This study focuses on a centimeter-scale membrane design, where leakage is reduced by substrate selection, permeable polymer film coating, and stacking of three independent layers of graphene, while (selective) pores are created by high density ion bombardment. The three-layer graphene provides high resistance to gas flow, which decreases with ion bombardment and results in selectivity consistent with Knudsen effusion. The results suggest that the permeable pores created in three layer graphene were larger than those required for molecular sieving and that designs based on single layer graphene may lend themselves more easily to molecular sieving of gases.

  10. Mechanical and bone ingrowth properties of a polymer-coated, porous, synthetic, coralline hydroxyapatite bone-graft material.

    PubMed

    Tencer, A F; Woodard, P L; Swenson, J; Brown, K L

    1988-01-01

    CHAG, that is, porous hydroxyapatite hydrothermally converted from the calcium carbonate exoskeleton of a coral (genus Goniopora), has been shown to be effective as a scaffold for bone ingrowth. The large pores in the material, however, resulted in low compressive strengths. Compressive testing was performed to assess the changes in mechanical properties by coating the internal surfaces of CHAG with DL-PLA. Plugs of CHAG with thick (3:1 chloroform to DL-PLA by weight), medium (10:1), and thin (30:1) coatings as well as uncoated CHAG were then implanted transcortically in the proximal third of the diaphysis of rabbit tibiae to assess the in vivo response. The mechanical tests demonstrated significantly improved compressive strength, stiffness, and energy absorption for coated specimens compared with uncoated specimens. Coated specimens were not significantly different from canine tibial cancellous bone in strength and stiffness although they achieved only 36% of the energy absorption capacity. Specimens from rabbit tibiae were harvested at 3, 12, and 24 weeks for interface shear strength determination and contralaterally for histological and histomorphometric assessment. At 12 weeks, uncoated CHAG plugs developed an average ultimate interface shear stress of 26.7 MPa compared with 17 MPa for specimens with 30:1 coatings and 8 MPa for specimens with 10:1 and 3:1 coatings. At 24 weeks, there were no significant differences in shear stress between any of the specimens. Histomorphometric assessments showed that the ratio of area fraction of new bone to area fraction of new bone and void space increased from 68-70% for specimens with 3:1 and 10:1 coatings at 3 weeks to 85.5-89.5% at 24 weeks. In comparison, uncoated and 30:1 specimens had area fraction ratios of about 82% at 3 weeks and 93% at 24 weeks. Histologic sections demonstrated direct apposition of new bone to both the coating and the hydroxyapatite as well as degradation of the coating.

  11. Antibacterial polymer coatings.

    SciTech Connect

    Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan; Tucker, Mark David; Hibbs, Michael R.

    2009-09-01

    A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores on its surface.

  12. Applying Uniform Polymer Coatings To Microspheres

    NASA Technical Reports Server (NTRS)

    Lee, M. C.

    1985-01-01

    Acoustic levitation yields even coating on glass microsphres. Automatic Coating Apparatus injects polymer into acoustic levitator, moves glass sphere into polymer, dries polymer, and removes coated sphere. Apparatus injects more polymer for coating another sphere, and cycle repeats.

  13. Antithrombogenic Polymer Coating.

    DOEpatents

    Huang, Zhi Heng; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2003-01-21

    An article having a non-thrombogenic surface and a process for making the article are disclosed. The article is formed by (i) coating a polymeric substrate with a crosslinked chemical combination of a polymer having at least two amino substituted side chains, a crosslinking agent containing at least two crosslinking functional groups which react with amino groups on the polymer, and a linking agent containing a first functional group which reacts with a third functional group of the crosslinking agent, and (ii) contacting the coating on the substrate with an antithrombogenic agent which covalently bonds to a second functional group of the linking agent. In one example embodiment, the polymer is a polyamide having amino substituted alkyl chains on one side of the polyamide backbone, the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl, the linking agent is a polyhydrazide and the antithrombogenic agent is heparin.

  14. Thermal Spray Formation of Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Coquill, Scott; Galbraith, Stephen L.; Tuss. Darren L.; Ivosevic, Milan

    2008-01-01

    This innovation forms a sprayable polymer film using powdered precursor materials and an in-process heating method. This device directly applies a powdered polymer onto a substrate to form an adherent, mechanically-sound, and thickness-regulated film. The process can be used to lay down both fully dense and porous, e.g., foam, coatings. This system is field-deployable and includes power distribution, heater controls, polymer constituent material bins, flow controls, material transportation functions, and a thermal spray apparatus. The only thing required for operation in the field is a power source. Because this method does not require solvents, it does not release the toxic, volatile organic compounds of previous methods. Also, the sprayed polymer material is not degraded because this method does not use hot combustion gas or hot plasma gas. This keeps the polymer from becoming rough, porous, or poorly bonded.

  15. Electrospun porous conductive polymer membranes

    NASA Astrophysics Data System (ADS)

    Wang, Jingwen; Naguib, Hani E.; Bazylak, Aimy

    2012-04-01

    In this work, two methodologies were used in fabricating conductive electrospun polymer fibers with nano features. We first investigated the addition of multiwall carbon nanotubes (MWCNT) as conductive fillers at concentrations ranging from 1 to 10% into a polystyrene (PS) matrix. Electrospinning conditions were tailored to produce fibers with minimal beads. Next, we investigated the effects of coating electrospun fibers with nano structured conductive polymer. Oxidant (FeCl3) fibers were electrospun in PS and then exposed to a pyrrole (Py) monomer in a vacuum chamber. As a result, polypyrrole (PPy) was coated on the fibers creating conductive pathways. In both methods, the electrospun conductive fibers were characterized in terms of their morphologies, thermal stability and electrical conductivity. Strong correlations were found among PPy coating nanostructures, oxidant concentration and polymerization time. Electrospun fibrous membranes with conductive polymer coating exhibit much higher electrical conductivities compare to fibers with conductive fillers. Highest conductivity achieved was 9.5E-4 S/cm with 40% FeCl3/PS fibers polymerized with Py for 140 min.

  16. Transport and deposition of polymer-modified Fe0 nanoparticles in 2-D heterogeneous porous media: effects of particle concentration, Fe0 content, and coatings.

    PubMed

    Phenrat, Tanapon; Cihan, Abdullah; Kim, Hye-Jin; Mital, Menka; Illangasekare, Tissa; Lowry, Gregory V

    2010-12-01

    Concentrated suspensions of polymer-modified Fe(0) nanoparticles (NZVI) are injected into heterogeneous porous media for groundwater remediation. This study evaluated the effect of porous media heterogeneity and the dispersion properties including particle concentration, Fe(0) content, and adsorbed polymer mass and layer thickness which are expected to affect the delivery and emplacement of NZVI in heterogeneous porous media in a two-dimensional (2-D) cell. Heterogeneity in hydraulic conductivity had a significant impact on the deposition of NZVI. Polymer modified NZVI followed preferential flow paths and deposited in the regions where fluid shear is insufficient to prevent NZVI agglomeration and deposition. NZVI transported in heterogeneous porous media better at low particle concentration (0.3 g/L) than at high particle concentrations (3 and 6 g/L) due to greater particle agglomeration at high concentration. High Fe(0) content decreased transport during injection due to agglomeration promoted by magnetic attraction. NZVI with a flat adsorbed polymeric layer (thickness ∼30 nm) could not be transported effectively due to pore clogging and deposition near the inlet, while NZVI with a more extended adsorbed layer thickness (i.e., ∼70 nm) were mobile in porous media. This study indicates the importance of characterizing porous media heterogeneity and NZVI dispersion properties as part of the design of a robust delivery strategy for NZVI in the subsurface.

  17. Stretchable and strong cellulose nanopaper structures based on polymer-coated nanofiber networks: an alternative to nonwoven porous membranes from electrospinning.

    PubMed

    Sehaqui, Houssine; Morimune, Seira; Nishino, Takashi; Berglund, Lars A

    2012-11-12

    Nonwoven membranes based on electrospun fibers are of great interest in applications such as biomedical, filtering, and protective clothing. The poor mechanical performance is a limitation, as is some of the electrospinning solvents. To address these problems, porous nonwoven membranes based on nanofibrillated cellulose (NFC) modified by a hydroxyethyl cellulose (HEC) polymer coating are prepared. NFC/HEC aqueous suspensions are subjected to simple vacuum filtration in a paper-making fashion, followed by supercritical CO(2) drying. These nonwoven nanocomposite membranes are truly nanostructured and exhibit a nanoporous network structure with high specific surface area, as analyzed by nitrogen adsorption and FE-SEM. Mechanical properties evaluated by tensile tests show high strength combined with remarkably high strain to failure of up to 55%. XRD analysis revealed significant fibril realignment during tensile stretching. After postdrawing of the random mats, the modulus and strength are strongly increased. The present preparation route uses components from renewable resources, is environmentally friendly, and results in permeable membranes of exceptional mechanical performance.

  18. Porous polymers: enabling solutions for energy applications.

    PubMed

    Thomas, Arne; Kuhn, Pierre; Weber, Jens; Titirici, Maria-Magdalena; Antonietti, Markus

    2009-02-18

    A new generation of porous polymers was made for various energy-related applications, e.g., as fuel cell membranes, as electrode materials for batteries, for gas storage, partly from renewable resources. This review intends to catch this emerging field by reporting on a variety of different approaches to make high performing polymers porous. This includes template techniques, polymers with inherent microporosity, polymer frameworks by ionothermal polymerization, and the polymerization of carbon from appropriate precursors and by hydrothermal polymerization. In this process, we try to not only identify the current status of the field, but also point to open question and tasks to identify the potentially relevant progress.

  19. Functional porous organic polymers for heterogeneous catalysis.

    PubMed

    Zhang, Yugen; Riduan, Siti Nurhanna

    2012-03-21

    Porous organic polymers (POPs), a class of highly crosslinked amorphous polymers possessing nano-pores, have recently emerged as a versatile platform for the deployment of catalysts. The bottom-up approach for porous organic polymer synthesis provides the opportunity for the design of polymer frameworks with various functionalities, for their use as catalysts or ligands. This tutorial review focuses on the framework structures and functionalities of catalytic POPs. Their structural design, functional framework synthesis and catalytic reactions are discussed along with some of the challenges.

  20. Thiazolothiazole-linked porous organic polymers

    SciTech Connect

    Zhu, Xiang; Tian, Chengcheng; Jin, Tian; Wang, Jitong; Mahurin, Shannon Mark; Mei, Wenwen; Xiong, Yan; Hu, Jun; Feng, Xinliang; Liu, Honglai; Dai, Sheng

    2014-10-07

    In this study, thiazolothiazole-linked porous organic polymers have been synthesized from a facile catalyst-free condensation reaction between aldehydes and dithiooxamide under solvothermal conditions. The resultant porous frameworks exhibit a highly selective uptake of CO2 over N2 under ambient conditions.

  1. Thiazolothiazole-linked porous organic polymers

    DOE PAGES

    Zhu, Xiang; Tian, Chengcheng; Jin, Tian; ...

    2014-10-07

    In this study, thiazolothiazole-linked porous organic polymers have been synthesized from a facile catalyst-free condensation reaction between aldehydes and dithiooxamide under solvothermal conditions. The resultant porous frameworks exhibit a highly selective uptake of CO2 over N2 under ambient conditions.

  2. Adsorption Kinetics in Nanoscale Porous Coordination Polymers

    SciTech Connect

    Nune, Satish K.; Thallapally, Praveen K.; McGrail, Benard Peter; Annapureddy, Harsha V. R.; Dang, Liem X.; Mei, Donghai; Karri, Naveen; Alvine, Kyle J.; Olszta, Matthew J.; Arey, Bruce W.; Dohnalkova, Alice

    2015-10-07

    Nanoscale porous coordination polymers were synthesized using simple wet chemical method. The effect of various polymer surfactants on colloidal stability and shape selectivity was investigated. Our results suggest that the nanoparticles exhibited significantly improved adsorption kinetics compared to bulk crystals due to decreased diffusion path lengths and preferred crystal plane interaction.

  3. Porous polymers based on aryleneethynylene building blocks.

    PubMed

    Bunz, Uwe H F; Seehafer, Kai; Geyer, Florian L; Bender, Markus; Braun, Ingo; Smarsly, Emanuel; Freudenberg, Jan

    2014-09-01

    Porous conjugated polymers are synthesized by metal-catalyzed coupling reactions. The progress for porous polymers when planar or tetrahedral building blocks are connected by alkyne units into novel materials is highlighted. The most prominent reaction for the buildup of the microporous alkyne-bridged polymers is the Sonogashira reaction, connecting alkynes to aromatic iodides or bromides. The availability of the building blocks and the potency of the Sonogashira reaction allow preparing a large variety of intrinsically porous polymeric materials, in which rigid struts connect multipronged centers. The microporous polymers are used as catalysts and as storage materials for gases and sensors. Postfunctionalization schemes, understanding of structure-property relationships, and the quest for high porosity are pertinent.

  4. Oxidation protection coatings for polymers

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Sovey, J. S.; Banks, B. A. (Inventor)

    1985-01-01

    A polymeric substrate is coated with a metal oxide film to provide oxidation protection in low Earth orbital environments. The film contains about 4 volume percent polymer to provide flexibility. A coil of polymer material moves through an ion beam as it is fed between reels. The ion beam first cleans the polymer material surface and then sputters the film material from a target onto this surface.

  5. Microfluidic devices and methods including porous polymer monoliths

    DOEpatents

    Hatch, Anson V; Sommer, Gregory J; Singh, Anup K; Wang, Ying-Chih; Abhyankar, Vinay V

    2014-04-22

    Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

  6. Microfluidic devices and methods including porous polymer monoliths

    SciTech Connect

    Hatch, Anson V.; Sommer, Gregory j.; Singh, Anup K.; Wang, Ying-Chih; Abhyankar, Vinay

    2015-12-01

    Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

  7. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1990-03-13

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  8. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1988-05-26

    A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

  9. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  10. Thin film-coated polymer webs

    DOEpatents

    Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

    1992-02-04

    The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

  11. The controlled resorption of porous alpha-tricalcium phosphate using a hydroxypropylcellulose coating.

    PubMed

    Kitamura, Makoto; Ohtsuki, Chikara; Iwasaki, Haruna; Ogata, Shin-Ichi; Tanihara, Masao; Miyazaki, Toshiki

    2004-10-01

    Tricalcium phosphate (TCP) ceramic is known in orthopedics to be a bioresorbable bone substitute. A porous TCP ceramic body also has high potential as a drug delivery system in bony defects. Porous alpha-TCP ceramic can be easily fabricated using conventional sintering of beta-TCP, since alpha-TCP is the thermodynamically stable phase at temperatures above 1 100 degrees C. However, the solubility of alpha-TCP is much higher than that of beta-TCP. Therefore, the dissolution of porous alpha-TCP progresses at a higher rate than bone repair. In the present study, we attempted to reduce the dissolution rate of porous alpha-TCP by employing an organic polymer coating. We fabricated porous alpha-TCP ceramic with a continuous 10-50 microm diameter pore structure by sintering a body made from a beta-TCP and potato starch slurry. The porous body obtained was coated with hydroxypropylcellulose (HPC), and then subjected to heat treatment. The chemical durability and mechanical properties of the body were examined before and after coating with the HPC. The dissolution of porous alpha-TCP in buffered solutions was reduced by coating with HPC and drying at 60 degrees C. The compressive strength of the porous alpha-TCP was also improved by coating with HPC. The results of in vivo experiments showed that some parts of the porous alpha-TCP ceramic coated with HPC remained in the canal of the tibia of a rabbit four weeks after implantation, whereas no residual was observed in a non-coated alpha-TCP ceramic. Coating with HPC was found to be effective for controlling bioresorption and improving the workability of porous alpha-TCP ceramic. The prepared porous alpha-TCP ceramic is expected to be useful as a novel material for bone fillers by incorporating it with drugs or osteoinductive factors.

  12. A Novel Method to Make Breath Figure Patterns by Spin Coating under Dry Environment: One-step Preparation of Porous Polymer Films

    NASA Astrophysics Data System (ADS)

    Park, Min Soo; Kim, Jin Kon

    2004-03-01

    We introduce a novel method for fabricating breath figure patterns on a homopolymer film by spin coating of polymer solutions with various solvents. The homopolymers employed in this study were cellulose acetate butyrate (CAB), mono-carboxylated end-functional polystyrene (PS-mCOOH) and poly(methyl methacrylate) (PMMA). Breath figure patterns were generated even when a water-miscible solvent such as tetrahydrofuran (THF) was used as a solvent. We even succeeded in generating breath figure patterns by spin coating even under a dry environment (relative humidity less than 30 With the combination of the spin coating method, pores with few hundreds nanometers to several micrometers have been generated. We found that the pore size becomes larger with increasing water content in THF solution and decreasing rotating speed. This is equivalent to increasing humidity and decreasing evaporation speed, respectively, in the conventional method, direct solvent evaporation under a humid environment. Thus, compared with the conventional method for making breath figure patterns, this method would be very convenient for fabricating large-scale films with various pore sizes.

  13. Production of porous coating on a prosthesis

    DOEpatents

    Sump, Kenneth R.

    1987-01-01

    Preselected surface areas of a prosthesis are covered by a blend of matching primary metallic particles and expendable particles. The particles are compressed and heated to assure that deformation and metallurgical bonding occurs between them and between the primary particles and the surface boundaries of the prosthesis. Porosity is achieved by removal of the expendable material. The result is a coating including discrete bonded particles separated by a network of interconnected voids presenting a homogeneous porous coating about the substrate. It has strength suitable for bone implant usage without intermediate adhesives, and adequate porosity to promote subsequent bone ingrowth.

  14. Porous Polyolefin Films via Polymer Blends

    NASA Astrophysics Data System (ADS)

    Macosko, Chris

    Porous polymer films have broad application including battery separators, membrane supports and filters. Polyolefins are attractive for these applications because of their solvent resistance, low electrical and thermal conductivity, easy fabrication and cost. We will describe fabrication of porous films using cocontinuous blends of a polyolefin with another polymer which can be readily removed with a solvent. Methods to image and control the cocontinuous morphology will be presented.Bell, J. R., K. Chang, C. R. Lopez-Barron, C. W. Macosko, and D. C. Morse, ''Annealing of cocontinuous polymer blends: effect of block copolymer molecular weight and architecture,'' Macromolecules 43, 5024-5032 (2010).Lopez-Barron, C. R., and C. W. Macosko, ''Direct measurement of interface anisotropy of bicontinuous structures via 3D image analysis,'' Langmuir 26, 14284-14293 (2010).Trifkovic, M., A. T. Hedegaard, K. Huston, M. Sheikhzadeh, and C. W. Macosko, ''Porous films via PE/PEO cocontinuous blends,'' Macromolecules 45, 6036-6044 (2012).Hedegaard, A.T., L.L. Gu and C. W. Macosko, ``Effect of Extensional Viscosity on Cocontinuity of Immiscible Polymer Blends'' J. Rheol. 59, 1397-1417 (2015).

  15. Ammonia hardening of porous silica antireflective coatings

    NASA Astrophysics Data System (ADS)

    Belleville, Philippe F.; Floch, Herve G.

    1994-10-01

    The adhesion of sol-gel antireflective porous silica coatings on vitreous optical substrates has been dramatically improved by exposure to ammonia vapors or a dip in basic solutions. The approximately 70 to 270-nm thick coatings consisted of monolayers of spherical, 20-nm diameter amorphous silica particles deposited from ethanolic colloidal suspensions by conventional liquid coating techniques. Although, the as-deposited coatings had only low adhesion and were easily damaged when cleaned by standard drag-wiping procedures, coatings exposed over 5 hours to ammonia vapors passed both adhesive-tape and moderate abrasive- resistance tests. The increase in strength was accompanied by a roughly 20% shrinkage of the original coating thickness but the antireflective properties were retained. Our explanation of this chemical effect is a base-catalyzed phenomenon leading to surface silanol condensation and hydrogen-bonding of neighbor silica particles. In addition, since this basic treatment enhanced the laser damage resistance, such strengthened antireflective coatings have been successfully evaluated on flashlamps used on Phebus, Europe's most powerful laser. This allows an increase of the laser-disk pumping efficiency.

  16. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, R.K.; Bystroff, R.I.; Miller, D.E.

    1986-08-27

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  17. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, Richard K.; Bystroff, Roman I.; Miller, Dale E.

    1987-01-01

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  18. Distributed Pore Chemistry in Porous Organic Polymers

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1998-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The sub-strate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic region, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  19. Distributed Pore Chemistry in Porous Organic Polymers

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1999-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge. wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions. and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  20. Porous polymer membranes via selectively wetted surfaces.

    PubMed

    Magerl, Annemarie; Goedel, Werner A

    2012-04-03

    Here, we show that porous polymeric membranes can be prepared using the principles of offset printing: an offset printing plate is structured into hydrophobic and hydrophilic regions with the help of photolithography and is selectively wetted with a solution of calcium chloride in water at the hydrophilic regions. Then, a polymer solution (poly(methyl methacrylate) in chloroform) is applied to this surface and forms a hydrophobic layer that is structured by the aqueous droplets. Deviating from standard offset printing, this layer is not transferred to another surface in its liquid state but is solidified and subsequently is separated from the printing plate. The thickness of the polymer film is chosen in such a way that the aqueous droplets on the surface protrude from the film. Thus, we obtain polymer membranes with pores in the size of the protruding aqueous droplets. These membranes are then characterized by the filtration of model dispersions.

  1. Coating of fertilizers by degradable polymers.

    PubMed

    Devassine, M; Henry, F; Guerin, P; Briand, X

    2002-08-21

    The conventional agriculture leads to some important pollution of ground water (particularly, by nitrates). The solution is the coating of fertilizers by degradable polymers. In this work, we have studied the water vapour and liquid diffusion through polymer films detached from their support. Therefore, we may classify polymers as a function of their properties like water vapour and liquid barrier. We may choose the best polymer(s) for coating.coated fertilizers by chosen polymer(s) with mechanical techniques such as fluidised bed and pan coating. Moreover, the electron microscopy used to see the quality of the wall has showed the presence of pores due to the rapid evaporation of solvent. A drying in air current and an annealing could be done to avoid this problem.followed the ions release of fertilizers immersed in distilled water by conductimetry. The more interesting result was obtained with fertilizers coated by polylactic acid. In effect, the total release reached three weeks.

  2. Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.

    2011-01-01

    This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

  3. Evaluation of a novel microextraction technique for aqueous samples: porous membrane envelope filled with multiwalled carbon nanotubes coated with molecularly imprinted polymer.

    PubMed

    Tan, Feng; Deng, Minjie; Liu, Xue; Zhao, Hongxia; Li, Xiaona; Quan, Xie; Chen, Jingwen

    2011-03-01

    A novel microextraction technique based on membrane-protected multiwalled carbon nanotubes coated with molecularly imprinted polymer (MWCNTs-MIP) was developed. In this technique, MWCNTs-MIP were packed inside a polypropylene membrane envelope, which was then clamped onto a paper clip. For extraction, the packed membrane envelope was first impregnated with toluene and then placed in sample solutions. Target analytes in the solutions were first extracted into toluene in the membrane envelope, and were then extracted specifically onto the MWCNTs-MIP. After the extraction, target analytes were desorbed in methanol for liquid chromatography analysis. MWCNTs-MIP of prometryn were used as a model to demonstrate the feasibility of this novel microextraction technique. Factors affecting the extraction including organic solvent, stirring rate, extraction time, salt concentration, and pH were investigated. Under the optimized conditions, the limits of detection (a signal-to-noise ratio of 3) for the selected triazine herbicides were 0.08-0.38 μg/L. The prepared membrane envelope could be used at least 50 times. The developed method was used for the analysis of the triazines spiked in river water, wastewater, and liquid milk, with recoveries ranging from 79.3-97.4, 58.9-110.3 and 76.2-104.9%, respectively.

  4. Alignment mechanism of liquid crystal in a stretched porous polymer film

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Kuboki, Masashi; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-09-01

    This article discusses the mechanism of nematic liquid crystal alignment in stretched porous polymer films. The polymer films were formed by extreme stretching of an isotropic porous polyolefin, such that the draw ratio was 12:1. A 6-μm-thick porous film with a high porosity coefficient of 92% revealed fine string-shaped areas that exhibited optical anisotropy due to their possessing a high degree of molecular alignment. The porous film was filled with nematic liquid crystal and then the composite film was sandwiched between transparent electrodes coated onto glass substrates, without the use of conventional alignment layers. From polarizing microscopy observations it was found that the string-like polymer areas induce liquid crystal molecular alignment. The liquid crystal cells can exhibit an electrically controlled birefringence effect. This alignment technique enables us to realize three-dimensional control of liquid crystal alignment.

  5. Silver/hydroxyapatite composite coatings on porous titanium surfaces by sol-gel method.

    PubMed

    Qu, Jie; Lu, Xiong; Li, Dan; Ding, Yonghui; Leng, Yang; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio

    2011-04-01

    Hydroxyapatite (HA) coatings loaded with nanosilver particles is an attractive method to impart the HA coating with antibacterial properties. Producing Ag/HA coatings on porous Ti substrates have been an arduous job since commonly used line-of-sight techniques are not able to deposit uniform coatings on the inner pore surfaces of the porous Ti. In this study, porous Ti scaffolds with high porosity and interconnected structures were prepared by polymer impregnating method. A sol-gel process was used to produce uniform Ag/HA composite coatings on the surfaces of porous Ti substrates. Ca(NO(3) )(2) ·4H(2) O and P(2) O(5) in an ethyl alcohol based system was selected to prepare the sol, which ensured the homogeneous distribution of Ag in the sol. The characterization revealed that silver particles uniformly distributed in the coatings without agglomeration. High antibacterial ratio (>95%), against E. coli and S. albus was expressed by the silver-containing coatings (Ag/HA 0.8 and 1.6 wt %). The biocompatibility of the Ag/HA 0.8 surfaces was as good as that of pure HA surface, as revealed by culturing osteoblasts on them. The results indicated that Ag/HA 0.8 had the good balance between the biocompatibility and antibacterial properties of the coatings.

  6. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, Kevin M.; Watson, Lloyd D.; McAtee, Richard E.; Ploger, Scott A.

    1993-01-01

    A method of forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous.

  7. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, K.M.; Watson, L.D.; McAtee, R.E.; Ploger, S.A.

    1993-10-12

    A method is described for forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous. 4 figures.

  8. Spray-Deposited Superconductor/Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Tran, Sang Q.; Hooker, Matthew W.

    1993-01-01

    Coatings that exhibit the Meissner effect formed at relatively low temperature. High-temperature-superconductor/polymer coatings that exhibit Meissner effect deposited onto components in variety of shapes and materials. Simple, readily available equipment needed in coating process, mean coatings produced economically. Coatings used to keep magnetic fields away from electronic circuits in such cryogenic applications as magnetic resonance imaging and detection of infrared, and in magnetic suspensions to provide levitation and/or damping of vibrations.

  9. Electrocatalysts using porous polymers and method of preparation

    DOEpatents

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2016-08-02

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  10. Electrocatalysts using porous polymers and method of preparation

    DOEpatents

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2015-04-21

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  11. Porous Ceramic Coating for Transpiration Cooling of Gas Turbine Blade

    NASA Astrophysics Data System (ADS)

    Arai, M.; Suidzu, T.

    2013-06-01

    A transpiration cooling system for gas turbine applications has significant benefit for reducing the amount of cooling air and increasing cooling efficiency. In this paper, the porous ceramic coating, which can infiltrate cooling gas, is developed with plasma spraying process, and the properties of the porous coating material such as permeability of cooling gas, thermal conductivity, and adhesion strength are examined. The mixture of 8 wt.% yttria-stabilized zirconia and polyester powders was employed as the coating material, in order to deposit the porous ceramic coating onto Ni-based super alloy substrate. It was shown that the porous ceramic coating has superior permeability for cooling gas. The adhesion strength of the porous coating was low only 20% compared with the thermal barrier coating utilized in current gas turbine blades. Simulation test of hot gas flow around the gas turbine blade verified remarkable reduction of the coating surface temperature by the transpiration cooling mechanism. It was concluded that the transpiration cooling system for the gas turbine could be achieved using the porous ceramic coating developed in this study.

  12. Organosiloxane-grafted natural polymer coatings

    DOEpatents

    Sugama, Toshifumi

    1998-01-01

    A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation.

  13. Porous alumina based ordered nanocomposite coating for wear resistance

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Muthukumar, M.; Bobji, M. S.

    2016-08-01

    Uniformly dispersed nanocomposite coating of aligned metallic nanowires in a matrix of amorphous alumina is fabricated by pulsed electrodeposition of copper into the pores of porous anodic alumina. Uniform deposition is obtained by controlling the geometry of the dendritic structure at the bottom of pores through stepwise voltage reduction followed by mild etching. The tribological behaviour of this nanocomposite coating is evaluated using a ball on flat reciprocating tribometer under the dry contact conditions. The nanocomposite coating has higher wear resistance compared to corresponding porous alumina coating. Wear resistant nanocomposite coating has wide applications especially in protecting the internal surfaces of aluminium internal combustion engines.

  14. Comparison on mechanical properties of single layered and bilayered chitosan-gelatin coated porous hydroxyapatite scaffold prepared through freeze drying method

    NASA Astrophysics Data System (ADS)

    Effendi, M. D.; Gustiono, D.; Lukmana; Ayu, D.; Kurniawati, F.

    2017-02-01

    Biopolymer coated porous hydroxyapatite (HA) scaffolds were prepared for tissue engineering trough freeze drying method and impregnation. in this study, to mimic the mineral and organic component of natural bone, synthetic hydroxapatite (HA) scaffolds coated by polymer were prepared. Highly porous Hap scaffolds, fabricated by synthetic HA impregnation method on polyurethane foam, were coated with polymer coating solution, consisting of chitosan, Gelatin, and bilayered chitosan-gelatin prepared by aging and impregnating technique. For the purpose of comparison, The bare scaffolds without polymer coating layer were investigated. The Bare scaffolds were highly porous and interconnected with a pore size of around 150 µm–714 µm, has porosity at around 67,7% -85,7%, and has mechanical strength at around 0.06 Mpa - 0.071 Mpa, which is suitable for osteoblast cell Proliferation. Chitosan coated porous HA scaffold and gelatin coated porous HA scaffold had mechanical strength at around 0.81-0.85 Mpa, and 1.32-1.34 Mpa, respectively, with weight ratio of biopolymer and Hap was around 18%-22%. To compare these results, the coating on the bare scaffold with gelatin and chitosan had been conducted. Based on the result of FTIR, it could be concluded that coating procedure applied on porous hydroxy apatite (HA) coated by gelatin, chitosan coated HA scaffold, and bilayered Gelatin-chitosan coated porous HA scaffold, confirming that for allsampleshad no significant chemical effect on the coating structure. The compressive strength of bilayered Gelatin-chitosan coated HA scaffold had middle values between the rest, at around 1,06-1.2 Mpa for the samples at the same weight ratio of biopolymer: HA (around 18% - 22%). These results also confirming that coating by gelatin on porous hydroxyapatite was highest compresive strength and can be applied to improve mechanical properties of porous hydroxyapatite bare scaffold

  15. The flow around circular cylinders partially coated with porous media

    NASA Astrophysics Data System (ADS)

    Ruck, Bodo; Klausmann, Katharina; Wacker, Tobias

    2012-05-01

    There are indications that the flow resistance of bodies can be reduced by a porous coating or porous sheath. A few numerical investigations exists in this field, however, experimental evidence is lacking. In order to investigate this phenomenon, the drag resistance of cylinders with porous coating has been investigated qualitatively and quantitatively in wind tunnel experiments. The Reynolds number was systematically varied in the range from 104 to 1.3*105. The results show that the boundary layer over the porous surface is turbulent right from the beginning and thickens faster because of the possible vertical momentum exchange at the interface. The region of flow detachment is widened resulting in a broader area with almost vanishing low flow velocities. All in all, the measurements show that a full porous coating of the cylinders increase the flow resistance. However, the measurements show that a partial coating only on the leeward side can decrease the flow resistance of the body. This effect seems due to the fact that the recirculating velocity and the underpressure in the wake is reduced significantly through a leeward porous coating. Thus, combining a smooth non-permeable windward side with a porous-coated leeward side can lead to a reduction of the body's flow resistance. These findings can be applied advantageously in many technical areas, such as energy saving of moving bodies (cars/trains/planes) or in reducing fluid loads on submersed bodies.

  16. Hierarchical porous polymer scaffolds from block copolymers.

    PubMed

    Sai, Hiroaki; Tan, Kwan Wee; Hur, Kahyun; Asenath-Smith, Emily; Hovden, Robert; Jiang, Yi; Riccio, Mark; Muller, David A; Elser, Veit; Estroff, Lara A; Gruner, Sol M; Wiesner, Ulrich

    2013-08-02

    Hierarchical porous polymer materials are of increasing importance because of their potential application in catalysis, separation technology, or bioengineering. Examples for their synthesis exist, but there is a need for a facile yet versatile conceptual approach to such hierarchical scaffolds and quantitative characterization of their nonperiodic pore systems. Here, we introduce a synthesis method combining well-established concepts of macroscale spinodal decomposition and nanoscale block copolymer self-assembly with porosity formation on both length scales via rinsing with protic solvents. We used scanning electron microscopy, small-angle x-ray scattering, transmission electron tomography, and nanoscale x-ray computed tomography for quantitative pore-structure characterization. The method was demonstrated for AB- and ABC-type block copolymers, and resulting materials were used as scaffolds for calcite crystal growth.

  17. Antireflective Coatings for Glass and Transparent Polymers.

    PubMed

    Buskens, Pascal; Burghoorn, Marieke; Mourad, Maurice Christian Danho; Vroon, Zeger

    2016-07-12

    Antireflective coatings (ARCs) are applied to reduce surface reflections. We review coatings that reduce the reflection of the surface of the transparent substrates float glass, polyethylene terephthalate, poly(methyl methacrylate), and polycarbonate. Three main coating concepts exist to lower the reflection at the interface of a transparent substrate and air: multilayer interference coatings, graded index coatings, and quarter-wave coatings. We introduce and discuss these three concepts, and zoom in on porous quarter-wave coatings comprising colloidal particles. We extensively discuss the four routes for introducing porosity in quarter-wave coatings through the use of colloidal particles, which have the highest potential for application: (1) packing of dense nanospheres, (2) integration of voids through hollow nanospheres, (3) integration of voids through sacrificial particle templates, and (4) packing of nonspherical nanoparticles. Finally, we address the remaining challenges in the field of ARCs, and elaborate on potential strategies for future research in this area.

  18. Porous inorganic—organic shape memory polymers

    PubMed Central

    Zhang, Dawei; Burkes, William L.; Schoener, Cody A.; Grunlan, Melissa A.

    2012-01-01

    Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic–organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL40-block-PDMS37-block-PCL40. To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained. PMID:22956854

  19. Photoinitiated grafting of porous polymer monoliths and thermoplastic polymers for microfluidic devices

    DOEpatents

    Frechet, Jean M. J.; Svec, Frantisek; Rohr, Thomas

    2008-10-07

    A microfluidic device preferably made of a thermoplastic polymer that includes a channel or a multiplicity of channels whose surfaces are modified by photografting. The device further includes a porous polymer monolith prepared via UV initiated polymerization within the channel, and functionalization of the pore surface of the monolith using photografting. Processes for making such surface modifications of thermoplastic polymers and porous polymer monoliths are set forth.

  20. Aqueous vinylidene fluoride polymer coating composition

    NASA Technical Reports Server (NTRS)

    Bartoszek, Edward J. (Inventor); Christofas, Alkis (Inventor)

    1978-01-01

    A water-based coating composition which may be air dried to form durable, fire resistant coatings includes dispersed vinylidene fluoride polymer particles, emulsified liquid epoxy resin and a dissolved emulsifying agent for said epoxy resin which agent is also capable of rapidly curing the epoxy resin upon removal of the water from the composition.

  1. Organosiloxane-grafted natural polymer coatings

    DOEpatents

    Sugama, Toshifumi

    1998-12-01

    A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation. 17 figs.

  2. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    SciTech Connect

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  3. Advanced Porous Coating for Low-Density Ceramic Insulation Materials

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1988-01-01

    The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.

  4. Macromolecular coatings on porous silicon: Applications in drug delivery, biosensing, and composites

    NASA Astrophysics Data System (ADS)

    Perelman, Loren Avery

    Two classes of macromolecules, proteins and polymers, are coated onto porous Si films in a variety of geometries in order to study fundamental behaviors of these coatings and their potential device applications. The unique preparation control that porous Si allows in both nano-morphology and surface functionalization provides the means for the coatings. In chapter two, a drug delivery platform using bovine serum albumin (BSA) protein as a stimuli-responsive capping layer on porous Si is described and characterized. It was found that the surface chemistry of the porous Si film has a profound influence on both drug loading capacity and drug release kinetics, providing for control over these drug release variables. The BSA is observed to act as a pH-responsive trigger for the release of vancomycin from the porous Si film. The drug is safely stored in the porous matrix at pH 4 and is released after triggering with pH 7.4 phosphate buffered saline. Chapter three discusses a porous SiO2-based biosensor that is prepared by oxidizing a porous Si film, adsorbing BSA to the surface as a coating, and functionalizing the protein with specific target probes for vancomycin. The BSA was observed to adsorb strongly to the surface, resisting desoprtion in both phosphate buffered saline and triton-X buffer solutions. Quantitative binding information for the tripeptide Ac-L-Lysine-D-Alanine-D-Alanine and vancomycin is determined using the optical properties of the porous Si as a transduction methodology. Chapters four and five describe the fabrication of thermoresponsive and multifunctional nanohybrids, respectively, using stimuli-responsive hydrogels to infiltrate and coat oxidized porous Si films. The optical properties of the porous Si films are used to study the response of the hydrogel phase of the hybrids to a variety of stimuli. The optical changes correspond to previously-described physical changes in the hydrogel phase, and it was determined that this platform provides a

  5. Coating to enhance metal-polymer adhesion

    SciTech Connect

    Parthasarathi, A.; Mahulikar, D.

    1996-12-31

    An ultra-thin electroplated coating has been developed to enhance adhesion of metals to polymers. The coating was developed for microelectronic packaging applications where it greatly improves adhesion of metal leadframes to plastic molding compounds. Recent tests show that the coating enhances adhesion of different metals to other types of adhesives as well and may thus have wider applicability. Results of adhesion tests with this coating, as well as its other characteristics such as corrosion resistance, are discussed. The coating is a very thin transparent electroplated coating containing zinc and chromium. It has been found to be effective on a variety of metal surfaces including copper alloys, Fe-Ni alloys, Al alloys, stainless steel, silver, nickel, Pd/Ni and Ni-Sn. Contact resistance measurements show that the coating has little or no effect on electrical resistivity.

  6. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    NASA Astrophysics Data System (ADS)

    Abdal-hay, Abdalla; Dewidar, Montasser; Lim, Jae Kyoo

    2012-11-01

    The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  7. Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Craig, Bradley Dene

    The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in

  8. Compressibility of porous TiO2 nanoparticle coating on paperboard.

    PubMed

    Stepien, Milena; Saarinen, Jarkko J; Teisala, Hannu; Tuominen, Mikko; Haapanen, Janne; Mäkelä, Jyrki M; Kuusipalo, Jurkka; Toivakka, Martti

    2013-10-25

    Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure. PACS: 61.46.-w; 68.08.Bc; 81.07.-b.

  9. Compressibility of porous TiO2 nanoparticle coating on paperboard

    PubMed Central

    2013-01-01

    Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure. PACS 61.46.-w; 68.08.Bc; 81.07.-b PMID:24160373

  10. Compressibility of porous TiO2 nanoparticle coating on paperboard

    NASA Astrophysics Data System (ADS)

    Stepien, Milena; Saarinen, Jarkko J.; Teisala, Hannu; Tuominen, Mikko; Haapanen, Janne; Mäkelä, Jyrki M.; Kuusipalo, Jurkka; Toivakka, Martti

    2013-10-01

    Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure.

  11. Formation of titanium carbide coating with micro-porous structure

    NASA Astrophysics Data System (ADS)

    Luo, Yong; Ge, Shirong; Jin, Zhongmin; Fisher, John

    2010-03-01

    Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular TiC coating with micro-porous structure.

  12. 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.

  13. Transport in Porous Media of Poly(Acrylic Acid) Coated Ferrihydrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Xiang, A.; Koel, B. E.

    2012-12-01

    Augmentation of soils with iron to enhance biological processes such as uranium reduction via iron reducing bacteria, e.g., Geobacter sp., might be achieved via the injection of iron nanoparticles into the subsurface. The challenge is to make these nanoparticles transportable in the subsurface while not affecting the iron bioavailability. Poorly crystallized 2-line ferrihydrite iron oxide nanoparticles were synthesized and coated with different amounts of poly(acrylic acid) polymers (Na-PAA6K or Na-PAA140K). Analyses were then performed on these particles, including sorption/desorption of the polymer onto the iron nanoparticles, particle size, zeta potential, transport in sand and soil columns, and bioavailabity of the Fe(III) in the absence and presence of the coating to iron reducing organisms. Results showed that at pH values of environmental relevance, the zeta potential of the particles varied from about 3 mV (pH=8.2) for the non-coated particles to about -30 mV for the particles coated with the polymers to their highest sorption capacity. The coated particle diameter was shown to be in the range of 200 nm. Column transport experiments showed that for the highest polymer coating the nanoparticle breakthrough was virtually identical to that of bromide, while significant filtration was observed for particles with an intermediate coating, and complete particle removal via filtration was observed for the non-coated particles. These results held for sand as well as for soil, which had been previously characterized, from a field site at Rifle, CO. Bioavailability experiments showed no difference in the iron reduction rate between the untreated and treated nanoparticles. These results show that it is possible to manufacture iron nanoparticles to enhance biological iron reduction, and that the transport properties of these treated particles is tunable so that a desired retention in the porous medium can be achieved.

  14. Porous coatings from wire mesh for bone implants

    DOEpatents

    Sump, Kenneth R.

    1986-01-01

    A method of coating areas of bone implant elements and the resulting implant having a porous coating are described. Preselected surface areas are covered by a preform made from continuous woven lengths of wire. The preform is compressed and heated to assure that diffusion bonding occurs between the wire surfaces and between the surface boundaries of the implant element and the wire surfaces in contact with it. Porosity is achieved by control of the resulting voids between the bonded wire portions.

  15. Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

    DOEpatents

    Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

    2006-05-02

    An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

  16. Bulk metallic glass coating of polymer substrates

    NASA Astrophysics Data System (ADS)

    Soinila, Erno; Sharma, Parmanand; Heino, Markku; Pischow, Kaj; Inoue, Akihisa; Hänninen, Hannu

    2009-01-01

    Bulk Metallic Glass (BMG) alloy with the composition of Zr55Cu30Al10Ni5 was deposited by sputtering as thin films on several different engineering polymers and polymer composites. Polycarbonate, polymethyl methacrylate, polyamide 12, polyarylamide (50GF=50 % glass fibers), polyphenylene sulfide (30GF) and polybutylene terephthalate (30GF) were used as substrates. The microstructure of the deposited BMG coatings was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of XRD and SEM studies were consistent with amorphous microstructure. Elemental compositions of the coatings were verified by energy dispersive spectroscopy (EDS). Mechanical properties of the coatings were compared to copper mould cast BMG using nano- indentation tests with similar results. According to the cross-cut tape tests good adhesion was achieved between the studied BMG alloy and all other polymer substrates except polycarbonate. Nano-indentation results showed similar mechanical properties for coating and cast BMG. The results of this study look promising as they open new opportunities for BMG- polymer composite applications.

  17. Electrochemical Impedance Spectroscopy of Conductive Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; MacDowell, Louis G.

    1996-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion protection performance of twenty nine proprietary conductive polymer coatings for cold rolled steel under immersion in 3.55 percent NaCl. Corrosion potential as well as Bode plots of the data were obtained for each coating after one hour immersion, All coatings, with the exception of one, have a corrosion potential that is higher in the positive direction than the corrosion potential of bare steel under the same conditions. Group A consisted of twenty one coatings with Bode plots indicative of the capacitive behavior characteristic of barrier coatings. An equivalent circuit consisting of a capacitor in series with a resistor simulated the experimental EIS data for these coatings very well. Group B consisted of eight coatings that exhibited EIS spectra showing an inflection point which indicates that two time constants are present. This may be caused by an electrochemical process taking place which could be indicitive of coating failing. These coatings have a lower impedance that those in Group A.

  18. Temperature dependence of porous silica antireflective (AR) coating

    NASA Astrophysics Data System (ADS)

    Tang, Yongxing; Le, Yueqin; Zhang, Weiqing; Jiang, Minhua; Sun, Jinren; Liu, Xiaolin

    1998-02-01

    In this paper, the antireflective coatings consisting of porous silica particles from a silica sol are applied by dip method. The relationships among composition, viscosity and temperature have been studied. The coating homogeneity is opium for the laser wavelengths of 1064 nm, 532 nm and 355 nm. The peak transmission of coated BK-7 glass substrate is higher than 99.5%. The laser induced damage thresholds of the antireflective coatings were range of 7 - 10 J/cm2, for 1 ns pulse width and 1064 nm wavelength. These damage thresholds were suitable for our national ICF program. It is noted that the optical homogeneity of coating and the viscosity of coating sol were strongly influenced by the temperatures in the duration of sol ripening.

  19. Thermal Imaging Processes of Polymer Nanocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Meth, Jeffrey

    2015-03-01

    Laser induced thermal imaging (LITI) is a process whereby infrared radiation impinging on a coating on a donor film transfers that coating to a receiving film to produce a pattern. This talk describes how LITI patterning can print color filters for liquid crystal displays, and details the physical processes that are responsible for transferring the nanocomposite coating in a coherent manner that does not degrade its optical properties. Unique features of this process involve heating rates of 107 K/s, and cooling rates of 104 K/s, which implies that not all of the relaxation modes of the polymer are accessed during the imaging process. On the microsecond time scale, the polymer flow is forced by devolatilization of solvents, followed by deformation akin to the constrained blister test, and then fracture caused by differential thermal expansion. The unique combination of disparate physical processes demonstrates the gamut of physics that contribute to advanced material processing in an industrial setting.

  20. Hybrid high refractive index polymer coatings

    NASA Astrophysics Data System (ADS)

    Wang, Yubao; Flaim, Tony; Mercado, Ramil; Fowler, Shelly; Holmes, Douglas; Planje, Curtis

    2005-04-01

    Thermally curable hybrid high refractive index polymer solutions have been developed. These solutions are stable up to 6 months under room temperature storage conditions and can be easily spin-coated onto a desired substrate. When cured at elevated temperature, the hybrid polymer coating decomposes to form a metal oxide-rich film that has a high refractive index. The resulting films have refractive indices higher than 1.90 in the entire visible region and achieve film thicknesses of 300-900 nm depending on the level of metal oxide loading, cure temperature being used, and number of coatings. The formed films show greater than 90% internal transmission in the visible wavelength (400-700 nm). These hybrid high refractive index films are mechanically robust, are stable upon exposure to both heat and UV radiation, and are currently being investigated for microlithographic patterning potential.

  1. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    SciTech Connect

    Kanatzidis, Mercouri G.; Katsoulidis, Alexandros

    2016-10-18

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  2. Entropy-induced separation of star polymers in porous media

    SciTech Connect

    Blavats'ka, V.; Ferber, C. von; Holovatch, Yu.

    2006-09-15

    We present a quantitative picture of the separation of star polymers in a solution where part of the volume is influenced by a porous medium. To this end, we study the impact of long-range-correlated quenched disorder on the entropy and scaling properties of f-arm star polymers in a good solvent. We assume that the disorder is correlated on the polymer length scale with a power-law decay of the pair correlation function g(r){approx}r{sup -a}. Applying the field-theoretical renormalization group approach we show in a double expansion in {epsilon}=4-d and {delta}=4-a that there is a range of correlation strengths {delta} for which the disorder changes the scaling behavior of star polymers. In a second approach we calculate for fixed space dimension d=3 and different values of the correlation parameter a the corresponding scaling exponents {gamma}{sub f} that govern entropic effects. We find that {gamma}{sub f}-1, the deviation of {gamma}{sub f} from its mean field value is amplified by the disorder once we increase {delta} beyond a threshold. The consequences for a solution of diluted chain and star polymers of equal molecular weight inside a porous medium are that star polymers exert a higher osmotic pressure than chain polymers and in general higher branched star polymers are expelled more strongly from the correlated porous medium. Surprisingly, polymer chains will prefer a stronger correlated medium to a less or uncorrelated medium of the same density while the opposite is the case for star polymers.

  3. Fabrication of hydroxycarbonate apatite coatings with hierarchically porous structures.

    PubMed

    Guo, Yaping; Zhou, Yu; Jia, Dechang

    2008-03-01

    Hierarchically porous hydroxycarbonate apatite is known to have a high bioactivity to regenerate bone, but its application in bone graft substitutes has been restricted due to its poor mechanical properties. This drawback has been addressed by (i) depositing calcium carbonate coatings on Ti6Al4V substrates by electrophoresis; and (ii) converting the coatings to hydroxycarbonate apatite coatings with hierarchically porous structures by treatment with a phosphate buffer solution (PBS). After soaking calcium carbonate coatings in PBS for 1 day, calcium-deficient hydroxycarbonate apatite nanocrystals are deposited on the surfaces of calcium carbonate particles via a dissolution-precipitation reaction. The aggregation of the nanocrystals produces plate-like hydroxycarbonate apatite. Mesopores with a pore size of approximately 3.8nm and macropores or apertures with an aperture size of approximately 1 microm are formed within and among the plates, respectively. After soaking for 9 days, the pore size of mesopores decreases and the mesopores disappear partly due to the crystal growth of hydroxycarbonate apatite. Simulated body fluid immersion tests reveal that the good in vitro bioactivity of hydroxycarbonate apatite coatings is attributed to the calcium deficiencies in apatite lattice and the hierarchically porous structures.

  4. Method for dialysis on microchips using thin porous polymer membrane

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2009-05-19

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  5. Dialysis on microchips using thin porous polymer membranes

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2007-09-04

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and form a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  6. 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.

  7. Polymer Coatings Reduce Electro-osmosis

    NASA Technical Reports Server (NTRS)

    Herren, Blair J.; Snyder, Robert; Shafer, Steven G.; Harris, J. Milton; Van Alstine, James M.

    1989-01-01

    Poly(ethylene glycol) film controls electrostatic potential. Electro-osmosis in quartz or glass chambers reduced or reversed by coating inside surface of chambers with monomacromolecular layers of poly(ethylene glycol). Stable over long times. Electrostatic potential across surface of untreated glass or plastic chamber used in electro-phoresis is negative and attracts cations in aqueous electrolyte. Cations solvated, entrains flow of electrolyte migrating toward cathode. Electro-osmotic flow interferes with desired electrophoresis of particles suspended in electrolyte. Polymer coats nontoxic, transparent, and neutral, advantageous for use in electrophoresis.

  8. Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications

    NASA Astrophysics Data System (ADS)

    Chebbi, A.; Stokes, J.

    2012-06-01

    Flame sprayed biocompatible polymer coatings, made of biodegradable and non-biodegradable polymers, were investigated as single coatings on titanium and as top coatings on plasma sprayed Hydroxyapatite. Biocompatible polymers can act as drug carriers for localized drug release following implantation. The polymer matrix consisted of a biodegradable polymer, polyhydroxybutyrate 98%/ polyhydroxyvalerate 2% (PHBV) and a non-biodegradable polymer, polymethylmethacrylate (PMMA). Screening tests were performed to determine the suitable range of spraying parameters, followed by a Design of Experiments study to determine the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), and to optimize the coating properties accordingly. Coatings characterization showed that optimized flame sprayed biocompatible polymers underwent little chemical degradation, did not produce acidic by-products in vitro, and that cells proliferated well on their surface.

  9. Polymer coatings to functionalize carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Abou Rich, S.; Yedji, M.; Amadou, J.; Terwagne, G.; Felten, A.; Avril, L.; Pireaux, J.-J.

    2012-03-01

    Multi-walled carbon nanotubes (MWCNTs) were modified by plasma polymerization with methyl methacrylate (MMA) and allylamine (AA) as monomers. Conditions of the MMA and AA plasma polymerization processes in a specially designed reactor and the plasma-polymerized MMA and AA coatings were studied. The chemical composition of the surface was analyzed by X-ray Photoelectron Spectroscopy (XPS); the polymer deposited on the CNTs surface was visualized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), while Fourier Transform Infrared spectroscopy (FTIR) allowed checking for the chemical structure of deposited plasma polymers (PP). In this work, we show that plasma functionalization creates C=O and C-O-C functional groups, or C-NH2 at the MWCNT surface, as a result of polymer deposited during the MMA or AA plasma treatments, respectively.

  10. Durable polymer-aerogel based superhydrophobic coatings, a composite material

    DOEpatents

    Kissel, David J; Brinker, Charles Jeffrey

    2014-03-04

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  11. Durable polymer-aerogel based superhydrophobic coatings: a composite material

    DOEpatents

    Kissel, David J.; Brinker, Charles Jeffrey

    2016-02-02

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  12. Porous polymer films templated by marangoni flow-induced water droplet arrays.

    PubMed

    Cai, Yangjun; Zhang Newby, Bi-min

    2009-07-07

    In this article, we report the development of a novel, simple, and cost-effective method for fabricating porous polymer films with controllable interpore distances, pore sizes, and arrangements using water droplets induced by Marangoni flow as templates. First, a spread-thin ethanol film on a partially water-wettable substrate is exposed to a humid airflow, facilitating the evaporation and recession of the ethanol film. Meanwhile, water in the airflow condenses on the ethanol film and accumulates near the receding contact line, which induces the formation of water fingers at the receding contact line and, finally, ordered arrays of water droplets after detachment. The formation of the hexagonal and square arrays of water droplets is due to the pinning and sliding of the water fingers on the silicone oxide (SiOx) and silicon (Si) substrates, respectively. By varying the thickness of the ethanol film spread on the Si substrate, the sliding velocity of water fingers can be tuned, subsequently leading to the fabrication of other arrangements. The interdroplet distance and droplet size can be dependently controlled by tuning the humidity of the airflow. The ordered arrays of water droplets on the substrate are then utilized to fabricate porous polymer films by dip-coating the substrate with a polystyrene solution. Films with hexagonal and square (and other arrangements) arrays of pores are fabricated on the silicon oxide (SiOx) and silicon (Si) substrates, respectively. The pore size can also be independently tuned by further condensation or evaporation of formed water droplets, leading to porous polymer films with both close- and non-close-packed arrays of pores. The ordered porous polymer films can be further used as templates for fabricating metal post patterns.

  13. Cell-Culture Reactor Having a Porous Organic Polymer Membrane

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    2000-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphory1choline groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  14. Durability of an inorganic polymer concrete coating

    NASA Astrophysics Data System (ADS)

    Wasserman, Kenneth

    The objective of the research program reported in this thesis is to evaluate the durability of an inorganic polymer composite coating exposed to freeze/thaw cycling and wet-dry cycling. Freeze/thaw cycling is performed following ASTM D6944-09 Standard Practice for Resistance of Cured Coatings to Thermal Cycling and wet/dry cycling is performed following guidelines set forth in a thesis written by Ronald Garon at Rutgers University. For both sets of experiments, four coating mixture proportions were evaluated. The variables were: silica/alumina ratio, mixing protocol using high shear and normal shear mixing, curing temperatures of 70 and 120 degrees Fahrenheit and use of nano size constituent materials. The mix with highest silica/alumina ratio was designated as Mix 1 and mixes with lower ratios were designated as Mix 2 and Mix 3. Mix 4 had nano silica particles. Four prisms were used for each variable including control that had no coating. The performance of the coating was evaluated using adhesion strength measured using: ASTM D7234 Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Adhesion Testers. Tests were performed after every five consecutive cycles of thermal conditioning and six consecutive cycles of wet-dry exposure. Results from the thermal cycling and wet-dry testing demonstrate that all coating formulations are durable. The minimum adhesion strength was 300 psi even though a relatively weak base concrete surface was chosen for the study. The weak surface was chosen to simulate aged concrete surfaces present in actual field conditions. Due to the inherent nature of the test procedure the variation in test results is high. However, based on the test results, high shear mixer and high temperature curing are not recommended. As expected nano size constituent materials provide better performance.

  15. Carbon coatings on polymers and their biocompatibility

    NASA Astrophysics Data System (ADS)

    Hubáček, T.; Siegel, J.; Khalili, R.; Slepičková-Kasálková, N.; Švorčík, V.

    2013-06-01

    In this paper we modified the surface properties of polymer foils (polyethyleneterephthalate (PET) and polytetrafluoroethylene (PTFE)) by flash evaporation of carbon layers (C-layers). Adhesion and proliferation of vascular smooth muscle cells (VSMC) on carbon coated PTFE and PET were studied in vitro. Chemical composition of deposited C-layers was determined by Raman spectroscopy, surface contact angle was measured by goniometry. Surface morphology of carbon coated samples was studied using atomic force microscopy. Electrical properties of deposited C-layers were determined by measuring its sheet resistance. It was found that the carbon deposition leads to a decrease of surface roughness of PTFE and PET and to a significant increase of sample wettability. Electrical resistance and wettability of deposited C-layers depends significantly on both the thickness of C-layer and the type of polymeric substrate used. It was found that maximal stimulation of the VSMC (adhesion and proliferation) on carbon coated polymers depends on the surface roughness and contact angle of cell carriers used.

  16. Porous light-emitting compositions

    SciTech Connect

    Burrell, Anthony K; McCleskey, Thomas Mark; Jia, Quanxi; Bauer, Eve; Mueller, Alexander H

    2012-04-17

    Light-emitting devices are prepared by coating a porous substrate using a polymer-assisted deposition process. Solutions of metal precursor and soluble polymers having binding properties for metal precursor were coated onto porous substrates. The coated substrates were heated at high temperatures under a suitable atmosphere. The result was a substrate with a conformal coating that did not substantially block the pores of the substrate.

  17. Protection of alodine coatings from thermal aging by removable polymer coatings.

    SciTech Connect

    Wagstaff, Brett R.; Bradshaw, Robert W.; Whinnery, LeRoy L., Jr.

    2006-12-01

    Removable polymer coatings were evaluated as a means to suppress dehydration of Alodine chromate conversion coatings during thermal aging and thereby retain the corrosion protection afforded by Alodine. Two types of polymer coatings were applied to Alodine-treated panels of aluminum alloys 7075-T73 and 6061-T6 that were subsequently aged for 15 to 50 hours at temperatures between 135 F to 200 F. The corrosion resistance of the thermally aged panels was evaluated, after stripping the polymer coatings, by exposure to a standard salt-fog corrosion test and the extent of pitting of the polymer-coated and untreated panels compared. Removable polymer coatings mitigated the loss of corrosion resistance due to thermal aging experienced by the untreated alloys. An epoxide coating was more effective than a fluorosilicone coating as a dehydration barrier.

  18. Corrosion-protective coatings from electrically conducting polymers

    NASA Technical Reports Server (NTRS)

    Thompson, Karen Gebert; Bryan, Coleman J.; Benicewicz, Brian C.; Wrobleski, Debra A.

    1991-01-01

    In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

  19. Corrosion-protective coatings from electrically conducting polymers

    SciTech Connect

    Thompson, K.G.; Bryan, C.J.; Benicewicz, B.C.; Wrobleski, D.A.

    1991-12-31

    In a joint research effort involving the Kennedy Space Center and the Los Alamos National Laboratory, electrically conductive polymer coatings have been developed as corrosion-protective coatings for metal surfaces. At the Kennedy Space Center, the launch environment consists of marine, severe solar, and intermittent high acid/elevated temperature conditions. Electrically conductive polymer coatings have been developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

  20. Hypercrosslinked porous polymer materials: design, synthesis, and applications.

    PubMed

    Tan, Liangxiao; Tan, Bien

    2017-02-22

    Hypercrosslinked polymers (HCPs) are a series of permanent microporous polymer materials initially reported by Davankov, and have received an increasing level of research interest. In recent years, HCPs have experienced rapid growth due to their remarkable advantages such as diverse synthetic methods, easy functionalization, high surface area, low cost reagents and mild operating conditions. Judicious selection of monomers, appropriate length crosslinkers and optimized reaction conditions yielded a well-developed polymer framework with an adjusted porous topology. Post fabrication of the as developed network facilitates the incorporation of various chemical functionalities that may lead to interesting properties and enhance the selection toward a specific application. To date, numerous HCPs have been prepared by post-crosslinking polystyrene-based precursors, one-step self-polycondensation or external crosslinking strategies. The advent of these methodologies has prompted researchers to construct well-defined porous polymer networks with customized micromorphology and functionalities. In this review, we describe not only the basic synthetic principles and strategies of HCPs, but also the advancements in the structural and morphological study as well as the frontiers of potential applications in energy and environmental fields such as gas storage, carbon capture, removal of pollutants, molecular separation, catalysis, drug delivery, sensing etc.

  1. Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.; Daroonparvar, M.; Kasiri-Asgarani, M.; Shah, A. M.; Medraj, M.

    2016-09-01

    A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density ( i corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.

  2. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    PubMed

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS.

  3. Fabrication of Porous Ag/TiO2/Au Coatings with Excellent Multipactor Suppression.

    PubMed

    Wu, Duoduo; Ma, Jianzhong; Bao, Yan; Cui, Wanzhao; Hu, Tiancun; Yang, Jing; Bai, Yuanrui

    2017-03-10

    Porous Ag/TiO2/Au coatings with excellent multipactor suppression were prepared by fabrication of porous Ag surface through two-step wet chemical etching, synthesis of TiO2 coatings by electroless-plating-like solution deposition and deposition of Au coatings via electroless plating. Porous structure of Ag surface, TiO2 coatings on porous Ag surface and Au coatings on porous Ag/TiO2 surface were verified by field-emission scanning electron microscopy, the composition and crystal type of TiO2 coatings was characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Secondary electron yield (SEY) measurement was used to monitor the SEY coefficient of the porous Ag coatings and Ag/TiO2/Au coatings. The as-obtained porous Ag coatings were proved exhibiting low SEY below 1.2, and the process was highly reproducible. In addition, the porous Ag/TiO2/Au coatings showed excellent multipactor suppression with the SEY 1.23 and good environmental stability. It is worth mentioning that the whole preparation process is simple and feasible, which would provide a promising application in RF devices.

  4. Fabrication of Porous Ag/TiO2/Au Coatings with Excellent Multipactor Suppression

    NASA Astrophysics Data System (ADS)

    Wu, Duoduo; Ma, Jianzhong; Bao, Yan; Cui, Wanzhao; Hu, Tiancun; Yang, Jing; Bai, Yuanrui

    2017-03-01

    Porous Ag/TiO2/Au coatings with excellent multipactor suppression were prepared by fabrication of porous Ag surface through two-step wet chemical etching, synthesis of TiO2 coatings by electroless-plating-like solution deposition and deposition of Au coatings via electroless plating. Porous structure of Ag surface, TiO2 coatings on porous Ag surface and Au coatings on porous Ag/TiO2 surface were verified by field-emission scanning electron microscopy, the composition and crystal type of TiO2 coatings was characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Secondary electron yield (SEY) measurement was used to monitor the SEY coefficient of the porous Ag coatings and Ag/TiO2/Au coatings. The as-obtained porous Ag coatings were proved exhibiting low SEY below 1.2, and the process was highly reproducible. In addition, the porous Ag/TiO2/Au coatings showed excellent multipactor suppression with the SEY 1.23 and good environmental stability. It is worth mentioning that the whole preparation process is simple and feasible, which would provide a promising application in RF devices.

  5. Fabrication of Porous Ag/TiO2/Au Coatings with Excellent Multipactor Suppression

    PubMed Central

    Wu, Duoduo; Ma, Jianzhong; Bao, Yan; Cui, Wanzhao; Hu, Tiancun; Yang, Jing; Bai, Yuanrui

    2017-01-01

    Porous Ag/TiO2/Au coatings with excellent multipactor suppression were prepared by fabrication of porous Ag surface through two-step wet chemical etching, synthesis of TiO2 coatings by electroless-plating-like solution deposition and deposition of Au coatings via electroless plating. Porous structure of Ag surface, TiO2 coatings on porous Ag surface and Au coatings on porous Ag/TiO2 surface were verified by field-emission scanning electron microscopy, the composition and crystal type of TiO2 coatings was characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Secondary electron yield (SEY) measurement was used to monitor the SEY coefficient of the porous Ag coatings and Ag/TiO2/Au coatings. The as-obtained porous Ag coatings were proved exhibiting low SEY below 1.2, and the process was highly reproducible. In addition, the porous Ag/TiO2/Au coatings showed excellent multipactor suppression with the SEY 1.23 and good environmental stability. It is worth mentioning that the whole preparation process is simple and feasible, which would provide a promising application in RF devices. PMID:28281546

  6. Polymer retention and adsorption in the flow of polymer solutions through porous media

    SciTech Connect

    Cohen, Y.; Christ, F.R.

    1986-03-01

    A new experimental technique based on a surface treatment process was developed for determining mobility reduction as a result of polymer adsorption in flow of polymer solutions through porous media. The experimental method also allowed the direct determination of adsorptive and nonadsorptive polymer retention from flow experiments. The adsorptive mobility reduction for the flow of polyacrylamide (J333) mobility control polymer through silica sand was found to be as high as 14% at the lowest experimental stress level of 3.75 dynes/cm/sup 2/ (0.375 Pa). This corresponded to an effective hydrodynamic thickness (EHT) of the adsorbed polymer layer of 0.57 ..mu..m. Both the mobility reduction and the EHT decreased with an increase in shear stress. The amount of adsorptive retention accounted for about 35.2% of the total retained polymer.

  7. Porous polymer nanostructures fabricated by the surface-induced phase separation of polymer solutions in anodic aluminum oxide templates.

    PubMed

    Wei, Tzu-Hui; Chi, Mu-Huan; Tsai, Chia-Chan; Ko, Hao-Wen; Chen, Jiun-Tai

    2013-08-13

    We study the formation of porous polymer nanostructures fabricated by the surface-induced phase separation of polymer solutions in anodic aluminum oxide (AAO) templates. Poly(methyl methacrylate) (PMMA) and tetrahydrofuran (THF) are used to investigate the evolution process of the surface-induced phase separation. With the longer immersion time of the AAO template in the polymer solution, the size of the solvent-rich droplet is increased by the coarsening process, resulting in the formation of porous polymer nanostructures. The coarsening mechanism is further evaluated by changing the experimental parameters including the immersion time, the polymer concentration, the polymer molecular weight, and the solvent quality. Under conditions in which polymer solutions have higher viscosities, the coarsening process is slowed down and the formation of the porous nanostructures is prohibited. The prevention of the porous nanostructures can also be realized by adding water to the PMMA/THF solution before the immersion process.

  8. Composite layers for barrier coatings on polymers

    NASA Astrophysics Data System (ADS)

    Brochhagen, Markus; Vorkoetter, Christoph; Boeke, Marc; Benedikt, Jan

    2016-09-01

    Amorphous hydrogenated carbon (a-C:H), amorphous hydrogenated silicon (a-Si:H), and SiO2 thin films are of high interest because they can serve as a gas barrier on polymers. To understand how the coating changes the overall barrier properties of the thin film-polymer system, optical, mechanical, and barrier properties have to be studied. One of the important characteristic of such coatings is their compressive stress, which has beneficial as well as unwanted effects. The stress can cause deformation of the bulk material or de-lamination of the film. The mechanical stability can be improved and it is possible to reduce cracking due to elongation, as the compressive stress can compensate externally applied tensile strain. Stress and mechanical properties of composite layers can be manipulated directly by embedding nanoparticles in an amorphous matrix film. Therefore nanoparticles and amorphous layers are investigated before they can be assembled in a composite layer. Growth rates as well as optical and mechanical properties are explored in this work. An inductively coupled plasma source was used for all amorphous layers and the silicon nanoparticles with diameter around 5 nm were produced in a capacitively coupled plasma reactor. This work is supported by DFG within SFB-TR87.

  9. Countercurrent Gaseous Diffusion Model of Oxidation Through a Porous Coating

    SciTech Connect

    Holcomb, G.R.

    1996-07-01

    A countercurrent gaseous diffusion model was developed to describe oxidation through porous coatings and scales. The specific system modeled involved graphite oxidized through a porous alumina (Al{sub 2}O{sub 3}) overcoat between 570 C (1,058 F) and 975 C (1,787 F). The model separated the porous Al{sub 2}O{sub 3} coating into two gas diffusion regions separated by a flame front, where oxygen (O{sub 2}) and carbon monoxide (CO) react to form carbon dioxide (CO{sub 2}). In the outer region O{sub 2} and CO{sub 2} counterdiffused. In the inner region, CO{sub 2} and CO counterdiffused. Concentration gradients of each gaseous specie in the pores of the Al{sub 2}O{sub 3} were determined, and the oxidation rate was calculated. The model was verified by oxidation experiments using graphite through various porous Al{sub 2}O{sub 3} overcoats. The Al{sub 2}O{sub 3} overcoats ranged in fractional porosity and in average pore radius from 0.077 {micro}m (3.0 x 10{sup -6} in., Knudsen diffusion) to 10.0 {micro}m (3.9 x 10{sup -4} in., molecular diffusion). Predicted and measured oxidation rates were shown to have the same dependence upon porosity, pore radius, temperature, and oxygen partial pressure (P{sub O{sub 2}}). Use of the model was proposed for other oxidation systems and for chemical vapor infiltration (CVI). This work was part of the U.S. Bureau of Mines corrosion research program.

  10. Multilayered Polymer Coated Carbon Nanotubes to Deliver Dasatinib

    PubMed Central

    Moore, Thomas L.; Grimes, Stuart W.; Lewis, Robert L.; Alexis, Frank

    2014-01-01

    Multilayered, multifunctional polymer coatings were grafted onto carbon nanotubes (CNT) using a one-pot, ring-opening polymerization in order to control the release kinetic and therapeutic efficacy of dasatinib. Biocompatible, biodegradable multilayered coatings composed of poly(glycolide) (PGA), and poly(lactide) (PLA) were polymerized directly onto hydroxyl-functionalized CNT surfaces. Sequential addition of monomers into the reaction vessel enabled multilayered coatings of PLA-PGA, or PGA-PLA. Poly(ethylene glycol) capped the polymer chain ends, resulting in a multifunctional amphiphilic coating. Multilayer polymer coatings on CNTs enabled control of anticancer dasatinib’s release kinetics and enhanced the in vitro therapeutic efficacy against U-87 glioblastoma compared to monolayer polymer coatings. PMID:24294824

  11. Cysteine could change the transport mechanism of PVP-coated silver nanoparticles in porous media

    NASA Astrophysics Data System (ADS)

    Yang, X.; Lin, S.; Wiesner, M.

    2012-12-01

    Silver nanoparticles (AgNPs) can hardly be removed by wastewater treatment plant and have big potential to enter groundwater, jeopardizing the water quality & aquatic ecosystem. Most AgNPs have surface coatings such as polyvinylpyrrolidone (PVP) which dominate their transport in porous media. Our previous study shows that PVP may promote the deposition of AgNPs on silica surface by a bridging mechanism. This study further explored how cysteine, a natural organic matter type, may influence the role of the PVP coating on AgNP translocation. Dynamic Light Scattering (DLS) measurement (Figure 1A) shows that the PVP coating rendered the AgNP dispersion high stability during the measuring period (3hrs). Addition of 100 ppm cysteine to the dispersion resulted in a rapid decrease in particle size from 100nm to 52nm within one hour, following which no further decline in particle size occurred. Column experiment results (Figure 1B) show that corresponding to the particle size change was a substantial decrease in particle deposition rates: introduction of 100 ppm cysteine into the particle dispersion resulted in a decrease in AgNP attenuation by the porous medium from 67% to 26%. The decline in particle size suggested that cysteine may have displaced the macromolecular PVP from the particle surface. Desorption of PVP resulted in a weakening or vanish of polymer bridging effect which in turn lowered the deposition rates substantially. This study demonstrated an implication of environmental transformation of coated AgNPs to their mobility in saturated sand aquifers. Acknowledgment Xinyao Yang appreciates the Natural Science Foundation of China (Grant No.:41101475) for covering the registration fee and traveling costs.igure 1 Particle size measurement (A) and breakthrough curves (B) of PVP-coated silver nanoparticle in the absence and presence of cysteine: pH=7.0, ionic strength=1mM, flow rate=1ml/min.

  12. New Polymer Coatings for Chemically Selective Mass Sensors

    NASA Technical Reports Server (NTRS)

    Sims, S. C.; Wright, Cassandra; Cobb, J.; McCalla, T.; Revelle, R.; Morris, V. R.; Pollack, S. K.

    1997-01-01

    There is a current need to develop sensitive and chemically specific sensors for the detection of nitric acid for in-situ measurements in the atmosphere. Polymer coatings have been synthesized and tested for their sensitivity and selectivity to nitric acid. A primary requirement for these polymers is detectability down to the parts per trillion range. The results of studies using these polymers as coatings for quartz crystal microbalances (QCM) and surface acoustic wave (SAW) devices will be presented.

  13. Modeling Methane Adsorption in Interpenetrating Porous Polymer Networks

    SciTech Connect

    Martin, RL; Shahrak, MN; Swisher, JA; Simon, CM; Sculley, JP; Zhou, HC; Smit, B; Haranczyk, M

    2013-10-03

    Porous polymer networks (PPNs) are a class of porous materials of particular interest in a variety of energy-related applications because of their stability, high surface areas, and gas uptake capacities. Computationally derived structures for five recently synthesized PPN frameworks, PPN-2, -3, -4, -5, and -6, were generated for various topologies, optimized using semiempirical electronic structure methods, and evaluated using classical grand canonical Monte Carlo simulations. We show that a key factor in modeling the methane uptake performance of these materials is whether, and how, these material frameworks interpenetrate and demonstrate a computational approach for predicting the presence, degree, and nature of interpenetration in PPNs that enables the reproduction of experimental adsorption data.

  14. Characterization of Porous, Dexamethasone-Releasing Polyurethane Coatings for Glucose Sensors

    PubMed Central

    Vallejo-Heligon, Suzana G.; Klitzman, Bruce; Reichert, William M.

    2014-01-01

    Commercially available implantable needle-type glucose sensors for diabetes management are robust analytically but can be unreliable clinically primarily due to tissue-sensor interactions. Here, we present the physical, drug release, and bioactivity characterization of tubular, porous dexamethasone (Dex) releasing polyurethane coatings designed to attenuate local inflammation in the tissue-sensor interface. Porous polyurethane coatings were produced by the salt-leaching/gas-foaming method. Scanning electron microscopy (SEM) and Micro-computed tomography (Micro-CT) showed a controlled porosity and coating thickness. In vitro drug release from coatings monitored over two weeks presented an initial fast release followed by a slower release. Total release from coatings was highly dependent on initial drug loading amount. Functional in vitro testing of glucose sensors deployed with porous coatings against glucose standards demonstrated that highly porous coatings minimally affected signal strength and response rate. Bioactivity of the released drug was determined by monitoring Dex-mediated, dose-dependent apoptosis of human peripheral blood derived monocytes in culture. Acute animal studies were used to determine the appropriate Dex payload for the implanted porous coatings. Pilot short-term animal studies showed that Dex released from porous coatings implanted in rat subcutis attenuated the initial inflammatory response to sensor implantation. These results suggest that deploying sensors with the porous, Dex-releasing coatings is a promising strategy to improve glucose sensor performance. PMID:25065548

  15. Characterization of porous, dexamethasone-releasing polyurethane coatings for glucose sensors.

    PubMed

    Vallejo-Heligon, Suzana G; Klitzman, Bruce; Reichert, William M

    2014-11-01

    Commercially available implantable needle-type glucose sensors for diabetes management are robust analytically but can be unreliable clinically primarily due to tissue-sensor interactions. Here, we present the physical, drug release and bioactivity characterization of tubular, porous dexamethasone (Dex)-releasing polyurethane coatings designed to attenuate local inflammation at the tissue-sensor interface. Porous polyurethane coatings were produced by the salt-leaching/gas-foaming method. Scanning electron microscopy and micro-computed tomography (micro-CT) showed controlled porosity and coating thickness. In vitro drug release from coatings monitored over 2 weeks presented an initial fast release followed by a slower release. Total release from coatings was highly dependent on initial drug loading amount. Functional in vitro testing of glucose sensors deployed with porous coatings against glucose standards demonstrated that highly porous coatings minimally affected signal strength and response rate. Bioactivity of the released drug was determined by monitoring Dex-mediated, dose-dependent apoptosis of human peripheral blood derived monocytes in culture. Acute animal studies were used to determine the appropriate Dex payload for the implanted porous coatings. Pilot short-term animal studies showed that Dex released from porous coatings implanted in rat subcutis attenuated the initial inflammatory response to sensor implantation. These results suggest that deploying sensors with the porous, Dex-releasing coatings is a promising strategy to improve glucose sensor performance.

  16. Porous polymers by controlling phase separation during vapor deposition polymerization.

    PubMed

    Tao, Ran; Anthamatten, Mitchell

    2013-11-01

    A template-free method is described to fabricate continuous-phase, porous polymer films by simultaneous phase separation during vapor deposition polymerization. The technique involves concurrent polymerization, crosslinking, and phase separation of condensed species and reaction products. Deposited films form open-cell, macroporous structures consisting of crosslinked and glassy poly(glycidyl methacrylate). By limiting phase separation during vapor phase deposition, spatially dependent morphologies, such as layered morphologies, can be grown. Results show that combining vapor deposition polymerization with phase separation establishes morphological control, which may be applied to applications including cellular scaffolds, thin cushions and vibration dampers, and membranes for separations.

  17. Synthesis and characterization of porous polyaniline conductive polymers

    NASA Astrophysics Data System (ADS)

    Price, Aaron D.; Naguib, Hani E.

    2007-04-01

    Polyaniline conductive polymers exhibit great potential for linear actuator applications. Many recent studies report methods to develop polyaniline-based materials with increased mechanical properties, electrical conductivity, and faster response time during actuation. In this study, porous blends of poly(methylmethacrylate) and polyaniline are processed using a two phase batch foaming setup. The effect of materials, processing, and system parameters on the physical properties of the resulting cellular structure are investigated. Hence, the effect of density and cell morphology on the electrical conductivity is elucidated.

  18. Chemistry and application of flexible porous coordination polymers*

    PubMed Central

    Bureekaew, Sareeya; Shimomura, Satoru; Kitagawa, Susumu

    2008-01-01

    Porous coordination polymers (PCPs), which are microporous materials, have been given much attention from both scientific and commercial aspects regarding their application to gas storage, gas separation and catalytic reaction because of the regularity of their pore shape and pore size, accompanied with the functionality. Moreover, in recent years, flexible PCPs, which are structurally transformable depending upon external stimuli, have been attractive because they provide unique properties, dissimilar to those of zeolites. In this review, the chemistry and application of flexible crystalline PCPs are summarized and discussed. PMID:27877934

  19. Synthesis and characterization of porous hydroxyapatite and hydroxyapatite coatings

    SciTech Connect

    Nieh, T G; Choi, B W; Jankowski, A F

    2000-10-25

    A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using water-soluble compounds and then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously reported. Resulting from the fact that the starting HAp powders were extremely fine, a relatively low activation energy for sintering was obtained. In the present study, both porous and dense structures were produced by varying powder morphology and sintering parameters. Porous structures consisting of open cells were constructed. Sintered structures were characterized using scanning electron microscopy and x-ray tomography. In the present paper, hydroxyapatite coatings produced by magnetron sputtering on silicon and titanium substrates will also be presented. The mechanical properties of the coatings were measured using nanoindentation techniques and microstructures examined using transmission electron microscopy.

  20. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects.

    PubMed

    Roland, Laura; Grau, Michael; Matena, Julia; Teske, Michael; Gieseke, Matthias; Kampmann, Andreas; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-12-22

    For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL) and poly-(3-hydroxybutyrate)/poly-(4-hydroxybutyrate) (P(3HB)/P(4HB)). As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB). Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI) with Green fluorescent protein (GFP)-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death.

  1. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects

    PubMed Central

    Roland, Laura; Grau, Michael; Matena, Julia; Teske, Michael; Gieseke, Matthias; Kampmann, Andreas; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-01-01

    For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL) and poly-(3-hydroxybutyrate)/poly-(4-hydroxybutyrate) (P(3HB)/P(4HB)). As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB). Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI) with Green fluorescent protein (GFP)-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death. PMID:26703586

  2. Electrochemical deposition and evaluation of electrically conductive polymer coating on biodegradable magnesium implants for neural applications.

    PubMed

    Sebaa, Meriam A; Dhillon, Shan; Liu, Huinan

    2013-02-01

    In an attempt to develop biodegradable, mechanically strong, biocompatible, and conductive nerve guidance conduits, pure magnesium (Mg) was used as the biodegradable substrate material to provide strength while the conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) was used as a conductive coating material to control Mg degradation and improve cytocompatibility of Mg substrates. This study explored a series of electrochemical deposition conditions to produce a uniform, consistent PEDOT coating on large three-dimensional Mg samples. A concentration of 1 M 3,4-ethylenedioxythiophene in ionic liquid was sufficient for coating Mg samples with a size of 5 × 5 × 0.25 mm. Both cyclic voltammetry (CV) and chronoamperometry coating methods produced adequate coverage and uniform PEDOT coating. Low-cost stainless steel and copper electrodes can be used to deposit PEDOT coatings as effectively as platinum and silver/silver chloride electrodes. Five cycles of CV with the potential ranging from -0.5 to 2.0 V for 200 s per cycle were used to produce consistent coatings for further evaluation. Scanning electron micrographs showed the micro-porous structure of PEDOT coatings. Energy dispersive X-ray spectroscopy showed the peaks of sulfur, carbon, and oxygen, indicating sufficient PEDOT coating. Adhesion strength of the coating was measured using the tape test following the ASTM-D 3359 standard. The adhesion strength of PEDOT coating was within the classifications of 3B to 4B. Tafel tests of the PEDOT coated Mg showed a corrosion current (I(CORR)) of 6.14 × 10(-5) A as compared with I(CORR) of 9.08 × 10(-4) A for non-coated Mg. The calculated corrosion rate for the PEDOT coated Mg was 2.64 mm/year, much slower than 38.98 mm/year for the non-coated Mg.

  3. Improved electrochemical performance of lithium iron phosphate in situ coated with hierarchical porous nitrogen-doped graphene-like membrane

    NASA Astrophysics Data System (ADS)

    zhang, Yue; Huang, Yudai; Wang, Xingchao; Guo, Yong; Jia, Dianzeng; Tang, Xincun

    2016-02-01

    LiFePO4 in situ coated with hierarchical porous nitrogen-doped graphene-like membrane (HPNGM) composite derived from a electrospun polymer membrane (EPM) precursor has been achieved for the first time. The N-doped graphene-like membrane which is in situ coating on LiFePO4 can provide a highly conductive layer, and the hierarchical porous structure facilitates Li+ transfer. The composite exhibits a high reversible capacity (171 mAh g-1 at 0.1 C), excellent high-rate capability and cycling stability. In addition to construct the traditional structure of nanofiber or nanowire, the EPM can also form graphene-like structure after annealing, which is a new application in constructing sheet structure by electrospinning.

  4. Polycaprolactone coated porous tricalcium phosphate scaffolds for controlled release of protein for tissue engineering

    PubMed Central

    Xue, Weichang; Bandyopadhyay, Amit; Bose, Susmita

    2010-01-01

    Polycaprolactone (PCL) was coated on porous tricalcium phosphate (TCP) scaffolds to achieve controlled protein delivery. Porous TCP scaffolds were fabricated using reticulated polyurethane foam as sacrificial scaffold with a porosity of 70–90 vol %. PCL was coated on sintered porous TCP scaffolds by dipping-drying process. The compressive strength of TCP scaffolds increased significantly after PCL coating. The highest strength of 2.41 MPa at a porosity of 70% was obtained for the TCP scaffold coated with 5% PCL solution. Model protein bovine serum albumin (BSA) was encapsulated efficiently within the PCL coating. The amount of BSA encapsulation was controlled by varying proteins’ composition in the PCL coating. The FTIR analysis confirmed that BSA retained its structural conformation and did not show significant denaturization during PCL coating. The release kinetics in phosphate buffer solution indicated that the protein release was controlled and sustained, and primarily dependant on protein concentration encapsulated in the PCL coating. PMID:19572301

  5. Porous polymer electrolytes with high ionic conductivity and good mechanical property for rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Liang, Bo; Jiang, Qingbai; Tang, Siqi; Li, Shengliang; Chen, Xu

    2016-03-01

    Porous polymer electrolytes (PPEs) are attractive for developing lithium-ion batteries because of the combined advantages of liquid and solid polymer electrolytes. In the present study, a new porous polymer membrane doped with phytic acid (PA) is prepared, which is used as a crosslinker in polymer electrolyte matrix and can also plasticize porous polymer electrolyte membranes, changing them into soft tough flexible materials. A PEO-PMMA-LiClO4-x wt.% PA (x = weight of PA/weight of polymer, PEO: poly(ethylene oxide); PMMA: poly(methyl methacrylate)) polymer membrane is prepared by a simple evaporation method. The effects of the ratio of PA to PEO-PMMA on the properties of the porous membrane, including morphology, porous structure, and mechanical property, are systematically studied. PA improves the porous structure and mechanical properties of polymer membrane. The maximum tensile strength and elongation of the porous polymer membranes are 20.71 MPa and 45.7% at 15 wt.% PA, respectively. Moreover, the PPEs with 15 wt.% PA has a conductivity of 1.59 × 10-5 S/cm at 20 °C, a good electrochemical window (>5 V), and a low interfacial resistance. The results demonstrate the compatibility of the mechanical properties and conductivity of the PPEs, indicating that PPEs have good application prospects for lithium-ion batteries.

  6. Periodic porous stripe patterning in a polymer blend film induced by phase separation during spin-casting.

    PubMed

    Kim, Jae-Kyung; Taki, Kentaro; Nagamine, Shinsuke; Ohshima, Masahiro

    2008-08-19

    A periodic striping pattern with microscale pore size is observed on the surface of thin films prepared by spin-casting from a polystyrene (PS) and polyethylene glycol (PEG) blend solution. The pattern is created by the convection generated by thermal gradients in the solution between the substrate and film solution during solvent evaporation, the radial flow of the spin-coated solution, and the primary and secondary phase separation of the PS and PEG solutions. The formation mechanism of the periodic porous stripe pattern is discussed, wherein the effects of the polymer blend weight ratio, polymer concentration, and drying rate on the formation of the periodic porous striping pattern are investigated using scanning electron and atomic force microscopy.

  7. Development of bioactive glass based scaffolds for controlled antibiotic release in bone tissue engineering via biodegradable polymer layered coating.

    PubMed

    Nooeaid, Patcharakamon; Li, Wei; Roether, Judith A; Mouriño, Viviana; Goudouri, Ourania-Menti; Schubert, Dirk W; Boccaccini, Aldo R

    2014-12-01

    Highly porous 45S5 Bioglass(®)-based scaffolds coated with two polymer layers were fabricated to serve as a multifunctional device with controlled drug release capability for bone regeneration applications. An interior poly(d,l-lactide)/poly(ethylene glycol)-(polypropylene glycol)-poly(ethylene glycol) triblock copolymer (Pluronic P123) coating improved the mechanical stability of Bioglass-based scaffolds, while an exterior natural polymer (alginate or gelatin) coating served as an antibiotic drug carrier. The results showed improved mechanical properties of Bioglass-based scaffolds by the bilayer polymer coating. In addition, hydrochloride tetracycline loaded in either alginate or gelatin coatings was released rapidly at the initial stage (∼1 h), while the released rate subsequently decreased and was sustained for 14 days in phosphate buffered saline. Therefore, these layered polymer coated scaffolds exhibit attractive characteristics in terms of improved mechanical properties and controlled drug release, simultaneously with the added advantage that the drug release rate is decoupled from the intrinsic scaffold Bioglass degradation mechanism. The layered polymer coated scaffolds are of interest for drug-delivery enhanced bone regeneration applications.

  8. Investigation of the rheology and transport of polymers in porous media using network models

    SciTech Connect

    Sorbie, K.S.; Clifford, P.J.

    1988-05-01

    Polymers have been used in improved oil recovery operations as mobility control agents in surfactant and polymer flooding and in gel treatments. In order to predict the outcome of such processes, it is necessary to have a good understanding of the rheology and transport of polymer solutions in porous media. The rheological behavior refers essentially to the pressure drop/flow rate relationship observed for the polymer solution in the porous medium. It is relatively straightforward to measure rheological properties of bulk polymer solutions such as the viscosity/shear rate behavior or, for elastic fluids, the normal stress differences. However, the pressure drop/flow rate behavior of the polymers in flow through porous media may be either qualitatively quite similar or very different from bulk flow behavior as measured, for example, in a capillary viscometer. In both the rheology and dispersion behavior of polymers in porous media, they see that the phenomenon being observed macroscopically is a result of the interaction between a fluid or molecular property and the stochastic nature of the porous medium at the microscopic level. If one views the porous medium as a network of joined capillaries, then the rheological behavior in each capillary will be quite well defined, e.g. through a single constitutive relationship. In the investigation of hydrodynamic dispersion of polymer and tracer in porous media, the role of the stochastic nature of the medium is clearly evident.

  9. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

    PubMed

    Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials.

  10. Polymer Coats Leads on Implantable Medical Device

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Langley Research Center s Soluble Imide (LaRC-SI) was discovered by accident. While researching resins and adhesives for advanced composites for high-speed aircraft, Robert Bryant, a Langley engineer, noticed that one of the polymers he was working with did not behave as predicted. After putting the compound through a two-stage controlled chemical reaction, expecting it to precipitate as a powder after the second stage, he was surprised to see that the compound remained soluble. This novel characteristic ended up making this polymer a very significant finding, eventually leading Bryant and his team to win several NASA technology awards, and an "R&D 100" award. The unique feature of this compound is the way that it lends itself to easy processing. Most polyimides (members of a group of remarkably strong and incredibly heat- and chemical-resistant polymers) require complex curing cycles before they are usable. LaRC-SI remains soluble in its final form, so no further chemical processing is required to produce final materials, like thin films and varnishes. Since producing LaRC-SI does not require complex manufacturing techniques, it has been processed into useful forms for a variety of applications, including mechanical parts, magnetic components, ceramics, adhesives, composites, flexible circuits, multilayer printed circuits, and coatings on fiber optics, wires, and metals. Bryant s team was, at the time, heavily involved with the aircraft polymer project and could not afford to further develop the polymer resin. Believing it was worth further exploration, though, he developed a plan for funding development and submitted it to Langley s chief scientist, who endorsed the experimentation. Bryant then left the high-speed civil transport project to develop LaRC-SI. The result is an extremely tough, lightweight thermoplastic that is not only solvent-resistant, but also has the ability to withstand temperature ranges from cryogenic levels to above 200 C. The thermoplastic

  11. Apparatus and method for depositing coating onto porous substrate

    DOEpatents

    Isenberg, A.O.; Zymboly, G.E.

    1986-09-02

    Disclosed is an apparatus for forming a chemically vapor deposited coating on a porous substrate where oxygen from a first gaseous reactant containing a source of oxygen permeates through the pores of the substrate to react with a second gaseous reactant that is present on the other side of the substrate. The apparatus includes means for controlling the pressure and flow rate of each gaseous reactant, a manometer for measuring the difference in pressure between the gaseous reactants on each side of the substrate, and means for changing the difference in pressure between the gaseous reactants. Also disclosed is a method of detecting and closing cracks in the coating by reducing the pressure difference between the two gaseous reactants whenever the pressure difference falls suddenly after gradually rising, then again increasing the pressure difference on the two gases. The attack by the by-products of the reaction on the substrate are reduced by maintaining the flow rate of the first reactant through the pores of the substrate. 1 fig.

  12. Apparatus and method for depositing coating onto porous substrate

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is an apparatus for forming a chemically vapor deposited coating on a porous substrate where oxygen from a first gaseous reactant containing a source of oxygen permeates through the pores of the substrate to react with a second gaseous reactant that is present on the other side of the substrate. The apparatus includes means for controlling the pressure and flow rate of each gaseous reactant, a manometer for measuring the difference in pressure between the gaseous reactants on each side of the substrate, and means for changing the difference in pressure between the gaseous reactants. Also disclosed is a method of detecting and closing cracks in the coating by reducing the pressure difference between the two gaseous reactants whenever the pressure difference falls suddenly after gradually rising, then again increasing the pressure difference on the two gases. The attack by the by-products of the reaction on the substrate are reduced by maintaining the flow rate of the first reactant through the pores of the substrate.

  13. Apparatus for producing oxidation protection coatings for polymers

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J. (Inventor); Sovey, J. S. (Inventor); Banks, A. (Inventor)

    1986-01-01

    A polymeric substrate is coated with a metal oxide film to provide oxidation protection in low Earth orbital environments. The film contains about 4 volume percent polymer to provide flexibility. A coil of polymer materials moves through an ion beam as it is fed between reels. The ion beam first cleans the polymer material surface and then sputters the film material from a target onto this surface.

  14. Fabrication of coated polymer microneedles for transdermal drug delivery.

    PubMed

    Chen, Yang; Chen, Bo Zhi; Wang, Qi Lei; Jin, Xuan; Guo, Xin Dong

    2017-03-23

    As an alternative to hypodermic needles, coated polymer microneedles (MNs) are able to deliver drugs to subcutaneous tissues after being inserted into the skin. The dip-coating process is a versatile, rapid fabricating method that can form coated MNs in a short time. However, it is still a challenge to fabricate coated MNs with homogeneous and precise drug doses in the dip-coating process. In this study, to fabricate coated polymer microneedles with controlled drug loading, an adjustable apparatus that can be lifted and lowered was designed to immerse a polylactic acid (PLA) MN patch in the coating solutions. Using the coating solution containing 0.5% (w/w) sulforhodamine B, the drug loadings were up to 12ng, 14ng, and 18ng per needle for the MNs with heights of 550μm, 650μm, and 750μm, respectively. Moreover, for the MNs with a 650-μm height, when increasing the viscosity of the coating solutions from 150mPa·s to 1360mPa·s, 2850mPa·s, and 8200mPa·s, the drug loading increased from 2.5ng to 5ng, 14ng, and 22ng per needle, respectively. Meanwhile, the drug delivery efficiencies of these MNs were approximately 90%. In the insertion experiments, the MNs could successfully penetrate the skin and deliver the coated drug with approximately 90% efficiency when the MN tips were exposed to the outer environment. In vivo studies in mice indicated that the coated polymer MNs continuously delivered drugs, and the skin recovered without any injuries. These results demonstrated that the coated polymer MN was a safe and effective method for transdermal drug delivery.

  15. Coating of uniform inorganic particles with polymers, I

    SciTech Connect

    Oyama, H.T.; Sprycha, R.; Xie, Yuming; Partch, R.E.; Matijevic, E. . Center for Advanced Materials Processing)

    1993-10-15

    Uniform spherical silica particles have been first coated with aluminum hydrous oxide and then with poly(divinylbenzene). To produce the outer shell, the inorganic cores were pretreated with a vinyl coupling agent, then divinylbenzene, and an initiator in hot mineral spirits. The thickness of the alumina or polymer layers could be controlled by adjusting the experimental parameters. The same procedure was used to coat irregularly shaped commercial alumina particles. The charge of the so prepared particles was determined by potentiometric titrations, which showed that the polymer coating was permeable to the reactants. Thus, the titration curves were determined by the properties of the cores.

  16. Graphene–polymer coating for the realization of strain sensors

    PubMed Central

    Bonavolontà, Carmela; Aramo, Carla; Pepe, Giampiero; De Nicola, Sergio; Carotenuto, Gianfranco; Longo, Angela; Palomba, Mariano; Boccardi, Simone; Meola, Carosena

    2017-01-01

    In this work we present a novel route to produce a graphene-based film on a polymer substrate. A transparent graphite colloidal suspension was applied to a slat of poly(methyl methacrylate) (PMMA). The good adhesion to the PMMA surface, combined with the shear stress, allows a uniform and continuous spreading of the graphite nanocrystals, resulting in a very uniform graphene multilayer coating on the substrate surface. The fabrication process is simple and yields thin coatings characterized by high optical transparency and large electrical piezoresitivity. Such properties envisage potential applications of this polymer-supported coating for use in strain sensing. The electrical and mechanical properties of these PMMA/graphene coatings were characterized by bending tests. The electrical transport was investigated as a function of the applied stress. The structural and strain properties of the polymer composite material were studied under stress by infrared thermography and micro-Raman spectroscopy. PMID:28144561

  17. Experimental study of the effect of a passive porous coating on disturbances in a hypersonic boundary layer 2. Effect of the porous coating location

    NASA Astrophysics Data System (ADS)

    Lukashevich, S. V.; Morozov, S. O.; Shiplyuk, A. N.

    2016-09-01

    The effect of the location of a passive porous coating on natural disturbances in a hypersonic boundary layer is studied experimentally. The experiments are performed in the flow around a sharp cone aligned at a zero angle of attack with the free-stream Mach number M∞ = 5.8, stagnation temperature T 0 = 370 ± 5 K, and unit Reynolds numbers Re1∞ = 2.6 · 106, 4.6 · 106, 6.6 · 106, and 107 m-1. The wave characteristics of the boundary layer are calculated with the use of the linear stability theory for flow parameters corresponding to experimental values. A comparison of experimental and predicted results shows that the presence of a porous coating in the region where the second mode is unstable leads to reduction of its amplitude at the measurement point, whereas the presence of a porous coating in the region of second mode stability leads to enhancement of the amplitude.

  18. Molecular Dynamics Simulations of Nanoparticles Coated with Charged Polymers

    NASA Astrophysics Data System (ADS)

    Wen, Chengyuan; Cheng, Shengfeng

    Polymer coating is frequently used to stabilize colloidal and nano-sized particles. We employ molecular dynamics simulations to study nanoparticles coated with polymer chains that contain ionizable groups. In a polar solvent, the chains become charged with counterions dissociated. In the computational model, we treat the solvent as a uniform dielectric background and use the bead-spring model for the polymer chains. Counterions are explicitly included as mobile beads. The nanoparticle is modeled as a layer of sites uniformly distributed on a spherical surface with a certain fraction of sites serving as the tether points of the grafted polymer brush. We vary the grafting density and calculate the distribution of polymer beads and counterions around the nanoparticle. Our results indicate that charged chains adopt extended conformations because of their mutual repulsions. We further study the interactions between two polymer-coated nanoparticles and obtain the potential of mean force. We also find an interesting transition of a confined single layer of such polymer-coated nanoparticles into two layers when the confinement is removed. Results show that the brush-brush contact has a nonuniform distribution and the nanoparticles tend to form dipole-like structures.

  19. Does hydroxyapatite coating have no advantage over porous coating in primary total hip arthroplasty? A meta-analysis.

    PubMed

    Chen, Yun-Lin; Lin, Tiao; Liu, An; Shi, Ming-Min; Hu, Bin; Shi, Zhong-Li; Yan, Shi-Gui

    2015-01-28

    There are some arguments between the use of hydroxyapatite and porous coating. Some studies have shown that there is no difference between these two coatings in total hip arthroplasty (THA), while several other studies have shown that hydroxyapatite has advantages over the porous one. We have collected the studies in Pubmed, MEDLINE, EMBASE, and the Cochrane library from the earliest possible years to present, with the search strategy of "(HA OR hydroxyapatite) AND ((total hip arthroplasty) OR (total hip replacement)) AND (RCT* OR randomiz* OR control* OR compar* OR trial*)". The randomized controlled trials and comparative observation trials that evaluated the clinical and radiographic effects between hydroxyapatite coating and porous coating were included. Our main outcome measurements were Harris hip score (HHS) and survival, while the secondary outcome measurements were osteolysis, radiolucent lines, and polyethylene wear. Twelve RCTs and 9 comparative observation trials were included. Hydroxyapatite coating could improve the HHS (p < 0.01), reduce the incidence of thigh pain (p = 0.01), and reduce the incidence of femoral osteolysis (p = 0.01), but hydroxyapatite coating had no advantages on survival (p = 0.32), polyethylene wear (p = 0.08), and radiolucent lines (p = 0.78). Hydroxyapatite coating has shown to have an advantage over porous coating. The HHS and survival was duration-dependent-if given the sufficient duration of follow-up, hydroxyapatite coating would be better than porous coating for the survival. The properties of hydroxyapatite and the implant design had influence on thigh pain incidence, femoral osteolysis, and polyethylene wear. Thickness of 50 to 80 μm and purity larger than 90% increased the thigh pain incidence. Anatomic design had less polyethylene wear.

  20. Influence of biodegradable polymer coatings on corrosion, cytocompatibility and cell functionality of Mg-2.0Zn-0.98Mn magnesium alloy.

    PubMed

    Witecka, Agnieszka; Yamamoto, Akiko; Idaszek, Joanna; Chlanda, Adrian; Święszkowski, Wojciech

    2016-08-01

    Four kinds of biodegradable polymers were employed to prepare bioresorbable coatings on Mg-2.0Zn-0.98Mn (ZM21) alloy to understand the relationship between polymer characteristics, protective effects on substrate corrosion, cytocompatibility and cell functionality. Poly-l-lactide (PLLA), poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(lactic-co-glycolic) acid (PLGA) was spin-coated on ZM21, obtaining a smooth, non-porous coating less than 0.5μm in thickness. Polymer coating characterization, a degradation study, and biocompatibility evaluations were performed. After 4 w of immersion into cell culture medium, degradation of PLGA and PLLA coatings were confirmed by ATR-FTIR observation. The coatings of PLLA, PHB and PHBV, which have lower water permeability and slower degradation than PLGA, provide better suppression of initial ZM21 degradation and faster promotion of human osteosarcoma cell growth and differentiation.

  1. Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

    PubMed

    Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

    2016-02-02

    We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested

  2. Dual-Functional Antifogging/Antimicrobial Polymer Coating.

    PubMed

    Zhao, Jie; Ma, Li; Millians, William; Wu, Tiehang; Ming, Weihua

    2016-04-06

    Dual-functional antifogging/antimicrobial polymer coatings were prepared by forming a semi-interpenetrating polymer network (SIPN) of partially quaternized poly(2-(dimethylamino)ethyl methacrylate-co-methyl methacrylate) and polymerized ethylene glycol dimethacrylate network. The excellent antifogging behavior of the smooth coating was mainly attributed to the hydrophilic/hydrophobic balance of the partially quaternized copolymer, while the covalently bonded, hydrophobic quaternary ammonium compound (5 mol % in the copolymer) rendered the coating strongly antimicrobial, as demonstrated by the total kill against both Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli. The antimicrobial action of the SIPN coating was based on contact killing, without leaching of bactericidal species, as revealed by a zone-of-inhibition test. This type of dual-functional coating may find unique applications where both antimicrobial and antifogging properties are desired.

  3. Polymer coatings as separator layers for microbial fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Watson, Valerie J.; Saito, Tomonori; Hickner, Michael A.; Logan, Bruce E.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production.

  4. In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

    PubMed

    Ghani, Milad; Frizzarin, Rejane M; Maya, Fernando; Cerdà, Víctor

    2016-07-01

    Herein we report the use of cobalt porous coordination polymers (PCP) as intermediates to prepare advanced extraction media based on layered double hydroxides (LDH) supported on melamine polymer foam. The obtained dissolvable Ni-Co LDH composite sponges can be molded and used as sorbent for the in-syringe solid-phase extraction (SPE) of phenolic acids from fruit juices. The proposed sorbent is obtained due to the surfactant-assisted self-assembly of Co(II)/imidazolate PCPs on commercially available melamine foam, followed by the in situ conversion of the PCP into the final dissolvable LDH coating. Advantageous features for SPE are obtained by using PCPs with hierarchical porosity (HPCPs). The LDH-sponge prepared using intermediate HPCPs (HLDH-sponge) is placed in the headspace of a glass syringe, enabling flow-through extraction followed by analyte elution by the dissolution of the LDH coating in acidic conditions. Three phenolic acids (gallic acid, p-hydroxybenzoic acid and caffeic acid) were extracted and quantified using high performance liquid chromatography. Using a 5mL sample volume, the obtained detection limits were 0.15-0.35μgL(-1). The proposed method for the preparation of HLDH-sponges showed a good reproducibility as observed from the intra- and inter-day RSD's, which were <10% for all analytes. The batch-to-batch reproducibility for three different batches of HLDH-sponges was 10.6-11.2%. Enrichment factors of 15-21 were obtained. The HLDH-sponges were applied satisfactorily to the determination of phenolic acids in natural and commercial fruit juices, obtaining relative recoveries among 89.7-95.3%.

  5. An instant multi-responsive porous polymer actuator driven by solvent molecule sorption

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Dunlop, John W. C.; Qiu, Xunlin; Huang, Feihe; Zhang, Zibin; Heyda, Jan; Dzubiella, Joachim; Antonietti, Markus; Yuan, Jiayin

    2014-07-01

    Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20 °C) at a speed of an order of magnitude faster than the state-of-the-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-to-make and survives even after hydrothermal processing (200 °C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn ‘inert’ objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.

  6. Polymer derived ceramic composites as environmental barrier coatings on steel

    NASA Astrophysics Data System (ADS)

    Torrey, Jessica D.

    Polymer derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as fibers and coatings. They offer advantages over traditional ceramic processing routes including lower pyrolysis temperatures and the ability to employ polymeric processing techniques. The main drawback to preceramic polymers is that they undergo a shrinkage during pyrolysis that can be greater than 50-volume%. One way to overcome this shrinkage is to add filler particles, usually elemental or binary metals, which will expand upon reaction with the pyrolysis atmosphere, thereby compensating for the shrinkage of the polymer. The aim of this study is to develop a polymer derived ceramic composite coating on steel as a barrier to oxidation and carburization, while concurrently gaining insight as to the fundamental mechanisms for compositional and microstructural evolution within the system. A systematic approach to selecting the preceramic polymer and expansion agents was taken. Six commercially available poly(silsesquioxane) polymers and a polysiloxane were studied. Several metals and an intermetallic were considered as potential expansion agents. The most desirable polymer/expansion agent combination was achieved with poly(hydridomethylsiloxane) as the matrix and titanium disilicide as the filler. Processing parameters have been optimized and a relationship derived to predict final coating thickness based on slurry viscosity and dip coating withdrawal speed. Microstructural analysis reveals an amorphous composite coating of oxidized filler particles in a silica matrix. A diffusion layer is visible at the coating-steel interface, indicating good bonding. The optimized coatings are ˜18mum thick, have some residual porosity and a density of 2.57g/cm3. A systematic study of the phase transformations and microstructural changes in the coating and its components during pyrolysis in air is also presented. The system evolves from a polymer filled with a binary metal at

  7. Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

    2014-01-01

    Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 μm of the Cu-polymer coating to 206 μm of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

  8. Improvement of the compressive strength of a cuttlefish bone-derived porous hydroxyapatite scaffold via polycaprolactone coating.

    PubMed

    Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun

    2013-10-01

    Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications.

  9. Ordered mesoporous polymers in situ coated on a stainless steel wire for a highly sensitive solid phase microextraction fibre

    NASA Astrophysics Data System (ADS)

    Zheng, Juan; Liang, Yeru; Liu, Shuqin; Ding, Yajuan; Shen, Yong; Luan, Tiangang; Zhu, Fang; Jiang, Ruifen; Wu, Dingcai; Ouyang, Gangfeng

    2015-07-01

    Development of facile and effective methods for fabrication of high-performance solid phase microextraction (SPME) fibres remains a great challenge. Herein, a new class of ordered mesoporous polymers (OMPs) in situ coated on a stainless steel wire were successfully developed and utilized as a highly sensitive and stable SPME fibre for the first time. Because of the highly ordered mesoporous structure of its OMP coating, the π-π interactions and the dispersion forces, the OMP-coated SPME fibre exhibited much better extraction properties as compared to the commercial PDMS fibre. The findings could provide a new benchmark for preparing well-defined porous materials for the SPME application.Development of facile and effective methods for fabrication of high-performance solid phase microextraction (SPME) fibres remains a great challenge. Herein, a new class of ordered mesoporous polymers (OMPs) in situ coated on a stainless steel wire were successfully developed and utilized as a highly sensitive and stable SPME fibre for the first time. Because of the highly ordered mesoporous structure of its OMP coating, the π-π interactions and the dispersion forces, the OMP-coated SPME fibre exhibited much better extraction properties as compared to the commercial PDMS fibre. The findings could provide a new benchmark for preparing well-defined porous materials for the SPME application. Electronic supplementary information (ESI) available: Experimental details, Fig. S1-S3 and Tables S1-S3. See DOI: 10.1039/c5nr02674a

  10. In vitro and in vivo characterization of porous poly-l-lactic acid coatings for subcutaneously implanted glucose sensors

    PubMed Central

    Koschwanez, H. E.; Yap, F. Y.; Klitzman, B.; Reichert, W. M.

    2014-01-01

    The purpose of this study was to test the hypothesis that porous poly-l-lactic acid (PLLA) sensor coatings reduce fibrosis and promote blood microvessel formation in tissue adjacent to the sensor surface. Porous PLLA coatings were produced using ammonium bicarbonate as the gas foaming/salt leaching agent, and deployed on functional and nonfunctional sensors. The porous coatings minimally affected sensor accuracy and response rate in vitro. Three-week subcutaneous rat studies of nonfunctional glucose sensors showed the anticipated effect of porous coatings enhancing vascularity and decreasing collagen deposition. In contrast, percutaneous functional sensors with and without porous coatings showed no significant difference in terms of histology or sensor response. In spite of the observation that texturing increases the vascularity of the tissue that surrounds implanted sensors, other factors such as the additional mechanical stresses imposed by percutaneous tethering may override the beneficial effects of the porous coatings. PMID:18200540

  11. Surface-initiated hyperbranched polyglycerol as an ultralow-fouling coating on glass, silicon, and porous silicon substrates.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; McPhee, Gordon; Thissen, Helmut; Voelcker, Nicolas H

    2014-09-10

    Anionic ring-opening polymerization of glycidol was initiated from activated glass, silicon, and porous silicon substrates to yield thin, ultralow-fouling hyperbranched polyglycerol (HPG) graft polymer coatings. Substrates were activated by deprotonation of surface-bound silanol functionalities. HPG polymerization was initiated upon the addition of freshly distilled glycidol to yield films in the nanometer thickness range. X-ray photoelectron spectroscopy, contact angle measurements, and ellipsometry were used to characterize the resulting coatings. The antifouling properties of HPG-coated surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells. The adsorption of bovine serum albumin and collagen type I was found to be reduced by as much as 97 and 91%, respectively, in comparison to untreated surfaces. Human glioblastoma and mouse fibroblast attachment was reduced by 99 and 98%, respectively. HPG-grafted substrates outperformed polyethylene glycol (PEG) grafted substrates of comparable thickness under the same incubation conditions. Our results demonstrate the effectiveness of antifouling HPG graft polymer coatings on a selected range of substrate materials and open the door for their use in biomedical applications.

  12. Stable capillary coating with successive multiple ionic polymer layers.

    PubMed

    Katayama, H; Ishihama, Y; Asakawa, N

    1998-06-01

    A stable modification of the inner wall of a fused silica capillary was established by a simple coating procedure, successive multiple ionic-polymer layer (SMIL) coating. An anionic polymer was tightly fixed to the capillary wall by the SMIL coating, in which a cationic polymer was sandwiched between the anionic polymer and the uncoated fused silica capillary by noncovalent bonding. The SMIL-coated capillary showed a long lifetime. The endurance of the SMIL-coated capillary was more than 100 runs, and it was also tolerant to organic solvents, 1 M NaOH, and a surfactant. The coating efficiency did not depend on capillary sources, and the relative standard deviation of capillary-to-capillary reproducibility was less than 1%. In this study, dextran sulfate (DS) was used as the anionic polymer, and Polybrene was used as the cationic polymer for SMIL modification. The DS-modified capillary (SMIL-DS capillary) exhibited a pH-independent electroosmotic flow (EOF) from anode to cathode in the pH range of 2-11. The SMIL-DS capillary showed good performance for acidic protein analyses under physiological conditions (pH 7.4). Also, the presence of EOF under acidic conditions permitted new applications. Simultaneous separations of cationic, anionic, and neutral amino acids were achieved by capillary zone electrophoresis, and separations of cresol isomers were achieved by micellar electrokinetic chromatography under the acidic conditions. The SMIL-DS capillary was also useful for fast and precise determination of the pKa of acidic functional groups.

  13. Synthesis of a further improved porous polymer for the separation of nitrogen, oxygen, argon, and carbon monoxide by gas chromatography

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.

    1986-01-01

    A further improvement has been made in the synthesis of an N-type porous polymer for the separation of permanent gases. Changing the ratios of reactants and diluting the Hi-DVB with styrene led to a porous polymer gas chromatographic packing which is superior to commercial products and to the author's own previously reported custom-made polymer.

  14. Computational Strategies for Polymer Coated Steel Sheet Forming Simulations

    SciTech Connect

    Owen, D. R. J.; Andrade Pires, F. M.; Dutko, M.

    2007-05-17

    This contribution discusses current issues involved in the numerical simulation of large scale industrial forming processes that employ polymer coated steel sheet. The need for rigorous consideration of both theoretical and algorithmic issues is emphasized, particularly in relation to the computational treatment of finite strain deformation of polymer coated steel sheet in the presence of internal degradation. Other issues relevant to the effective treatment of the problem, including the modelling of frictional contact between the work piece and tools, low order element technology capable of dealing with plastic incompressibility and thermo mechanical coupling, are also addressed. The suitability of the overall approach is illustrated by the solution of an industrially relevant problem.

  15. Computational Strategies for Polymer Coated Steel Sheet Forming Simulations

    NASA Astrophysics Data System (ADS)

    Owen, D. R. J.; Andrade Pires, F. M.; Dutko, M.

    2007-05-01

    This contribution discusses current issues involved in the numerical simulation of large scale industrial forming processes that employ polymer coated steel sheet. The need for rigorous consideration of both theoretical and algorithmic issues is emphasized, particularly in relation to the computational treatment of finite strain deformation of polymer coated steel sheet in the presence of internal degradation. Other issues relevant to the effective treatment of the problem, including the modelling of frictional contact between the work piece and tools, low order element technology capable of dealing with plastic incompressibility and thermo mechanical coupling, are also addressed. The suitability of the overall approach is illustrated by the solution of an industrially relevant problem.

  16. Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication.

    PubMed

    Reboul, Julien; Furukawa, Shuhei; Horike, Nao; Tsotsalas, Manuel; Hirai, Kenji; Uehara, Hiromitsu; Kondo, Mio; Louvain, Nicolas; Sakata, Osami; Kitagawa, Susumu

    2012-06-24

    The spatial organization of porous coordination polymer (PCP) crystals into higher-order structures is critical for their integration into separation systems, heterogeneous catalysts, ion/electron transport and photonic devices. Here, we demonstrate a rapid method to spatially control the nucleation site, leading to the formation of mesoscopic architecture made of PCPs, in both two and three dimensions. Inspired by geological processes, this method relies on the morphological replacement of a shaped sacrificial metal oxide used both as a metal source and as an 'architecture-directing agent' by an analogous PCP architecture. Spatiotemporal harmonization of the metal oxide dissolution and the PCP crystallization allowed the preservation of very fine mineral morphological details of periodic alumina inverse opal structures. The replication of randomly structured alumina aerogels resulted in a PCP architecture with hierarchical porosity in which the hydrophobic micropores of the PCP and the mesopores/macropores inherited from the parent aerogels synergistically enhanced the material's selectivity and mass transfer for water/ethanol separation.

  17. Coating carbon nanotubes with polymer in supercritical carbon dioxide.

    PubMed

    Wang, Jiawei; Khlobystov, Andrei N; Wang, Wenxin; Howdle, Steven M; Poliakoff, Martyn

    2006-04-21

    A facile and efficient method has been developed for coating MWNTs with solvent resistant polymer in scCO2, which permits the selective deposition of high molecular weight fluorinated graft poly(methyl vinyl ether-alt-maleic anhydride) polymer onto MWNTs in scCO2 under 100-170 bar at 40 degrees C and forms quasi one-dimensional nanostructures with conducting cores and insulating surfaces.

  18. Doubly renewable cellulose polymer for water-based coatings.

    PubMed

    Tristram, Cameron J; Mason, Jennifer M; Williams, D Bradley G; Hinkley, Simon F R

    2015-01-01

    A levulinoyl ester-containing cellulose polymer is introduced as a waterborne coating. Incorporation of the biomass-derived levulinic acid proceeds via an unexpected intermediate and provides the unusual feature of a cellulose derivative that is readily chemically modified. The levulinoyl-cellulose ester could be chemically manipulated, allowing it to be dispersed to generate a waterborne hydrocolloid latex. This was capable of film-formation at room temperature, and was formulated for use as a coating of high-renewable content.

  19. Recognition of Bread Key Odorants by Using Polymer Coated QCMs

    NASA Astrophysics Data System (ADS)

    Nakai, Takashi; Kouno, Shinji; Hiruma, Naoya; Shuzo, Masaki; Delaunay, Jean-Jacques; Yamada, Ichiro

    Polyisobutylene (PIB) polymer and methylphenylsiloxane (25%) diphenylsiloxane (75%) copolymer (OV25) were coated on Quartz Crystal Microbalance (QCM) sensors and used in recognition of bread key odorants. Representative compounds of key roasty odorants of bread were taken as 3-acetylpyridine and benzaldehyde, and representative key fatty odorants were hexanal and (E)-2-nonenal. Both OV25- and PIB-coated QCM fabricated sensors could detect concentration as low as 0.9 ppm of 3-acetylpyridine and 1.2 ppm of (E)-2-nonenal. The sensitivity to 3-acetylpyridine of the OV25-coated QCM was about 1000 times higher than that of ethanol, the major interference compound in bread key odorant analysis. Further, the OV25-coated QCM response was 5-6 times and 2-3 times larger than that of the PIB-coated QCM when exposed to roasty odorants and to fatty odorants, respectively. The difference in sensitivity of the OV25- and PIB-coated QCMs we fabricated made possible to discriminate roasty from fatty odorants as was evidenced by the odor recognition map representing the frequency shifts of the OV25-coated QCM against the frequency shift of the PIB-coated QCM. In conclusion, we found that the combination of an OV25-coated QCM and a PIB-coated QCM was successful in discriminating roasty odorants from fatty odorants at the ppm level.

  20. Porous niobium coatings fabricated with selective laser melting on titanium substrates: Preparation, characterization, and cell behavior.

    PubMed

    Zhang, Sheng; Cheng, Xian; Yao, Yao; Wei, Yehui; Han, Changjun; Shi, Yusheng; Wei, Qingsong; Zhang, Zhen

    2015-08-01

    Nb, an expensive and refractory element with good wear resistance and biocompatibility, is gaining more attention as a new metallic biomaterial. However, the high price of the raw material, as well as the high manufacturing costs because of Nb's strong oxygen affinity and high melting point have limited the widespread use of Nb and its compounds. To overcome these disadvantages, porous Nb coatings of various thicknesses were fabricated on Ti substrate via selective laser melting (SLM), which is a 3D printing technique that uses computer-controlled high-power laser to melt the metal. The morphology and microstructure of the porous Nb coatings, which had pores ranging from 15 to 50 μm in size, were characterized with scanning electron microscopy (SEM). The average hardness of the coating, which was measured with the linear intercept method, was 392±37 HV. In vitro tests of the porous Nb coating which was monitored with SEM, immunofluorescence, and CCK-8 counts of cells, exhibited excellent cell morphology, attachment, and growth. The simulated body fluid test also proved the bioactivity of the Nb coating. Therefore, these new porous Nb coatings could potentially be used for enhanced early biological fixation to bone tissue. In addition, this study has shown that SLM technique could be used to fabricate coatings with individually tailored shapes and/or porosities from group IVB and VB biomedical metals and their alloys on stainless steel, Co-Cr, and other traditional biomedical materials without wasting raw materials.

  1. Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants

    NASA Astrophysics Data System (ADS)

    Lindahl, Carl; Xia, Wei; Engqvist, Håkan; Snis, Anders; Lausmaa, Jukka; Palmquist, Anders

    2015-10-01

    The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 °C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.

  2. Bioresponsive polymer coated drug nanorods for breast cancer treatment

    NASA Astrophysics Data System (ADS)

    Laemthong, Tunyaboon; Kim, Hannah H.; Dunlap, Kelly; Brocker, Caitlin; Barua, Dipak; Forciniti, Daniel; Huang, Yue-Wern; Barua, Sutapa

    2017-01-01

    Ineffective drug release at the target site is among the top challenges for cancer treatment. This reflects the facts that interaction with the physiological condition can denature active ingredients of drugs, and low delivery to the disease microenvironment leads to poor therapeutic outcomes. We hypothesize that depositing a thin layer of bioresponsive polymer on the surface of drug nanoparticles would not only protect drugs from degradation but also allow the release of drugs at the target site. Here, we report a one-step process to prepare bioresponsive polymer coated drug nanorods (NRs) from liquid precursors using the solvent diffusion method. A thin layer (10.3 ± 1.4 nm) of poly(ε-caprolactone) (PCL) polymer coating was deposited on the surface of camptothecin (CPT) anti-cancer drug NRs. The mean size of PCL-coated CPT NRs was 500.9 ± 91.3 nm length × 122.7 ± 10.1 nm width. The PCL polymer coating was biodegradable at acidic pH 6 as determined by Fourier transform infrared spectroscopy. CPT drugs were released up to 51.5% when PCL coating dissolved into non-toxic carboxyl and hydroxyl groups. Trastuzumab (TTZ), a humanized IgG monoclonal antibody, was conjugated to the NR surface for breast cancer cell targeting. Combination treatments using CPT and TTZ decreased the HER-2 positive BT-474 breast cancer cell growth by 66.9 ± 5.3% in vitro. These results suggest effective combination treatments of breast cancer cells using bioresponsive polymer coated drug delivery.

  3. Protective coatings for high-temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Harding, David R.; Sutter, James K.; Papadopoulos, Demetrios S.

    1993-01-01

    Plasma-enhanced chemical vapor deposition was used to deposit silicon nitride on graphite-fiber-reinforced polyimide composites to protect against oxidation at elevated temperatures. The adhesion and integrity of the coating were evaluated by isothermal aging (371 C for 500 hr) and thermal cycling. The amorphous silicon nitride (a-SiN:H) coating could withstand stresses ranging from approximately 0.18 GPa (tensile) to -1.6 GPa (compressive) and provided a 30 to 80 percent reduction in oxidation-induced weight loss. The major factor influencing the effectiveness of a-SiN:H as a barrier coating against oxidation is the surface finish of the polymer composite.

  4. Degradation of Polymer-Coated Materials

    DTIC Science & Technology

    2013-10-01

    However, the filaments were thinner than was observed when a Boegel conversion coating was used. Comparisons were also made on corrosion site growth at...Movie 1.4.3. With the CCC, corrosion filaments were thinner than with Boegel. Furthermore, the corrosion front was more irregular than with Boegel...should be noted that the corrosion propagation for these coating systems was similar to the samples without topcoat. However, the corrosion filaments

  5. Development and characterization of porous polypyrrole-polylactic acid electroactive polymer blends

    NASA Astrophysics Data System (ADS)

    Chan, Christine; Chan, Ellen; Naguib, Hani E.

    2009-03-01

    Conducting polymers have sparked much research interest due to their unique ability to be electrically stimulated. However, these polymers are very brittle and have poor mechanical properties. In order to improve upon its structural integrity, it can be blended with other host polymers that have better mechanical properties. These blended composites would then possess the benefits of conductive properties while having sufficient mechanical properties to be more suitable for practical applications. Polypyrrole-polylactic acid blends were processed using chemical oxidative polymerization and compression molding, followed by gas foaming and saturation techniques to create porous structures. Characterization of these porous blends included its physical, thermal, and mechanical properties.

  6. Positron lifetime spectroscopy for investigation of thin polymer coatings

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Sprinkle, Danny R.; Eftekhari, Abe

    1993-01-01

    In the aerospace industry, applications for polymer coatings are increasing. They are now used for thermal control on aerospace structures and for protective insulating layers on optical and microelectronic components. However, the effectiveness of polymer coatings depends strongly on their microstructure and adhesion to the substrates. Currently, no technique exists to adequately monitor the quality of these coatings. We have adapted positron lifetime spectroscopy to investigate the quality of thin coatings. Results of measurements on thin (25-micron) polyurethane coatings on aluminum and steel substrates have been compared with measurements on thicker (0.2-cm) self-standing polyurethane discs. In all cases, we find positron lifetime groups centered around 560 psec, which corresponds to the presence of 0.9-A(exp 3) free-volume cells. However, the number of these free-volume cells in thin coatings is larger than in thick discs. This suggests that some of these cells may be located in the interfacial regions between the coatings and the substrates. These results and their structural implications are discussed in this report.

  7. Investigation of porous polymer gas chromatographic packings for atmospheric analysis of extraterrestrial bodies

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.

    1986-01-01

    Measurement of the permanent gases in the atmospheres of mission targets is a major objective. A 16 meter long Porapak N column was used on the Venus probe and required a rather high carrier gas flow rate. The researchers have, therefore, surveyed commercial porous polymer types which had some ability to resolve nitrogen, oxygen, argon and carbon monoxide gases. Porapaks N and Q appeared superior to most. Batch to batch variation, however, was quite wide, so the researchers learned how to synthesize porous polymer and investigated some of the factors affecting the separations. A polymer was synthesized which was superior to all commercial products and allowed at least a 50% reduction in length and flow rate of carrier gas. Similar studies were made concerning the separation of hydrocarbons and new porous polymers have been synthesized which represent significant improvements in time of analysis, column, and carrier gas flow rate.

  8. Long-lasting Antifouling Coating from Multi-Armed Polymer

    PubMed Central

    Mizrahi, Boaz; Khoo, Xiaojuan; Chaing, Homer H.; Sher, Katalina J.; Feldman, Rose G.; Lee, Jung-Jae; Irusta, Silvia; Kohane, Daniel S.

    2013-01-01

    We describe a new antifouling surface coating, based on aggregation of a short amphiphilic four-armed PEG-dopamine polymer into particles, and on surface binding by catechol chemistry. An unbroken and smooth polymeric coating layer with an average thickness of approximately 4 microns was formed on top of titanium oxide surfaces by a single step reaction. Coatings conferred excellent resistance to protein adhesion. Cell attachment was completely prevented for at least eight weeks, although the membranes themselves did not appear to be intrinsically cytotoxic. When linear PEG or four-armed PEG of higher molecular weight were used, the resulting coatings were inferior in thickness and in preventing protein adhesion. This coating method has potential applicability for biomedical devices susceptible to fouling after implantation. PMID:23855875

  9. Titania sol-gel coatings with silver on non-porous titanium and titanium alloys

    NASA Astrophysics Data System (ADS)

    Horkavcova, D.; Cerny, M.; Sanda, L.; Novak, P.; Jablonska, E.; Zlamalova-Cflova, Z.; Helebrant, A.

    2016-04-01

    The objective of the work was to prepare and characterize titania sol-gel coatings on non-porous titanium and newly developed titanium alloys. Basic titania sol contained two forms of silver. Titania sol without silver was used as a reference sample. Coatings were prepared by dip-coating technique during stirring and fired. Coatings after firing were characterized by scanning electron microscopy. All titania coatings were measured to determine their adhesive and bactericidal properties. Adhesion of the coatings to the substrate was measured by tape test. Gram-negative bacteria E. coli was used for the bactericidal test. Coated substrates were immersed into suspension of E. coli in physiological solution for 24 hours. The in vitro cytotoxicity test was performed after one day. The bactericidal effect without toxicity was confirmed for selected coatings.

  10. Effect of polymer coating on leakage losses in Bragg fibers

    NASA Astrophysics Data System (ADS)

    Uspenskii, Yu. A.; Uzorin, E. E.; Vinogradov, A. V.; Likhachev, M. E.; Semjonov, S. L.; Bubnov, M. M.; Dianov, E. M.; Jamier, R.; Février, S.

    2007-05-01

    It is found that the reflection of leaky radiation from the interface between the outer silica cladding and the coating polymer greatly modifies the loss spectrum of Bragg fibers. A simple model that describes this effect is proposed and confirmed by measurement and computation.

  11. Simultaneous sorption and mechanical entrapment during polymer flow through porous media

    NASA Astrophysics Data System (ADS)

    Farajzadeh, R.; Bedrikovetsky, P.; Lotfollahi, M.; Lake, L. W.

    2016-03-01

    Physical adsorption and mechanical entrapment are two major causes of polymer retention in porous media. Physical adsorption is considered an equilibrium process and is often modeled by assuming a Langmuir isotherm. The outcome is a steady state pressure response because the permeability reduction is also accounted for by adsorption. However, some experimental data show gradual increase of pressure with time, implying that polymer retention is a time-dependent process. We discuss simultaneous effect of sorption and mechanical entrapment on the polymer retention in porous media. An exact solution for 1-D flow problem for the case of constant filtration coefficient and Langmuir-sorption isotherm, including explicit formulae for breakthrough concentration and pressure drop across the core is derived. The general model with a varying filtration coefficient was successfully matched with experimental data confirming the occurrence of simultaneous sorption with deep-bed filtration during polymer flow in porous media. In the absence of mechanical entrapment, the physical adsorption causes delay in the polymer front and does not affect the polymer concentration behind the front. Addition of mechanical entrapment results in slow recovery of the injected concentration at the outlet (for a varying filtration coefficient) or reaching to a steady state concentration, which is only a fraction of the injected concentration (for a constant filtration coefficient). Accurate assessment and quantification of the polymer retention requires both pressure and effluent concentration data at the outlet of the porous medium.

  12. Thermal Protective Coating for High Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  13. Metallated porphyrin based porous organic polymers as efficient electrocatalysts

    NASA Astrophysics Data System (ADS)

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-10-01

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm-2) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm-2). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e- pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both

  14. The electret effect and electromechanical properties of solid and porous polymers

    NASA Astrophysics Data System (ADS)

    Tai, Liang Shiang

    Electret effect, pseudo-piezoelectricity and electrostriction of solid and porous polymers were investigated in this study where solid polymers include polyethylene terephthalate (PET), polyvinylidenefluoride (PVDF), poly(vinylidenefluoride-trifluoroethylene) P(VDF-TrFE), polytetrafluoroethylene (PTFE) and fluoroethylenepropylene (FEP). Besides porous PTFE, new porous copolymer P(VDF-TrFE) films were also prepared and used in this work. Capacitive probe and high resolution TSDC techniques were employed for the measurement of surface potential and relaxation of thermal current respectively. Quasi-static piezoelectricity (d33) of solid and porous polymers were determined by measuring the change of induced charge density from the samples after a static load was applied in the thickness direction. By using a modified Michelson interferometer capable of resolving displacements of 3 nm, field-induced strains of the corona-charged samples were measured along the direction of the applied electric field. After corona charging, multi-layer polar PET films were inspected and it was found that the characteristics of polarization and space charges of the individual layers were quite similar to each other. Almost identical surface potentials and TSDC responses were observed for single film and multi-layer sample. New porous ferroelectric P(VDF-TrFE) 56/44 and 70/30 films were fabricated successfully by electrospinning method. These porous and highly flexible polymer films consisted of nano-sized fibril connected with micro-sized spheres and the porosity was about 80%. Dielectric analysis revealed that these porous copolymers possessed the relaxor-like ferroelectric properties with low effective dielectric constant (epsilonr ˜ 1.6). The quasi-static piezoelectric coefficients (d 33 ˜ 300 pC/N) of the porous copolymers were comparable to solid and porous PTFE. Pseudo-piezoelectric effects of double and triple layers based on porous copolymer with bulk PET were significantly

  15. Mussel-inspired dendritic polymers as universal multifunctional coatings.

    PubMed

    Wei, Qiang; Achazi, Katharina; Liebe, Hendrik; Schulz, Andrea; Noeske, Paul-Ludwig Michael; Grunwald, Ingo; Haag, Rainer

    2014-10-20

    A rapid and universal approach for multifunctional material coatings was developed based on a mussel-inspired dendritic polymer. This new kind of polymer mimics not only the functional groups of mussel foot proteins (mfps) but also their molecular weight and molecular structure. The large number of catechol and amine groups set the basis for heteromultivalent anchoring and crosslinking. The molecular weight reaches 10 kDa, which is similar to the most adhesive mussel foot protein mfp-5. Also, the dendritic structure exposes its functional groups on the surface like the folded proteins. As a result, a very stable coating can be prepared on virtually any type of material surface within 10 min by a simple dip-coating method, which is as fast as the formation of mussel byssal threads in nature.

  16. Direct synthesis of nanoporous carbon nitride fibers using Al-based porous coordination polymers (Al-PCPs).

    PubMed

    Hu, Ming; Reboul, Julien; Furukawa, Shuhei; Radhakrishnan, Logudurai; Zhang, Yuanjian; Srinivasu, Pavuluri; Iwai, Hideo; Wang, Hongjing; Nemoto, Yoshihiro; Suzuki, Norihiro; Kitagawa, Susumu; Yamauchi, Yusuke

    2011-07-28

    We report a new synthetic route for preparation of nanoporous carbon nitride fibers with graphitic carbon nitride polymers, by calcination of Al-based porous coordination polymers (Al-PCPs) with dicyandiamide (DCDA) under a nitrogen atmosphere.

  17. A novel processing of carbon nanotubes grown on molecular sieve coated porous ceramics

    NASA Astrophysics Data System (ADS)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu; Zhao, Wei; Kim, Sukyoung; Kim, Ik Jin

    2015-08-01

    The present study focuses on the growth of carbon nanotubes (CNTs) on Fe-containing zeolites coated porous ceramics by implementing three different and independent techniques, successively. Direct foaming-derived porous ceramics were subjected to hydrothermal reaction for on-site growth of NaA zeolites within it. The porous ceramics-zeolite composite was subjected to ion-exchange reaction to obtain the catalyst for CNT synthesis. Multi-walled CNTs (MWCNTs) were grown by catalytic chemical vapour deposition (CCVD) process using acetylene as carbon source. Microstructural, thermogravimetric and spectroscopic analyses showed distinctive differences in terms of hollow structural feature, yield and crystallinity of the MWCNTs with different reaction temperatures.

  18. Assessment of bone ingrowth potential of biomimetic hydroxyapatite and brushite coated porous E-beam structures.

    PubMed

    Biemond, J Elizabeth; Eufrásio, Tatiane S; Hannink, Gerjon; Verdonschot, Nico; Buma, Pieter

    2011-04-01

    The bone ingrowth potential of biomimetic hydroxyapatite and brushite coatings applied on porous E-beam structure was examined in goats and compared to a similar uncoated porous structure and a conventional titanium plasma spray coating. Specimens were implanted in the iliac crest of goats for a period of 3 (4 goats) or 15 weeks (8 goats). Mechanical implant fixation generated by bone ingrowth was analyzed by a push out test. Histomorphometry was performed to assess the bone ingrowth depth and bone implant contact. The uncoated and hydroxyapatite-coated cubic structure had significantly higher mechanical strength at the interface compared to the Ti plasma spray coating at 15 weeks of implantation. Bone ingrowth depth was significantly larger for the hydroxyapatite- and brushite-coated structures compared to the uncoated structure. In conclusion, the porous E-beam surface structure showed higher bone ingrowth potential compared to a conventional implant surface after 15 weeks of implantation. Addition of a calcium phosphate coating to the E-beam structure enhanced bone ingrowth significantly. Furthermore, the calcium phosphate coating appears to work as an accelerator for bone ingrowth.

  19. Durability of nanostructured coatings based on PTFE nanoparticles deposited on porous aluminum alloy

    NASA Astrophysics Data System (ADS)

    Ghalmi, Zahira; Farzaneh, Masoud

    2014-09-01

    Ice accumulation on outdoor structures is a serious problem in cold climate regions of the world. To address this issue, several surface treatment methods have been developed for structures made of aluminum alloys. In this study, an Al2O3 porous oxide layer was formed by anodization using a phosphoric acid electrolyte. Subsequently, polytetrafluoroethylene (PTFE) was used to coat the porous surface. After PTFE impregnation, a nanostructured surface along with a low surface energy of PTFE resulted in significantly reduced ice adhesion strength. In fact, even after fifteen icing/deicing cycles, the PTFE-based coating remained highly hydrophobic with static contact angles higher than smooth Teflon® surface.

  20. Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity

    PubMed Central

    Gu, Cheng; Huang, Ning; Wu, Yang; Xu, Hong; Jiang, Donglin

    2015-01-01

    Porous organic polymers allow the integration of various π-units into robust porous π-networks, but they are usually synthesized as unprocessable solids with poor light-emitting performance as a result of aggregation-related excitation dissipation. Herein, we report a general strategy for the synthesis of highly emissive photofunctional porous polymer films on the basis of a complementary scheme for the structural design of aggregation-induced-emissive π-systems. We developed a high-throughput and facile method for the direct synthesis of large-area porous thin films at the liquid–electrode interface. The approach enables the preparation of microporous films within only a few seconds or minutes and allows precise control over their thickness with sub-nanometer precision. By virtue of rapid photoinduced electron transfer, the thin films can detect explosives with enhanced sensitivity to low parts-per-million levels in a selective manner. PMID:26234636

  1. Click Chemistry Immobilization of Antibodies on Polymer Coated Gold Nanoparticles.

    PubMed

    Finetti, Chiara; Sola, Laura; Pezzullo, Margherita; Prosperi, Davide; Colombo, Miriam; Riva, Benedetta; Avvakumova, Svetlana; Morasso, Carlo; Picciolini, Silvia; Chiari, Marcella

    2016-07-26

    The goal of this work is to develop an innovative approach for the coating of gold nanoparticles (AuNPs) with a synthetic functional copolymer. This stable coating with a thickness of few nanometers provides, at the same time, stabilization and functionalization of the particles. The polymeric coating consists of a backbone of polydimethylacrylamide (DMA) functionalized with an alkyne monomer that allows the binding of azido modified molecules by Cu(I)-catalyzed azide/alkyne 1,3-dipolar cycloaddition (CuAAC, click chemistry). The thin polymer layer on the surface stabilizes the colloidal suspension whereas the alkyne functions pending from the backbone are available for the reaction with azido-modified proteins. The reactivity of the coating is demonstrated by immobilizing an azido modified anti-mouse IgG antibody on the particle surface. This approach for the covalent binding of antibody to a gold-NPs is applied to the development of gold labels in biosensing techniques.

  2. Acoustic emission during fatigue of porous-coated Ti-6Al-4V implant alloy.

    PubMed

    Kohn, D H; Ducheyne, P; Awerbuch, J

    1992-01-01

    Acoustic emission (AE) events and event intensities (e.g., event amplitude, counts, duration, and energy counts) were recorded and analyzed during fatigue loading of uncoated and porous-coated Ti-6Al-4V. AE source location, spatial filtering, event, and event intensity distributions were used to detect, monitor, analyze, and predict failures. AE provides the ability to spatially and temporally locate multiple fatigue cracks, in real time. Fatigue of porous-coated Ti-6Al-4V is governed by a sequential, multimode fracture process of: transverse fracture in the porous coating; sphere/sphere and sphere/substrate debonding; substrate fatigue crack initiation; slow and rapid substrate fatigue crack propagation. Because of the porosity of the coating, the different stages of fracture within the coating occur in a discontinuous fashion. Therefore, the AE events generated are intermittent and the onset of each mode of fracture in the porous coating can be detected by increases in AE event rate. Changes in AE event rate also correspond to changes in crack extension rate, and may therefore be used to predict failure. AE offers two distinct advantages over conventional optical and microscopic methods of analyzing fatigue cracks--it is more sensitive and it can determine the time history of damage progression. The magnitude of the AE event intensities increased with increasing stress. Failure mechanisms are best differentiated by analyzing AE event amplitudes. Intergranular fracture and microvoid coalescence generated the highest AE event amplitudes (100 dB), whereas, plastic flow and friction generated the lowest AE event amplitudes (55-65 dB). Fractures in the porous coating were characterized by AE event amplitudes of less than 80 dB.

  3. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables

    PubMed Central

    Alvarez, Noe T.; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R.; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J.; Shanov, Vesselin

    2014-01-01

    Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter—which is approximately four times the diameter of a red blood cell—is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core. PMID:28344254

  4. In vitro evaluation of coating polymers for enteric coating and human ileal targeting.

    PubMed

    Huyghebaert, Nathalie; Vermeire, An; Remon, Jean Paul

    2005-07-14

    Recombinant interleukin-10 producing Lactococcus lactis is an alternative therapy for Crohn's disease. For in vivo interleukin-10 production, thymidine, the essential feed component of these recombinant bacteria should be coadministered. Different coating polymers were evaluated in vitro for enteric properties and targeting suitability to the ileum, the major site of inflammation in Crohn's disease. To guarantee ileal delivery, the polymer must dissolve from pH 6.8 and allow complete release within 40 min. Aqoat AS-HF coated pellets (15%) showed poor enteric properties and thymidine was released below pH 6.8. Eudragit FS30D coated pellets (15%) showed good enteric properties, but no thymidine was released within 40 min at pH 6.8. Eudragit S coated pellets (15%) showed good enteric properties after curing at elevated temperature while no thymidine was released within 40 min at pH 6.8. In another approach to pass the proximal small intestine intact, pellets were coated with 30% Eudragit L30D-55. At pH 6.0, they showed a lag-phase of 20 min. No influence of layer thickness was seen above pH 6.5. Alternatively, pellets were coated with a mixture of Eudragit FS30D/L30D-55 but they showed poor enteric properties and thymidine was released below pH 6.8. In conclusion, none of the tested polymers/mixtures ensured enteric properties and ileal targeting.

  5. Systems and strippable coatings for decontaminating structures that include porous material

    DOEpatents

    Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

    2011-12-06

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  6. Anti-icing Behavior of Thermally Sprayed Polymer Coatings

    NASA Astrophysics Data System (ADS)

    Koivuluoto, Heli; Stenroos, Christian; Kylmälahti, Mikko; Apostol, Marian; Kiilakoski, Jarkko; Vuoristo, Petri

    2017-01-01

    Surface engineering shows an increasing potential to provide a sustainable approach to icing problems. Currently, several passive anti-ice properties adoptable to coatings are known, but further research is required to proceed for practical applications. This is due to the fact that icing reduces safety, operational tempo, productivity and reliability of logistics, industry and infrastructure. An icing wind tunnel and a centrifugal ice adhesion test equipment can be used to evaluate and develop anti-icing and icephobic coatings for a potential use in various arctic environments, e.g., in wind power generation, oil drilling, mining and logistic industries. The present study deals with evaluation of icing properties of flame-sprayed polyethylene (PE)-based polymer coatings. In the laboratory-scale icing tests, thermally sprayed polymer coatings showed low ice adhesion compared with metals such as aluminum and stainless steel. The ice adhesion strength of the flame-sprayed PE coating was found to have approximately seven times lower ice adhesion values compared with metallic aluminum, indicating a very promising anti-icing behavior.

  7. Adhesion of preceramic inorganic polymer coatings to carbon fibers

    SciTech Connect

    Chaudhry, T.M.; Drzal, L.T.; Ho, H.; Laine, R.

    1996-12-31

    To determine whether the preceramic inorganic polymer coating can provide not only the thermal oxidative protection during both processing and use in metal matrix composites or ceramic matrix composites but also the appropriate composite properties, it is desirable to know how and at what point in the thermal processing cycle the coating-carbon fiber interface undergoes changes that affect the interfacial adhesion and failure mode. Also, it is important to identify the locus of interfacial failure i.e. between fiber and coating or between coating and matrix. This work is directed at determining the interfacial changes and the locus of failure in order to optimize both the coating chemistry and the conversion process. The characteristics of the benchmark interface coating material, silicon oxycarbide, SiO{sub x}C{sub y} or black glass have been studied. SiO{sub x}C{sub y} was chosen because (1) SiO{sub x}C{sub y} is amorphous, (2) it is possible to prepare very well-defined materials, where the chemistry and the evolution of the material with time and temperature are known in detail, and (3) SiO{sub x}C{sub y} is a matrix material used in commercial composites. It has been shown that these coatings are effective in increasing the oxidation resistance of the carbon fibers themselves.

  8. Bonding bases coated with porous metal powder: a comparison with foil mesh.

    PubMed

    Hanson, G H; Gibbon, W M; Shimizu, H

    1983-01-01

    This study was undertaken to test the theory that a special porous metal powder coating can provide better mechanical keying than mesh by virtue of its greater surface area and intricate microscopic void network. Identical brackets were laser-welded to an equal number of conventional foil-mesh and powder-coated bases of identical shape and peripheral dimensions. The experimental base material was found to provide significantly greater tensile bond strength at the metal/adhesive interface.

  9. Water-thinnable polymers for durable coatings for different materials

    SciTech Connect

    Jankowski, Piotr Kijowska, Dorota

    2014-05-15

    The methods of obtaining water-thinnable polymers - water-thinnable unsaturated polyester resins (WTUPR) - by polycondensation were elaborate and optimized. As hydrophilic monomers different types of sulfonate monomers were used. The monomers, with sulfonate groups and other reactive groups, were obtained by sulfonation of organic compounds with satisfactory yield. All products were analyzed by {sup 1}H NMR and {sup 13}C NMR spectra. WTUPR were used as polymeric binders for coatings applications. Coatings with relatively high pendulum hardness, good properties and durability, useful for practical applications, were obtained. Typical existing equipment for the production of unsaturated polyester resins can be applied for the industrial preparation of WTUPR.

  10. Enhanced transport of Si-coated nanoscale zero-valent iron particles in porous media.

    PubMed

    HonetschlÄgerová, Lenka; Janouškovcová, Petra; Kubal, Martin

    2016-01-01

    Laboratory column experiments were conducted to evaluate the effect of previously described silica coating method on the transport of nanoscale zero-valent iron (nZVI) in porous media. The silica coating method showed the potential to prevent the agglomeration of nZVI. Transport experiments were conducted using laboratory-scale sand-packed columns at conditions that were very similar of natural groundwater. Transport properties of non-coated and silica-coated nZVI are investigated in columns of 40 cm length, which were filled with porous media. A suspension was injected in three different Fe particle concentrations (100, 500, and 1000 mg/L) at flow 5  mL/min. Experimental results were compared using nanoparticle attachment efficiency and travel distances which were calculated by classical particle filtration theory. It was found that non-coated particles were essentially immobile in porous media. In contrast, silica-coated particles showed significant transport distances at the tested conditions. Results of this study suggest that silica can increase nZVI mobility in the subsurface.

  11. Porous networks derived from synthetic polymer-clay complexes

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Elder, D.L.

    1995-05-12

    Synthetic hectorites were hydrothermally crystallized with direct incorporation of a cationic polymer poly(dimethyl diallyl ammonium chloride) (PDDA), and two neutral cellulosic polymers hydroxypropyl methylcellulose (HPMC) and hydroxyethyl cellulose (HEC). Synthetic PDDA-hectorite displays the lowest d-spacing at 15.8 {Angstrom} along with less polymer incorporation (7.8 wt % organic) than the neutral polymers (18--22 wt % organic). Thermal analysis and small angle neutron scattering were used to further examine the polymer-clay systems. Clay platelets of the largest size and best stacking order occur when cationic PDDA polymer is used. PDDA also enhances these properties over the crystallites prepared for a control mineral, where no polymer is used. HEC acts to aggregate the silica, leaving less to react to form clay. The clay platelets which result from HEC are small, not stacked to a large degree, and oriented randomly. Neutral HPMC acts more like cationic PDDA in that larger clay platelets are allowed to form. The extended microstructure of the clay network remains undisturbed after polymer is removed by calcination. When no polymer is used, the synthetic hectorite has a N{sub 2} BET surface area of 200 M{sup 2}/gm, even after calcination. This increases by 20--50% for the synthetic polymer-hectorites after the polymer is removed by calcination.

  12. Gas chromatographic separation of nitrogen, oxygen, argon, and carbon monoxide using custom-made porous polymers from high purity divinylbenzene

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Ohara, D.; Hollis, O. L.

    1984-01-01

    Existing porous polymers were surveyed for their ability to separate the subject gases. Certain products that showed more promise than others were synthesized and the existing synthetic procedures studied and modified to produce new polymers with enhanced ability to separate the subject gases. Evaluation of the porous polymers was carried out practically by gas chromatography at ambient temperature. The modified synthetic procedures were somewhat simpler than the originals. The new porous polymers made with high purity divinylbenzene enabled use of shorter columns to obtain the separations desired.

  13. Advanced Coatings from Natural-Based Polymers for Metals

    DTIC Science & Technology

    2000-07-01

    polysaccharide biopolymers originating from pectin, starch , and chitosan as renewable agricultural and marine resources, and on assessing their potential as the...excellent salt-spray resistance. 14. SUBJECT TERMS 15. NUMBER IF PAGES Coating, Corrosion, Aluminum, Biopolymer, Starch , Chitosan 7 16. PRICE CODE 17...The natural polymers used in this program were the corn-or potato- starch and crab or shrimp shells-chitosan obtained from renewable agricultural and

  14. Liquid Crystal Alignment Control Using Polymer Filament and Polymer Layers Coated on Substrates

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2005-04-01

    We investigated liquid crystal (LC) alignment in LC cells containing an aligned cellulose filament sandwiched by thin polymer layers coated on substrates. Three types of polymer material, namely polystyrene (PS), polyvinyl alcohol (PVA) and polyimide (PI), were used as polymer layers. LC alignment areas induced on both sides of the filament were large in the order of PS, PVA and PI. In the case of the PS layer, the average LC alignment area reached approximately 100 μm in the direction perpendicular to the polymer filament. The molecular interaction between the LC and the PS layer is thought to be weak and it does not disturb the LC alignment due to the polymer filament. On the other hand, rubbed PS layers were used as polymer layers of the LC cell, where the LC alignment direction induced by the rubbed PS layer was perpendicular to the polymer filament. It was found that the LC alignment near the polymer filament gradually bent in the cell plane. The result suggests that various three-dimensional LC alignments can be realized by the combination of the polymer filament and substrate surface.

  15. Design of sustained release fine particles using two-step mechanical powder processing: particle shape modification of drug crystals and dry particle coating with polymer nanoparticle agglomerate.

    PubMed

    Kondo, Keita; Ito, Natsuki; Niwa, Toshiyuki; Danjo, Kazumi

    2013-09-10

    We attempted to prepare sustained release fine particles using a two-step mechanical powder processing method; particle-shape modification and dry particle coating. First, particle shape of bulk drug was modified by mechanical treatment to yield drug crystals suitable for the coating process. Drug crystals became more rounded with increasing rotation speed, which demonstrates that powerful mechanical stress yields spherical drug crystals with narrow size distribution. This process is the result of destruction, granulation and refinement of drug crystals. Second, the modified drug particles and polymer coating powder were mechanically treated to prepare composite particles. Polymer nanoparticle agglomerate obtained by drying poly(meth)acrylate aqueous dispersion was used as a coating powder. The porous nanoparticle agglomerate has superior coating performance, because it is completely deagglomerated under mechanical stress to form fine fragments that act as guest particles. As a result, spherical drug crystals treated with porous agglomerate were effectively coated by poly(meth)acrylate powder, showing sustained release after curing. From these findings, particle-shape modification of drug crystals and dry particle coating with nanoparticle agglomerate using a mechanical powder processor is expected as an innovative technique for preparing controlled-release coated particles having high drug content and size smaller than 100 μm.

  16. 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.

  17. Porous polymer film calcium ion chemical sensor and method of using the same

    DOEpatents

    Porter, M.D.; Chau, L.K.

    1991-02-12

    A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porous polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction. 1 figure.

  18. Enhanced bistability by guest inclusion in Fe(II) spin crossover porous coordination polymers.

    PubMed

    Muñoz Lara, Francisco J; Gaspar, Ana B; Aravena, Daniel; Ruiz, Eliseo; Muñoz, M Carmen; Ohba, Masaaki; Ohtani, Ryo; Kitagawa, Susumu; Real, José A

    2012-05-16

    Inclusion of thiourea guest molecules in the tridimensional spin crossover porous coordination polymers {[Fe(pyrazine)[M(CN)(4)]} (M = Pd, Pt) leads to novel clathrates exhibiting unprecedented large thermal hysteresis loops of ca. 60 K wide centered near room temperature.

  19. 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.

  20. One-dimensional alignment of strong Lewis acid sites in a porous coordination polymer.

    PubMed

    Kajiwara, Takashi; Higuchi, Masakazu; Yuasa, Akihiro; Higashimura, Hideyuki; Kitagawa, Susumu

    2013-11-18

    A new lanthanoid porous coordination polymer, La-BTTc (BTTc = benzene-1,3,5-tris(2-thiophene-5-carboxylate)), was synthesized and structurally characterized to have densely aligned one-dimensional open metal sites, which were found to act as strong Lewis acid sites after the removal of the coordinated solvent.

  1. Nanostructured porous silicon-polymer-based hybrids: from biosensing to drug delivery.

    PubMed

    Bonanno, Lisa M; Segal, Ester

    2011-12-01

    Organic-inorganic hybrids with controlled morphology at the nanometer scale represent an exciting class of materials that can display unique properties that are culminated by the characteristics of each building block. Recent research highlights their potential as biomimetic composites and application in biosensing, lab-on-chip devices, drug delivery and tissue engineering. Here we focus on the emerging class of biomaterials that integrate polymers with nanostructured porous silicon and emphasize the design of advanced 'smart' functions. Porous silicon is an appealing biomaterial due to the ease of tuning its many attractive properties, including pore morphology, photonic properties, biocompatibility, biodegradation and surface chemistry. An overview is presented of the principle concepts of design and fabrication of porous silicon-polymer hybrids. Current achievements in biomedical applications are reviewed and future prospects and challenges for healthcare technologies are discussed.

  2. Corrosion resistance of biodegradable Mg with a composite polymer coating.

    PubMed

    Chen, Peng; Sun, Jiadi; Zhu, Ye; Yu, Xun; Meng, Long; Li, Yang; Liu, Xiaoya

    2016-12-01

    Degrading Mg and its alloys are a category of implant materials for bone surgery, but rapid corrosion in physiological environment limits their clinical applications. To improve the corrosion resistance of Mg-based implants, a biodegradable composite polymer coating is deposited on an Mg rod in this work. The strategy is to decorate Mg surfaces with poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin/hydroxyapatite (γ-PGA-g-AMC/HAp) composite nanoparticles through electrophoretic deposition in ethanol. The morphology and chemical composition of the resulting coating material are determined by scanning electron microscopy and Fourier transform infrared spectroscopy. Sample rods of bare Mg and coated Mg are implanted intramedullary into the femora of New Zealand white rabbits, periodic radiography and post-autopsy histopathology of each sample are analyzed. The obtained in vivo results clearly confirm that the coating material decreases degradation rate of the underlying Mg sample and appears good histocompatibility and osteoinductivity. The main aim of this work is to investigate the degradation process of bare Mg and coated Mg samples in bone environment and their effect on the surrounding bone tissue.

  3. Coating of zinc ferrite particles with a conducting polymer, polyaniline.

    PubMed

    Stejskal, Jaroslav; Trchová, Miroslava; Brodinová, Jitka; Kalenda, Petr; Fedorova, Svetlana V; Prokes, Jan; Zemek, Josef

    2006-06-01

    Particles of zinc ferrite, ZnOFe2O3, were coated with polyaniline (PANI) phosphate during the in situ polymerization of aniline in an aqueous solution of phosphoric acid. The PANI-ferrite composites were characterized by FTIR spectroscopy. X-ray photoelectron spectroscopy was used to determine the degree of coating with a conducting polymer. Even a low content of PANI, 1.4 wt%, resulted in the 45% coating of the particles' surface. On the other hand, even at high PANI content, the coating of ferrite surface did not exceeded 90%. This is explained by the clustering of hydrophobic aniline oligomers at the hydrophilic ferrite surface and the consequent irregular PANI coating. The conductivity increased from 2 x 10(-9) to 6.5 S cm(-1) with increasing fraction of PANI phosphate in the composite. The percolation threshold was located at 3-4 vol% of the conducting component. In the absence of any acid, a conducting product, 1.4 x 10(-2) Scm(-1), was also obtained. As the concentration of phosphoric acid increased to 3 M, the conductivity of the composites reached 1.8 S cm(-1) at 10-14 wt% of PANI. The ferrite alone can act as an oxidant for aniline; a product having a conductivity 0.11 S cm(-1) was obtained after a one-month immersion of ferrite in an acidic solution of aniline.

  4. Erosion Resistant Coatings for Polymer Matrix Composites in Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Sutter, James K.; Naik, Subhash K.; Horan, Richard; Miyoshi, Kazuhisa; Bowman, Cheryl; Ma, Kong; Leissler, George; Sinatra, Raymond; Cupp, Randall

    2003-01-01

    Polymer Matrix Composites (PMCs) offer lightweight and frequently low cost alternatives to other materials in many applications. High temperature PMCs are currently used in limited propulsion applications replacing metals. Yet in most cases, PMC propulsion applications are not in the direct engine flow path since particulate erosion degrades PMC component performance and therefore restricts their use in gas turbine engines. This paper compares two erosion resistant coatings (SANRES and SANPRES) on PMCs that are useful for both low and high temperature propulsion applications. Collaborating over a multi-year period, researchers at NASA Glenn Research Center, Allison Advanced Developed Company, and Rolls-Royce Corporation have optimized these coatings in terms of adhesion, surface roughness, and erosion resistance. Results are described for vigorous hot gas/particulate erosion rig and engine testing of uncoated and coated PMC fan bypass vanes from the AE 3007 regional jet gas turbine engine. Moreover, the structural durability of these coatings is described in long-term high cycle fatigue tests. Overall, both coatings performed well in all tests and will be considered for applications in both commercial and defense propulsion applications.

  5. Sector spin coating for fast preparation of polymer libraries.

    PubMed

    de Gans, Berend-Jan; Wijnans, Sanne; Woutes, Daan; Schubert, Ulrich S

    2005-01-01

    The feasibility of sector spin coating (or combinatorial spin-coating) is demonstrated (i.e., spin coating of various samples onto one single substrate using a metal template to divide the substrate into sectors). Film thickness increases in an angular direction against the sense of rotation. In the radial direction, the film thickness is constant within 2%. A library of 8 poly(methyl methacrylate)/polystyrene-blends with varying composition was spin coated and subsequently analyzed using automated atomic force microscopy: 24 measurements could be performed within 72 min. The contact angles of a library of 16 polyoxazoline diblock copolymers were measured using one substrate with 16 spin-coated sectors. Forty-eight measurements could be performed within 50 min. On the basis of the surface energies calculated using the Owens-Wendt-Rath-Kaeble method, the library can be divided into three groups of polymers: those containing a dispersive nonyloxazoline block, those containing a polar phenyloxazoline block, and those containing neither.

  6. Substrate dependent stability of conducting polymer coatings on medical electrodes.

    PubMed

    Green, Rylie A; Hassarati, Rachelle T; Bouchinet, Lucie; Lee, Chaekyung S; Cheong, Gin L M; Yu, Jin F; Dodds, Christopher W; Suaning, Gregg J; Poole-Warren, Laura A; Lovell, Nigel H

    2012-09-01

    Conducting polymer (CP) coatings on medical electrodes have the potential to provide superior performance when compared to conventional metallic electrodes, but their stability is strongly dependant on the substrate properties. The aim of this study was to examine the effect of laser roughening of underlying platinum (Pt) electrode surfaces on the mechanical, electrical and biological performance of CP coatings. In addition, the impact of dopant type on electrical performance and stability was assessed. The CP poly(ethylene dioxythiophene) (PEDOT) was coated on Pt microelectrode arrays, with three conventional dopant ions. The in vitro electrical characteristics were assessed by cyclic voltammetry and biphasic stimulation. Results showed that laser roughening of the underlying substrate did not affect the charge injection limit of the coated material, but significantly improved the passive stability and chronic stimulation lifetime without failure of the coating. Accelerated material ageing and long-term biphasic stimulus studies determined that some PEDOT variants experienced delamination within as little as 10 days when the underlying Pt was smooth, but laser roughening to produce a surface index of 2.5 improved stability, such that more than 1.3 billion stimulation cycles could be applied without evidence of failure. PEDOT doped with paratoluene sulfonate (PEDOT/pTS) was found to be the most stable CP on roughened Pt, and presented a surface topography which encouraged neural cell attachment.

  7. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.

  8. Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

    PubMed Central

    Shayganpour, Amirreza; Rebaudi, Alberto; Cortella, Pierpaolo; Diaspro, Alberto

    2015-01-01

    Summary Clinical long-term osteointegration of titanium-based biomedical devices is the main goal for both dental and orthopedical implants. Both the surface morphology and the possible functionalization of the implant surface are important points. In the last decade, following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure titanium. We anodized dental implants made of commercial grade titanium under different experimental conditions and characterized the resulting surface morphology with scanning electron microscopy equipped with an energy dispersive spectrometer. The appearance of nanopores on these implants confirm that anodic porous titania can be obtained not only on ultrapure and flat titanium but also as a conformal coating on curved surfaces of real objects made of industrial titanium alloys. Raman spectroscopy showed that the titania phase obtained is anatase. Furthermore, it was demonstrated that by carrying out the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities. PMID:26665091

  9. Porous polymer/bioactive glass composites for soft-to-hard tissue interfaces.

    PubMed

    Zhang, Kai; Ma, Yue; Francis, Lorraine F

    2002-09-15

    Porous composites consisting of a polysulfone (or cellulose acetate) matrix and bioactive glass particles were prepared by phase separation techniques. Microstructures were designed for potential application as an interconnect between artificial cartilage and bone. The effects of polymer type, concentration and molecular weight, as well as bioactive glass size and content, on the microstructures of the composites were studied. The composites have asymmetric structures with dense top layers and porous structures beneath. The microstructural features depend most strongly on the type of polymer, the interaction between the polymer and bioactive glass, and the glass content. The dense top layer could be removed by abrasion to make a structure with large pores (20-150 microm) exposed. Composites were immersed in simulated body fluid at body temperature. The growth of hydroxycarbonate apatite inside and on the composites demonstrates their potential for integration with bone. Composite modulus and break strength increased with increasing glass content due to the change in composition and pore content.

  10. Synthesis of nanostructured porous silica coatings on titanium and their cell adhesive and osteogenic differentiation properties.

    PubMed

    Inzunza, Débora; Covarrubias, Cristian; Von Marttens, Alfredo; Leighton, Yerko; Carvajal, Juan Carlos; Valenzuela, Francisco; Díaz-Dosque, Mario; Méndez, Nicolás; Martínez, Constanza; Pino, Ana María; Rodríguez, Juan Pablo; Cáceres, Mónica; Smith, Patricio

    2014-01-01

    Nanostructured porous silica coatings were synthesized on titanium by the combined sol-gel and evaporation-induced self-assembly process. The silica-coating structures were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen sorptometry. The effect of the nanoporous surface on apatite formation in simulated body fluid, protein adsorption, osteoblast cell adhesion behavior, and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) is reported. Silica coatings with highly ordered sub-10 nm porosity accelerate early osteoblast adhesive response, a favorable cell response that is attributed to an indirect effect due to the high protein adsorption observed on the large-specific surface area of the nanoporous coating but is also probably due to direct mechanical stimulus from the nanostructured topography. The nanoporous silica coatings, particularly those doped with calcium and phosphate, also promote the osteogenic differentiation of hBMSCs with spontaneous mineral nodule formation in basal conditions. The bioactive surface properties exhibited by the nanostructured porous silica coatings make these materials a promising alternative to improve the osseointegration properties of titanium dental implants and could have future impact on the nanoscale design of implant surfaces.

  11. Preparation, antibacterial effects and corrosion resistant of porous Cu-TiO2 coatings

    NASA Astrophysics Data System (ADS)

    Wu, Haibo; Zhang, Xiangyu; Geng, Zhenhua; Yin, Yan; Hang, Ruiqiang; Huang, Xiaobo; Yao, Xiaohong; Tang, Bin

    2014-07-01

    Antibacterial TiO2 coatings with different concentrations of Cu (Cu-TiO2) were prepared by micro-arc oxidation (MAO) on pre-sputtered CuTi films. The effect of Cu concentrations in CuTi films on the MAO process was investigated. The Cu-TiO2 coatings were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Cu-TiO2 coatings was evaluated via potentiodynamic polarization method. The antibacterial properties were assessed by two methods: spread plate method and fluorescence staining. The experimental results demonstrate that the coatings are porous and consist of anatase phase, rutile phase and unoxidized titanium. The CuTi films are almost completely oxidized and the thickness of all MAO coatings is about 5-10 μm. Cu mainly exists as CuO in the TiO2 coatings. The Cu-TiO2 coatings exhibit excellent antibacterial activities, and the antibacterial rate gradually rise with the increase in Cu concentration in the MAO coatings. The corrosion resistance of MAO coatings is also improved slightly.

  12. Synthesis of Highly Porous Coordination Polymers with Open Metal Sites for Enhanced Gas Uptake and Separation.

    PubMed

    Song, Kyung Seob; Kim, Daeok; Polychronopoulou, Kyriaki; Coskun, Ali

    2016-10-12

    Metal-containing amorphous microporous polymers are an emerging class of functional porous materials in which the surface properties and functions of polymers are dictated by the nature of the metal ions incorporated into the framework. In an effort to introduce coordinatively unsaturated metal sites into the porous polymers, we demonstrate herein an aqueous-phase synthesis of porous coordination polymers (PCPs) incorporating bis(o-diiminobenzosemiquinonato)-Cu(II) or -Ni(II) bridges by simply reacting hexaminotriptycene with CuSO4·5H2O [Cu(II)-PCP] or NiCl2·6H2O [Ni(II)-PCP] in H2O. The resulting polymers showed surface areas of up to 489 m(2) g(-1) along with a narrow pore size distribution. The presence of open metal sites significantly improved the gas affinity of these frameworks, leading to an exceptional isosteric heat of adsorption of 10.3 kJ·mol(-1) for H2 at zero coverage. The high affinities of Cu(II)- and Ni(II)-PCPs toward CO2 prompted us to investigate the removal of CO2 from natural and landfill gas conditions. We found that the higher affinity of Cu(II)-PCP compared to that of Ni(II)-PCP not only allowed for the tuning of the affinity of CO2 molecules toward the sorbent, but also led to an exceptional CO2/CH4 selectivity of 35.1 for landfill gas and 20.7 for natural gas at 298 K. These high selectivities were further verified by breakthrough measurements under the simulated natural and landfill gas conditions, in which both Cu(II)- and Ni(II)-PCPs showed complete removal of CO2. These results clearly demonstrate the promising attributes of metal-containing porous polymers for gas storage and separation applications.

  13. 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.

  14. Versatile surface engineering of porous nanomaterials with bioinspired polyphenol coatings for targeted and controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Li, Juan; Wu, Shuxian; Wu, Cuichen; Qiu, Liping; Zhu, Guizhi; Cui, Cheng; Liu, Yuan; Hou, Weijia; Wang, Yanyue; Zhang, Liqin; Teng, I.-Ting; Yang, Huang-Hao; Tan, Weihong

    2016-04-01

    The development of biocompatible drug delivery systems with targeted recognition and controlled release has experienced a number of design challenges, including, for example, complicated preparation steps and premature drug release. Herein, we address these problems through an in situ self-polymerization method that synthesizes biodegradable polyphenol-coated porous nanomaterials for targeted and controlled drug delivery. As a proof of concept, we synthesized polyphenol-coated mesoporous silica nanoparticles, termed MSN@polyphenol. The polyphenol coatings not only improved colloidal stability and prevented premature drug leakage, but also provided a scaffold for immobilization of targeting moieties, such as aptamers. Both immobilization of targeting aptamers and synthesis of polyphenol coating are easily accomplished without the aid of any other organic reagents. Importantly, the polyphenol coating (EGCg) used in this study could be biodegraded by acidic pH and intracellular glutathione, resulting in the release of trapped anticancer drugs. Based on confocal fluorescence microscopy and cytotoxicity experiments, drug-loaded and polyphenol-coated MSNs were shown to possess highly efficient internalization and an apparent cytotoxic effect on target cancer, but not control, cells. Our results suggest that these highly biocompatible and biodegradable polyphenol-coated MSNs are promising vectors for controlled-release biomedical applications and cancer therapy.The development of biocompatible drug delivery systems with targeted recognition and controlled release has experienced a number of design challenges, including, for example, complicated preparation steps and premature drug release. Herein, we address these problems through an in situ self-polymerization method that synthesizes biodegradable polyphenol-coated porous nanomaterials for targeted and controlled drug delivery. As a proof of concept, we synthesized polyphenol-coated mesoporous silica nanoparticles

  15. Effect of the properties of a porous coating on boundary layer stability. [considering porous slates

    NASA Technical Reports Server (NTRS)

    Gaponov, S. A.

    1978-01-01

    Drawing off gas from the boundary layer is a well-known method for increasing the stability of boundary layers. The increase in stability is primarily connected with a change in the velocity profile form in the case of suction. On the basis of the assumption that the velocity perturbations on a porous slate do not equal zero, the influence of the properties of a permeable surface upon the boundary layer stability were studied.

  16. Porous α-Al2O3 thermal barrier coatings with dispersed Pt particles prepared by cathode plasma electrolytic deposition

    NASA Astrophysics Data System (ADS)

    Wang, Peng; He, Ye-dong; Deng, Shun-jie; Zhang, Jin

    2016-01-01

    Porous α-Al2O3 thermal barrier coatings (TBCs) containing dispersed Pt particles were prepared by cathode plasma electrolytic deposition (CPED). The influence of the Pt particles on the microstructure of the coatings and the CPED process were studied. The prepared coatings were mainly composed of α-Al2O3. The average thickness of the coatings was approximately 100 μm. Such single-layer TBCs exhibited not only excellent high-temperature cyclic oxidation and spallation resistance, but also good thermal insulation properties. Porous α-Al2O3 TBCs inhibit further oxidation of alloy substrates because of their extremely low oxygen diffusion rate, provide good thermal insulation because of their porous structure, and exhibit excellent mechanical properties because of the toughening effect of the Pt particles and because of stress relaxation induced by deformation of the porous structure.

  17. Universal hydrophilic coating of thermoplastic polymers currently used in microfluidics.

    PubMed

    Zilio, Caterina; Sola, Laura; Damin, Francesco; Faggioni, Lucia; Chiari, Marcella

    2014-02-01

    A number of materials used to fabricate disposable microfluidic devices are hydrophobic in nature with water contact angles on their surface ranging from 80° to over 100°. This characteristic makes them unsuitable for a number of microfluidic applications. Both the wettability and analyte adsorption parameters are highly dependent on the surface hydrophobicity. In this article, we propose a general method to coat the surface of five materials: polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), polyethylene terephthalate (PET), polycarbonate (PC), and polytetrafluoroethylene (PTFE). This fast and robust process, which is easily implementable in any laboratory including microfabrication clean room facilities, was devised by combining gas-phase and wet chemical modification processes. Two different coatings that improve the surface hydrophilicity were prepared via the "dip and rinse" approach by immersing the plasma oxidized materials into an aqueous solution of two different poly(dimethylacrylamide) copolymers incorporating a silane moiety and functionalized with either N-acryloyloxysuccinimide (NAS) (poly(DMA-NAS-MAPS) or glycidyl methacrylate (GMA) (poly(DMA-GMA-MAPS). The coating formation was confirmed by contact angle (CA) analysis comparing the variation of CAs of uncoated and coated surfaces subjected to different aging treatments. The antifouling character of the polymer was demonstrated by fluorescence and interferometric detection of proteins adsorbed on the surafce. This method is of great interest in microfluidics due to its broad applicability to a number of materials with varying chemical compositions.

  18. Surface dynamics and mechanics in liquid crystal polymer coatings

    NASA Astrophysics Data System (ADS)

    Liu, Danqing; Broer, Dirk J.

    2015-03-01

    Based on liquid crystal networks we developed `smart' coatings with responsive surface topographies. Either by prepatterning or by the formation of self-organized structures they can be switched on and off in a pre-designed manner. Here we provide an overview of our methods to generate coatings that form surface structures upon the actuation by light. The coating oscillates between a flat surface and a surface with pre-designed 3D micro-patterns by modulating a light source. With recent developments in solid state lighting, light is an attractive trigger medium as it can be integrated in a device for local control or can be used remotely for flood or localized exposure. The basic principle of formation of surface topographies is based on the change of molecular organization in ordered liquid crystal polymer networks. The change in order leads to anisotropic dimensional changes with contraction along the director and expansion to the two perpendicular directions and an increase in volume by the formation of free volume. These two effects work in concert to provide local expansion and contraction in the coating steered by the local direction of molecular orientation. The surface deformation, expressed as the height difference between the activated regions and the non-activated regions divided by the initial film thickness, is of the order of 20%. Switching occurs immediately when the light is switched `on' and `off' and takes several tens of seconds.

  19. Flow of polymer solutions in porous media: inadequacy of the capillary model

    SciTech Connect

    Duda, J.L.; Klaus, E.E.; Hong, S.A.

    1983-08-01

    Experimental measurements show that conventional capillary models are inadequate for the description of the flow of nonlinear purely viscous solutions in porous media. A theoretical analysis indicates that any model for the flow of purely viscous polymer solutions in porous media must meet 2 criteria. First, the model must include expansion and contraction regions where excess pressure drops occur. Secondly, the rheologic model for the fluid must include the characteristic transition from Newtonian behavior at low shear rates to shear-thinning behavior at high shear rates. 17 references.

  20. Controlled drug release from antibiotic-loaded layered double hydroxide coatings on porous titanium implants in a mouse model.

    PubMed

    Badar, Muhammad; Rahim, Muhammad Imran; Kieke, Marc; Ebel, Thomas; Rohde, Manfred; Hauser, Hansjörg; Behrens, Peter; Mueller, Peter P

    2015-06-01

    As an alternative to degradable organic coatings the possibility of using layered double hydroxides (LDHs) to generate implant coatings for controlled drug delivery was evaluated in vivo and in vitro. Coatings prepared from LDH suspensions dissolved slowly and appeared compatible with cultured cells. LDH coatings loaded with an antibiotic resulted in antibacterial effects in vitro. The LDH coating prolonged the drug release period and improved the proliferation of adherent cells in comparison to pure drug coatings. However, during incubation in physiological solutions the LDH coatings became brittle and pieces occasionally detached from the surface. For stress protection porous titanium implants were investigated as a substrate for the coatings. The pores prevented premature detachment of the coatings. To evaluate the coated porous implants in vivo a mouse model was established. To monitor bacterial infection of implants noninvasive in vivo imaging was used to monitor luminescently labeled Pseudomonas aeruginosa. In this model porous implants with antibiotic-loaded LDH coatings could antagonize bacterial infections for over 1 week. The findings provide evidence that delayed drug delivery from LDH coatings could be feasible in combination with structured implant surfaces.

  1. Effective diffusion coefficient of biological liquids in porous calcium phosphate coatings

    NASA Astrophysics Data System (ADS)

    Nazarenko, N. N.; Knyazeva, A. G.

    2016-11-01

    The study offers a method to estimate effective diffusion coefficients for transfer of biological liquids in porous materials. The method is based on the analysis of areas occupied by pores and solid materials on slice images. The possibility is shown for ascertaining a correlation between the effective coefficient and technological conditions because different structure and porosity are observed experimentally. The correlations of effective diffusion coefficients with the production voltage for different coating-base compositions, on which the coating was grown, have been built.

  2. Effect of nano-hydroxyapatite coating on the osteoinductivity of porous biphasic calcium phosphate ceramics

    PubMed Central

    2014-01-01

    Background Porous biphasic calcium phosphate (BCP) ceramics exhibit good biocompatibility and bone conduction but are not inherently osteoinductive. To overcome this disadvantage, we coated conventional porous BCP ceramics with nano-hydroxyapatite (nHA). nHA was chosen as a coating material due to its high osteoinductive potential. Methods We used a hydrothermal deposition method to coat conventional porous BCP ceramics with nHA and assessed the effects of the coating on the physical and mechanical properties of the underlying BCP. Next, its effects on mesenchymal stem cell (MSC) attachment, proliferation, viability, and osteogenic differentiation were investigated. Results nHA formed a deposited layer on the BCP surface, and synthesized nHA had a rod-like shape with lengths ranging from ~50–200 nm and diameters from ~15–30 mm. The nHA coating did not significantly affect the density, porosity, flexural strength, or compressive strength of the underlying BCP (P > 0.1). Scanning electron microscopy showed MSC attachment to the scaffolds, with a healthy morphology and anchorage to nHA crystals via cytoplasmic processes. The densities of MSCs attached on BCP and nHA-coated BCP scaffolds were 62 ± 26 cells/mm2 and 63 ± 27 cells/mm2 (P > 0.1), respectively, after 1 day and 415 ± 62 cells/mm2 and 541 ± 35 cells/mm2 (P < 0.05) respectively, after 14 days. According to an MTT assay, MSC viability was higher on nHA-coated BCP scaffolds than on BCP scaffolds (P < 0.05). In addition, MSCs on nHA-coated BCP scaffolds produced more alkaline phosphatase, collagen type I, and osteocalcin than MSCs on BCP scaffolds (P < 0.05). Conclusions Our results demonstrate that BCP scaffolds coated with nHA were more conducive for MSC adhesion, proliferation, and osteogenic differentiation than conventional, uncoated BCP scaffolds, indicating that nHA coating can enhance the osteoinductive potential of BCP ceramics, making this material more

  3. Adhesion of E. coli to silver- or copper-coated porous clay ceramic surfaces

    NASA Astrophysics Data System (ADS)

    Yakub, I.; Soboyejo, W. O.

    2012-06-01

    Porous ceramic water filters (CWFs), produced by sintering a mixture of clay and a combustible material (such as woodchips), are often used in point-of-use water filtration systems that occlude microbes by size exclusion. They are also coated with colloidal silver, which serves as a microbial disinfectant. However, the adhesion of microbes to porous clay surfaces and colloidal silver coated clay surfaces has not been studied. This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion force between Escherichia coli bacteria, colloidal silver, and porous clay-based ceramic surfaces. The adhesion of silver and copper nanoparticles is also studied in control experiments on these alternative disinfectant materials. The adhesive force between the wide range of possible bi-materials was measured using pull-off measurements during force microscopy. These were combined with measurements of AFM tip radii/substrate roughness that were incorporated into adhesion models to obtain the adhesion energies for the pair wise interaction. Of the three antimicrobial metals studied, the colloidal silver had the highest affinity for porous ceramic surface (125 ± 32 nN and ˜0.29 J/m2) while the silver nanoparticles had the highest affinity for E. coli bacteria (133 ± 21 nN and ˜0.39 J/m2). The implications of the results are then discussed for the design of ceramic water filter that can purify water by adsorption and size exclusion.

  4. Acid-etched microtexture for enhancement of bone growth into porous-coated implants.

    PubMed

    Hacking, S A; Harvey, E J; Tanzer, M; Krygier, J J; Bobyn, J D

    2003-11-01

    We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant. These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation.

  5. Bioinspired porous membranes containing polymer nanoparticles for wound healing.

    PubMed

    Ferreira, Ana M; Mattu, Clara; Ranzato, Elia; Ciardelli, Gianluca

    2014-12-01

    Skin damages covering a surface larger than 4 cm(2) require a regenerative strategy based on the use of appropriate wound dressing supports to facilitate the rapid tissue replacement and efficient self-healing of the lost or damaged tissue. In the present work, A novel biomimetic approach is proposed for the design of a therapeutic porous construct made of poly(L-lactic acid) (PLLA) fabricated by thermally induced phase separation (TIPS). Biomimicry of ECM was achieved by immobilization of type I collagen through a two-step plasma treatment for wound healing. Anti-inflammatory (indomethacin)-containing polymeric nanoparticles (nps) were loaded within the porous membranes in order to minimize undesired cell response caused by post-operative inflammation. The biological response to the scaffold was analyzed by using human keratinocytes cell cultures. In this work, a promising biomimetic construct for wound healing and soft tissue regeneration with drug-release properties was fabricated since it shows (i) proper porosity, pore size, and mechanical properties, (ii) biomimicry of ECM, and (iii) therapeutic potential.

  6. Distributed Pore Chemistry in Porous Organic Polymers in Tissue Culture Flasks

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1999-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclose. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  7. Dynamics of polymer film formation during spin coating

    SciTech Connect

    Mouhamad, Y.; Clarke, N.; Jones, R. A. L.; Geoghegan, M.; Mokarian-Tabari, P.

    2014-09-28

    Standard models explaining the spin coating of polymer solutions generally fail to describe the early stages of film formation, when hydrodynamic forces control the solution behavior. Using in situ light scattering alongside theoretical and semi-empirical models, it is shown that inertial forces (which initially cause a vertical gradient in the radial solvent velocity within the film) play a significant role in the rate of thinning of the solution. The development of thickness as a function of time of a solute-free liquid (toluene) and a blend of polystyrene and poly(methyl methacrylate) cast from toluene were fitted to different models as a function of toluene partial pressure. In the case of the formation of the polymer blend film, a concentration-dependent (Huggins) viscosity formula was used to account for changes in viscosity during spin coating. A semi-empirical model is introduced, which permits calculation of the solvent evaporation rate and the temporal evolution of the solute volume fraction and solution viscosity.

  8. Porous Silicon and Polymer Nanocomposites for Delivery of Peptide Nucleic Acids as Anti-MicroRNA Therapies.

    PubMed

    Beavers, Kelsey R; Werfel, Thomas A; Shen, Tianwei; Kavanaugh, Taylor E; Kilchrist, Kameron V; Mares, Jeremy W; Fain, Joshua S; Wiese, Carrie B; Vickers, Kasey C; Weiss, Sharon M; Duvall, Craig L

    2016-09-01

    Self-assembled polymer/porous silicon nanocomposites overcome intracellular and systemic barriers for in vivo application of peptide nucleic acid (PNA) anti-microRNA therapeutics. Porous silicon (PSi) is leveraged as a biodegradable scaffold with high drug-cargo-loading capacity. Functionalization with a diblock polymer improves PSi nanoparticle colloidal stability, in vivo pharmacokinetics, and intracellular bioavailability through endosomal escape, enabling PNA to inhibit miR-122 in vivo.

  9. Nano-Textured Fiber Coatings for Energy Absorbing Polymer Matrix Composite Materials

    DTIC Science & Technology

    2004-12-01

    NANO-TEXTURED FIBER COATINGS FOR ENERGY ABSORBING POLYMER MATRIX COMPOSITE MATERIALS R. E. Jensen and S. H. McKnight Army Research Laboratory...Textured Fiber Coatings For Energy Absorbing Polymer Matrix Composite Materials 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  10. Corrosion protection comparison of a chromate conversion coating to a novel conductive polymer coating on aluminum alloys

    SciTech Connect

    Racicot, R.J.; Yang, S.C.; Brown, R.

    1997-12-01

    Comparisons of the corrosion resistance performance of a novel polyaniline based double strand conductive polymer coating versus a chromate conversion coating on two aluminum alloys were made. Potentiodynamic scans, electrochemical impedance spectroscopy (EIS) in 0.5N NaCl solutions and ASTM B-117 salt spray tests were performed on coated samples of AA7075-T6 and AA2024-T3 aluminum alloys. Results show the conductive polymer film offers, at the least, an equivalent protection performance as the chromate coating with a two order of magnitude reduction in corrosion current densities in cyclic polarization tests, near equivalent impedance values and less undercutting of a scribed area in salt spray test samples. In an acidic salt solution of pH 3.6, the conductive polymer offers an improved performance with a one order of magnitude higher impedance over the chromate coatings.

  11. Development of Polymer Coatings for the ProSEDS Tether

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; Kamenetsky, Rachel R.; Finckenor, Miria; Wright, Ken

    2000-01-01

    The ProSEDS mission is designed to provide an on-orbit demonstration of the electrodynamic propulsion capabilities of tethers in space. The ProSEDS experiment will be a secondary payload on a Delta 11 unmanned, expendable booster. A 5 km conductive tether is attached to the deployer baseplate on the Delta 11 second stage and collects current from the low Earth orbit (LEO) plasma to facilitate de-orbit of the Delta II second stage. The conductive tether is attached to a 10-15 km non-conductive tether, which in turn is attached to an endmass. A bare metal tether would have the best conductivity but thermal concerns preclude this design. A conductive polymer developed by Triton Systems has been optimized for optimum conductivity and thermo-optical properties. The current design for the ProSEDS conductive tether is seven individually coated strands of 28 AWG aluminum wire, coated with 12.7 micrometers (0.5 mil) atomic oxygen-resistant conductive polymer composed of a mixture of COR and PANi, wrapped around a braided Kevlar 29 core. Extensive testing has been performed at the Marshall Space Flight Center to qualify this material for flight on ProSEDS. Atomic oxygen exposure has been performed, with solar absorptance and infrared emittance measured before and after exposure. Plasma chamber tests have been completed, as well as tether deployment tests. Also developed for the ProSEDS mission was the insulating polymer TOR-BP. Approximately 200 meters of the conductive tether closest to the Delta II second stage is insulated to prevent any electron reconnection to the tether from the plasma contactor. The insulating material is TOR-BP with a dielectric strength of TBD.

  12. Development of electrically conductive DLC coated stainless steel separators for polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasuo; Watanabe, Masanori; Toda, Tadao; Fujii, Toshiaki

    2013-06-01

    Polymer electrolyte fuel cell (PEFC) as one of generation devices of electrical power is rapidly expanding the market as clean energy instead of petroleum and atomic energy. Residential fuel cell goes into quantity production and introduction of fuel cell for use in automobiles starts in the year 2015 in Japan. Critical subject for making fuel cell expand is how to reduce cost of fuel cell. In this paper we describe about separator plate which domains large ratio of cost in fuel cell stack. In present time, carbon is used in material of residential fuel cell separator. Metal separators are developed in fuel cell for use in automobiles because of need of mechanical strength at first. In order to make fuel cell expand in market, further cost reduction is required. But the metal separator has problem that by using metal separator contact resistance occurred by metal corrosion increases and catalyst layer and membrane degrade. In recent time we found out to protect from corrosion and dissolution of metals by coating the film of porous free conductive DLC with plasma ion implantation and deposition technology that we have developed. Film of electrically conductive DLC was formed with high speed of 13 μm/hr by ICP plasma, and coating cost breakout was performed.

  13. 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

  14. Facile one-pot synthesis of porphyrin based porous polymer networks (PPNs) as biomimetic catalysts

    SciTech Connect

    Zou, LF; Feng, DW; Liu, TF; Chen, YP; Fordham, S; Yuan, S; Tian, J; Zhou, HC

    2015-01-01

    Stable porphyrin based porous polymer networks, PPN-23 and PPN-24, have been synthesized through a facile one-pot approach by the aromatic substitution reactions of pyrrole and aldehydes. PPN-24(Fe) shows high catalytic efficiency as a biomimetic catalyst in the oxidation reaction of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) in the presence of H2O2.

  15. Novel lubricated surface of titanium alloy based on porous structure and hydrophilic polymer brushes

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Xiong, Dangsheng; Niu, Yuxiang

    2014-10-01

    On the purpose of improving the tribological properties of titanium alloy through mimicking natural articular cartilage, porous structure was prepared on the surface of Ti6Al4V alloy by anodic oxidation method, and then hydrophilic polymer brushes were grafted onto its surface. Surface morphology of porous oxidized film was investigated by metalloscope and scanning electron microscope (SEM). The composition and structure of modified surface were characterized by Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR/ATR), and the wettability was also evaluated. Friction and wear properties of modified alloys sliding against ultra-high molecular weight polyethylene (UHMWPE) were tested by a pin-on-disc tribometer in physiological saline. The results showed that, the optimum porous structure treated by anodic oxidation formed when the voltage reached as high as 100 V. Hydrophilic monomers [Acrylic acid (AA) and 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS)] were successfully grafted onto porous Ti6Al4V surface to form polymer brushes by UV radiation. The change of contact angle showed that wettability of modified Ti6Al4V was improved significantly. The friction coefficient of modified Ti6Al4V was much lower and more stable than untreated ones. The lowest friction coefficient was obtained when the sample was anodized at 100 V and grafted with DMMPPS, and the value was 0.132. The wear of modified samples was also obviously improved.

  16. Fabrication of Polymer Microneedle Electrodes Coated with Nanoporous Parylene

    NASA Astrophysics Data System (ADS)

    Nishinaka, Yuya; Jun, Rina; Setia Prihandana, Gunawan; Miki, Norihisa

    2013-06-01

    In this study, we demonstrate the fabrication of polymer microneedle electrodes covered with a nanoporous parylene film that can serve as flexible electrodes for a brain-machine interface. In brain wave measurement, the electric impedance of electrodes should be below 10 kΩ at 15 Hz, and the conductive layer needs to be protected to survive its insertion into the stratum corneum. Polymer microneedles can be used as substrates for flexible electrodes, which can compensate for the movement of the skin; however, the adhesion between a conductive metal film, such as a silver film, and a polymer, such as poly(dimethylsiloxane) (PDMS), is weak. Therefore, we coated the electrode surface with a nanoporous parylene film, following the vapor deposition of a silver film. When the porosity of the parylene film is appropriate, it protects the silver film while allowing the electrode to have sufficient conductivity. The porosity can be controlled by adjusting the amount of the parylene dimer used for the deposition or the parylene film thickness. We experimentally verified that a conductive membrane was successfully protected while maintaining a conductivity below 10 kΩ when the thickness of the parylene film was between 25 and 38 nm.

  17. Bioactive and Porous Metal Coatings for Improved Tissue Regeneration

    SciTech Connect

    Campbell, A. A.

    2000-01-01

    Our first objective was to develop the SIM process for the deposition of calcium phosphate films. This process is based on the observation that, in nature, living organisms use macromolecules to control the nucleation and growth of mineral phases. These macromolecules act as templates where various charged functional groups, contained within the molecule, can interact with the ions in the surrounding media, thus stimulating crystal nucleation and growth. Rather than using complex proteins or biopolymers, surface modification schemes were developed to place simple functional groups on the underlying substrate using self-assembling monolayers. Once the substrate was chemically modified, it was then placed into an aqueous solution containing soluble precursors of the desired mineral coating. Solution pH, ionic concentration and temperature is maintained in a regime where the solution is supersaturated with respect to the desired mineral phase, thereby creating the driving force for nucleation and growth.

  18. Revealing Amphiphilic Nanodornains of Anti-Biofouling Polymer Coatings

    SciTech Connect

    Amadei, CA; Yang, R; Chiesa, M; Gleason, KK; Santos, S

    2014-04-09

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be similar to 1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry.

  19. Hydrophobic liquid-infused porous polymer surfaces for antibacterial applications.

    PubMed

    Li, Junsheng; Kleintschek, Tanja; Rieder, Annika; Cheng, Yin; Baumbach, Tilo; Obst, Ursula; Schwartz, Thomas; Levkin, Pavel A

    2013-07-24

    Biofilms represent a fundamental problem in environmental biology, water technology, food hygiene as well as in medical and technical systems. Recently introduced slippery liquid-infused porous surface (SLIPS) showed great promise for preventing biofilm formation owing to the low surface energy of such surface in combination with its self-cleaning properties. In this study we demonstrated a novel hydrophobic liquid-infused porous poly(butyl methacrylate-co-ethylene dimethacrylate) surface (slippery BMA-EDMA) with bacteria-resistance in BM2 mineral medium and long-term stability in aqueous environments. We showed that the slippery BMA-EDMA surface prevents biofilm formation of different strains of opportunistic pathogen Pseudomonas aeruginosa for at least up to 7 days in low nutrient medium. Only ∼1.8% of the slippery surface was covered by the environmental P. aeruginosa PA49 strain under investigation. In uncoated glass controls the coverage of surfaces reached ∼55% under the same conditions. However, in high nutrient medium, more relevant to physiological conditions, the biofilm formation on the slippery surface turned out to be highly dependent on the bacterial strain. Although the slippery surface could prevent biofilm formation of most of the P. aeruginosa strains tested (∼1% surface coverage), the multiresistant P. aeruginosa strain isolated from wastewater was able to cover up to 12% of the surface during 7 days of incubation. RAPD-PCR analysis of the used P. aeruginosa strains demonstrated their high genome variability, which might be responsible for their difference in biofilm formation on the slippery BMA-EDMA surface. The results show that although the slippery BMA-EDMA surface has a great potential against biofilm formation, the generality of its bacteria resistant properties is still to be improved.

  20. Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks

    SciTech Connect

    Zhang, L.; Zhou, J.; Huang, J.; Gong, P. Zhou, Q.; Zheng, L.; Du, Y.

    1999-11-01

    Interpenetrating polymer network (IPN) coatings synthesized from castor-oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80--100 C for 2--5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity-average molecular weight, M{sub {eta}}, and the weight of the degraded films decreased sharply with the progress of degradation. The degradation half-lifes, t{sub 1/2}, of the films in soil at 30 C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC {gt} RCNC {gt} RCCH {gt} RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO{sub 2} evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO{sub 2}, H{sub 2}O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.

  1. Poorly water-soluble drug nanoparticles via solvent evaporation in water-soluble porous polymers.

    PubMed

    Roberts, Aled D; Zhang, Haifei

    2013-04-15

    A generic method is described to form poorly water-soluble drug nanoparticles within water-soluble porous polymer by solvent evaporation. The simple dissolution of porous polymer with drug nanoparticles results in stable aqueous drug nanoparticle suspension under the optimized conditions. The porous polymers were prepared by freeze-drying aqueous solutions of polyvinyl alcohol, polyethylene glycol, and a surfactant. They were then used as scaffolds for the formation of nanoparticles by initially soaking them in an organic drug solution, followed with removing the solvent via evaporation under ambient conditions. This process was optimized for an antifungal drug griseofulvin, before being translated to anticonvulsant carbamazepine and antineoplastic paclitaxel via a similar procedure, with an aim to improve the loading of drug nanoparticles. By varying certain process parameters a degree of control over the particle size and surface charge could be attained, as well as the drug to stabilizer ratio (drug payload). Noticeably, aqueous paclitaxel nanoparticles (500 nm) were prepared which used the equivalent of 46% less stabilizer than the formulation Taxol.

  2. Processing Methods Established To Fabricate Porous Oxide Ceramic Spheres for Thermal Barrier Coating Applications

    NASA Technical Reports Server (NTRS)

    Dynys, Frederick W.

    2003-01-01

    As gas turbine technology advances, the demand for efficient engines and emission reduction requires a further increase in operating temperatures, but combustion temperatures are currently limited by the temperature capability of the engine components. The existing thermal barrier coating (TBC) technology does not provide sufficient thermal load reduction at a 3000 F (1649 C) operating condition. Advancement in thermal barrier coating technology is needed to meet this aggressive goal. One concept for improving thermal barrier coating effectiveness is to design coating systems that incorporate a layer that reflects or scatters photon radiation. This can be achieved by using porous structures. The refractive index mismatch between the solid and pore, the pore size, and the pore density can be engineered to efficiently scatter photon radiation. Under NASA s Ultra-Efficient Engine Technology (UEET) Program, processing methods to fabricate porous ceramic spheres suitable for scattering photon radiation at elevated temperatures have been established. A straightforward templating process was developed at the NASA Glenn Research Center that requires no special processing equipment. The template was used to define particle shape, particle size, and pore size. Spherical organic cation exchange resins were used as a structure-directing template. The cation exchange resins have dual template capabilities that can produce different pore architectures. This process can be used to fabricate both metal oxide and metal carbide spheres.

  3. Ultra-Porous Nanoparticle Networks: A Biomimetic Coating Morphology for Enhanced Cellular Response and Infiltration

    PubMed Central

    Nasiri, Noushin; Ceramidas, Anthony; Mukherjee, Shayanti; Panneerselvan, Anitha; Nisbet, David R.; Tricoli, Antonio

    2016-01-01

    Orthopedic treatments are amongst the most common cause of surgery and are responsible for a large share of global healthcare expenditures. Engineering materials that can hasten bone integration will improve the quality of life of millions of patients per year and reduce associated medical costs. Here, we present a novel hierarchical biomimetic coating that mimics the inorganic constituent of mammalian bones with the aim of improving osseointegration of metallic implants. We exploit the thermally-driven self-organization of metastable core-shell nanoparticles during their aerosol self-assembly to rapidly fabricate robust, ultra-porous nanoparticle networks (UNN) of crystalline hydroxyapatite (HAp). Comparative analysis of the response of osteoblast cells to the ultra-porous nanostructured HAp surfaces and to the spin coated HAp surfaces revealed superior osseointegrative properties of the UNN coatings with significant cell and filopodia infiltration. This flexible synthesis approach for the engineering of UNN HAp coatings on titanium implants provides a platform technology to study the bone-implant interface for improved osseointegration and osteoconduction. PMID:27076035

  4. Reversible Photoinduced Switching of Permeability in a Cast Non-Porous Film Comprising Azobenzene Liquid Crystalline Polymer.

    PubMed

    Liu, Jian; Wang, Mingle; Dong, Mingling; Gao, Liude; Tian, Jingjing

    2011-10-04

    Permeation characteristics of an azobenzene-containing liquid crystalline (LC) non-porous film are investigated using a metallic corrosion method. Thin films (300 nm) are fabricated by the solution casting of an azobenzene side-chain LC polymer on freshly polished carbon steel coupons. Coated coupons are treated under the following conditions: a) gradual annealing at a cooling rate lower than 1 °C · min(-1) from 150 °C (above its Tg ) to room temperature, and b) irradiation at 465 nm (20 mW · cm(-2) ) with either circularly polarized light (CPL) or non-polarized light (NPL). The morphology of these films is characterized using X-ray diffraction, polarized optical microscopy, and transmission measurements. The results suggest that the annealing treatment resulted in the formation of a polydomain structure consisting of locally ordered small smectic domains that lack mutual orientation. Ordered micro domains are surrounded by disordered phases. CPL and NPL irradiation generates a monodomain orientated structure and an isotropic liquid crystal glass, respectively. The permeability of these non-porous films treated by CPL, NPL, and annealing are found to be 6.14 × 10(-4) , 1.92 × 10(-2) , and 1.56 × 10(-3) cm(3)  · m(-2)  · d(-1) . An orientation-dependent structure model is constructed to explain the permeation phenomenon, considering the ordered phase is impermeable, only the disordered phase is accessible to penetrating molecules. Fast switching of gas permeation is demonstrated by alternative irradiation of the film with CPL and NPL, which results in an approximately 30-fold difference in the permeability of the non-porous film.

  5. A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection

    DTIC Science & Technology

    2015-09-01

    Bulovic, Sensitivity gains in chemosensing by lasing action in organic polymers . Nature 434, 876 (2005). [11] C. Xie et al., Molecular imprinting at walls...ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for...ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for Chemical

  6. Towards a methodology for the effective surface modification of porous polymer scaffolds.

    PubMed

    Safinia, Laleh; Datan, Nathalie; Höhse, Marek; Mantalaris, Athanassios; Bismarck, Alexander

    2005-12-01

    A novel low-pressure radio-frequency plasma treatment protocol was developed to achieve the effective through-thickness surface modification of large porous poly (D,L-lactide) (PDLLA) polymer scaffolds using air or water: ammonia plasma treatments. Polymer films were modified as controls. Scanning electron micrographs and maximum bubble point measurements demonstrated that the PDLLA foams have the high porosity, void fraction and interconnected pores required for use as tissue engineering scaffolds. The polymer surface of the virgin polymer does contain acidic functional groups but is hydrophobic. Following exposure to air or water: ammonia plasma, an increased number of polar functional groups and improved wetting behaviour, i.e. hydrophilicity, of wet surfaces was detected. The number of polar surface functional groups increased (hence the decrease in water contact angles) with increasing exposure time to plasma. The change in surface composition and wettablility of wet polymer constructs was characterised by zeta potential and contact angle measurements. The hydrophobic recovery of the treated PDLLA polymer surfaces was also studied. Storage of the treated polymer constructs in ambient air caused an appreciable hydrophobic recovery, whereas in water only partial hydrophobic recovery occurred. However, in both cases the initial surface characteristics decay as function of time.

  7. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    NASA Astrophysics Data System (ADS)

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-08-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm-1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance.

  8. 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.

  9. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    PubMed

    Tang, Ze; Xie, Youtao; Yang, Fei; Huang, Yan; Wang, Chuandong; Dai, Kerong; Zheng, Xuebin; Zhang, Xiaoling

    2013-01-01

    Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS), which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs) and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration.

  10. Study on lotus-type porous copper electroplated with a Ni coating on inner surface of pores

    NASA Astrophysics Data System (ADS)

    Du, Hao; Song, Guihong; Nakajima, Hideo; Zhao, Yanhui; Xiao, Jinquan; Xiong, Tianying

    2013-01-01

    Deposition of Ni coating on inner surface of pores was attempted by electroplating for lotus-type porous copper with pore size of 0.6 mm and pore length of 6 mm. The surface morphology, thickness, thickness distribution along the pore length, and phase composition of the coating were characterized. It is proven that the Ni coating with a polycrystalline structure can be deposited on the inner surface of the pores with length/diameter of 10 for lotus-type porous copper by agitating the electroplating solution properly during the process. It is indicated that the coating thickness distributes uniformly along the pore depth and is about 4-5 μm. Furthermore, the mechanical properties including vicker hardness, compressive yield strength and absorbed energy ability of the electroplated porous copper were evaluated. It is found that the mechanical properties are improved significantly after depositing the nickel coating inside pores of the lotus-type porous copper. Among them, 0.2% yield stress increases from 22.96 to 30.15 MPa, while absorbed energy per volume from 60.83 to 96.01 MJ/m3 when compressed to strain of 80%, which is attributed mainly to the Ni coating as an obstacle to dislocation slip during deformation and its strengthening effect for the higher strength, and the good adhesion to the pore wall of the porous copper.

  11. Porous Tantalum Coatings Prepared by Vacuum Plasma Spraying Enhance BMSCs Osteogenic Differentiation and Bone Regeneration In Vitro and In Vivo

    PubMed Central

    Tang, Ze; Xie, Youtao; Yang, Fei; Huang, Yan; Wang, Chuandong; Dai, Kerong; Zheng, Xuebin; Zhang, Xiaoling

    2013-01-01

    Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS), which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs) and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration. PMID:23776648

  12. Water repellent porous silica films by sol-gel dip coating method.

    PubMed

    Rao, A Venkateswara; Gurav, Annaso B; Latthe, Sanjay S; Vhatkar, Rajiv S; Imai, Hiroaki; Kappenstein, Charles; Wagh, P B; Gupta, Satish C

    2010-12-01

    The wetting of solid surfaces by water droplets is ubiquitous in our daily lives as well as in industrial processes. In the present research work, water repellent porous silica films are prepared on glass substrate at room temperature by sol-gel process. The coating sol was prepared by keeping the molar ratio of methyltriethoxysilane (MTES), methanol (MeOH), water (H(2)O) constant at 1:12.90:4.74, respectively, with 2M NH(4)OH throughout the experiments and the molar ratio (M) of MTES/Ph-TMS was varied from 0 to 0.22. A simple dip coating technique is adopted to coat silica films on the glass substrates. The static water contact angle as high as 164° and water sliding angle as low as 4° was obtained for silica film prepared from M=0.22. The surface morphological studies of the prepared silica film showed the porous structure with pore sizes typically ranging from 200nm to 1.3μm. The superhydrophobic silica films prepared from M=0.22 retained their superhydrophobicity up to a temperature of 285°C and above this temperature the films became superhydrophilic. The porous and water repellent silica films are prepared by proper alteration of the Ph-TMS in the coating solution. The prepared silica films were characterized by surface profilometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, humidity tests, chemical aging tests, static and dynamic water contact angle measurements.

  13. Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Meijs, S.; Sørensen, C.; Sørensen, S.; Rechendorff, K.; Fjorback, M.; Rijkhoff, N. J. M.

    2016-04-01

    Objective. To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. Approach. Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. Main results. The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. Significance. This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

  14. Enhancement of Li+ ion conductivity in solid polymer electrolytes using surface tailored porous silica nanofillers

    NASA Astrophysics Data System (ADS)

    Mohanta, Jagdeep; Singh, Udai P.; Panda, Subhendu K.; Si, Satyabrata

    2016-09-01

    The current study represents the design and synthesis of polyethylene oxide (PEO)-based solid polymer electrolytes by solvent casting approach using surface tailored porous silica as nanofillers. The surface tailoring of porous silica nanostructure is achieved through silanization chemistry using 3-glycidyloxypropyl trimethoxysilane in which silane part get anchored to the silica surface whereas epoxy group get stellated from the silica surface. Surface tailoring of silica with epoxy group increases the room temperature electrochemical performances of the resulting polymer electrolytes. Ammonical hydrolysis of organosilicate precursor is used for both silica preparation and their surface tailoring. The composite solid polymer electrolyte films are prepared by solution mixing of PEO with lithium salt in presence of silica nanofillers and cast into film by solvent drying, which are then characterized by impedance measurement for conductivity study and wide angle x-ray diffraction for change in polymer crystallinity. Room temperature impedance measurement reveals Li+ ion conductivity in the order of 10-4 S cm-1, which is correlated to the decrease in PEO crystallinity. The enhancement of conductivity is further observed to be dependent on the amount of silica as well as on their surface characteristics.

  15. Manufacture of porous polymer nerve conduits through a lyophilizing and wire-heating process.

    PubMed

    Huang, Yi-Cheng; Huang, Yi-You; Huang, Chun-Chieh; Liu, Hwa-Chang

    2005-07-01

    We have developed a method for nerve tissue regeneration using longitudinally oriented channels within biodegradable polymers created by a combined lyophilizing and wire-heating process. This type of cell-adhesive scaffold provides increased area to support and guide extending axons subsequent to nerve injury. Utilizing Ni-Cr wires as mandrels to create channels in scaffold increased safety, effectiveness, and reproducibility. The scaffolds tested were made from different biodegradable polymers, chitosan and poly(D,L-lactide-co-glycolide) (PLGA), because of their availability, ease of processing, low inflammatory response, and approval by the FDA. According to our experimental results, the high permeability and the characteristic porous structure of chitosan proved to be a better material for nerve guidance than PLGA. The scanning electron micrographs revealed that the scaffolds were consistent along the longitudinal axis with channels being distributed evenly throughout the scaffolds. There was no evidence to suggest merging or splitting of individual channels. The diameter of the channels was about 100 mum, similar to the 115 micromameter of the Ni-Cr wire. Regulating the size and quantity of the Ni-Cr wires allow us to control the number and the diameter of the channels. Furthermore, the neutralizing processes significantly influenced the porous structure of chitosan scaffolds. Using weak base (NaHCO(3) 1M) to neutralize chitosan scaffolds made the porous structure more uniform. The innovative method of using Ni-Cr wires as mandrels could be easily tailored to other polymer and solvent systems. The high permeability and the characteristic porous structure of chitosan made it a superior material for nerve tissue engineering. These scaffolds could be useful for guiding regeneration of the peripheral nerve or spinal cord after a transection injury.

  16. Fabrication of Optical Multilayer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering.

    PubMed

    Caballero-Hernández, Jaime; Godinho, Vanda; Lacroix, Bertrand; Jiménez de Haro, Maria C; Jamon, Damien; Fernández, Asunción

    2015-07-01

    The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas. We successfully simulated, designed, and characterized Bragg reflectors and an optical microcavity that integrates these porous layers. The sharp interfaces between the dense and porous layers combined with the adequate control of the refractive index and thickness allowed for excellent agreement between the simulation and the experiments. The versatility of the magnetron sputtering technique allowed for the preparation of these structures for a wide range of substrates such as polymers while also taking advantage of the oblique angle deposition to prepare Bragg reflectors with a controlled lateral gradient in the stop band wavelengths.

  17. Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer

    NASA Astrophysics Data System (ADS)

    Alsbaiee, Alaaeddin; Smith, Brian J.; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E.; Dichtel, William R.

    2016-01-01

    The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

  18. Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer.

    PubMed

    Alsbaiee, Alaaeddin; Smith, Brian J; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E; Dichtel, William R

    2016-01-14

    The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

  19. Effect of polymers pore-filling on structural, optical and electrical properties of porous silicon

    NASA Astrophysics Data System (ADS)

    Kulathuraan, K.; Jeyakumar, P.; Ramadas, V.; Natarajan, B.

    2014-04-01

    We fabricate the heterojunction device by filling Porous Silicon (PS) with Polystyrene and Polyvinylchloride (PVC) in the present investigation. The rectifying characteristics of the Al/PS/c-Si/Al and Al/Polymers/PS/c-Si/Al were measured. Analyses of the structural properties using SEM and AFM have demonstrated that the PS layer filled with polymers have no significant changes in the structures except that the polymers were infiltrated in the pores. The refractive index values of the PS and Polymers/PS composites as a function of porosity were determined by Effective Medium Approximation (EMA) method. The Photoluminescence (PL) of the structures at room temperature showed that the emission intensity was very high as compared with that of the polymer films on PS layer. The PL peak in polymers/PS composites structures were not caused any blue shift of the PL peak energy. The band gap energy of PS device was determined from PL. This heterojunction device, especially due to charge storage in PS surface, which will be useful in sensor applications and diode in addition, it also possesses potential applications in the optoelectronic fields.

  20. Advanced polymer-inorganic hybrid hard coatings utilizing in situ polymerization method.

    PubMed

    Takaki, Toshihiko; Nishiura, Katsunori; Mizuta, Yasushi; Itou, Yuichi

    2006-12-01

    Hard coatings are frequently used to give plastics high scratch resistance. Coating hardness and adhesion to the substrate are considered to be key factors influencing scratch resistance, but it is difficult to produce coatings that have both properties. Hybridization of polymers and inorganic materials is a promising approach for solving this problem. We prepared polymer-silica hybrid coatings by using in situ polymerization to carry out radical polymerization of vinyl monomers in a sol-gel solution of alkoxysilanes, and measured the abrasion resistance of the coatings. However, the expected properties were not obtained because the sol-gel reaction did not perfectly proceed on the surface of the coatings under the N2 conditions. We found that curing the hybrid coatings by UV irradiation in air promoted the sol-gel reaction on the surface, resulting in coatings having excellent abrasion resistance.

  1. Hydrophilic polymer coated microporous membranes capable of use as a battery separator

    SciTech Connect

    Taskier, H.T.

    1984-03-20

    The present invention is directed to microporous membranes having a surfactant impregnated therein which is coated on at least one surface thereof with a polymer coating, such as cellulose acetate. The polymer coating possesses functional groups in the presence of an aqueous alkaline environment which permits it to undergo hydrogen bonding with water and to transport battery electrolyte through the coating by diffusion. The presence of the coating on the normally hydrophobic substrate membrane, when used in conjunction with a suitable surfactant, increases the wettability of the substrate membrane and thereby lowers its electrical resistance. The coating also serves to immobilize various soluble electrode derived ions at the coating-electrolyte interface thereby hindering their penetration into the pores of the substrate microporous membrane. Consequently, the plugging of the pores of the substrate membrane by these ions is substantially reduced thereby increasing the life of a battery in which said coated membranes are used as battery separators.

  2. Fabrication and in vitro characterization of magnetic hydroxycarbonate apatite coatings with hierarchically porous structures.

    PubMed

    Guo, Yaping; Zhou, Yu; Jia, Dechang; Meng, Qingchang

    2008-07-01

    Hydroxycarbonate apatite/Fe(3)O(4) composite coatings (MHACs) with hierarchically porous structures were fabricated by electrophoretic deposition of CaCO(3)/Fe(3)O(4) particles on Ti6Al4V substrates followed by treatment with phosphate buffer solution (PBS) at 37 degrees C. The effects of Fe(3)O(4) on the conversion rate of calcium carbonate to hydroxycarbonate apatite and the porous structures and in vitro bioactivity of MHACs were investigated. After soaking CaCO(3)/Fe(3)O(4) coatings in PBS, hydroxycarbonate apatite nucleates heterogeneously on the surfaces of CaCO(3)/Fe(3)O(4) particles and forms a plate-like structure. Fe(3)O(4) increases the velocity of nucleus formation of hydroxycarbonate apatite. After soaking for 1day, the percentage of unreacted calcium carbonate for MHACs is approximately 9.1%, lower than the approximately 41.0% for hydroxycarbonate apatite coatings (HCACs). As the CaCO(3)/Fe(3)O(4) coatings are converted to MHACs, macropores with a pore size of approximately 4mum on the coatings and mesopores with a pore size of approximately 3.9nm within the hydroxycarbonate apatite plates are formed. The mesopores remain in the MHACs after treatment with PBS for 9 days, while they disappear in the HCACs. Simulated body fluid immersion tests reveal that Fe(3)O(4) improves the in vitro bioactivity of biocoatings. The amount of bone-like apatite precipitated on the surfaces of MHACs is greater than that on the surfaces of HCACs.

  3. Thermal diffusivity measurements on porous carbon fiber reinforced polymer tubes

    NASA Astrophysics Data System (ADS)

    Gruber, Jürgen; Gresslehner, Karl Heinz; Mayr, Günther; Hendorfer, Günther

    2017-02-01

    This work presents the application of methods for the determination of the thermal diffusivity well suited for flat bodies adapted to cylindrical bodies. Green's functions were used to get the temperature time history for small and large times, for the approach of intersecting these two straight lines. To verify the theoretical considerations noise free data are generated by finite element simulations. Furthermore effects of inhomogeneous excitation and the anisotropic heat conduction of carbon fiber reinforced polymers were taken into account in these numerical simulations. It could be shown that the intersection of the two straight lines is suitable for the determination of the thermal diffusivity, although the results have to be corrected depending on the ratio of the cylinders inner and outer radii. Inhomogeneous excitation affects the results of this approach as it lead to multidimensional heat flux. However, based on the numerical simulations a range of the azimuthal angle exists, where the thermal diffusivity is nearly independent of the angle. The method to determine the thermal diffusivity for curved geometries by the well suited Thermographic Signal Reconstruction method and taking into account deviations from the slab by a single correction factor has great advantages from an industrial point of view, just like an easy implementation into evaluation software and the Thermographic Signal Reconstruction methods rather short processing time.

  4. Light wave interference during laser drilling of polymer coatings

    NASA Astrophysics Data System (ADS)

    Pargellis, A. N.; Au, D. T. W.; Kestenbaum, A.

    1988-12-01

    A CO2 laser has been used to drill holes in a 150-μm-thick, UV-curable, modified acrylate, polymer coating a copper substrate. A typical hole is 100-150 μm in diameter. The holes in this study were each made with a single laser pulse of 10.6-μm wavelength, duration 100 or 200 μs, and 4-20 mJ energy. Two superimposed sets of periodic ripples have been observed on the hole walls. The shorter wavelength varies from 4.0 μm at the top of the hole to 5.3 μm at the bottom of the hole. The longer wavelength appears to be 13.2 μm and is attenuated as the wave propagates towards the copper substrate. The experimental data are compared with values calculated using a model that considers the interference of a standing wave inside the hole with radiation propagating through the dielectric surrounding the hole. The amplitude (trough-to-peak distance) of the waves in the hole wall is about half the wavelength of the standing waves. The long-wavelength waves (13.2 μm) yield ripples in the wall of 6.5-μm amplitude. These ripples give 13.0 μm (0.5 mils) as an ultimate lower limit for laser drilling holes using the 10.6-μm wavelengths obtained with a CO2 laser. Chemical etching of the polymer causes all of the holes to have thin rims surrounding the top of the hole. This is due to accelerated etching of the less cured polymer material inside the hole. A chemical etching process etches away some of the ripple pattern, particularly near the top of the hole.

  5. Antibacterial chitosan coating on nano-hydroxyapatite/polyamide66 porous bone scaffold for drug delivery.

    PubMed

    Huang, Di; Zuo, Yi; Zou, Qin; Zhang, Li; Li, Jidong; Cheng, Lin; Shen, Juan; Li, Yubao

    2011-01-01

    This study describes a new drug-loaded coating scaffold applied in infection therapy during bone regeneration. Chitosan (CS) containing antibacterial berberine was coated on a nano-hydroxyapatite/polyamide66 (n-HA/PA66) scaffold to realize bone regeneration together with antimicrobial properties. The porous scaffold was fabricated using the phase-inversion method with a porosity of about 84% and macropore size of 400-600 μm. The morphology, mechanical properties and drug-release behavior were investigated at different ratios of chitosan to berberine. The results show that the elastic modulus and compressive strength of the coated scaffolds were improved to 35.4 MPa and 1.7 MPa, respectively, about 7 times and 3 times higher than the uncoated scaffolds. After a burst release of berberine within the first 3 h in PBS solution, a continuous berberine release can last 150 h, which is highly dependent on the coating concentration and suitable for antibacterial requirement of orthopaedic surgery. The bactericidal test confirms a strong antibiotic effect of the delivery system and the minimum inhibitory concentration of the drug is 0.02 mg/ml. Moreover, in vitro biological evaluation demonstrates that the coating scaffolds act as a good matrix for MG63 adhesion, crawl, growth and proliferation, suggesting that the antibacterial delivery system has no cytotoxicity. We expect the drug-delivery system to have a potential application in bone regeneration or defect repair.

  6. Water Vapor Sorption and Diffusion in Secondary Dispersion Barrier Coatings: A Critical Comparison with Emulsion Polymers.

    PubMed

    Liu, Yang; Soer, Willem-Jan; Scheerder, Jürgen; Satgurunathan, Guru; Keddie, Joseph L

    2015-06-10

    The conventional method for synthesizing waterborne polymer colloids is emulsion polymerization using surfactants. An emerging method is the use of secondary dispersions (SD) of polymers in water, which avoids the addition of any surfactant. Although there are numerous studies of the water barrier properties (sorption, diffusion, and permeability) of waterborne emulsion (Em) polymer coatings, the properties of SD coatings, in comparison, have not been thoroughly investigated. Here, dynamic water vapor sorption analysis is used to compare the equilibrium sorption isotherms of the two forms of styrene-acrylate copolymers (Em and SD) with the same monomer composition. From an analysis of the kinetics of vapor sorption, the diffusion coefficient of water in the polymer coatings is determined. The combined effects of particle boundaries and surfactant addition were investigated through a comparison of the properties of SD and Em coatings to those of (1) solvent-cast polymer coatings (of the same monomer composition), (2) Em polymers that underwent dialysis to partially remove the water-soluble species, and (3) SD polymers with added surfactants. The results reveal that both the particle boundaries and the surfactants increase vapor sorption. The diffusion coefficients of water are comparable in magnitude in all of the polymer systems but are inversely related to water activity because of molecular clustering. Compared to all of the other waterborne polymer systems, the SD barrier coatings show the lowest equilibrium vapor sorption and permeability coefficients at high relative humidities as well as the lowest water diffusion coefficient at low humidities. These barrier properties make SD coatings an attractive alternative to conventional emulsion polymer coatings.

  7. Facile approach in fabricating superhydrophobic SiO2/polymer nanocomposite coating

    NASA Astrophysics Data System (ADS)

    Chen, Hengzhen; Zhang, Xia; Zhang, Pingyu; Zhang, Zhijun

    2012-11-01

    We have developed a facile spin-coating method to prepare water-repellent SiO2/polymer composite coating without any surface chemical modification. The wettability can be adjusted by controlling the content of SiO2 nanoparticles. The coating demonstrates sustainable superhydrophobicity in the condition of continuous contact with corrosive liquids. Importantly, the coating can be fabricated on various metal substrates to prevent metal from corrosion.

  8. AC magnetic field-assisted method to develop porous carbon nanotube/conducting polymer composites for application in thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Chuang, Chun-Yu; Yang, Shu-Chian; Chang, Su-Hua; Yang, Ta-I.

    2015-04-01

    Thermoelectric materials are very effective in converting waste heat sources into useful electricity. Researchers are continuing to develop new polymeric thermoelectric materials. The segregated-network carbon nanotube (CNT)- polymer composites are most promising. Thus, the goal of this study is to develop novel porous CNT -polymer composites with improved thermoelectric properties. The research efforts focused on modifying the surface of the CNT with magnetic nanoparticles so that heat was released when subjecting to an AC magnetic field. Subsequently, polymers covered on the surface of the CNT were crosslinked. The porous CNT -polymer composites can be obtained by removing the un-crosslinked polymers. Polydimethylsiloxane polymer was utilized to investigate the effect of porosity and electrical conductivity on the thermoelectric properties of the composites. This AC magnetic field-assisted method to develop porous carbon nanotube/polymer composites for application in thermoelectric materials is introduced for the first time. The advantage of this method is that the electrical conductivity of the composites was high since we can easily to manipulate the CNT to form a conducting path. Another advantage is that the high porosity significantly reduced the thermal conductivity of the composites. These two advantages enable us to realize the polymer composites for thermoelectric applications. We are confident that this research will open a new avenue for developing polymer thermoelectric materials.

  9. Gas turbine ceramic-coated-vane concept with convection-cooled porous metal core

    NASA Technical Reports Server (NTRS)

    Kascak, A. F.; Liebert, C. H.; Handschuh, R. F.; Ludwig, L. P.

    1981-01-01

    Analysis and flow experiments on a ceramic-coated-porous-metal vane concept indicated the feasibility, from a heat transfer standpoint, of operating in a high-temperature (2500 F) gas turbine cascade facility. The heat transfer and pressure drop calculations provided a basis for selecting the ceramic layer thickness (to 0.08 in.), which was found to be the dominant factor in the overall heat transfer coefficient. Also an approximate analysis of the heat transfer in the vane trailing edge revealed that with trailing-edge ejection the ceramic thickness could be reduced to (0.01 in.) in this portion of the vane.

  10. Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods

    NASA Astrophysics Data System (ADS)

    Yoon, Joonsung

    The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and

  11. Evaluation of methods of reducing permeability in porous media by in situ polymer treatments. Final report

    SciTech Connect

    Wilhite, G.P.; Green, D.W.; Young, T.S.; Thiele, J.L.; Michnick, M.J.; Vossoughi, S.; Terry, R.E.

    1986-02-01

    Several processes have been developed to reduce the permeability of reservoir rocks using high-molecular-weight, water-soluble polymers. This report describes a study of two processes which are used commercially to cross link polyacrylamides. Both processes are based upon the controlled release of multivalent metal ions which form a ''crosslink'' of some form between polymers. The first process, called the ''chromium redox process'', consists of the displacement of a polymer slug containing chromium in the +6 oxidation state, followed by a slug of polymer containing a reducing agent. A reaction occurs when the two slugs mix with Cr(VI) being reduced to Cr(III). The Cr(III) reacts with the polymer to form a gel. The second process, called the combination process, consists of the sequential injection of slugs containing polymer, aluminum citrate and polymer followed by resumption of water injection. The research described in this report investigated these two methods of reducing the permeability of porous rocks using polyacrylamides. Research was conducted on properties of bulk gels as they formed as well as in situ gelation in sandpacks and Berea core material. The research was organized in six parts: (1) characterization of gel systems; (2) correlation of gelation times and process variables for chromium(III) systems; (3) kinetics of reactions involving reduction of chromium(VI); (4) rheological studies of gelling processes; (5) insitu gelation of chromium(III) systems; and (6) permeability reduction with alternate slugs of aluminum citrate and polymer. Progress reports in each of these areas are presented. 71 figs., 81 tabs.

  12. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion

    PubMed Central

    Totani, Masayasu; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Tanihara, Masao

    2014-01-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78–88% relative to noncoated PET surface) and Escherichia coli (94–97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria. PMID:25485105

  13. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion.

    PubMed

    Totani, Masayasu; Ando, Tsuyoshi; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Kuroda, Kenichi; Tanihara, Masao

    2014-09-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78-88% relative to noncoated PET surface) and Escherichia coli (94-97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria.

  14. Dry powder process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1997-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  15. A Dry Powder Process for Preparing Uni-Tape Prepreg from Polymer Powder Coated Filamentary Towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1995-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  16. Novel thiophene-bearing conjugated microporous polymer honeycomb-like porous spheres with ultrahigh iodine uptake.

    PubMed

    Ren, Feng; Zhu, Zhaoqi; Qian, Xin; Liang, Weidong; Mu, Peng; Sun, Hanxue; Liu, Jiehua; Li, An

    2016-07-28

    Two conjugated microporous polymers containing thiophene-moieties (SCMPs) were obtained by the polymerization of 3,3',5,5'-tetrabromo-2,2'-bithiophene and ethynylbenzene monomers through the palladium-catalyzed Sonogashira-Hagihara crosscoupling reaction. The resulting SCMPs show high thermal stability with a decomposition temperature above 300 °C. Scanning electron microscopy images show that the resulting SCMPs formed as an aggregation composed of micrometer-sized SCMP spheres, in which honeycomb-like porous spheres with penetrated pores on the surface were observed. Taking advantage of such a unique honeycomb-like porous morphology as well as π-conjugated structures, the SCMPs show ultrahigh absorption performance for iodine vapour with an uptake of up to 345 wt% obtained, which is the highest value reported to date for CMPs, thus making the resulting SCMPs ideal absorbent materials for reversible iodine capture to address environmental issues.

  17. Structure of porous electrodes in polymer electrolyte membrane fuel cells: An optical reconstruction technique

    NASA Astrophysics Data System (ADS)

    Berejnov, Viatcheslav; Sinton, David; Djilali, Ned

    Computing flows and phase transport in porous media requires a physically representative geometric model. We present a simple method of digitizing the structure of fibrous porous media commonly used in polymer electrolyte membrane (PEM) fuel cells, the so-called gas diffusion layer (GDL). Employing an inverted microscope and image recognition software we process images of the GDL surface collected manually at different focal lengths with micrometer accuracy. Processing the series of images allows retrieval of local depths of the salient in-focus structural elements in each of the different images. These elements are then recombined into a depth-map representing the three-dimensional structure of the GDL surface. Superimposition of the in-focus portions of the structural elements distributed throughout the stack of images yields digitized data describing the geometry and structural attributes of the 3D surface of the GDL fibrous material.

  18. Effects of Calcination Condition on Porous Reduced Titanium Oxides and Oxynitrides via Preceramic Polymer Route

    SciTech Connect

    Hasegawa, George; Sato, Tatsuya; Kanamori, Kazuyoshi; Sun, Cheng-Jun; Ren, Yang; Kobayashi, Yoji; Kageyama, Hiroshi; Abe, Takeshi; Nakanishi, Kazuki

    2015-03-16

    The preceramic polymer route from titanium-based inorganic-organic hybrid networks provides electro conductive N-doped reduced titanium oxides (TinO2n–1) and titanium oxynitrides (TiOxNy) with a monolithic shape as well as well-defined porous structure. This methodology demonstrates advantageously lower temperature of crystal phase transition compared to the reduction of TiO2 by carbon or H2. In this study, effects of calcination condition on various features of the products have been explored by adopting three different atmospheric conditions and varying the calcination temperature. The detailed crystallographic and elemental analyses disclose the distinguished difference in phase transition behavior with respect to calcination atmosphere. Correlation between the crystallization and nitridation behaviors, porous properties and electric conductivities in the final products has been discussed.

  19. Modular design of domain assembly in porous coordination polymer crystals via reactivity-directed crystallization process.

    PubMed

    Fukushima, Tomohiro; Horike, Satoshi; Kobayashi, Hirokazu; Tsujimoto, Masahiko; Isoda, Seiji; Foo, Maw Lin; Kubota, Yoshiki; Takata, Masaki; Kitagawa, Susumu

    2012-08-15

    The mesoscale design of domain assembly is crucial for controlling the bulk properties of solids. Herein, we propose a modular design of domain assembly in porous coordination polymer crystals via exquisite control of the kinetics of the crystal formation process. Employing precursors of comparable chemical reactivity affords the preparation of homogeneous solid-solution type crystals. Employing precursors of distinct chemical reactivity affords the preparation of heterogeneous phase separated crystals. We have utilized this reactivity-directed crystallization process for the facile synthesis of mesoscale architecture which are either solid-solution or phase-separated type crystals. This approach can be also adapted to ternary phase-separated type crystals from one-pot reaction. Phase-separated type frameworks possess unique gas adsorption properties that are not observed in single-phasic compounds. The results shed light on the importance of crystal formation kinetics for control of mesoscale domains in order to create porous solids with unique cooperative functionality.

  20. In vitro bioactive behavior of hydroxylapatite-coated porous Al(2)O(3).

    PubMed

    Shi, D; Jiang, G; Wen, X

    2000-09-01

    To produce bioactive materials for bone substitutes, two major deposition methods, suspension method and thermal deposition method, were employed to develop bioactive, mechanically strong, and porous ceramics. Hydroxylapatite (HA) has been uniformly coated onto inner pore surfaces of reticulated alumina substrates. It has been found that the in vitro bioactivity of HA coatings was affected by both structural crystallinity and specific surface area. Well-crystallized HA heat-treated at high temperatures has resulted in reduced bioactivity. The bio-reaction rate was found to increase with the surface area of HA. We have found that the stability of the well-crystallized HA is associated with the high driving force required for the formation of hydroxy-carbonate apatite (HCA) phase.

  1. Strengthening of polymer ordered porous materials based on a layered nanocomposite internal structure

    NASA Astrophysics Data System (ADS)

    Heng, Liping; Guo, Xieyou; Guo, Tianqi; Wang, Bin; Jiang, Lei

    2016-07-01

    Ordered porous polymeric films attract more and more attention because they have many advantages and broad application prospects in many fields. But because of their large flexibility and poor mechanical properties, some of the scope for application is greatly limited. Inspired by the ordered pore structure of the honeycomb and the layered structure of natural nacre, we prepared an ordered porous polymer film with a layered structure in the pore wall by the solvent-evaporation-restriction assisted hard template method. Compared with other samples, this kind of film with the layered structure showed both excellent mechanical properties and good stability. This kind of film with high mechanical strength, is considered to have wide applications in the areas of separation, biomedicine, precision instruments, aerospace, environmental protection and so on.Ordered porous polymeric films attract more and more attention because they have many advantages and broad application prospects in many fields. But because of their large flexibility and poor mechanical properties, some of the scope for application is greatly limited. Inspired by the ordered pore structure of the honeycomb and the layered structure of natural nacre, we prepared an ordered porous polymer film with a layered structure in the pore wall by the solvent-evaporation-restriction assisted hard template method. Compared with other samples, this kind of film with the layered structure showed both excellent mechanical properties and good stability. This kind of film with high mechanical strength, is considered to have wide applications in the areas of separation, biomedicine, precision instruments, aerospace, environmental protection and so on. Electronic supplementary information (ESI) available: SEM image of hexagonal silicon pillar templates, AFM images of clay platelets on a silicon substrate, photographs of free-standing gels, X-ray diffraction profiles for dried materials, FTIR and TGA of the samples, and

  2. Process to produce lithium-polymer batteries

    DOEpatents

    MacFadden, Kenneth Orville

    1998-01-01

    A polymer bonded sheet product suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance.

  3. Process to produce lithium-polymer batteries

    DOEpatents

    MacFadden, K.O.

    1998-06-30

    A polymer bonded sheet product is described suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance. 1 fig.

  4. Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Mihelcic, Judith A.

    1989-01-01

    Protection for polymeric surfaces is needed to make them durable in the low Earth orbital environment, where oxidation by atomic oxygen is the predominant failure mechanism. Thin film coatings of oxides such as silicon dioxide are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies occurring during the deposition process, handling, or micrometeoroid and debris bombardment in low Earth orbit. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of silicon dioxide on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

  5. Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Mihelcic, Judith A.

    1989-01-01

    Protection for polymeric surfaces is needed to make them durable in the low earth orbital environment. Thin film coatings of oxides such as SiO2 are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of SiO2 on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

  6. Novel mucoadhesion tests for polymers and polymer-coated particles to design optimal mucoadhesive drug delivery systems.

    PubMed

    Takeuchi, Hirofumi; Thongborisute, Jringjai; Matsui, Yuji; Sugihara, Hikaru; Yamamoto, Hiromitsu; Kawashima, Yoshiaki

    2005-11-03

    To design an effective particulate drug delivery system having mucoadhesive function, several mucoadhesion tests for polymers and the resultant particulate systems were developed. Mucin particle method is a simple mucoadhesion test for polymers, in which the commercial mucin particles are used. By measuring the change in particle size or zeta potential of the mucin particle in a certain concentration of polymer solution, we could estimate the extent of their mucoadhesive property. BIACORE method is also a novel mucoadhesion test for polymers. On passing through the mucin suspension on the polymer-immobilized chip of BIACORE instrument, the interaction was quantitatively evaluated with the change in its response diagram. By using these mucoadhesion tests, we detected a strong mucoadhesive property of several types of chitosan and Carbopol. Evaluation of mucoadhesive property of polymer-coated particulate systems was demonstrated with the particle counting method developed by us. To detect the mucoadhesive phenomena in the intestinal tract, we observed the rat intestine with the confocal laser scanning microscope (CLSM) after oral administration of the particulate systems. The resultant photographs clearly showed a longer retention of submicron-sized chitosan-coated liposomes (ssCS-Lip) in the intestinal tract than other liposomal particles tested such as non-coated liposomes and chitosan-coated multilamellar one. These observations explained well the superiority of the ssCS-Lip as drug carrier in oral administration of calcitonin in rats than other liposomal particles.

  7. Controlled release from drug microparticles via solventless dry-polymer coating.

    PubMed

    Capece, Maxx; Barrows, Jason; Davé, Rajesh N

    2015-04-01

    A novel solvent-less dry-polymer coating process employing high-intensity vibrations avoiding the use of liquid plasticizers, solvents, binders, and heat treatments is utilized for the purpose of controlled release. The main hypothesis is that such process having highly controllable processing intensity and time may be effective for coating particularly fine particles, 100 μm and smaller via exploiting particle interactions between polymers and substrates in the dry state, while avoiding breakage yet achieving conformal coating. The method utilizes vibratory mixing to first layer micronized polymer onto active pharmaceutical ingredient (API) particles by virtue of van der Waals forces and to subsequently mechanically deform the polymer into a continuous film. As a practical example, ascorbic acid and ibuprofen microparticles, 50-500 μm, are coated with the polymers polyethylene wax or carnauba wax, a generally recognized as safe material, resulting in controlled release on the order of seconds to hours. As a novelty, models are utilized to describe the coating layer thickness and the controlled-release behavior of the API, which occurs because of a diffusion-based mechanism. Such modeling would allow the design and control of the coating process with application for the controlled release of microparticles, particularly those less than 100 μm, which are difficult to coat by conventional solvent coating methods.

  8. Toward compositional design of reticular type porous films by mixing and coating titania-based frameworks with silica

    NASA Astrophysics Data System (ADS)

    Kimura, T.

    2015-12-01

    A recently developed reticular type porous structure, which can be fabricated as the film through the soft colloidal block copolymer (e.g., PS-b-PEO) templating, is very promising as the porous platform showing high-performance based on its high surface area as well as high diffusivity of targeted organic molecules and effective accommodation of bulky molecules, but the compositional design of oxide frameworks has not been developed so enough to date. Here, I report reliable synthetic methods of the reticular type porous structure toward simple compositional variations. Due to the reproducibility of reticular type porous titania films from titanium alkoxide (e.g., TTIP; titanium tetraisopropoxide), a titania-silica film having similar porous structure was obtained by mixing silicon alkoxide (e.g., tetraethoxysilane) and TTIP followed by their pre-hydrolysis, and the mixing ratio of Ti to Si composition was easily reached to 1.0. For further compositional design, a concept of surface coating was widely applicable; the reticular type porous titania surfaces can be coated with other oxides such as silica. Here, a silica coating was successfully achieved by the simple chemical vapor deposition of silicon alkoxide (e.g., tetramethoxysilane) without water (with water at the humidity level), which was also utilized for pore filling with silica by the similar process with water.

  9. Guest-Dependent Spin-Transition Behavior of Porous Coordination Polymers.

    PubMed

    Ohtani, Ryo; Hayami, Shinya

    2017-02-16

    The host-guest composites of Hofmann-type iron(II) spin-transition (ST) porous coordination polymers incorporating guest molecules show guest-dependent ST behavior in accordance with the respective guest species, which may be a gas, solvent, halogen, or organic molecule. The guest also works as a chemical stimulant to switch the spin state of the host between high and low spin at room temperature. In this review, we discuss guest properties including size, shape, flexibility, chemical properties, and pore loading content, which impact the spin states of the host framework and the ST behavior exhibited by the host-guest composites.

  10. Evaluation of Metal-Organic Frameworks and Porous Polymer Networks for CO2 -Capture Applications.

    PubMed

    Verdegaal, Wolfgang M; Wang, Kecheng; Sculley, Julian P; Wriedt, Mario; Zhou, Hong-Cai

    2016-03-21

    This manuscript presents experimental data for 20 adsorption materials (metal-organic frameworks, porous polymer networks, and Zeolite-5A), including CO2 and N2 isotherms and heat capacities. With input from only experimental data, working capacities per energy for each material were calculated. Furthermore, by running seven different carbon-capture scenarios in which the initial flue-gas composition and process temperature was systematically changed, we present a range of performances for each material and quantify how sensitive each is to these varying parameters. The presented calculations provide researchers with a tool to investigate promising carbon-capture materials more easily and completely.

  11. An ultra-sensitive microfluidic immunoassay using living radical polymerization and porous polymer monoliths.

    SciTech Connect

    Abhyankar, Vinay V.; Singh, Anup K.; Hatch, Anson V.

    2010-07-01

    We present a platform that combines patterned photopolymerized polymer monoliths with living radical polymerization (LRP) to develop a low cost microfluidic based immunoassay capable of sensitive (low to sub pM) and rapid (<30 minute) detection of protein in 100 {micro}L sample. The introduction of LRP functionality to the porous monolith allows one step grafting of functionalized affinity probes from the monolith surface while the composition of the hydrophilic graft chain reduces non-specific interactions and helps to significantly improve the limit of detection.

  12. Soluble Metal-Nanoparticle-Decorated Porous Coordination Polymers for the Homogenization of Heterogeneous Catalysis.

    PubMed

    Huang, Yuan-Biao; Wang, Qiang; Liang, Jun; Wang, Xusheng; Cao, Rong

    2016-08-17

    Ultrasmall metal nanoparticles (MNPs) were decorated on soluble porous coordination polymers (PCPs) with high metal loadings. The solubility of the composite and the size of the MNPs can be controlled by varying the ratio of the precursors to the supports. The soluble PCPs can serve as a platform to homogenize heterogeneous MNPs catalysts, which exhibited excellent activity and recyclability in C-H activation and Suzuki reactions. This strategy combines the advantages of homogeneous and heterogeneous catalysis and may bring new inspiration to catalysis.

  13. Effect of porous polymer films (track membranes) on the isothermal evaporation kinetics of water

    NASA Astrophysics Data System (ADS)

    Novikov, S. N.; Ermolaeva, A. I.; Timoshenkov, S. P.; Korobova, N. E.; Goryunova, E. P.

    2016-06-01

    The kinetics of isothermal evaporation of distilled water that was in remote (10-15-mm) contact with porous polymer films (track membranes (TMs)) was studied by microgravimetry (derivatograph). When the H2O-TM system contained a disperse medium, the supramolecular structure of water changed, and the number of clusters (coherent domains) drastically decreased. The extraction of the light phase from liquid water was correlated with the chemisorption of H2O molecules containing the para-isomer of hydrogen, which predominantly form coherent domains of water.

  14. Selective Adsorption of CO2 from Light Gas Mixtures Using a Structurally Dynamic Porous Coordination Polymer**

    SciTech Connect

    Kristi L. Kauffman, Jeffrey T. Culp, Andrew J. Allen, Laura Espinal, Winnie Wong-Ng, Thomas D. Brown, Angela Goodman, Mark P. Bernardo, Russel J. Pancoast, Danielle Chirdon, Christopher Matranga*

    2010-01-01

    The selective adsorption of CO{sub 2} from mixtures with N{sub 2}, CH{sub 4}, and N{sub 2}O in a dynamic porous coordination polymer (see monomer structure) was evaluated by ATR-FTIR spectroscopy, GC, and SANS. All three techniques indicate highly selective adsorption of CO{sub 2} from CO{sub 2}/CH{sub 4} and CO{sub 2}/N{sub 2} mixtures at 30 C, with no selectivity observed for the CO{sub 2}/N{sub 2}O system.

  15. Surface characterization and effectiveness evaluation of anti-graffiti coatings on highly porous stone materials

    NASA Astrophysics Data System (ADS)

    Lettieri, Mariateresa; Masieri, Maurizio

    2014-01-01

    In this study, two commercial sacrificial anti-graffiti systems, provided as water emulsion, were applied on a highly porous stone. The behavior of the anti-graffiti treatments was investigated by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy in attenuated total reflectance mode (ATR-FTIR), colorimetric tests, and water static contact angle measurements. The presence of a protective coating enhanced the removal of paint sprayed on the stone. However, penetration of the staining agent below the surface, due to the high porosity of the substrate, caused difficulties in eliminating the paint. In fact, repeated cleaning procedures, involving hot water, mechanical action, and chemical removers, did not allow a complete removal of the paint. The examined systems behaved against graffiti in different ways. No affinity between the wax-based product and the paint was observed; nevertheless, this behavior did not result in good anti-graffiti performances. On the contrary, the penetration of the paint into the fluorine-based coating yielded a good anti-graffiti effectiveness, since the stain was easily eliminated from the surfaces. The anti-graffiti coatings survived in limited areas after the cleaning processes, although the studied compounds are suggested as sacrificial products. Such behavior may affect the maintenance activities, when the surface is no longer protected and the coating need to be renewed, since compatibility problems, as well as harmful accumulation, could occur because of further treatments on these surfaces.

  16. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    PubMed

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers.

  17. A mesomechanical analysis of the deformation and fracture in polycrystalline materials with ceramic porous coatings

    NASA Astrophysics Data System (ADS)

    Balokhonov, R. R.; Zinoviev, A. V.; Romanova, V. A.; Batukhtina, E. E.

    2015-10-01

    The special features inherent in the mesoscale mechanical behavior of a porous ceramic coating-steel substrate composite are investigated. Microstructure of the coated material is accounted for explicitly as initial conditions of a plane strain dynamic boundary-value problem solved by the finite difference method. Using a mechanical analogy method, a procedure for generating a uniform curvilinear finite difference computational mesh is developed to provide a more accurate description of the complex grain boundary geometry. A modified algorithm for generation of polycrystalline microstructure of the substrate is designed on the basis of the cellular automata method. The constitutive equations for a steel matrix incorporate an elastic-plastic model for a material subjected to isotropic hardening. The Hall-Petch relation is used to account for the effect of the grain size on the yield stress and strain hardening history. A brittle fracture model for a ceramic coating relying on the Huber criterion is employed. The model allows for crack nucleation in the regions of triaxial tension. The complex inhomogeneous stress and plastic strain patterns are shown to be due to the presence of interfaces of three types: coating-substrate interface, grain boundaries, and pore surfaces.

  18. Multicomponent polymer coating to block photocatalytic activity of TiO2 nanoparticles.

    PubMed

    Lee, Wilson A; Pernodet, Nadine; Li, Bingquan; Lin, Chien H; Hatchwell, Eli; Rafailovich, Miriam H

    2007-12-07

    Chemical grafting of anti-oxidant molecules with an additional hydrophobic polymer coating directly onto TiO(2) particle surfaces, using sonochemistry, is found to eliminate photocatalytic degradation enabling highly effective screening against UV radiation.

  19. Optimization of Cardiovascular Stent against Restenosis: Factorial Design-Based Statistical Analysis of Polymer Coating Conditions

    PubMed Central

    Acharya, Gayathri

    2012-01-01

    The objective of this study was to optimize the physicodynamic conditions of polymeric system as a coating substrate for drug eluting stents against restenosis. As Nitric Oxide (NO) has multifunctional activities, such as regulating blood flow and pressure, and influencing thrombus formation, a continuous and spatiotemporal delivery of NO loaded in the polymer based nanoparticles could be a viable option to reduce and prevent restenosis. To identify the most suitable carrier for S-Nitrosoglutathione (GSNO), a NO prodrug, stents were coated with various polymers, such as poly (lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG) and polycaprolactone (PCL), using solvent evaporation technique. Full factorial design was used to evaluate the effects of the formulation variables in polymer-based stent coatings on the GSNO release rate and weight loss rate. The least square regression model was used for data analysis in the optimization process. The polymer-coated stents were further assessed with Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy analysis (FTIR), Scanning electron microscopy (SEM) images and platelet adhesion studies. Stents coated with PCL matrix displayed more sustained and controlled drug release profiles than those coated with PLGA and PEG. Stents coated with PCL matrix showed the least platelet adhesion rate. Subsequently, stents coated with PCL matrix were subjected to the further optimization processes for improvement of surface morphology and enhancement of the drug release duration. The results of this study demonstrated that PCL matrix containing GSNO is a promising system for stent surface coating against restenosis. PMID:22937015

  20. Thermal and flow analysis of a convection air-cooled ceramic coated porous metal concept for turbine vanes

    NASA Technical Reports Server (NTRS)

    Stepka, F. S.

    1981-01-01

    The heat transfer and pressure drop through turbine vanes made of a sintered, porous metal coated with a thin layer of ceramic and convection cooled by spanwise flow of cooling air were analyzed. The analysis was made to determine the feasibility of using this concept for cooling very small turbines, primarily for short duration applications such as in missile engines. The analysis was made for gas conditions of approximately 10 and 40 atm and 1644 K and with turbine vanes made of felt type porous metals with relative densities from 0.2 to 0.6 and ceramic coating thicknesses of 0.076 to 0.254 mm.

  1. Porous Silica-Coated Gold Nanorods: A Highly Active Catalyst for the Reduction of 4-Nitrophenol.

    PubMed

    Mohanta, Jagdeep; Satapathy, Smithsagar; Si, Satyabrata

    2016-02-03

    The successful coating of thin porous silica layers of various thicknesses [(10±1), (12±1), and (14±1) nm] on cetyl trimethylammonium bromide (CTAB) capped gold nanorods was achieved through a modified Stöber procedure. The resulting material was applied as a novel catalyst for the reduction of 4-nitrophenol. The catalytic activities of the gold nanorods increased up to eight times after coating with a layer of porous silica and the reaction followed a zero-order kinetics, having a rate constant as high as 2.92×10(-1) mol L(-1) min(-1). The spectral changes during the reduction reaction of 4-nitrophenol were observed within a very short span of time and a complete conversion to 4-aminophenol occured within 5-6 mins, including the induction period of ≈2 mins. The reusability of the catalyst was studied by running the catalytic reaction during five consecutive cycles with good efficiency without destroying the nanostructure. The methodology can be effectively applied to the development of composite catalysts with highly enhanced catalytic activity.

  2. Patterned Polymer Coatings Increase the Efficiency of Dew Harvesting.

    PubMed

    Al-Khayat, Omar; Hong, Jun Ki; Beck, David M; Minett, Andrew I; Neto, Chiara

    2017-03-03

    Micropatterned polymer surfaces, possessing both topographical and chemical characteristics, were prepared on three-dimensional copper tubes and used to capture atmospheric water. The micropatterns mimic the structure on the back of a desert beetle that condenses water from the air in a very dry environment. The patterned coatings were prepared by the dewetting of thin films of poly-4-vinylpyridine (P4VP) on top of polystyrene films (PS) films, upon solvent annealing, and consist of raised hydrophilic bumps on a hydrophobic background. The size and density distribution of the hydrophilic bumps could be tuned widely by adjusting the initial thickness of the P4VP films: the diameter of the produced bumps and their height could be varied by almost 2 orders of magnitude (1-80 μm and 40-9000 nm, respectively), and their distribution density could be varied by 5 orders of magnitude. Under low subcooling conditions (3 °C), the highest rate of water condensation was measured on the largest (80 μm diameter) hydrophilic bumps and was found to be 57% higher than that on flat hydrophobic films. These subcooling conditions are achieved spontaneously in dew formation, by passive radiative cooling of a surface exposed to the night sky. In effect, the pattern would result in a larger number of dewy nights than a flat hydrophobic surface and therefore increases water capture efficiency. Our approach is suited to fabrication on a large scale, to enable the use of the patterned coatings for water collection with no external input of energy.

  3. Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte

    PubMed Central

    2014-01-01

    This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance (1H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte. PMID:25317101

  4. Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte.

    PubMed

    Plylahan, Nareerat; Maria, Sébastien; Phan, Trang Nt; Letiche, Manon; Martinez, Hervé; Courrèges, Cécile; Knauth, Philippe; Djenizian, Thierry

    2014-01-01

    This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance ((1)H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte.

  5. Formulation and evaluation of press coated tablets for pulsatile drug delivery using hydrophilic and hydrophobic polymers.

    PubMed

    Rane, Ashish Babulal; Gattani, Surendra Ganeshlal; Kadam, Vinayak Dinkar; Tekade, Avinash Ramrao

    2009-11-01

    The aim of present investigation was to develop press coated tablet for pulsatile drug delivery of ketoprofen using hydrophilic and hydrophobic polymers. The drug delivery system was designed to deliver the drug at such a time when it could be most needful to patient of rheumatoid arthritis. The press coated tablets containing ketoprofen in the inner core was formulated with an outer shell by different weight ratio of hydrophobic polymer (micronized ethyl cellulose powder) and hydrophilic polymers (glycinemax husk or sodium alginate). The release profile of press coated tablet exhibited a lag time followed by burst release, in which outer shell ruptured into two halves. Authors also investigated factors influencing on lag time such as particle size and viscosity of ethyl cellulose, outer coating weight and paddle rpm. The surface morphology of the tablet was examined by a scanning electron microscopy. Differential scanning calorimeter and Fourier transformed infrared spectroscopy study showed compatibility between ketoprofen and coating material.

  6. Porous Polymer Networks: Synthesis, Porosity, and Applications in Gas Storage/Separation

    SciTech Connect

    Lu, Weigang; Yuan, Daqiang; Zhao, Dan; Schilling, Christine Inge; Plietzsch, Oliver; Muller, Thierry; Braese, Stefano; Guenther, Johannes; Blumel, Janet; Krishna, Rajamani; Li, Zhen; Zhou, Hong-Cai

    2010-11-09

    Three porous polymer networks (PPNs) have been synthesized by the homocoupling of tetrahedral monomers. Like other hyper-cross-linked polymer networks, these materials are insoluble in conventional solvents and exhibit high thermal and chemical stability. Their porosity was confirmed by N₂ sorption isotherms at 77 K. One of these materials, PPN-3, has a Langmuir surface area of 5323 m² g-1. Their clean energy applications, especially in H₂, CH₄, and CO₂ storage, as well as CO₂/CH₄ separation, have been carefully investigated. Although PPN-1 has the highest gas affinity because of its smaller pore size, the maximal gas uptake capacity is directly proportional to their surface area. PPN-3 has the highest H₂ uptake capacity among these three (4.28 wt %, 77 K). Although possessing the lowest surface area, PPN-1 shows the best CO₂/CH₄ selectivity among them.

  7. Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

    SciTech Connect

    Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; Dai, Sheng

    2015-07-15

    We report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent- free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60– 90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

  8. Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

    DOE PAGES

    Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; ...

    2015-07-15

    We report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent- free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60– 90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture,more » and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.« less

  9. Polymer coating for immobilizing soluble ions in a phosphate ceramic product

    DOEpatents

    Singh, Dileep; Wagh, Arun S.; Patel, Kartikey D.

    2000-01-01

    A polymer coating is applied to the surface of a phosphate ceramic composite to effectively immobilize soluble salt anions encapsulated within the phosphate ceramic composite. The polymer coating is made from ceramic materials, including at least one inorganic metal compound, that wet and adhere to the surface structure of the phosphate ceramic composite, thereby isolating the soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic composite.

  10. Polymer Coating for Immobilizing Soluble Ions in a Phosphate Ceramic Product

    SciTech Connect

    Singh, Dileep; Wagh, Arun S.; Patel, Kartikey D.

    1999-05-05

    A polymer coating is applied to the surface of a phosphate ceramic composite to effectively immobilize soluble salt anions encapsulated within the phosphate ceramic composite. The polymer coating is made from ceramic materials, including at least one inorganic metal compound, that wet and adhere to the surface structure of the phosphate ceramic composite, thereby isolating the soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic composite.

  11. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration.

    PubMed

    Widmer, M S; Gupta, P K; Lu, L; Meszlenyi, R K; Evans, G R; Brandt, K; Savel, T; Gurlek, A; Patrick, C W; Mikos, A G

    1998-11-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  12. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    NASA Technical Reports Server (NTRS)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  13. Optimal rheological characteristics in dynamic stability of polymer flow through porous media: Topical report

    SciTech Connect

    Gao, H.W.; French, T.R.

    1988-04-01

    To identify the optimal rheological characteristics for maintaining the dynamic stability of polymer solutions flowing through porous media, displacement tests with a Newtonian fluid and a non-Newtonian fluid were performed in a 4-ft Berea sandstone core. A solution of 63 wt pct gylcerin in 53 meg/1 NaCL and a solution of 1500 ppM Pusher 500 in 53 meq/1 NaCl were used as the Newtonian fluid and non-Newtonian fluid, respectively. Two flow rates one in the purely viscous regime and one in the viscoelastic flow regime of Pusher 500 in Berea sandstone, were used in the displacement tests. The effluents collected were analyzed to determine polymer and tracer concentrations. The viscosities of the effluents were also measured with a Contraves viscometer. By comparing the concentration profiles obtained in tests with Pusher 500 and in those with gylcerin, the effects of flow rate, mobility ratio, and rheological characteristics on the dynamic stability of polymer flow in porous media were determined. At both leading and trailing edges of the polymer slug, stability increases with decreasing mobility ratio. At both high and low flow rates, a Newtonian fluid gives a more stable displacement at the fluid front than does a non-Newtonian fluid. Measurements on the mixing lengths at the back edge show that the size of the mobility buffer bank required for a flow rate at reservior conditions (viscous flow regime) would be less for a Newtonian fluid than for a non-Newtonian fluid. At a flow rate in the viscoelastic flow regime, the required size of the mobility buffer bank is less for a non-Newtonian fluid than for a Newtonian fluid. 39 refs., 13 figs., 1 tab.

  14. A digital microfluidic method for in situ formation of porous polymer monoliths with application to solid-phase extraction.

    PubMed

    Yang, Hao; Mudrik, Jared M; Jebrail, Mais J; Wheeler, Aaron R

    2011-05-15

    We introduce the marriage of two technologies: digital microfluidics (DMF), a technique in which droplets are manipulated by application of electrostatic forces on an array of electrodes coated by an insulator, and porous polymer monoliths (PPMs), a class of materials that is popular for use for solid-phase extraction and chromatography. In this work, circular PPM discs were formed in situ by dispensing and manipulating droplets of monomer solutions to designated spots on a DMF device followed by UV-initiated polymerization. We used PPM discs formed in this manner to develop a digital microfluidic solid-phase extraction (DMF-SPE) method, in which PPM discs are activated and equilibrated, samples are loaded, PPM discs are washed, and the samples are eluted, all using microliter droplets of samples and reagents. The new method has extraction efficiency (93%) comparable to that of pipet-based ZipTips and is compatible with preparative sample extraction and recovery for on-chip desalting, removal of surfactants, and preconcentration. We anticipate that DMF-SPE may be useful for a wide range of applications requiring preparative sample cleanup and concentration.

  15. A data-driven approach to establishing microstructure-property relationships in porous transport layers of polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Çeçen, A.; Fast, T.; Kumbur, E. C.; Kalidindi, S. R.

    2014-01-01

    The diffusion media (DM) has been shown to be a vital component for performance of polymer electrolyte fuel cells (PEFCs). The DM has a dual-layer structure composed of a macro-substrate referred to as the gas diffusion layer (GDL) coated with a micro-porous layer (MPL). Efficient prediction of the effective transport properties of the DM from its internal structure is essential to optimizing the multifunctional characteristics of this critical component. In this work, a unique data-driven approach to establishing structure-property correlations is introduced and applied to the case of gas diffusion in the GDL and MPL. This new approach provides an automated process to produce unbiased estimators to microstructural variance, in contrast to many process-related (hence biased) parameters employed by prominent correlations in the field. The present approach starts with a rigorous quantification of microstructure in the form of n-point statistics. It is followed by the identification of the key aspects of the internal structure through the use of principle component analysis. A data-driven correlation is established when the principal components are related to effective diffusivity by multivariate linear regression. This data-driven approach is compared to the conventional correlations and shown to achieve a very high accuracy for capturing the diffusive transport in the tested PEFC components.

  16. [An investigation of HAP/organic polymer composite coatings prepared by electrochemical co-deposition technique].

    PubMed

    Hu, Haobing; Lin, Changjian; Leng, Yang

    2003-03-01

    An electrochemical co-deposition technique has been developed to prepare a hydroxyapatite (HAP)/organic polymer composite coatings on Ti surface as new biomaterial of hard tissue. The composite coating of organic polymer and calcium phosphate is formed by adding a water soluble polymer of the ethylene series to NH4H2PO4-Ca (NO3)2 solution when conducting an appropriate electrochemical co-deposition experiment. The XRD, SEM, XPS, SIMS and nano indent measurements were performed to characterize the morphology, composition, structure and surface stiffness of the composite coating. It was found that the morphology and surface hardness of the coatings showed a remarkable modification when introducing a minor polymer to HAP coating, and the bonding force between the coating and metal substrate was distinctly increased. The incorporation of minor organic polymer into the HAP compound at molecular level will improve the mechanical properties and morphology of the composite coatings, and this may be helpful to raising its bio-activity.

  17. Sandwich-type polymer nanofiber structure of poly(furfuryl alcohol): an effective template for ordered porous films.

    PubMed

    Gao, Feng; Lu, Qingyi; Pang, Huan; Komarneni, Sridhar

    2009-09-17

    A brand new sandwich-type poly(furfuryl alcohol) (PFA) nanostructure as well as ordered PFA nanofiber arrays has been successfully obtained through a novel two-step polymerization method by using a porous alumina membrane as the template. This novel structure is made up of ordered PFA nanopillars supported by two PFA films on the top and bottom. The thickness of the PFA films on both sides could be adjusted from several micrometers to tens of micrometers, and the flexibility of the membrane could be controlled in a certain range. This sandwich-type polymer nanostructure can be used as an effective template for constructing other ordered porous films resembling the structure of the parent alumina membrane, and in this study, ordered porous titania membrane has been successfully obtained. Theoretically, many other novel porous (or meso- and macro-mixed porous) materials could be synthesized through this novel template.

  18. Next-generation resorbable polymer scaffolds with surface-precipitated calcium phosphate coatings.

    PubMed

    Kim, Jinku; Magno, Maria Hanshella R; Ortiz, Ophir; McBride, Sean; Darr, Aniq; Kohn, Joachim; Hollinger, Jeffrey O

    2015-03-01

    Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components. In this article, we continue our exploration of E1001(1k), a tyrosine-derived polycarbonate, as an orthopedic implant material. Specifically, we use E1001(1k), which is degradable, nontoxic, and osteoconductive, to fabricate porous bone regeneration scaffolds that were enhanced by two different types of calcium phosphate (CP) coatings: in one case, pure dicalcium phosphate dihydrate was precipitated on the scaffold surface and throughout its porous structure (E1001(1k) + CP). In the other case, bone matrix minerals (BMM) such as zinc, manganese and fluoride were co-precipitated within the dicalcium phosphate dihydrate coating (E1001(1k) + BMM). These scaffold compositions were compared against each other and against ChronOS (Synthes USA, West Chester, PA, USA), a clinically used bone graft substitute (BGS), which served as the positive control in our experimental design. This BGS is composed of poly(lactide co-ε-caprolactone) and beta-tricalcium phosphate. We used the established rabbit calvaria critical-sized defect model to determine bone regeneration within the defect for each of the three scaffold compositions. New bone formation was determined after 2, 4, 6, 8 and 12 weeks by micro-computerized tomography (μCT) and histology. The experimental tyrosine-derived polycarbonate, enhanced with dicalcium phosphate dihydrate, E1001(1k) + CP, supported significant bone formation within the defects and was superior to the same scaffold containing a mix of BMM, E1001(1k) + BMM. The comparison with the commercially available BGS was complicated by the large variability in bone formation observed for the laboratory preparations of E1001(1k) scaffolds. At all time points, there was a trend for E1001(1k) + CP to be superior to the commercial BGS. However, only at the 6-week time point did this trend reach statistical significance

  19. Porous coordination polymers as novel sorption materials for heat transformation processes.

    PubMed

    Janiak, Christoph; Henninger, Stefan K

    2013-01-01

    Porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) are inorganic-organic hybrid materials with a permanent three-dimensional porous metal-ligand network. PCPs or MOFs are inorganic-organic analogs of zeolites in terms of porosity and reversible guest exchange properties. Microporous water-stable PCPs with high water uptake capacity are gaining attention for low temperature heat transformation applications in thermally driven adsorption chillers (TDCs) or adsorption heat pumps (AHPs). TDCs or AHPs are an alternative to traditional air conditioners or heat pumps operating on electricity or fossil fuels. By using solar or waste heat as the operating energy TDCs or AHPs can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. TDCs and AHPs are based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The process is driven and controlled by the microporosity and hydrophilicity of the employed sorption material. Here we summarize the current investigations, developments and possibilities of PCPs/MOFs for use in low-temperature heat transformation applications as alternative materials for the traditional inorganic porous substances like silica gel, aluminophosphates or zeolites.

  20. Large deformation ionic polymer-metal composites actuators based on porous Nafion membranes

    NASA Astrophysics Data System (ADS)

    Zhao, Dongxu; Li, Dichen; Wang, Yanjie; Luo, Meng; Chen, Hualing

    2016-04-01

    With advantages of low driving voltage, good flexibility and high electromechanical efficiency, ionic polymer-metal composites (IPMCs), which are one of the most attractive smart materials, have been research hotspot in actuators, sensors and artificial muscles. However, a serious drawback of little deformation of thick IPMC actuator limits its application. In this paper, we fabricated thick porous Nafion membranes by freeze-drying process. A series of Thermogravimetric analyses (TGA), Field emission scanning electron microscopy (FE-SEM) and Water uptake (WUP) tests were performed to examine the validity of the freeze-drying process and the pore size and the porosity. Then, the porous IPMCs were fabricated with the freeze-drying processed Nafion membranes by the solution casting and reducing plating. Finally, the IPMC actuators with the dimensions of 25× 5× 1 in millimeters were achieved and tested. The terminal deformation of the porous IPMC actuator increased by 739.7%, compared with the ordinary IPMC actuator with the same dimensions under the driving voltage of 2VDC.

  1. Optical pH sensor based on the chemical modification of a porous polymer film

    SciTech Connect

    Jones, T.P.; Porter, M.D.

    1988-03-01

    A new approach to the design and construction of an optical pH sensor has been developed by immobilizing a direct azo dye at a porous cellulosic polymer film. This sensor was fabricated by binding Congo Red to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. Advantageous features of the design include (1) a rapid equilibration time (< 1.3 s), (2) a large dynamic range (> 4 pH units), and (3) ease of fabrication. The rapid response results from the porous structure of the polymeric support, which minimizes barriers to mass transport. The large dynamic range results from both the polyprotic acid-base reactivity of Congo Red and the large optical absorptivities of its various ionic forms. Furthermore, these results indicate that a variety of optical sensors which exhibit a rapid and sensitive response for the analysis of pH can be easily fabricated by immobilizing carefully selected direct dyes at porous polymeric substrates such as hydrolyzed cellulose acetate.

  2. Piezoelectric biosensor with a ladder polymer substrate coating

    DOEpatents

    Renschler, Clifford L.; White, Christine A.; Carter, Robert M.

    1998-01-01

    A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor.

  3. In silico design of porous polymer networks: high-throughput screening for methane storage materials.

    PubMed

    Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

    2014-04-02

    Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

  4. In vitro cytotoxicity evaluation of porous TiO₂-Ag antibacterial coatings for human fetal osteoblasts.

    PubMed

    Necula, B S; van Leeuwen, J P T M; Fratila-Apachitei, L E; Zaat, S A J; Apachitei, I; Duszczyk, J

    2012-11-01

    Implant-associated infections (IAIs) may be prevented by providing antibacterial properties to the implant surface prior to implantation. Using a plasma electrolytic oxidation (PEO) technique, we produced porous TiO₂ coatings bearing various concentrations of Ag nanoparticles (Ag NPs) (designated as 0 Ag, 0.3 Ag and 3.0 Ag) on a Ti-6Al-7Nb biomedical alloy. This study investigates the cytotoxicity of these coatings using a human osteoblastic cell line (SV-HFO) and evaluates their bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA). The release of Ag and the total amount of Ag in the coatings were determined using a graphite furnace atomic absorption spectrometry technique (GF-AAS) and flame-AAS, respectively. Cytotoxicity was evaluated using the AlamarBlue assay coupled with the scanning electron microscopy (SEM) observation of seeded cells and by fluorescence microscopy examination of the actin cytoskeleton and nuclei after 48 h of incubation. Antibacterial activity was assessed quantitatively using a direct contact assay. AlamarBlue viability assay, SEM and fluorescence microscopy observation of the SV-HFO cells showed no toxicity for 0 Ag and 0.3 Ag specimens, after 2, 5 and 7 days of culture, while 3.0 Ag surfaces appeared to be extremely cytotoxic. All Ag-bearing surfaces had good antibacterial activity, whereas Ag-free coatings showed an increase in bacterial numbers. Our results show that the 0.3 Ag coatings offer conditions for optimum cell growth next to antibacterial properties, which makes them extremely useful for the development of new antibacterial dental and orthopedic implants.

  5. In vitro antimicrobial properties of silver-polysaccharide coatings on porous fiber-reinforced composites for bone implants.

    PubMed

    Nganga, Sara; Travan, Andrea; Marsich, Eleonora; Donati, Ivan; Söderling, Eva; Moritz, Niko; Paoletti, Sergio; Vallittu, Pekka K

    2013-12-01

    Biostable fiber-reinforced composite (FRC) implants prepared from bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate resin reinforced with E-glass fibers have been successfully used in cranial reconstructions in 15 patients. Recently, porous FRC structures were suggested as potential implant materials. Compared with smooth surface, porous surface allows implant incorporation via bone ingrowth, but is also a subject to bacterial attachment. Non-cytotoxic silver-polysaccharide nanocomposite coatings may provide a way to decrease the risk of bacterial contamination of porous FRC structures. This study is focused on the in vitro characterization of the effect porosity on the antimicrobial efficiency of the coatings against Staphylococcus aureus and Pseudomonas aeruginosa by a series of microbiological tests (initial adhesion, antimicrobial efficacy, and biofilm formation). Characterization included confocal laser scanning microscopy and scanning electron microscopy. The effect of porosity on the initial attachment of S. aureus was pronounced, but in the case of P. aeruginosa the effect was negligible. There were no significant effects of the coatings on the initial bacterial attachment. In the antimicrobial efficacy test, the coatings were potent against both strains regardless of the sample morphology. In the biofilm tests, there were no clear effects either of morphology or of the coating. Further coating development is foreseen to achieve a longer-term antimicrobial effect to inhibiting bacterial implant colonization.

  6. Polymer coating of glass microballoons levitated in a focused acoustic field

    SciTech Connect

    Young, A.T.; Lee, M.C.; Feng, I.A.; Elleman, D.D.; Wang, T.G.

    1981-01-01

    Inertial confinement fusion (ICF) glass microballoons (GMBs) levitated in a focusing radiator acoustic device can be coated with liquid materials by deploying the liquid into the levitation field with a stepped-horn atomizer. The GMB can be forced to the center of the coating liquid with a strong acoustically generated centering force. Water solutions of organic polymers, uv-curable liquid organic monomers, and paraffin waxes have been used to prepare solid coatings on the surface of GMBs using this technique.

  7. Development and characterization of polymer-coated liposomes for vaginal delivery of sildenafil citrate.

    PubMed

    Refai, Hanan; Hassan, Doaa; Abdelmonem, Rehab

    2017-11-01

    Vaginal administration of sildenafil citrate has shown recently to develop efficiently the uterine lining with subsequent successful embryo implantation following in vitro fertilization. The aim of the present study was to develop sildenafil-loaded liposomes coated with bioadhesive polymers for enhanced vaginal retention and improved drug permeation. Three liposomal formulae were prepared by thin-film method using different phospholipid:cholesterol ratios. The optimal liposomal formulation was coated with bioadhesive polymers (chitosan and HPMC). A marked increase in liposomal size and zeta potential was observed for all coated liposomal formulations. HPMC-coated liposomes showed the greater bioadhesion and higher entrapment efficiency than chitosan-coated formulae. The in vitro release studies showed prolonged release of sildenafil from coated liposomes as compared to uncoated liposomes and sildenafil solution. Ex vivo permeation study revealed the enhanced permeation of coated relative to uncoated liposomes. Chitosan-coated formula demonstrated highest drug permeation and was thus selected for further investigations. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the successful coating of the liposomes by chitosan. Histopathological in vivo testing proved the efficacy of chitosan-coated liposomes to improve blood flow to the vaginal endometrium and to increase endometrial thickness. Chitosan-coated liposomes can be considered as potential novel drug delivery system intended for the vaginal administration of sildenafil, which would prolong system's retention at the vaginal site and enhance the permeation of sildenafil to uterine blood circulation.

  8. The Mechanical Robustness of Atomic-Layer- and Molecular-Layer-Deposited Coatings on Polymer Substrates

    DTIC Science & Technology

    2009-01-01

    The mechanical robustness of atomic-layer- and molecular-layer-deposited coatings on polymer substrates David C. Miller,1,2,a Ross R. Foster,1,2...00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE The mechanical robustness of atomic-layer- and molecular-layer-deposited coatings on polymer ...fracture related to the sharp grip teeth, polymer strips “Flex-o-Pane,” Warp Brothers, Inc. were attached over the grip ends outside of the gage region

  9. Porous silica coated spherical microresonator for vapor phase sensing of ammonia at a sub-ppm level

    NASA Astrophysics Data System (ADS)

    Mallik, Arun K.; Farrell, Gerald; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Semenova, Yuliya

    2016-05-01

    A new type of fiber optic sensor for the detection and quantification of ammonia (NH3) vapor levels is proposed and experimentally demonstrated. This sensor is based on a spherical silica micro resonator coated with porous silica gel. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling to a tapered fiber with a 3.3 μm waist diameter. The optical properties of the porous silica layer change when it is exposed to ammonia vapor, leading to a spectral shift of the WGM resonant wavelengths. The sensitivity of the proposed sensor has been tested by exposing it to different low level concentrations of ammonia: 4 ppm, 8 ppm, 12 ppm and 30 ppm at a constant relative humidity (50% RH) and constant temperature (23°C). The detection limit is calculated from experimental results as 57 ppb of ammonia for a 282 μm diameter porous silica coated microsphere.

  10. Preparation and in-vitro Antibacterial Evaluation of Electroless Silver Coated Polymers.

    PubMed

    Fazeli, Mohammad Reza; Hosseini, Vahid; Shamsa, Fazel; Jamalifar, Hossein

    2010-01-01

    Long-term use of indwelling medical catheters has often been hindered by catheter-associated nosocomial infections. In this study the effectiveness of silver coating of polystyrene and polyethylene polymers was investigated. Polymer pieces of 2 cm(2) each were coated with a thin layer of silver using electroless plating technique. Silver-coated polymers were challenged with cultures of four different microorganisms known for their involvement in nosocomial infections in both solid and broth media. The tested bacteria included Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Silver release from the coated polymers was 2-5 μg/cm(2) which was confirmed by chemical and biological methods. The silver coating thickness ranged between 20-450 nm. P. aeruginosa and S. aureus were the most adherent bacteria to polystyrene sheets while E. coli showed minimum adherence effect. The survival rate of different bacteria after 80 min in a time course experiment tended to dominate E. coli as the most sensitive bacteria to the effect of silver with zero survival rate while around 4% of P. aeruginosa were detected after same period. Silver coating of indwelling polymers by electroless technique seems promising in combating nosocomial infections due to long-term catheterization.

  11. Cotton Fabric Coated with Conducting Polymers and its Application in Monitoring of Carnivorous Plant Response.

    PubMed

    Bajgar, Václav; Penhaker, Marek; Martinková, Lenka; Pavlovič, Andrej; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2016-04-08

    The paper describes the electrical plant response to mechanical stimulation monitored with the help of conducting polymers deposited on cotton fabric. Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers in aqueous medium. Thus, modified fabrics were again coated with polypyrrole or polyaniline, respectively, in order to investigate any synergetic effect between both polymers with respect to conductivity and its stability during repeated dry cleaning. The coating was confirmed by infrared spectroscopy. The resulting fabrics have been used as electrodes to collect the electrical response to the stimulation of a Venus flytrap plant. This is a paradigm of the use of conducting polymers in monitoring of plant neurobiology.

  12. Cotton Fabric Coated with Conducting Polymers and its Application in Monitoring of Carnivorous Plant Response

    PubMed Central

    Bajgar, Václav; Penhaker, Marek; Martinková, Lenka; Pavlovič, Andrej; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2016-01-01

    The paper describes the electrical plant response to mechanical stimulation monitored with the help of conducting polymers deposited on cotton fabric. Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers in aqueous medium. Thus, modified fabrics were again coated with polypyrrole or polyaniline, respectively, in order to investigate any synergetic effect between both polymers with respect to conductivity and its stability during repeated dry cleaning. The coating was confirmed by infrared spectroscopy. The resulting fabrics have been used as electrodes to collect the electrical response to the stimulation of a Venus flytrap plant. This is a paradigm of the use of conducting polymers in monitoring of plant neurobiology. PMID:27070612

  13. Effect of soluble polymer binder on particle distribution in a drying particulate coating.

    PubMed

    Buss, Felix; Roberts, Christine C; Crawford, Kathleen S; Peters, Katharina; Francis, Lorraine F

    2011-07-01

    Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely.

  14. Study on iron oxide nanoparticles coated with glucose-derived polymers for biomedical applications

    NASA Astrophysics Data System (ADS)

    Herea, D. D.; Chiriac, H.; Lupu, N.; Grigoras, M.; Stoian, G.; Stoica, B. A.; Petreus, T.

    2015-10-01

    This study reports an approach for a facile one-step synthesis of magnetic nanoparticles (MNPs) coated with glucose-derived polymers (GDP) through a mechanochemical hydrothermal process for biomedical applications. Polymer-coated magnetic nanoparticles (Fe2O3/Fe3O4), with sizes below 10 nm, exhibited superparamagnetic behavior, with a specific magnetization saturation value of about 40 emu/g, and a maximum specific absorption rate (SAR) of 30 W/g in AC magnetic fields. Depending on the intensity of the applied AC magnetic field, a temperature of 42 °C can be achieved in 4-17 min. The surface polymerized layer affords functional hydroxyl groups for binding to biomolecules containing carboxyl, thiol, or amino groups, thereby making the coated nanoparticles feasible for bio-conjugation. In vitro cytotoxicity evaluation pointed out that a relatively high concentration of polymer-coated magnetic nanoparticles (GDP-MNPs) did not induce severe cell alteration, suggesting a good biocompatibility.

  15. Cold Spray Coating Deposition Mechanism on the Thermoplastic and Thermosetting Polymer Substrates

    NASA Astrophysics Data System (ADS)

    Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

    2013-12-01

    Cold spraying is a successful and promising coating technique for many engineering applications due to its high-rate and high-dense coating development abilities. Nevertheless, their practical use in polymer substrate is still in the fledgling phase. There are very few articles about the cold spray coating on polymers; however, the interaction of metallic particle with the polymer substrate is poorly understood, and thus a thick coating has not successfully been developed on the polymer substrate. In order to rationalize as full as possible the entire behavior of the high velocity particle with the polymer substrate, we used thermoplastic and thermosetting polymer materials as substrates. The particle behaviors with the substrate were observed under various gas pressure and temperature, and with various particles feed rate. The result showed that the particle behaviors were unique with respect to the substrate. Also it was clearly understood that the metal particles not experienced any plastic deformation due to the soft nature of the polymer substrates. The particles attached to the thermoplastic substrate either through adhesive bonding and/or mechanical inter locking, whereas only pure localized fracture observed on the thermosetting substrate and thus no particles attached firmly on the substrate.

  16. Localized cell stimulation by nitric oxide using a photoactive porous coordination polymer platform

    PubMed Central

    Diring, Stéphane; Wang, Dan Ohtan; Kim, Chiwon; Kondo, Mio; Chen, Yong; Kitagawa, Susumu; Kamei, Ken-ichiro; Furukawa, Shuhei

    2013-01-01

    Functional cellular substrates for localized cell stimulation by small molecules provide an opportunity to control and monitor cell signalling networks chemically in time and space. However, despite improvements in the controlled delivery of bioactive compounds, the precise localization of gaseous biomolecules at the single-cell level remains challenging. Here we target nitric oxide, a crucial signalling molecule with site-specific and concentration-dependent activities, and we report a synthetic strategy for developing spatiotemporally controllable nitric oxide-releasing platforms based on photoactive porous coordination polymers. By organizing molecules with poor reactivity into polymer structures, we observe increased photoreactivity and adjustable release using light irradiation. We embed photoactive polymer crystals in a biocompatible matrix and achieve precisely controlled nitric oxide delivery at the cellular level via localized two-photon laser activation. The biological relevance of the exogenous nitric oxide produced by this strategy is evidenced by an intracellular change in calcium concentration, mediated by nitric oxide-responsive plasma membrane channel proteins. PMID:24158008

  17. 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.

  18. Semi-permeable coatings fabricated from comb-polymers efficiently protect proteins in vivo

    NASA Astrophysics Data System (ADS)

    Liu, Mi; Johansen, Pål; Zabel, Franziska; Leroux, Jean-Christophe; Gauthier, Marc A.

    2014-11-01

    In comparison to neutral linear polymers, functional and architecturally complex (that is, non-linear) polymers offer distinct opportunities for enhancing the properties and performance of therapeutic proteins. However, understanding how to harness these parameters is challenging, and studies that capitalize on them in vivo are scarce. Here we present an in vivo demonstration that modification of a protein with a polymer of appropriate architecture can impart low immunogenicity, with a commensurably low loss of therapeutic activity. These combined properties are inaccessible by conventional strategies using linear polymers. For the model protein L-asparaginase, a comb-polymer bio-conjugate significantly outperformed the linear polymer control in terms of lower immune response and more sustained bioactivity. The semi-permeability characteristics of the coatings are consistent with the phase diagram of the polymer, which will facilitate the application of this strategy to other proteins and with other therapeutic models.

  19. Self-healing antimicrobial polymer coating with efficacy in the presence of organic matter

    NASA Astrophysics Data System (ADS)

    Bastarrachea, Luis J.; Goddard, Julie M.

    2016-08-01

    A method to prepare a self-healing, antimicrobial polymer coating that retains efficacy against Escherichia coli O157:H7 in the presence of organic matter is reported. A coating composed of branched polyethyleneimine (PEI) and styrene maleic anhydride copolymer (SMA) was applied to a maleic anhydride functionalized polypropylene support. The chemistry of the polymer coating was designed to impart hydrophobicity due to the styrene subunits, intrinsic antimicrobial character (>99.9% reduction) from the cationic primary amine groups, and enhanced antimicrobial character (> 99.99% reduction) after chlorination of N-halamine forming groups. Antimicrobial effectiveness was demonstrated under conditions of increasing organic load. Up to 500 ppm horse serum, chlorinated coatings retained full antimicrobial character (>99.99% reduction). Even at 50,000 ppm of horse serum, the coating provided ∼90% reduction as prepared, and between ∼75% and ∼80% reduction in the form of N-halamines. Microscopy confirmed no evidence of bacterial adhesion on the coating surface. Finally, the coating exhibited self-healing properties after exposure to acid and alkaline solutions and restoration by heat, as confirmed through spectroscopy from the rebuilding of characteristic chemical bonds. Such robust antimicrobial polymer coatings with efficacy under conditions of increasing organic load may support reducing microbial cross-contamination in food and biomedical industries.

  20. Piezoelectric biosensor with a ladder polymer substrate coating

    DOEpatents

    Renschler, C.L.; White, C.A.; Carter, R.M.

    1998-09-29

    A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor. 3 figs.

  1. Application of hybrid organic/inorganic polymers as coatings on metallic substrates

    NASA Astrophysics Data System (ADS)

    Augustinho, T. R.; Motz, G.; Ihlow, S.; Machado, R. A. F.

    2016-09-01

    Acrylic polymers, particularly poly (methyl methacrylate) (PMMA), have certain specific properties, such as good film formation, transparency, and good mechanical properties, which have been widely used in paints, coatings and adhesives. However, the limited chemical and physical stability of these pure polymers limits their applications when exposed to hostile conditions, as in ship hulls, for example. A suitable way to enhance PMMA properties is the addition of silicon polymers with very good protective characteristics. In this study, a PMMA and HTT 1800 (commercial silazane) copolymer were applied on metallic substrate and compared to pure PMMA and HTT 1800. All the materials were applied as coatings. They were applied on stainless steel via dip-coating to investigate the coating properties. Thermal cycling was employed to analyze coating durability at high temperatures (50 °C to 600 °C). Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the coated surfaces, and the adhesion of pure PMMA, pure HTT 1800 and PMMA/HTT 1800 coatings on metallic substrate was investigated by Cross-Cut-Test (ASTM D 3359). The sessile drop method was used to determine the contact angle. PMMA coatings presented complete degradation from 250 °C, while hybrid coatings of PMMA and HTT 1800 have good protection until 400 °C. The adherence of the coating on metallic substrate showed improvement in all synthesized materials when compared to pure PMMA, obtaining the best adherence possible. The contact angle test showed that the hydrophobicity of the hybrid coatings is higher than that of the pure coatings.

  2. Effects of hydrophilic macropore fillings and coatings on the infiltration into water repellent porous media

    NASA Astrophysics Data System (ADS)

    Suetsugu, A.; Mori, Y.

    2012-12-01

    Macropores generate rapid flow paths in the surface soils by their high permeability under saturated/near-saturated moisture conditions. In natural soils, some macropores are filled/coated with various materials including decayed plant roots (Meek et al., 1989), exudates from plants/soil organisms (Jegou et al., 2001), iron oxides or other precipitates from preferentially-introduced solutes/colloids to the macropores (Rasmussen et al., 2001), or the surrounding soils with reduced bulk density (Ela et al., 1992). When we expect infiltration into water repellent soils through macropores or hydrophilic patches created from the macropore cementation processes, hydrophilicity of the macropore fillings/coatings should be understood. In the present study, we conducted an infiltration experiment with water repellent porous media and some macropore fillings/coatings, in order to clarify the roles of hydrophilic macropore fillings/coatings in infiltration. Ponding depth and flow distribution were monitored with a micro-focus X-ray computational tomography apparatus (SMX-90CT, Shimadzu Corp., Kyoto, Japan) at 90 kV and 110 μA. Dilute CsCl(aq) (density: 1.04 Mg m-3) was used as the contrast media to avoid density-driven alteration of the flows. Water repellency of the samples was evaluated by the water drop penetration time (WDPT, Van't Woudt, 1959). A glass beads (mean diameter: 0.46 mm, BZ-04, ASONE Corp., Osaka, Japan) was used as water repellent porous media. The glass beads sample was packed in 50-mL polypropylene centrifugation tubes at 1.55 Mg m-3 bulk density. A 2-mm hole was made at the bottom of each centrifugation tube for ventilation. The hole was covered with mesh cloth. Macroporous structure was made at the center of each tube from the surface. Each macroporous structure had 4-mm diameter and 30-mm length. Six types of macropores were prepared including 1) no macropore, 2) empty macropore, 3) an aluminum (Al) pipe (4-mm inner diameter, 5-mm outer diameter), 4) a

  3. Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures.

    PubMed

    Gu, Shuai; He, Jianqiao; Zhu, Yunlong; Wang, Zhiqiang; Chen, Dongyang; Yu, Guipeng; Pan, Chunyue; Guan, Jianguo; Tao, Kai

    2016-07-20

    The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation.

  4. Nanocrystalline porous TiO2 electrode with ionic liquid impregnated solid polymer electrolyte for dye sensitized solar cells.

    PubMed

    Singh, Pramod K; Kim, Kang-Wook; Kim, Ki-Il; Park, Nam-Gyu; Rhee, Hee-Woo

    2008-10-01

    This communication reports the detailed fabrication of electrodes and solid polymer electrolyte with ionic liquid (IL) as an electrolyte for dye sensitized solar cell (DSSC). Thick porous TiO2 film has been obtained by spreading and sintering TiO2 colloidal paste using "doctor blade" and characterized by SEM, TEM and XRD. The polymer electrolyte was PEO:KI/I2 incorporated with 1-ethyl 3-methylimidazolium thiocyanate (EMImSCN) as IL. Dispersal of IL in the polymer electrolyte improved the ionic conductivity and cell efficiency.

  5. 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.

  6. Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

    PubMed

    Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

    2015-11-01

    The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic.

  7. A novel, polymer-coated oncolytic measles virus overcomes immune suppression and induces robust antitumor activity

    PubMed Central

    Nosaki, Kaname; Hamada, Katsuyuki; Takashima, Yuto; Sagara, Miyako; Matsumura, Yumiko; Miyamoto, Shohei; Hijikata, Yasuki; Okazaki, Toshihiko; Nakanishi, Yoichi; Tani, Kenzaburo

    2016-01-01

    Although various therapies are available to treat cancers, including surgery, chemotherapy, and radiotherapy, cancer has been the leading cause of death in Japan for the last 30 years, and new therapeutic modalities are urgently needed. As a new modality, there has recently been great interest in oncolytic virotherapy, with measles virus being a candidate virus expected to show strong antitumor effects. The efficacy of virotherapy, however, was strongly limited by the host immune response in previous clinical trials. To enhance and prolong the antitumor activity of virotherapy, we combined the use of two newly developed tools: the genetically engineered measles virus (MV-NPL) and the multilayer virus-coating method of layer-by-layer deposition of ionic polymers. We compared the oncolytic effects of this polymer-coated MV-NPL with the naked MV-NPL, both in vitro and in vivo. In the presence of anti-MV neutralizing antibodies, the polymer-coated virus showed more enhanced oncolytic activity than did the naked MV-NPL in vitro. We also examined antitumor activities in virus-treated mice. Complement-dependent cytotoxicity and antitumor activities were higher in mice treated with polymer-coated MV-NPL than in mice treated with the naked virus. This novel, polymer-coated MV-NPL is promising for clinical cancer therapy in the future. PMID:27847861

  8. Water Vapor Permeation of Metal Oxide/Polymer Coated Plastic Films

    NASA Astrophysics Data System (ADS)

    Numata, Yukihiro; Oya, Toshiyuki; Kuwahara, Mitsuru; Ito, Katsuya

    Barrier performance to water vapor permeation of ceramic coated layers deposited on flexible polymer films is of great interest to food packaging, medical device packaging and flat panel display industries. In this study, a new type film in which a ceramic layer is deposited on a polymer coated film was proposed for lower water vapor permeation. It is important how to control interfacial properties between each layer and film for good barrier performance. Several kinds of polymer coated materials were prepared for changing surface free energy of the films before and after depositing the ceramic layer. The ceramic layer, which is composed of mixed material of SiO2 and Al2O3, was adopted under the same conditions. The following results were obtained; 1) Water vapor permeation is not related to the surface energy of polymer coated films, 2) After depositing the ceramic layer, however, a strong correlation is observed between the water vapor permeation and surface free energy. 3) The phenomenon is considered that the polarity of the polymer layers plays a key role in changing the structure of ceramic coated layers.

  9. A novel, polymer-coated oncolytic measles virus overcomes immune suppression and induces robust antitumor activity.

    PubMed

    Nosaki, Kaname; Hamada, Katsuyuki; Takashima, Yuto; Sagara, Miyako; Matsumura, Yumiko; Miyamoto, Shohei; Hijikata, Yasuki; Okazaki, Toshihiko; Nakanishi, Yoichi; Tani, Kenzaburo

    2016-01-01

    Although various therapies are available to treat cancers, including surgery, chemotherapy, and radiotherapy, cancer has been the leading cause of death in Japan for the last 30 years, and new therapeutic modalities are urgently needed. As a new modality, there has recently been great interest in oncolytic virotherapy, with measles virus being a candidate virus expected to show strong antitumor effects. The efficacy of virotherapy, however, was strongly limited by the host immune response in previous clinical trials. To enhance and prolong the antitumor activity of virotherapy, we combined the use of two newly developed tools: the genetically engineered measles virus (MV-NPL) and the multilayer virus-coating method of layer-by-layer deposition of ionic polymers. We compared the oncolytic effects of this polymer-coated MV-NPL with the naked MV-NPL, both in vitro and in vivo. In the presence of anti-MV neutralizing antibodies, the polymer-coated virus showed more enhanced oncolytic activity than did the naked MV-NPL in vitro. We also examined antitumor activities in virus-treated mice. Complement-dependent cytotoxicity and antitumor activities were higher in mice treated with polymer-coated MV-NPL than in mice treated with the naked virus. This novel, polymer-coated MV-NPL is promising for clinical cancer therapy in the future.

  10. Segment-Structured Diamond-Like Carbon Coatings on Polymer Catheter

    NASA Astrophysics Data System (ADS)

    Nakagawa, Taku; Ohishi, Ryusuke; Ohtake, Naoto; Takai, Osamu; Tsutsui, Nobumasa; Tsutsui, Yasuhiro; Muraki, Yasuhiro; Ogura, Jyunpei

    Diamond-like carbon (DLC) has remarkable mechanical and tribological properties. Besides those mechanical properties, it has been clarified that DLC shows high biocompatibility in recent years. DLC coating can give high strength, abrasion resistance, and biocompatibility for surface of substrates. Hence DLC is a candidate for the coating material for medical devices such as artificial organ, joint, catheter, etc. The objective of this study is to develop safety protection films for implantable medical polymer devices utilizing segment-structured DLC (S-DLC) coatings. S-DLC and continuous-structured DLC were deposited on polyurethane and nylon sheet for balloon catheters. As a result, friction coefficient of DLC coated polyurethane sheet was approximately one-sixth of that of pristine polyurethane sheet, and S-DLC showed very low friction coefficient of μ=0.1-0.15. DLC coating can prevent polyurethane sheet from worn out. The puncture-resistance of nylon sheets increased 0.2MPa on average by DLC coatings regardless of the film structure. It was confirmed that DLC inhibits adsorption of blood coagulation factor. In conclusion, we succeed to verify that these DLC films can improve tribological property, abrasion-resistance, puncture-resistance, and anti-thrombogenicity of polymer catheters. Moreover, segment-structured DLC films exhibits high performance for protection of polymer material for polymer catheters.

  11. Ex Situ Integration of Multifunctional Porous Polymer Monoliths into Thermoplastic Microfluidic Chips

    PubMed Central

    Kendall, Eric L.; Wienhold, Erik; Rahmanian, Omid D.; DeVoe, Don L.

    2014-01-01

    A unique method for incorporating functional porous polymer monolith elements into thermoplastic microfluidic chips is described. Monolith elements are formed in a microfabricated mold, rather than within the microchannels, and chemically functionalized off chip before insertion into solvent-softened thermoplastic microchannels during chip assembly. Because monoliths may be trimmed prior to final placement, control of their size, shape, and uniformity is greatly improved over in-situ photopolymerization methods. A characteristic trapezoidal profile facilitates rapid insertion and enables complete mechanical anchoring of the monolith periphery, eliminating the need for chemical attachment to the microchannel walls. Off-chip processing allows the parallel preparation of monoliths of differing compositions and surface chemistries in large batches. Multifunctional flow-through arrays of multiple monolith elements are demonstrated using this approach through the creation of a fluorescent immunosensor with integrated controls, and a microfluidic bubble separator comprising a combination of integrated hydrophobic and hydrophilic monolith elements. PMID:25018587

  12. A systematic study on the stability of porous coordination polymers against ammonia.

    PubMed

    Kajiwara, Takashi; Higuchi, Masakazu; Watanabe, Daisuke; Higashimura, Hideyuki; Yamada, Teppei; Kitagawa, Hiroshi

    2014-11-17

    To establish a strategy for designing porous coordination polymers (PCPs) for ammonia capture, the first systematic study on the stability of PCPs against ammonia was conducted. Various types of PCPs were investigated by comparing their powder XRD patterns before and after treatment with ammonia. Among the PCPs tested, ZIF-8, MIL-53(Al), Al-BTB, MOF-76(M) (M=Y or Yb), MIL-101(Cr), and MOF-74(Mg) were stable up to 350 °C under an ammonia atmosphere at ambient pressure. The origin of the stability of PCPs is discussed from the viewpoint of their components, metal cations, and organic linkers. Furthermore, adsorption isotherm measurements show that the adsorptive behavior of PCPs is independent of their stability.

  13. Control of molecular rotor rotational frequencies in porous coordination polymers using a solid-solution approach.

    PubMed

    Inukai, Munehiro; Fukushima, Tomohiro; Hijikata, Yuh; Ogiwara, Naoki; Horike, Satoshi; Kitagawa, Susumu

    2015-09-30

    Rational design to control the dynamics of molecular rotors in crystalline solids is of interest because it offers advanced materials with precisely tuned functionality. Herein, we describe the control of the rotational frequency of rotors in flexible porous coordination polymers (PCPs) using a solid-solution approach. Solid-solutions of the flexible PCPs [{Zn(5-nitroisophthalate)x(5-methoxyisophthalate)1-x(deuterated 4,4'-bipyridyl)}(DMF·MeOH)]n allow continuous modulation of cell volume by changing the solid-solution ratio x. Variation of the isostructures provides continuous changes in the local environment around the molecular rotors (pyridyl rings of the 4,4'-bipyridyl group), leading to the control of the rotational frequency without the need to vary the temperature.

  14. Chemistry of porous coordination polymers having multimodal nanospace and their multimodal functionality.

    PubMed

    Seo, Joobeom; Sakamoto, Hirotoshi; Matsuda, Ryotaro; Kitagawa, Susumu

    2010-01-01

    Remarkable advances in the recent development of porous coordination polymers (PCPs) or metal organic frameworks (MOFs) have paved the way toward functional chemistry having potential application such as molecular storage, separation, and catalysis. Moreover flexible PCPs, which are structurally transformable depending upon guest molecules adsorption/desorption, have received much attention because they provide unique properties, dissimilar to those of zeolites. PCPs can be categorized into structurally monomodal and multimodal classes. Monomodal PCPs possess single uniform pores in the framework. In contrast, multimodal PCPs have more than two types of pores in the framework. Interpenetrated PCPs can possess more than two types of pores with different sizes and shapes in the same framework depending on relative position of individual motifs, resulting in multimodal PCPs. Moreover, interpenetrated PCPs have several advantages, such as high thermal stability, flexibility, and ultramicropore for effective adsorption. In this review, chemistry of PCPs based on monomodal and multimodal PCPs are summarized and discussed.

  15. Polymer-coated fibrous materials as the stationary phase in packed capillary gas chromatography.

    PubMed

    Saito, Yoshihiro; Tahara, Ai; Imaizumi, Motohiro; Takeichi, Tsutomu; Wada, Hiroo; Jinno, Kiyokatsu

    2003-10-15

    Synthetic polymer filaments have been introduced as the support material in packed capillary gas chromatography (GC). The filaments of the heat-resistant polymers, Zylon, Kevlar, Nomex, and Technora, were longitudinally packed into a short fused-silica capillary, followed by the conventional coating process for open-tubular GC columns. The separation of several test mixtures such as n-alkylbenzenes and n-alkanes was carried out with these polymer-coated fiber-packed capillary columns. With the coating by various polymeric materials on the surface of these filaments, the retentivity was significantly improved over the parent fiber-packed column (without polymer coating) as well as a conventional open-tubular capillary of the same length. The results demonstrated a good combination of Zylon as the support and poly(dimethylsiloxane)-based materials as the coating liquid-phase for the successful GC separation of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while successful applications for other separations such as poly(ethylene glycol) coating for the separation of alcohols were also obtained. From the results it has been suggested that the selectivity of the fiber-packed column could be tuned by selecting different coating materials, indicating the promising possibility for a novel usage of fine fibrous polymers as the support material that can be combined with newly synthesized coating materials specially designed for particular separations. Taking advantage of good thermal stability of the fibers, the column temperature could be elevated to higher than 350 degrees C with the combination of a short metallic capillary.

  16. Polymer functionalized nanostructured porous silicon for selective water vapor sensing at room temperature

    NASA Astrophysics Data System (ADS)

    Dwivedi, Priyanka; Das, Samaresh; Dhanekar, Saakshi

    2017-04-01

    This paper highlights the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature. A simple and low cost technique was used for fabrication and functionalization of PSi. Spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface. Morphological and structural studies were conducted to analyze samples using SEM and XRD/Raman spectroscopy respectively. Contact angle measurements were performed for assessing the wettability of the surfaces. PSi and functionalized PSi samples were tested as sensors in presence of different analytes like ethanol, acetone, isopropyl alcohol (IPA) and water vapors in the range of 50-500 ppm. Electrical measurements were taken from parallel aluminium electrodes fabricated on the functionalized surface, using metal mask and thermal evaporation. Functionalized PSi sensors in comparison to non-functionalized sensors depicted selective and enhanced response to water vapor at room temperature. The results portray an efficient and selective water vapor detection at room temperature.

  17. Singlet oxygen generation using a porous monolithic polymer supported photosensitizer: potential application to the photodynamic destruction of melanoma cells.

    PubMed

    Burguete, M Isabel; Galindo, Francisco; Gavara, Raquel; Luis, Santiago V; Moreno, Miguel; Thomas, Paul; Russell, David A

    2009-01-01

    Photogeneration of singlet oxygen (1O2) by rose bengal is improved through the use of a porous monolithic polymer (PMP) as a support, as compared to a classic gel-type resin matrix. This type of monolithic polymeric matrix can be made at a multigram scale in quantitative yields enabling the preparation of large amounts of supported photosensitizer at low cost. The singlet oxygen induced oxidation of 9,10-diphenylanthracene has been used as a benchmark reaction, and a comparative study using rose bengal in solution, entrapped within gel-type derived polymer and entrapped within a porous monolithic polymer (PMP) has been performed. The enhanced photoreactivity of the PMP-rose bengal conjugates has been utilised for the successful photodynamic therapy (PDT) of melanoma cells.

  18. Improving the quality of polymer-coated urea with recycled plastic, proper additives, and large tablets.

    PubMed

    Yang, Yue-Chao; Zhang, Min; Li, Yuncong; Fan, Xiao-Hui; Geng, Yu-Qing

    2012-11-14

    Polymer-coated urea (PCU) has great potential for increasing crop production and enhancing nitrogen (N) fertilizer use efficiency, benefiting the ecosystem. However, current PCUs are used only in a limited market, and the main obstacle to the wider use of PCUs is high cost compared to that of conventional N fertilizers. In this study, the low cost PCU and large tablet polymer-coated urea (LTPCU) were prepared by using recycling polystyrene foam and various sealants as the coating materials. The structural and chemical characteristics of the coating shells of the coated fertilizers were examined. The N release characteristics of coated fertilizers were determined in 25 °C water under laboratory conditions. The relationship between the N release longevity and the amount of coating material and the percentage of different sealants were evaluated. The results indicated that recycling polystyrene foam was the ideal coating material of the controlled release fertilizer. The polyurethane that was synthesized by the reaction of castor oil and isocyanate was better than the wax as the additive to delay the N release rate of coated urea. The coating material used for LTPCU was 70-80% less than those used for commercial PCUs under the same N release longevity. The cost of the recycling polystyrene foam used for coating one ton of pure N of the LTPCU was about one-seventh to one-eighth of the cost of the traditional polymer used for the commercial PCU. The experimental data showed that the LTPCU with good controlled-release capacities, being economical and eco-friendly, could be promising for wide use in agriculture and horticulture.

  19. Understanding the role of dip-coating process parameters in the mechanical performance of polymer-coated bioglass robocast scaffolds.

    PubMed

    Motealleh, Azadeh; Eqtesadi, Siamak; Perera, Fidel Hugo; Pajares, Antonia; Guiberteau, Fernando; Miranda, Pedro

    2016-12-01

    The effect of different dip-coating variables-solvent, deposition temperature and polymer concentration-on the mechanical performance of polycaprolactone-coated 45S5 bioglass robocast scaffolds is systematically analyzed in this work. The reproducible geometry of the scaffolds produced by this additive manufacturing technique makes them an optimal model system and facilitates the analysis. The results suggest that the mechanical performance of the hybrid scaffolds is improved monotonically with polymer concentration, but this concentration cannot be increased indefinitely if the macroporosity interconnectivity, and thus the scaffold׳s capacity to promote tissue ingrowth, are to be preserved. An optimal concentration, and therefore viscosity (~1-4Pas in the present case), exists for any given set of process variables (scaffold geometry and material, polymer, solvent and process temperature) that yields coatings with optimal reinforcement and minimal reduction of scaffold functionality. Solvent and process temperature do not directly affect the strengthening provided by the polymeric coating. However they can determine the maximum concentration at the critical viscosity, and thereby the maximum achievable mechanical performance of the resulting hybrid scaffold.

  20. Porous coordination polymers with ubiquitous and biocompatible metals and a neutral bridging ligand

    PubMed Central

    Noro, Shin-ichiro; Mizutani, Junya; Hijikata, Yuh; Matsuda, Ryotaro; Sato, Hiroshi; Kitagawa, Susumu; Sugimoto, Kunihisa; Inubushi, Yasutaka; Kubo, Kazuya; Nakamura, Takayoshi

    2015-01-01

    The design of inexpensive and less toxic porous coordination polymers (PCPs) that show selective adsorption or high adsorption capacity is a critical issue in research on applicable porous materials. Although use of Group II magnesium(II) and calcium(II) ions as building blocks could provide cheaper materials and lead to enhanced biocompatibility, examples of magnesium(II) and calcium(II) PCPs are extremely limited compared with commonly used transition metal ones, because neutral bridging ligands have not been available for magnesium(II) and calcium(II) ions. Here we report a rationally designed neutral and charge-polarized bridging ligand as a new partner for magnesium(II) and calcium(II) ions. The three-dimensional magnesium(II) and calcium(II) PCPs synthesized using such a neutral ligand are stable and show selective adsorption and separation of carbon dioxide over methane at ambient temperature. This synthetic approach allows the structural diversification of Group II magnesium(II) and calcium(II) PCPs. PMID:25592677

  1. On the nature of interface of carbon nanotube coated carbon fibers with different polymers

    NASA Astrophysics Data System (ADS)

    Singh Bedi, Harpreet; Padhee, Srikant S.; Agnihotri, Prabhat K.

    2016-07-01

    Experimental investigations are carried out to analyse the wetting behaviour of carbon nanotube (CNT) coated carbon fiber to determine their suitability to process carbon nanotube coated carbon fiber/polymer multiscale composites for structural applications. To overcome the problem of agglomeration, CNTs are grown directly on the surface of carbon fibers as well as fabric using thermal chemical vapour deposition (CVD) technique. The term multiscale is used because different reinforcement mechanisms operate at the scale of long fibers and CNTs which are of few micrometers in length. The load carrying capacity of these multiscale composites critically depends on the efficiency and extent of load transfer from low strength matrix to high strength fiber which in turn depends on the interfacial strength between CNT coated carbon fiber and polymer matrix. A systematic analysis of wetting behaviour of CNT coated carbon fiber with epoxy and polyester matrix is carried out in this study. It is shown that CNT coated carbon fibers as well as fabric show better wettability with epoxy matrix as compared to polyester matrix. This results in stronger interface of CNT coated carbon fiber with epoxy as compared to polyester in multiscale composite system. A similar observation is made in nanoindentation testing of single fiber multiscale composites processed with epoxy and polyester matrix. In addition, it is observed that wettability, interfacial strength and average properties of CNT coated carbon fiber/polymer composites are a function of CNT density on the surface of carbon fibers.

  2. Fabrication of a novel polymer-free nanostructured drug-eluting coating for cardiovascular stents.

    PubMed

    Wang, Yao; Zhang, Wenli; Zhang, Jixi; Sun, Wei; Zhang, Ruiyan; Gu, Hongchen

    2013-10-23

    Angioplasty with stents is the most important method for the treatment of coronary artery disease (CAD). However, the drug-eluting stents (DES) that are widely used have the increased risks of inflammatory reactions and late stent thrombosis (LST) because of the persistence of the polymer coatings. To improve the biosafety, a novel polymer-free-composite drug-eluting coating composed of magnetic mesoporous silica nanoparticles (MMSNs) and carbon nanotubes (CNTs) was constructed using the electrophoretic deposition (EPD) method in this study. A crack-free two-layered coating with impressive network nanotopologies was successfully obtained by regulating the composition and structures. This nanostructured coating exhibits excellent mechanical flexibility and blood compatibility in vitro, and the drug-loading and release performance is satisfactory as well. The in vivo study shows that this composite coating has the obvious advantage of rapid endothelialization because of its unique 3D nanostructured topology in comparison with the commercial polymer-coated DES. This study aims to provide new ideas and reliable data to design novel functional coatings that could accelerate the re-endothelialization process and avoid inflammatory reactions, thus improving the in vivo biosafety of DES.

  3. Adhesion of metals to spin-coated fluorocarbon polymer films

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Kil; Chang, Chin-An; Schrott, A. G.

    1990-01-01

    Adhesion between metals and fluorocarbon polymer films has been studied for Cu, Cr, Ti, Al, and Au on polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films. Polymer films were applied on the Cr/SiO2 /Si substrate by spinning the aqueous dispersions of the polymer resin particles, followed by thermal curing. Strips of different metals were deposited on the polymers, and adhesion was measured at 90° peel test. The peel strengths were invariably higher for the metals on FEP than those of the corresponding metals on PTFE. Among the metals, Ti showed the highest peel strength for both polymers, followed by Cr and Al, with Cu and Au being the lowest. The peel strengths of Ti, Cr, and Cu on FEP are 85, 45, and 12 g/mm, respectively, and the corresponding ones on PTFE are 23, 5, and 2 g/mm, respectively. X-ray photoelectron spectroscopic analysis shows that the metal-polymer bonding involves the metal-carbon interactions. The strongest interaction is observed for Ti with the polymers, forming Ti carbidelike bonds. Cr also shows strong interaction with the two polymers, but to a lesser degree compared with Ti. Only a weak bonding is shown for Cu. The difference in peel strengths among the metals shows a correlation with the difference in electronegativities between the metals and carbon. Little contribution to the observed peel strengths is seen from the surface morphological analysis of the untreated polymers.

  4. Stable dispersions of polymer-coated graphitic nanoplatelets

    NASA Technical Reports Server (NTRS)

    Stankovich, Sasha (Inventor); Nguyen, Sonbinh T. (Inventor); Ruoff, Rodney S. (Inventor)

    2011-01-01

    A method of making a dispersion of reduced graphite oxide nanoplatelets involves providing a dispersion of graphite oxide nanoplatelets and reducing the graphite oxide nanoplatelets in the dispersion in the presence of a reducing agent and a polymer. The reduced graphite oxide nanoplatelets are reduced to an extent to provide a higher C/O ratio than graphite oxide. A stable dispersion having polymer-treated reduced graphite oxide nanoplatelets dispersed in a dispersing medium, such as water or organic liquid is provided. The polymer-treated, reduced graphite oxide nanoplatelets can be distributed in a polymer matrix to provide a composite material.

  5. Bone formation in transforming growth factor beta-1-coated porous poly(propylene fumarate) scaffolds.

    PubMed

    Vehof, Johan W M; Fisher, John P; Dean, David; van der Waerden, Jan-Paul C M; Spauwen, Paul H M; Mikos, Antonios G; Jansen, John A

    2002-05-01

    This study determined the bone growth into pretreated poly(propylene fumarate) (PPF) scaffolds implanted into a subcritical size, rabbit cranial defect. PPF scaffolds were constructed by using a photocrosslinking-porogen leaching technique. These scaffolds were then either prewetted (PPF-Pw), treated with RF glow-discharge (PPF-Gd), coated with fibronectin (PPF-Fn), or coated with rhTGF-beta1 (PPF-TGF-beta1). One of each scaffold type was then placed into the cranium of nine rabbits. The rabbits were sacrificed after 8 weeks, and the scaffolds were retrieved for histological analysis. The most bone formation was present in the PPF-TGF-beta1 implants; the newly formed bone had a trabecular appearance together with bone marrow-like tissue. Little or no bone formation was observed in implants without rhTGF-beta1. These histological findings were confirmed by image analysis. Bone surface area, bone area percentage, pore fill percentage, and pore area percentage were significantly higher in the rhTGF-beta1-coated implants than in the noncoated implants. No statistical difference was seen between the PPF-Fn, PPF-Pw, or PPF-Gd scaffolds for these parameters. Quadruple fluorochrome labeling showed that in PPF-TGF-beta1 implants bone formation mainly started in the interior of a pore and proceeded toward the scaffold. We conclude that (a) PPF-TGF-beta1 scaffolds can indeed adequately induce bone formation in porous PPF, and (b) PPF scaffolds prepared by the photocrosslinking-porogen leaching technique are good candidates for the creation of bone graft substitutes.

  6. Optimised process and formulation conditions for extended release dry polymer powder-coated pellets.

    PubMed

    Terebesi, Ildikó; Bodmeier, Roland

    2010-05-01

    The objective of this study was to improve the film formation and permeability characteristics of extended release ethylcellulose coatings prepared by dry polymer powder coating for the release of drugs of varying solubility. Ethylcellulose (7 and 10 cp viscosity grades) and Eudragit(R) RS were used for dry powder coating of pellets in a fluidised bed ball coater. Pre-plasticised ethylcellulose powder was prepared by spray-drying aqueous ethylcellulose dispersions (Surelease(R) and Aquacoat(R)) or by hot melt extrusion/cryogenic grinding of plasticised ethylcellulose. Chlorpheniramine maleate and theophylline were used as model drugs of different solubilities. The film formation process, polymeric films and coated pellets were characterised by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and dissolution testing. Film formation and extended drug release was achieved with ethylcellulose, a polymer with a high glass transition temperature (T(g)) without the use of water, which is usually required in dry powder coating. DMA-measurements revealed that plasticised ethylcellulose had a modulus of elasticity (E') similar to the low T(g) Eudragit(R) RS. With increasing plasticiser concentration, the T(g) of ethylcellulose was reduced and the mechanical properties improved, thus facilitating coalescence of the polymer particles. SEM-pictures revealed the formation of a dense, homogeneous film. The lower viscosity grade ethylcellulose (7 cp) resulted in better film formation than the higher viscosity grade (10 cp) and required less stringent curing conditions. Successful extended release ethylcellulose coatings were also obtained by coating with pre-plasticised spray-dried ethylcellulose powders as an alternative to the separate application of pure ethylcellulose powder and plasticiser. The permeability of the extended release coating could be controlled by using powder blends of ethylcellulose with the

  7. Carbon-coated LiFePO4-porous carbon composites as cathode materials for lithium ion batteries.

    PubMed

    Ni, Haifang; Liu, Jinkun; Fan, Li-Zhen

    2013-03-07

    This work introduces a facile strategy for the synthesis of carbon-coated LiFePO(4)-porous carbon (C-LiFePO(4)-PC) composites as a cathode material for lithium ion batteries. The LiFePO(4) particles obtained are about 200 nm in size and homogeneously dispersed in porous carbon matrix. These particles are further coated with the carbon layers pyrolyzed from sucrose. The C-LiFePO(4)-PC composites display a high initial discharge capacity of 152.3 mA h g(-1) at 0.1 C, good cycling stability, as well as excellent rate capability (112 mA h g(-1) at 5 C). The likely contributing factors to the excellent electrochemical performance of the C-LiFePO(4)-PC composites could be related to the combined effects of enhancement of conductivity by the porous carbon matrix and the carbon coating layers. It is believed that further carbon coating is a facile and effective way to improve the electrochemical performance of LiFePO(4)-PC.

  8. Optical absorption enhancement in 3D nanofibers coated on polymer substrate for photovoltaic devices.

    PubMed

    Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

    2015-06-01

    Recent research in the field of photovoltaics has shown that polymer solar cells have great potential to provide low-cost, lightweight and flexible electronic devices to harvest solar energy. In this paper, we propose a new method for the generation of three-dimensional nanofibers coated on polymer substrate induced by femtosecond laser pulses. In this new method, a thin layer of polymer is irradiated by megahertz femtosecond laser pulses under ambient conditions, and a thin fibrous layer is generated on top of the polymer substrate. This method is single step; no additional materials are added, and the layers of the three-dimensional (3D) polymer nanofibrous structures are grown on top of the substrate after laser irradiation. Light spectroscopy results show significant enhancement of light absorption in the generated 3D nanofibrous layers of polymer. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofiber cells by optimizing the laser parameters.

  9. Polymer-coated cannulas for the reduction of backflow during intraparenchymal infusions

    PubMed Central

    Vazquez, Louis C.; Hagel, Erik; Willenberg, Bradley J.; Dai, Wei; Casanova, Fernando; Batich, Christopher D.

    2012-01-01

    Infusate backflow or leak-back along the cannula track can occur during intraparenchymal infusions resulting in non-specific targeting of therapeutic agents. The occurrence of backflow depends on several variables including cannula radius, infusate flow rate, and tip location. In this study, polymer coatings that swell in situ were developed and tested with in vitro hydrogel experiments for backflow reduction. Coatings were applied to the external cannula surface in a dual layer arrangement with a poly(vinyl alcohol) outer layer atop an inner poly(ethylene oxide) and alginate layer. Once these coated cannulas were inserted and allotted an 8–10 min waiting period for hydration, backflow during infusions of 4.0 µl of a macromolecular tracer (Evans Blue labeled albumin) was reduced significantly under flow rates of 0.3–0.6 µl/min, allowing for more effective distribution within targeted regions. Polymer coating thicknesses before and after hydrations were 0.035 and 0.370 mm, respectively. Also, backflow data was fit to a model to estimate the effective local compressive stress caused by the hydrated polymers. After withdrawal of the cannula from the insertion site, the hydrated polymer coatings remained within the cavity left in the hydrogel tissue phantom and formed a seal at the infusion site that prevented further backflow during needle withdrawal. Ex vivo infusions in excised porcine brain tissues also showed significant backflow reduction while also demonstrating the ability to leave a polymer seal in the tissue cavity after cannula removal. Thus, application of these polymers as needle or cannula coatings offers a potentially simple method to improve targeting for local drug delivery. PMID:22710955

  10. Surface plasmon resonance image sensor module of spin-coated silver film with polymer layer.

    PubMed

    Son, Jung-Han; Lee, Dong Hun; Cho, Yong-Jin; Lee, Myung-Hyun

    2013-11-01

    Prism modules of 20 nm-, 40 nm-, and 60 nm-thick spin-coated silver films both without and with an upper 100 nm-thick spin-coated polymer layer were fabricated for surface plasmon resonance (SPR) image sensor applications. The prism modules were applied to an SPR image sensor system. The coefficients of determination (R2s) for the 20 nm-, 40 nm- and 60 nm-thick silver films without the polymer layer were 0.9231, 0.9901, and 0.9889, respectively, and with the polymer layer 0.9228, 0.9951, and 0.9880, respectively when standard ethanol solutions with 0.1% intervals in the range of 20.0% to 20.5% were applied. The upper polymer layer has no effect on the R2. The prism modules of the 40-nm-thick spin-coated silver films had the highest R2 value of approximately 0.99. The durability of the 40 nm-thick spin-coated silver film with the 100 nm-thick polymer layer is much better than that without the upper low-loss polymer layer. The developed SPR image sensor module of the 40 nm-thick spin-coated silver film with the upper 100 nm-thick low-loss polymer film is expected to be a very cost-effective and robust solution because the films are formed at low temperatures in a short period of time without requiring a vacuum system and are very durable.

  11. Electrochemical deposition of conducting polymer coatings on magnesium surfaces in ionic liquid

    PubMed Central

    Luo, Xiliang; Cui, Xinyan Tracy

    2012-01-01

    A conducting polymer based smart coating for magnesium (Mg) implants that can both improve the corrosion resistance of Mg and release drug in a controllable way is reported. As the ionic liquid is a highly conductive and stable solvent with a very wide electrochemical window, the conducting polymer coatings can be directly electrodeposited on the active metal Mg in ionic liquid at mild conditions, and Mg is considerably stable during the electrodeposition. The electrodeposited Poly(3,4-ethylenedioxythiophene) (PEDOT) coatings on Mg are uniform and can significantly improve the corrosion resistance of Mg. In addition, the PEDOT coatings can load the anti-inflammatory drug dexamethasone during the electrodeposition which can be subsequently released upon electric stimulation. PMID:20832505

  12. Effect of polymer coatings on fatigue strength of aluminum alloy 2024 box beams

    NASA Technical Reports Server (NTRS)

    Nordmark, G. E.; Kelsey, R. A.

    1972-01-01

    Previous investigators have shown that polymer coatings raise the fatigue strength of metals tested in air to about the same level as that of uncoated specimens tested in vacuum. The results are given of tests to determine if a polymer coating would improve the fatigue strength of built-up aluminum alloy members simulating aircraft construction. Aluminum alloy 2024-T4 riveted box beams were subjected to constant amplitude fatigue tests in air as well as in salt water fog. The coating did not improve the fatigue strength of beams tested in either environment. This is believed to result from the fact that most failures originated at rivet holes, which were isolated from both the coating and the environment.

  13. The Addition of Graphene to Polymer Coatings for Improved Weathering

    DOE PAGES

    Nuraje, Nurxat; Khan, Shifath I.; Misak, Heath; ...

    2013-01-01

    Graphene nanoflakes in different weight percentages were added to polyurethane top coatings, and the coatings were evaluated relative to exposure to two different experimental conditions: one a QUV accelerated weathering cabinet, while the other a corrosion test carried out in a salt spray chamber. After the exposure tests, the surface morphology and chemical structure of the coatings were investigated via atomic force microscopy (AFM) and Fourier transform infrared (FTIR) imaging. Our results show that the addition of graphene does in fact improve the resistance of the coatings against ultraviolet (UV) degradation and corrosion. It is believed that this process willmore » improve the properties of the polyurethane top coating used in many industries against environmental factors.« less

  14. Polymer-assisted conformal coating of TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Gillman, E. S.; Costello, D.; Moreno, M.; Raspopin, A.; Kasica, R.; Chen, L.

    2010-08-01

    Conformal coating of nanofabricated structures with a high-index dielectric material is a common problem for a diverse set of integrated photonic and plasmonic devices such as planar waveguides, on-chip spectrometers, gratings, flat panel displays, optical sensors, and integrated optical devices. In this paper we were recently able to demonstrate an alternate method for conformally coating photonic nanostructures using a low cost, polymer-assisted deposition (PAD) process for the metal-oxide TiO2. In a PAD process a thermally curable, hybrid high refractive index polymer solution is spin-coated onto a substrate. The polymer controls the viscosity and binds the metal ions, resulting in a homogeneous distribution of the precursor in solution. When cured at elevated temperature, the hybrid polymer coating decomposes to form a metal oxide-rich film that has a high refractive index that conformally fills the voids in nanofabricated structures. The resulting films have refractive indices higher than 1.83 in the visible region and film thicknesses between 250-500 nm depending on the level of metal-oxide loading, cure temperature, and number of coatings.

  15. Fabricating Nanometer-Thick Simultaneously Oleophobic/Hydrophilic Polymer Coatings via a Photochemical Approach.

    PubMed

    Wang, Yongjin; Dugan, Michael; Urbaniak, Brian; Li, Lei

    2016-07-05

    The simultaneously oleophobic/hydrophilic coatings are highly desirable in antifogging, oil-water separation, and detergent-free cleaning. However, such coatings require special chemical structure, i.e., perfluorinated backbone and polar end-groups, and are too expensive for real-life application. Here, we have developed an UV-based photochemical approach to make nanometer-thick perfluoropolyethers without polar end-groups, which are not intrinsically simultaneously oleophobic/hydrophilic but cost-effective, become simultaneously oleophobic/hydrophilic. The contact angle, ellipsometry, and X-ray photoelectron spectroscopy (XPS) results indicated that the UV irradiation results in the covalent bonding between the polymer and the substrate, which renders more ordered packing of polymer chains and thus the appropriately small interchain distance. As a result, the small water molecules penetrate the polymer network while large oil molecules do not. As a result, the oil contact angle is larger than the water contact angle and the coating shows the simultaneous oleophobicity/hydrophilicity. Moreover, we also demonstrated that this nanometer-thick simultaneously oleophobic/hydrophilic coating has improved long-term antifogging performance and detergent-free cleaning capability and is mechanically robust. The photochemical approach established here potentially can be applied on many other polymers and greatly accelerate the development and application of simultaneously oleophobic/hydrophilic coatings.

  16. Characteristics and cytocompatibility of biodegradable polymer film on magnesium by spin coating.

    PubMed

    Xu, Liping; Yamamoto, Akiko

    2012-05-01

    In recent years, magnesium and its alloys have been investigated as biodegradable metallic materials in cardiovascular stents and bone implants. However, rapid corrosion rate in the early stage of the degradation process greatly influences the cytocompatibility and hinters their application. In this research, biodegradable polymer films are prepared under same coating condition by spin coating in order to improve the early corrosion resistance and cytocompatibility of Mg. The results present that uniform, nonporous, amorphous PLLA and semi-crystalline PCL films are coated on Mg. PLLA film shows better adhesion strength to Mg substrate than that of PCL film. For both PLLA and PCL, low molecular weight (LMW) film is thinner and exhibits better adhesion strength than high molecular weight (HMW) one. SaOS-2 cells show significantly good attachment and high growth on the polymer-coated Mg, demonstrating that all the polymer films can significantly improve the cytocompatibility in the 7-day incubation. The pH measurement of the immersion medium and the quantification of released Mg(2+) during the cell culture clearly indicate that the corrosion resistance of Mg substrate is improved by the polymer films to different extents. It can be concluded that both PLLA and PCL films are promising protective coatings for improving the initial corrosion resistance and cytocompatibility.

  17. Superficially porous particles with 1000Å pores for large biomolecule high performance liquid chromatography and polymer size exclusion chromatography.

    PubMed

    Wagner, Brian M; Schuster, Stephanie A; Boyes, Barry E; Shields, Taylor J; Miles, William L; Haynes, Mark J; Moran, Robert E; Kirkland, Joseph J; Schure, Mark R

    2017-03-17

    To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core(®), core shell or porous shell) particles with very large (1000Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications.

  18. Fabrication of Ruthenium Nanoparticles in Porous Organic Polymers: Towards Advanced Heterogeneous Catalytic Nanoreactors.

    PubMed

    Mondal, John; Kundu, Sudipta K; Hung Ng, Wilson Kwok; Singuru, Ramana; Borah, Parijat; Hirao, Hajime; Zhao, Yanli; Bhaumik, Asim

    2015-12-21

    A novel strategy has been adopted for the construction of a copolymer of benzene-benzylamine-1 (BBA-1), which is a porous organic polymer (POP) with a high BET surface area, through Friedel-Crafts alkylation of benzylamine and benzene by using formaldehyde dimethyl acetal as a cross-linker and anhydrous FeCl3 as a promoter. Ruthenium nanoparticles (Ru NPs) were successfully distributed in the interior cavities of polymers through NaBH4, ethylene glycol, and hydrothermal reduction routes, which delivered Ru-A, Ru-B, and Ru-C materials, respectively, and avoided aggregation of metal NPs. Homogeneous dispersion, the nanoconfinement effect of the polymer, and the oxidation state of Ru NPs were verified by employing TEM, energy-dispersive X-ray spectroscopy mapping, cross polarization magic-angle spinning (13)C NMR spectroscopy, and X-ray photoelectron spectroscopy analytical tools. These three new Ru-based POP materials exhibited excellent catalytic performance in the hydrogenation of nitroarenes at RT (with a reaction time of only ≈ 30 min), with high conversion, selectivity, stability, and recyclability for several catalytic cycles, compared with other traditional materials, such as Ru@C, Ru@SiO2, and Ru@TiO2, but no clear agglomeration or loss of catalytic activity was observed. The high catalytic performance of the ruthenium-based POP materials is due to the synergetic effect of nanoconfinement and electron donation offered by the 3D POP network. DFT calculations showed that hydrogenation of nitrobenzene over the Ru (0001) catalyst surface through a direct reaction pathway is more favorable than that through an indirect reaction pathway.

  19. Zero-valent Iron Emplacement in Permeable Porous Media Using Polymer Additions

    SciTech Connect

    Oostrom, Mart; Wietsma, Thomas W.; Covert, Matthew A.; Vermeul, Vince R.

    2007-02-15

    At the Hanford Site in Washington, an extensive In Situ Redox Manipulation (ISRM) permeable reactive barrier was installed to prevent chromate from reaching the Columbia River. However, chromium has been detected in several wells, indicating a premature loss of the reductive capacity in the aquifer. One possible cause for premature chromate breakthrough is associated with the presence of high-permeability zones in the aquifer. The potential emplacement of zero-valent iron (Fe0) into high-permeability Hanford sediments to enhance the barrier’s reductive capacity using shear-thinning fluids containing polymers was investigated in three-dimensional wedge-shaped aquifer models. Porous media were packed in the wedge-shaped flow cell to create either a heterogeneous layered system with a high-permeability zone between two low-permeability zones or a high-permeability channel surrounded by low-permeability materials. The injection flow rate, polymer type, polymer concentration, and injected pore volumes were determined based on preliminary short- and long-column experiments. The flow cell experiments indicated that iron concentration enhancements of at least 0.6% (w/w) could be obtained using moderate flow rates and injection of 30 pore volumes. The aqueous pressure increased by a maximum of 25 KPa during infiltration, but a decrease in permeability was not observed. Under optimal conditions, the 0.6% amended Fe0 concentration would provide approximately 20 times the average reductive capacity that is provided by the dithionite-reduced Fe (II) in the ISRM barrier.

  20. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    NASA Astrophysics Data System (ADS)

    Ebrahimpour, Omid

    second part of the project. Alumina sol was synthesized by the hydrolysis of Aluminum isopropoxide using the Yoldas method. Alumina sol was homogenous and had a needle-like shape with a thickness of 2--3 nm. Crystalline changes during the heating process of alumina sol were studied using XRD. In addition, Fourier transform infrared (FTIR) spectroscopy was performed to identify the functional groups on the alumina sol surface as a function of temperature. In the third part of the project, the feasibility of the in-situ polymerization technique was investigated to fabricate porous SiC ceramics. In this part, the mixture of SiC and calcined alumina powders were coated by polyethylene via in-situ polymerizing referred to as the polymerization compounding process in a slurry phase. The polymerization was conducted under very moderate operational conditions using the Ziegler-Natta catalyst system. Differential scanning calorimetry (DSC) and TGA analysis and morphological studies (SEM and TEM) revealed the presence of a high density of polyethylene on the surface of SiC and alumina powders. The amount of polymer was controlled by the polymerization reaction time. Most parts of particles were coated by a thin layer of polyethylene and polymer. The porous SiC ceramics, which were fabricated by these treated particles showed higher mechanical and physical properties compared to the samples made without any treatment. The relative intensity of mullite was higher compared to the samples prepared by the traditional process. The effects of the sintering temperature, forming pressure and polymer content were also studied on the physical and mechanical properties of the final product. In the last phase of this research work, the focus of the investigation was to take advantage of both the sol-gel processing and in-situ polymerization method to develop a new process to manufacture mullite-bonded porous SiC ceramic with enhanced mechanical and physical properties. Therefore, first the Si

  1. Layer-by-layer click deposition of functional polymer coatings for combating marine biofouling.

    PubMed

    Yang, Wen Jing; Pranantyo, Dicky; Neoh, Koon-Gee; Kang, En-Tang; Teo, Serena Lay-Ming; Rittschof, Daniel

    2012-09-10

    "Click" chemistry-enabled layer-by-layer (LBL) deposition of multilayer functional polymer coatings provides an alternative approach to combating biofouling. Fouling-resistant azido-functionalized poly(ethylene glycol) methyl ether methacrylate-based polymer chains (azido-poly(PEGMA)) and antimicrobial alkynyl-functionalized 2-(methacryloyloxy)ethyl trimethyl ammonium chloride-based polymer chains (alkynyl-poly(META)) were click-assembled layer-by-layer via alkyne-azide 1,3-dipolar cycloaddition. The polymer multilayer coatings are resistant to bacterial adhesion and are bactericidal to marine Gram-negative Pseudomonas sp. NCIMB 2021 bacteria. Settlement of barnacle ( Amphibalanus (= Balanus ) amphitrite ) cyprids is greatly reduced on the multilayer polymer-functionalized substrates. As the number of the polymer layers increases, efficacy against bacterial fouling and settlement of barnacle cyprids increases. The LBL-functionalized surfaces exhibit low toxicity toward the barnacle cyprids and are stable upon prolonged exposure to seawater. LBL click deposition is thus an effective and potentially environmentally benign way to prepare antifouling coatings.

  2. Microbial bioavailability of covalently bound polymer coatings on model engineered nanomaterials.

    PubMed

    Kirschling, Teresa L; Golas, Patricia L; Unrine, Jason M; Matyjaszewski, Krzysztof; Gregory, Kelvin B; Lowry, Gregory V; Tilton, Robert D

    2011-06-15

    By controlling nanoparticle flocculation and deposition, polymer coatings strongly affect nanoparticle fate, transport, and subsequent biological impact in the environment. Biodegradation is a potential route to coating breakdown, but it is unknown whether surface-bound polymers are bioavailable. Here we demonstrate, for the first time, that polymer coatings covalently bound to nanomaterials are bioavailable. Model poly(ethylene oxide) (PEO) brush-coated nanoparticles (densely cross-linked bottle brush copolymers) with hydrophobic divinyl benzene cross-linked cores and hydrophilic PEO brush shells, having ~ 30 nm hydrodynamic radii, were synthesized to obtain a nanomaterial in which biodegradation was the only available coating breakdown mechanism. PEO-degrading enrichment cultures were supplied with either PEO homopolymer or PEO brush nanoparticles as the sole carbon source, and protein and CO₂ production were monitored as a measure of biological conversion. Protein production after 90 h corresponded to 14% and 8% of the total carbon available in the PEO homopolymer and PEO brush nanoparticle cultures, respectively, and CO₂ production corresponded to 37% and 3.8% of the carbon added to the respective system. These results indicate that the PEO in the brush is bioavailable. Brush biodegradation resulted in particle aggregation, pointing to the need to understand biologically mediated transformations of nanoparticle coatings in order to understand the fate and transport of nanoparticles in the environment.

  3. Robust antifogging antireflective coatings on polymer substrates by hydrochloric acid vapor treatment.

    PubMed

    Li, Tong; He, Junhui; Yao, Lin; Geng, Zhi

    2015-04-15

    Antireflective coatings on polymer substrates have received significant attention for their potential applications. In this paper, robust microporous antifogging antireflective coatings on polymer substrates were prepared from acid-catalyzed silica sol followed by hydrochloric acid vapor solidification at mild temperature below glass transition temperatures of common polymers. The coatings passed 3H pencil hardness test, sand flow test and water-drop test. They had excellent antireflective and antifogging properties. The maximum transmittance of coatings on PMMA substrates reached 100.0% (the maximum transmittance wavelength could be regulated) and average transmittance reached 99.0% in 400-800 nm. The advantage and mechanism of hydrochloric acid vapor solidification and mechanical strength enhancement of coatings are discussed in contrast to ammonia vapor treatment and air vapor treatment. The hydrochloric acid vapor treatment results in a dense integrated microporous film structure. Optical properties were characterized by a UV-Vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. Surface morphologies and structures of coatings were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atom force microscopy (AFM).

  4. A hierarchically porous anatase TiO2 coated-WO3 2D IO bilayer film and its photochromic properties.

    PubMed

    Li, Hua; Wu, Huazhong; Xiao, Jiajia; Su, Yanli; Robichaud, Jacques; Brüning, Ralf; Djaoued, Yahia

    2016-01-18

    A hierarchically porous anatase TiO2 coated-WO3 2D inverse opal (IO) bilayer film was fabricated on ITO glass using a layer by layer route with a hierarchically porous TiO2 top layer and an ordered super-macroporous WO3 2D IO bottom layer. This novel TiO2 coated-WO3 2D IO bilayer film was evaluated for photochromic applications.

  5. Chiral ligand-exchange chromatography of amino acids using porous graphitic carbon coated with a dinaphthyl derivative of neamine.

    PubMed

    Zaher, Mustapha; Ravelet, Corinne; Baussanne, Isabelle; Ravel, Anne; Grosset, Catherine; Décout, Jean-Luc; Peyrin, Eric

    2009-01-01

    In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl anchor system efficiently (1.15 micromol/m(2)) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.

  6. Superiority of Graphene over Polymer Coatings for Prevention of Microbially Induced Corrosion

    PubMed Central

    Krishnamurthy, Ajay; Gadhamshetty, Venkataramana; Mukherjee, Rahul; Natarajan, Bharath; Eksik, Osman; Ali Shojaee, S.; Lucca, Don A.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

    2015-01-01

    Prevention of microbially induced corrosion (MIC) is of great significance in many environmental applications. Here, we report the use of an ultra-thin, graphene skin (Gr) as a superior anti-MIC coating over two commercial polymeric coatings, Parylene-C (PA) and Polyurethane (PU). We find that Nickel (Ni) dissolution in a corrosion cell with Gr-coated Ni is an order of magnitude lower than that of PA and PU coated electrodes. Electrochemical analysis reveals that the Gr coating offers ~10 and ~100 fold improvement in MIC resistance over PU and PA coatings respectively. This finding is remarkable considering that the Gr coating (1–2 nm) is ~25 and ~4000 times thinner than the PA (40–50 nm), and PU coatings (20–80 μm), respectively. Conventional polymer coatings are either non-conformal when deposited or degrade under the action of microbial processes, while the electro-chemically inert graphene coating is both resistant to microbial attack and is extremely conformal and defect-free. Finally, we provide a brief discussion regarding the effectiveness of as-grown vs. transferred graphene films for anti-MIC applications. While the as-grown graphene films are devoid of major defects, wet transfer of graphene is shown to introduce large scale defects that make it less suitable for the current application. PMID:26350049

  7. Water-Based Assembly of Polymer-Metal Organic Framework (MOF) Functional Coatings

    SciTech Connect

    De, Souvik; Nandasiri, Manjula I.; Schaef, Herbert T.; McGrail, Benard Peter; Nune, Satish K.; Lutkenhaus, Jodie L.

    2016-12-27

    Metal organic frameworks (MOFs) have gained tremendous attention for their porosity, size selectivity, and structural diversity. There is a need for MOF-based coatings, particularly in applications such as separations, electronics and energy; yet forming thin, functional, conformal coatings is prohibitive because MOFs exist as a powder. Layer-by- layer assembly, a versatile thin film coating approach, offers a unique solution to this problem, but this approach requires MOFs that are water-dispersible and bear a surface charge. Here, we address these issues by examining water-based dispersions of MIL-101(Cr) that facilitate the formation of robust polymer-MOF hybrid coatings. Specifically, the substrate to be coated is alternately exposed to an aqueous solution of poly(styrene sulfonate) and dispersion MIL-101(Cr), yielding linear film growth and coatings with a MOF content as high as 77 wt%.This approach is surface-agnostic, in which the coating is successfully applied to silicon, glass, flexible plastic, and even cotton fabric, conformally coating individual fibers. In contrast, prior attempts at forming MOF-coatings were severely limited to a handful of surfaces, required harsh chemical treatment, and were not conformal. The approach presented here unambiguously confirms that MOFs can be conformally coated onto complex and unusual surfaces, opening the door for a wide variety of applications.

  8. Effects of rotational symmetry breaking in polymer-coated nanopores

    SciTech Connect

    Osmanović, D.; Hoogenboom, B. W.; Ford, I. J.; Kerr-Winter, M.; Eccleston, R. C.

    2015-01-21

    The statistical theory of polymers tethered around the inner surface of a cylindrical channel has traditionally employed the assumption that the equilibrium density of the polymers is independent of the azimuthal coordinate. However, simulations have shown that this rotational symmetry can be broken when there are attractive interactions between the polymers. We investigate the phases that emerge in these circumstances, and we quantify the effect of the symmetry assumption on the phase behavior of the system. In the absence of this assumption, one can observe large differences in the equilibrium densities between the rotationally symmetric case and the non-rotationally symmetric case. A simple analytical model is developed that illustrates the driving thermodynamic forces responsible for this symmetry breaking. Our results have implications for the current understanding of the behavior of polymers in cylindrical nanopores.

  9. Materials: A compilation. [considering metallurgy, polymers, insulation, and coatings

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Technical information is provided for the properties and fabrication of metals and alloys, as well as for polymeric materials, such as lubricants, coatings, and insulation. Available patent information is included in the compilation.

  10. Porous rod-like MgO complex membrane with good anti-bacterial activity directed by conjugated linolenic acid polymer

    NASA Astrophysics Data System (ADS)

    Wang, Hua-Jie; Chen, Meng; Mi, Li-Wei; Shi, Li-Hua; Cao, Ying

    2016-02-01

    The problem of infection in the tissue engineering substitutes is driving us to seek new coating materials. We previously found that conjugated linolenic acid (CLnA) has well biocompatibility and excellent membrane-forming property. The objective of this study is to endow the anti-bacterial activity to CLnA membra ne by linking with MgO. The results showed that the CLnA polymer membrane can be loaded with porous rod-like MgO and such complex membrane showed anti-bacterial sensitivity against gram-positive bacteria ( Staphylococcus aureus) even at the low concentration (0.15 μg/mm2). In the present study, the best zone of inhibition got to 18.2 ± 0.8 mm when the amount of MgO reach 2.42 ± 0.58 μg/mm2. It was deduced that the porous rod-like structure of MgO was directed by CLnA in its polymerization process. Such CLnA/MgO complex membrane can be helpful in the tissue engineering, medicine, food engineering, food preservation, etc. on the basis of its good anti-bacterial activity.

  11. Plasma Polymer Coatings to Prevent Pipeline Corrosion and Reduce Friction.

    DTIC Science & Technology

    1986-05-21

    34 praced on a coating surface. Using an Olympus zoom binocular * -5- - p ’. . . .,, v .t-. -\\ .’,’-’’’ "’ % , ’ --. microscope at lOx magnification, the... P ). The visual appearance further described the films as even or rainbow colored, peeled, or flaked. A particular sample (- could exhibit more than...and reasonable operating cost is an entirely feasible prospect. ( p :... -. -,.’ ! -10- RECOMMENI)ATIONS The investigation of plasma polymerized coatings

  12. Non-Isocyanate Polymer Design and Coating Development

    DTIC Science & Technology

    2012-09-11

    Allen - Manager of Coating Operations 3 Problem Statement ● 1.2 million gallons of Chemical Agent Resistant Coating (CARC) purchased in 2011  Up...Approach ● Project Management Principles  Frequent sample exchanges to ensure reproducibility and maintain program focus  Monthly team meetings...Maintenance Center (MDMC) Albany and a representative from that organization is included in the projet team. • Final field use will require introducing a

  13. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: spin coating vs electrochemical activation.

    PubMed

    Hernandez-Montelongo, J; Gallach, D; Naveas, N; Torres-Costa, V; Climent-Font, A; García-Ruiz, J P; Manso-Silvan, M

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering.

  14. Immobilization of calcium phosphate nano-clusters into alkoxy-derived porous TiO2 coatings.

    PubMed

    Shirkhanzadeh, M; Sims, S

    1997-10-01

    Alkoxy-derived porous coatings of titanium oxide were fabricated on commercially pure titanium substrates by an electrochemical method in methanolic electrolytes. Nano-clusters of brushite (CaHPO4. 2H2O) were immobilized into the pores of the oxide network by reacting these coatings in acidic calcium phosphate solutions at 50 degrees C. The acid-base reaction between calcium phosphate solutions and the hydroxyl groups of the oxide network resulted in the formation of nano-clusters of brushite crystals immobilized inside the oxide pores. This treatment resulted in the conversion of the porous oxide network into a coherent mass with improved physical integrity. Nano-clusters of brushite crystals immobilized in the oxide matrix were converted into amorphous calcium phosphate (ACP) and poorly crystallized hydroxyapatite (HA) by further treatment of the oxide in alkaline solutions. The porous oxide coating also reacted strongly with concentrated phosphoric acid. The phosphate-modified oxide resulting from this reaction was further treated in calcium hydroxide solution to form nano-clusters of poorly crystallized HA within the oxide network.

  15. Combined, Independent Small Molecule Release and Shape Memory via Nanogel-Coated Thiourethane Polymer Networks

    PubMed Central

    Dailing, Eric A.; Nair, Devatha P.; Setterberg, Whitney K.; Kyburz, Kyle A.; Yang, Chun; D’Ovidio, Tyler; Anseth, Kristi S.; Stansbury, Jeffrey W.

    2015-01-01

    Drug releasing shape memory polymers (SMPs) were prepared from poly(thiourethane) networks that were coated with drug loaded nanogels through a UV initiated, surface mediated crosslinking reaction. Multifunctional thiol and isocyanate monomers were crosslinked through a step-growth mechanism to produce polymers with a homogeneous network structure that exhibited a sharp glass transition with 97% strain recovery and 96% shape fixity. Incorporating a small stoichiometric excess of thiol groups left pendant functionality for a surface coating reaction. Nanogels with diameter of approximately 10 nm bearing allyl and methacrylate groups were prepared separately via solution free radical polymerization. Coatings with thickness of 10–30 μm were formed via dip-coating and subsequent UV-initiated thiol-ene crosslinking between the SMP surface and the nanogel, and through inter-nanogel methacrylate homopolymerization. No significant change in mechanical properties or shape memory behavior was observed after the coating process, indicating that functional coatings can be integrated into an SMP without altering its original performance. Drug bioactivity was confirmed via in vitro culturing of human mesenchymal stem cells with SMPs coated with dexamethasone-loaded nanogels. This article offers a new strategy to independently tune multiple functions on a single polymeric device, and has broad application toward implantable, minimally invasive medical devices such as vascular stents and ocular shunts, where local drug release can greatly prolong device function. PMID:27066114

  16. Can deformation of a polymer film with a rigid coating model geophysical processes?

    PubMed

    Volynskii, A L; Bazhenov, S L

    2007-12-01

    The structural and mechanical behavior of polymer films with a thin rigid coating is analyzed. The behavior of such systems under applied stress is accompanied by the formation of a regular wavy surface relief and by regular fragmentation of the coating. The above phenomena are shown to be universal. Both phenomena (stress-induced development of a regular wavy surface relief and regular fragmentation of the coating) are provided by the specific features of mechanical stress transfer from a compliant soft support to a rigid thin coating. The above phenomena are associated with a specific structure of the system, which is referred to as "a rigid coating on a soft substratum" system (RCSS). Surface microrelief in RCSS systems is similar to the ocean floor relief in the vicinity of mid-oceanic ridges. Thus, the complex system composed of a young oceanic crust and upper Earth's mantle may be considered as typically "a solid coating on a soft substratum" system. Specific features of the ocean floor relief are analyzed in terms of the approach advanced for the description of the structural mechanical behavior of polymer films with a rigid coating. This analysis allowed to estimate the strength of an ocean floor.

  17. PERFORMANCE OF A POLYMER SEALANT COATING IN AN ARCTIC MARINE ENVIRONMENT.

    SciTech Connect

    MOSKOWITZ,P.; COWGILL,M.; GRIFFITH,A.; CHERNAENKO,L.; DIASHEV,A.; NAZARIAN,A.

    2001-02-25

    The feasibility of using a polymer-based coating, Polibrid 705, to seal concrete and steel surfaces from permanent radioactive contamination in an Arctic marine environment has been successfully demonstrated using a combination of field and laboratory testing. A mobile, self-sufficient spraying device was developed to specifications provided by the Russian Northern Navy and deployed at the RTP Atomflot site, Murmansk, Russia. Demonstration coatings were applied to concrete surfaces exposed to conditions ranging from indoor pedestrian usage to heavy vehicle passage and container handling in a loading dock. A large steel container was also coated with the polymer, filled with solid radwaste, sealed, and left out of doors, exposed to the full annual Arctic weather cycle. The 12 months of field testing gave rise to little degradation of the sealant coating, except for a few chips and gouge marks on the loading bay surface that were readily repaired. Contamination resulting from radwaste handling was easily removed and the surface was not degraded by contact with the decontamination agents. The field tests were accompanied by a series of laboratory qualification tests carried out at a research laboratory in St. Petersburg. The laboratory tests examined a variety of properties, including bond strength between the coating and the substrate, thermal cycling resistance, wear resistance, flammability, and ease of decontamination. The Polibrid 705 coating met all the Russian Navy qualification requirements with the exception of flammability. In this last instance, it was decided to restrict application of the coating to land-based facilities.

  18. PERFORMANCE OF A POLYMER SEALANT COATING IN AN ARCTIC MARINE ENVIRONMENT

    SciTech Connect

    MOSKOWITZ,P.; COWGILL,M.; GRIFFITH,A.; CHERNAENKO,L.; DIASHEV,A.; NAZARIAN,A.

    2001-02-25

    The feasibility of using a polymer-based coating, Polibrid 705, to seal concrete and steel surfaces from permanent radioactive contamination in an Arctic marine environment has been successfully demonstrated using a combination of field and laboratory testing. A mobile, self-sufficient spraying device was developed to specifications provided by the Russian Northern Navy and deployed at the RTP Atomflot site, Murmansk, Russia. Demonstration coatings were applied to concrete surfaces exposed to conditions ranging from indoor pedestrian usage to heavy vehicle passage and container handling in a loading dock. A large steel container was also coated with the polymer, filled with solid radwaste, sealed, and left out of doors, exposed to the full annual Arctic weather cycle. The 12 months of field testing gave rise to little degradation of the sealant coating, except for a few chips and gouge marks on the loading bay surface that were readily repaired. Contamination resulting from radwaste handling was easily removed and the surface was not degraded by contact with the decontamination agents. The field tests were accompanied by a series of laboratory qualification tests carried out at a research laboratory in St. Petersburg. The laboratory tests examined a variety of properties, including bond strength between the coating and the substrate, thermal cycling resistance, wear resistance, flammability, and ease of decontamination. The Polibrid 705 coating met all the Russian Navy qualification requirements with the exception of flammability. In this last instance, it was decided to restrict application of the coating to land-based facilities.

  19. Spray-coated carbon nanotube carpets for creeping reduction of conducting polymer based artificial muscles

    NASA Astrophysics Data System (ADS)

    Simaite, Aiva; Delagarde, Aude; Tondu, Bertrand; Souères, Philippe; Flahaut, Emmanuel; Bergaud, Christian

    2017-01-01

    During cyclic actuation, conducting polymer based artificial muscles are often creeping from the initial movement range. One of the likely reasons of such behaviour is unbalanced charging during conducting polymer oxidation and reduction. To improve the actuation reversibility and subsequently the long time performance of ionic actuators, we suggest using spray-coated carbon nanotube (CNT) carpets on the surface of the conducting polymer electrodes. We show that carbon nanotubes facilitate a conducting polymer redox reaction and improve its reversibility. Consequently, in the long term, charge accumulation in the polymer film is avoided leading to a significantly improved lifetime performance during cycling actuation. To our knowledge, it is the first time a simple solution to an actuator creeping problem has been suggested.

  20. Spray-coated carbon nanotube carpets for creeping reduction of conducting polymer based artificial muscles.

    PubMed

    Simaite, Aiva; Delagarde, Aude; Tondu, Bertrand; Souères, Philippe; Flahaut, Emmanuel; Bergaud, Christian

    2017-01-13

    During cyclic actuation, conducting polymer based artificial muscles are often creeping from the initial movement range. One of the likely reasons of such behaviour is unbalanced charging during conducting polymer oxidation and reduction. To improve the actuation reversibility and subsequently the long time performance of ionic actuators, we suggest using spray-coated carbon nanotube (CNT) carpets on the surface of the conducting polymer electrodes. We show that carbon nanotubes facilitate a conducting polymer redox reaction and improve its reversibility. Consequently, in the long term, charge accumulation in the polymer film is avoided leading to a significantly improved lifetime performance during cycling actuation. To our knowledge, it is the first time a simple solution to an actuator creeping problem has been suggested.

  1. A shape-recovery polymer coating for the corrosion protection of metallic surfaces.

    PubMed

    Lutz, Alexander; van den Berg, Otto; Van Damme, Jonas; Verheyen, Karen; Bauters, Erwin; De Graeve, Iris; Du Prez, Filip E; Terryn, Herman

    2015-01-14

    Self-healing polymer coatings are a type of smart material aimed for advanced corrosion protection of metals. This paper presents the synthesis and characterization of two new UV-cure self-healing coatings based on acrylated polycaprolactone polyurethanes. On a macroscopic scale, the cured films all show outstanding mechanical properties, combining relatively high Young's modulus of up to 270 MPa with a strain at break above 350%. After thermal activation the strained films recover up to 97% of their original length. Optical and electron microscopy reveals the self-healing properties of these coatings on hot dip galvanized steel with scratches and microindentations. The temperature-induced closing of such defects restores the corrosion protection and barrier properties of the coating as shown by electrochemical impedance spectroscopy and scanning vibrating electrode technique. Therefore, such coatings are a complementary option for encapsulation-based autonomous corrosion protection systems.

  2. Next-generation resorbable polymer scaffolds with surface-precipitated calcium phosphate coatings

    PubMed Central

    Kim, Jinku; Magno, Maria Hanshella R.; Ortiz, Ophir; McBride, Sean; Darr, Aniq; Kohn, Joachim; Hollinger, Jeffrey O.

    2015-01-01

    Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components. In this article, we continue our exploration of E1001(1k), a tyrosine-derived polycarbonate, as an orthopedic implant material. Specifically, we use E1001(1k), which is degradable, nontoxic, and osteoconductive, to fabricate porous bone regeneration scaffolds that were enhanced by two different types of calcium phosphate (CP) coatings: in one case, pure dicalcium phosphate dihydrate was precipitated on the scaffold surface and throughout its porous structure (E1001(1k) + CP). In the other case, bone matrix minerals (BMM) such as zinc, manganese and fluoride were co-precipitated within the dicalcium phosphate dihydrate coating (E1001(1k) + BMM). These scaffold compositions were compared against each other and against ChronOS (Synthes USA, West Chester, PA, USA), a clinically used bone graft substitute (BGS), which served as the positive control in our experimental design. This BGS is composed of poly(lactide co-ε-caprolactone) and beta-tricalcium phosphate. We used the established rabbit calvaria critical-sized defect model to determine bone regeneration within the defect for each of the three scaffold compositions. New bone formation was determined after 2, 4, 6, 8 and 12 weeks by micro-computerized tomography (μCT) and histology. The experimental tyrosine-derived polycarbonate, enhanced with dicalcium phosphate dihydrate, E1001(1k) + CP, supported significant bone formation within the defects and was superior to the same scaffold containing a mix of BMM, E1001(1k) + BMM. The comparison with the commercially available BGS was complicated by the large variability in bone formation observed for the laboratory preparations of E1001(1k) scaffolds. At all time points, there was a trend for E1001(1k) + CP to be superior to the commercial BGS. However, only at the 6-week time point did this trend reach statistical significance

  3. Efficient solar photocatalytic activity of TiO2 coated nano-porous silicon by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Sampath, Sridhar; Maydannik, Philipp; Ivanova, Tatiana; Shestakova, Marina; Homola, Tomáš; Bryukvin, Anton; Sillanpää, Mika; Nagumothu, Rameshbabu; Alagan, Viswanathan

    2016-09-01

    In the present study, TiO2 coated nano-porous silicon (TiO2/PS) was prepared by atomic layer deposition (ALD) whereas porous silicon was prepared by stain etching method for efficient solar photocatalytic activity. TiO2/PS was characterized by FESEM, AFM, XRD, XPS and DRS UV-vis spectrophotometer. Absorbance spectrum revealed that TiO2/PS absorbs complete solar light with wave length range of 300 nm-800 nm and most importantly, it absorbs stronger visible light than UV light. The reason for efficient solar light absorption of TiO2/PS is that nanostructured TiO2 layer absorbs UV light and nano-porous silicon layer absorbs visible light which is transparent to TiO2 layer. The amount of visible light absorption of TiO2/PS directly increases with increase of silicon etching time. The effect of silicon etching time of TiO2/PS on solar photocatalytic activity was investigated towards methylene blue dye degradation. Layer by layer solar absorption mechanism was used to explain the enhanced photocatalytic activity of TiO2/PS solar absorber. According to this, the photo-generated electrons of porous silicon will be effectively injected into TiO2 via hetero junction interface which leads to efficient charge separation even though porous silicon is not participating in any redox reactions in direct.

  4. Formation and bioactivity of porous and nanostructured TiO2/beta-TCP coating on titanium.

    PubMed

    Hu, Hongjie; Liu, Xuanyong; Meng, Fanhao; Ding, Chuanxian

    2011-12-01

    Titanium and its alloys have been widely used as hard tissue implants due to their excellent mechanical properties and biocompatibility. However, their near bio-inertness and metallic ion release are still the problems with clinical uses. In this paper, porous and nanostructured TiO2/beta-tricalcium phosphate (beta-TCP) composite coatings were prepared on titanium substrates by plasma electrolytic oxidation (PEO) in a Ca and P-containing electrolyte. The influence of PEO electric current density on phase composition and bioactivity of the coatings were studied. X-ray diffraction, scanning electron microscopy and Fourier transfer infrared spectroscopy were utilized to characterize the phase composition and microstructure of the coatings. Simulated body fluid immersion tests were employed on the coatings to evaluate their bioactivity. The results reveal that TiO2/beta-TCP composite coating with pores size less than 10 microm and grains of 50-100 nm in size was prepared. The electric current density of PEO is an important factor in the formation of the composite coating. The TiO2/beta-TCP composite coating shows good bioactivity, which are attributed to the incorporation of beta-TCP.

  5. NASA Glenn/AADC-Rolls Royce Collaborated to Measure Erosion Resistance on Coated Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Mondry, Richard; Ma, Kong; Horan, Dick; Naik, Subhash; Cupp, Randall

    2003-01-01

    Polymer matrix composites (PMCs) are increasingly used in aerospace and automotive applications because of their light weight and high strength-to-weight ratio relative to metals. However, a major drawback of PMCs is poor abrasion resistance, which restricts their use, especially at high temperatures. Simply applying a hard coating on PMCs to improve abrasion and erosion resistance is not effective since coating durability is short lived (ref. 1). Generally, PMCs have higher coefficients of thermal expansion than metallic or ceramic coatings have, and coating adhesion suffers because of poor interfacial adhesion strength. One technique commonly used to improve coating adhesion or durability is the use of bond coats that are interleaved between a coating and a substrate with vastly different coefficients of thermal expansion. An example of this remedy is the use of bondcoats for ceramic thermal barrier coatings on metallic turbine components (ref. 2). Prior collaborative research between the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) demonstrated that bond coats sandwiched between PMCs and high-quality plasma-sprayed, erosion-resistant coatings substantially improved the erosion resistance of PMCs (ref. 3). One unresolved problem in this earlier collaboration was that there was no easy, accurate way to measure the coating erosion wear scar. Coating wear was determined by both profilometry and optical microscopy. Both techniques are time consuming. Wear measurement by optical microscopy requires sample destruction and does not provide a comprehensive measure of the entire wear volume. An even more subtle, yet critical, problem is that these erosion coatings contain two or more materials with different densities. Therefore, simply measuring specimen mass loss before and after erosion will not provide an accurate gauge for coating and/or substrate volume loss. By using a noncontact technique called scanning optical interferometry

  6. Macro- and micro-nutrient release characteristics of three polymer-coated fertilizers: Theory and measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of several published studies we have an incomplete understanding of the ion release mechanisms and characteristics of primary polymer-coated fertilizer (PCF) technologies. Here we extend current conceptual models describing release mechanisms and describe the critical effects of substrate m...

  7. Improvement of water barrier property of paperboard by coating application with biodegradable polymers.

    PubMed

    Han, Jaejoon; Salmieri, Stéphane; Le Tien, Canh; Lacroix, Monique

    2010-03-10

    Biopolymeric coatings were prepared and applied onto paperboard to improve its water barrier property. To prepare whey protein isolate (WPI)/cellulose-based films, WPI and glycerol were dissolved in water with glutaraldehyde (cross-linking agent) and cellulose xanthate. The solution was cast, dried, and insolubilized by entrapment of WPI in regenerated cellulose. Films were combined with beeswax (BW) into a bilayer coating system and then applied onto paperboard by heating compression. Another coating solution consisting of poly(vinyl butyral) (PVB)/zein was prepared by dissolving poly(vinyl alcohol) (PVA) and zein in 70% ethanol with glutaraldehyde and butyraldehyde (functionalization agent). The PVB/zein solution was applied onto paperboard after BW was sprayed. The structure of the PVB/zein-based coatings was analyzed by Fourier transform infrared spectroscopy (FTIR). The water vapor barrier property of coated paperboards was evaluated by water vapor transmission rate (WVTR) measurements. From the FTIR spectra, PVA functionalization after cross-linking and efficient acetalization into PVB were confirmed. WPI/cellulose and PVB/zein coating treatments improved the water barrier properties of paperboard by decreasing the WVTR by 77-78%. Although the BW coating was more efficient (decrease of WVTR by 89%), bilayer coatings composed of BW and polymer coatings had a stronger barrier effect with a decrease of WVTR to 92-95%, hence approaching commercial attributes required to ensure water vapor barrier in paperboard-based food containers (10 g/m(2).day). These results suggest that surface coating by biodegradable polymers may be utilized for the manufacture of paperboard containers in industrial applications.

  8. Characterizing metal coordination environments in porous organic polymers: a joint density functional theory and experimental infrared spectroscopy study.

    PubMed

    López-Encarnación, Juan M; Tanabe, Kristine K; Johnson, Marc J A; Jellinek, Julius

    2013-10-04

    Very POP right now! DFT computational analysis on the structural, energetic, and IR spectroscopic characteristics of a porous organic polymer support, [Ta(NMe2 )5 ] as a molecular precursor, and the catalytic material synthesized from these two components are presented and analyzed against recorded IR spectra of these systems. The analysis leads to unambiguous identification of the atomic structure of the POP-supported Ta-amide reaction center synthesized in the experiment.

  9. Salicylic acid-releasing polyurethane acrylate polymers as anti-biofilm urological catheter coatings.

    PubMed

    Nowatzki, Paul J; Koepsel, Richard R; Stoodley, Paul; Min, Ke; Harper, Alan; Murata, Hironobu; Donfack, Joseph; Hortelano, Edwin R; Ehrlich, Garth D; Russell, Alan J

    2012-05-01

    Biofilm-associated infections are a major complication of implanted and indwelling medical devices like urological and venous catheters. They commonly persist even in the presence of an oral or intravenous antibiotic regimen, often resulting in chronic illness. We have developed a new approach to inhibiting biofilm growth on synthetic materials through controlled release of salicylic acid from a polymeric coating. Herein we report the synthesis and testing of a ultraviolet-cured polyurethane acrylate polymer composed, in part, of salicyl acrylate, which hydrolyzes upon exposure to aqueous conditions, releasing salicylic acid while leaving the polymer backbone intact. The salicylic acid release rate was tuned by adjusting the polymer composition. Anti-biofilm performance of the coatings was assessed under several biofilm forming conditions using a novel combination of the MBEC Assay™ biofilm multi-peg growth system and bioluminescence monitoring for live cell quantification. Films of the salicylic acid-releasing polymers were found to inhibit biofilm formation, as shown by bioluminescent and GFP reporter strains of Pseudomonas aeruginosa and Escherichia coli. Urinary catheters coated on their inner lumens with the salicylic acid-releasing polymer significantly reduced biofilm formation by E. coli for up to 5 days under conditions that simulated physiological urine flow.

  10. Modular Fabrication of Polymer Brush Coated Magnetic Nanoparticles: Engineering the Interface for Targeted Cellular Imaging.

    PubMed

    Oz, Yavuz; Arslan, Mehmet; Gevrek, Tugce N; Sanyal, Rana; Sanyal, Amitav

    2016-08-03

    Development of efficient and rapid protocols for diversification of functional magnetic nanoparticles (MNPs) would enable identification of promising candidates using high-throughput protocols for applications such as diagnostics and cure through early detection and localized delivery. Polymer brush coated magnetic nanoparticles find use in many such applications. A protocol that allows modular diversification of a pool of parent polymer coated nanoparticles will lead to a library of functional materials with improved uniformity. In the present study, polymer brush coated parent magnetic nanoparticles obtained using reversible addition-fragmentation chain transfer (RAFT) polymerization are modified to obtain nanoparticles with different "clickable" groups. In this design, trithiocarbonate group terminated polymer brushes are "grafted from" MNPs using a catechol group bearing initiator. A postpolymerization radical exchange reaction allows installation of "clickable" functional groups like azides and maleimides on the chain ends of the polymers. Thus, modified MNPs can be functionalized using alkyne-containing and thiol-containing moieties like peptides and dyes using the alkyne-azide cycloaddition and the thiol-ene conjugation, respectively. Using the approach outlined here, a cell surface receptor targeting cyclic peptide and a fluorescent dye are attached onto nanoparticle surface. This multifunctional construct allows selective recognition of cancer cells that overexpress integrin receptors. Furthermore, the approach outlined here is not limited to the installation of azide and maleimide functional groups but can be expanded to a variety of "clickable" groups to allow nanoparticle modification using a broad range of chemical conjugations.

  11. Dry particle coating of polymer particles for tailor-made product properties

    SciTech Connect

    Blümel, C. Schmidt, J. Dielesen, A. Sachs, M. Winzer, B. Peukert, W. Wirth, K.-E.

    2014-05-15

    Disperse polymer powders with tailor-made particle properties are of increasing interest in industrial applications such as Selective Laser Beam Melting processes (SLM). This study focuses on dry particle coating processes to improve the conductivity of the insulating polymer powder in order to assemble conductive devices. Therefore PP particles were coated with Carbon Black nanoparticles in a dry particle coating process. This process was investigated in dependence of process time and mass fraction of Carbon Black. The conductivity of the functionalized powders was measured by impedance spectroscopy. It was found that there is a dependence of process time, respectively coating ratio and conductivity. The powder shows higher conductivities with increasing number of guest particles per host particle surface area, i.e. there is a correlation between surface functionalization density and conductivity. The assembled composite particles open new possibilities for processing distinct polymers such as PP in SLM process. The fundamentals of the dry particle coating process of PP host particles with Carbon Black guest particles as well as the influence on the electrical conductivity will be discussed.

  12. Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

    PubMed Central

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-01-01

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement. PMID:25490138

  13. Polymer coated CaAl-layered double hydroxide nanomaterials for potential calcium supplement.

    PubMed

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-12-05

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement.

  14. Stabilization of 2D assemblies of silver nanoparticles by spin-coating polymers

    NASA Astrophysics Data System (ADS)

    Hu, Longyu; Pfirman, Aubrie; Chumanov, George

    2015-12-01

    Silver nanoparticles self-assembled on poly(4-vinylpyridine) modified surfaces were spin-coated with poly(methyl methacrylate), poly(butyl methacrylate) and polystyrene from anisole and toluene solutions. The polymers filled the space between the particles thereby providing stabilization of the assemblies against particle aggregation when dried or chemically modified. The polymers did not coat the top surface of the nanoparticles offering the chemical accessibility to the metal surface. This was confirmed by converting the stabilized nanoparticles into silver sulfide and gold clusters. Etching the nanoparticles resulted in crater-like polymeric structures with the cavities extending down to the underlying substrate. Electrochemical reduction of silver inside the craters was performed. The approach can be extended to other nanoparticle assemblies and polymers.

  15. Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

    NASA Astrophysics Data System (ADS)

    Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

    2016-01-01

    In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

  16. A “green” strategy to construct non-covalent, stable and bioactive coatings on porous MOF nanoparticles

    PubMed Central

    Agostoni, V.; Horcajada, P.; Noiray, M.; Malanga, M.; Aykaç, A.; Jicsinszky, L.; Vargas-Berenguel, A.; Semiramoth, N.; Daoud-Mahammed, S.; Nicolas, V.; Martineau, C.; Taulelle, F.; Vigneron, J.; Etcheberry, A.; Serre, C.; Gref, R.

    2015-01-01

    Nanoparticles made of metal-organic frameworks (nanoMOFs) attract a growing interest in gas storage, separation, catalysis, sensing and more recently, biomedicine. Achieving stable, versatile coatings on highly porous nanoMOFs without altering their ability to adsorb molecules of interest represents today a major challenge. Here we bring the proof of concept that the outer surface of porous nanoMOFs can be specifically functionalized in a rapid, biofriendly and non-covalent manner, leading to stable and versatile coatings. Cyclodextrin molecules bearing strong iron complexing groups (phosphates) were firmly anchored to the nanoMOFs' surface, within only a few minutes, simply by incubation with aqueous nanoMOF suspensions. The coating procedure did not affect the nanoMOF porosity, crystallinity, adsorption and release abilities. The stable cyclodextrin-based coating was further functionalized with: i) targeting moieties to increase the nanoMOF interaction with specific receptors and ii) poly(ethylene glycol) chains to escape the immune system. These results pave the way towards the design of surface-engineered nanoMOFs of interest for applications in the field of targeted drug delivery, catalysis, separation and sensing. PMID:25603994

  17. A “green” strategy to construct non-covalent, stable and bioactive coatings on porous MOF nanoparticles

    NASA Astrophysics Data System (ADS)

    Agostoni, V.; Horcajada, P.; Noiray, M.; Malanga, M.; Aykaç, A.; Jicsinszky, L.; Vargas-Berenguel, A.; Semiramoth, N.; Daoud-Mahammed, S.; Nicolas, V.; Martineau, C.; Taulelle, F.; Vigneron, J.; Etcheberry, A.; Serre, C.; Gref, R.

    2015-01-01

    Nanoparticles made of metal-organic frameworks (nanoMOFs) attract a growing interest in gas storage, separation, catalysis, sensing and more recently, biomedicine. Achieving stable, versatile coatings on highly porous nanoMOFs without altering their ability to adsorb molecules of interest represents today a major challenge. Here we bring the proof of concept that the outer surface of porous nanoMOFs can be specifically functionalized in a rapid, biofriendly and non-covalent manner, leading to stable and versatile coatings. Cyclodextrin molecules bearing strong iron complexing groups (phosphates) were firmly anchored to the nanoMOFs' surface, within only a few minutes, simply by incubation with aqueous nanoMOF suspensions. The coating procedure did not affect the nanoMOF porosity, crystallinity, adsorption and release abilities. The stable cyclodextrin-based coating was further functionalized with: i) targeting moieties to increase the nanoMOF interaction with specific receptors and ii) poly(ethylene glycol) chains to escape the immune system. These results pave the way towards the design of surface-engineered nanoMOFs of interest for applications in the field of targeted drug delivery, catalysis, separation and sensing.

  18. Synthesis of Clickable Coating Polymers by Postpolymerization Modification: Applications in Microarray Technology.

    PubMed

    Sola, Laura; Damin, Francesco; Gagni, Paola; Consonni, Roberto; Chiari, Marcella

    2016-10-11

    In this paper, we report on the postpolymerization modification (PPM) of a polymer to introduce new functionalities that enable click chemistry reactions for microarray applications. The parent polymer, named copoly(DMA-NAS-MAPS), is composed of N,N-dimethylacrylamide (DMA), a monomer that self-adsorbs onto different materials through weak interactions such as hydrogen bonding or van der Waals forces, 3-(trimethoxysilyl)propyl methacrylate (MAPS) that strengthens the stability of the coating through the formation of covalent bonds with siloxane groups on the surface to be coated, and N-acryloyloxysuccinimide (NAS), an active ester group, highly reactive toward nucleophiles, which enables bioprobe immobilization. This copolymer has been widely exploited to coat surfaces for microarray applications but exhibits some limitations because of the potential hydrolysis of the active ester (NHS ester). The degradation of the NHS ester hampers the use of this coating in some situations, for example, when probe immobilization cannot be accomplished through a microspotting situation, but in large volumes, for example, in microchannel derivatization or micro-/nanoparticle functionalization. To overcome the limitations of NHS esters, we have developed a family of polymers that originate from the common copolymer precursor, by reacting the active ester contained in the polymer chain with a bifunctional amine. In particular, the functional groups introduced in the polymer using PPM enable click chemistry reactions such as azide/alkyne or thiol/maleimide "click" reactions, with suitably modified biomolecules. The advantages of such reactions are quantitative yields, orthogonality of functional groups, and insensitivity of the reaction to pH. The new click functionalities, inserted with quantitative yields, improve the stability of the coating, enabling the attachment of biomolecules directly from a solution and avoiding the spotting of reduced volumes (pL) of probes. Finally, we

  19. Reactive polymer coatings: A robust platform towards sophisticated surface engineering for biotechnology

    NASA Astrophysics Data System (ADS)

    Chen, Hsien-Yeh

    Functionalized poly(p-xylylenes) or so-called reactive polymers can be synthesized via chemical vapor deposition (CVD) polymerization. The resulting ultra-thin coatings are pinhole-free and can be conformally deposited to a wide range of substrates and materials. More importantly, the equipped functional groups can served as anchoring sites for tailoring the surface properties, making these reactive coatings a robust platform that can deal with sophisticated challenges faced in biointerfaces. In this work presented herein, surface coatings presenting various functional groups were prepared by CVD process. Such surfaces include aldehyde-functionalized coating to precisely immobilize saccharide molecules onto well-defined areas and alkyne-functionalized coating to click azide-modified molecules via Huisgen 1,3-dipolar cycloaddition reaction. Moreover, CVD copolymerization has been conducted to prepare multifunctional coatings and their specific functions were demonstrated by the immobilization of biotin and NHS-ester molecules. By using a photodefinable coating, polyethylene oxides were immobilized onto a wide range of substrates through photo-immobilization. Spatially controlled protein resistant properties were characterized by selective adsorption of fibrinogen and bovine serum albumin as model systems. Alternatively, surface initiator coatings were used for polymer graftings of polyethylene glycol) methyl ether methacrylate, and the resultant protein- and cell- resistant properties were characterized by adsorption of kinesin motor proteins, fibrinogen, and murine fibroblasts (NIH3T3). Accessibility of reactive coatings within confined microgeometries was systematically studied, and the preparation of homogeneous polymer thin films within the inner surface of microchannels was demonstrated. Moreover, these advanced coatings were applied to develop a dry adhesion process for microfluidic devices. This process provides (i) excellent bonding strength, (ii) extended

  20. Spin Coating Film Transfer and Hot-Pressing System for Uniform Dielectric Formation and Its Application to Porous Low-k Film Formation

    NASA Astrophysics Data System (ADS)

    Kawagoe, Masafumi; Adachi, Hideki; Yanagida, Takaaki; Komura, Tomoyuki; Saito, Hidenori; Sato, Norio; Kudou, Kazuhisa; Machida, Katsuyuki

    2008-01-01

    In this paper, we describe a transfer system that enables to form uniform dielectrics using spin coating film transfer and hot-pressing (STP) technology, and the applicability of a porous low-k material. The STP technology transfers a dielectric from a base film to a wafer by hot pressing in vacuum. We propose a processing unit that enables the handling of both the wafer and the base film. In the transfer unit, we also propose a scheme for transferring a dielectric to wafer uniformly. In the experiments, an organic porous low-k material, porous nanoporous polybenzoxazole dielectric (OxD) is used. The results on the film characteristics show no difference from those obtained by conventional spin coating. STP also enables planarization and sealing for patterned wafers with the porous OxD. It is confirmed that the STP process using porous OxD will be a candidate integration process.

  1. Porous coordination polymers of diverse topologies based on a twisted tetrapyridylbiaryl: application as nucleophilic catalysts for acetylation of phenols.

    PubMed

    Seth, Saona; Venugopalan, Paloth; Moorthy, Jarugu Narasimha

    2015-01-26

    Porous coordination polymers (CPs) with partially uncoordinated pyridyl rings based on rationally designed polypyridyl linkers are appealing from the point of view of their application as nucleophilic catalysts. A D2d -symmetric tetradentate organic linker L, that is, 2,2',6,6'-tetramethoxy-3,3',5,5'-tetrakis(4-pyridyl)biphenyl, was designed and synthesized for metal-assisted self-assembly aimed at porous CPs. Depending on the nature of the metal ion and the counter anion, the ligand L is found to function as a 3- or 4-connecting building block leading to porous CPs of diverse topologies. The reaction of L with Zn(NO3 )2 and Cd(NO3 )2 yields porous 2 D CPs of "fes" topology, in which the tetrapyridyl linker L serves as a 3-connecting unit with its free pyridyl rings well exposed into the pores. The functional utility of these porous CPs containing uncoordinated pyridyl rings is demonstrated by employing them as efficient heterogeneous nucleophilic catalysts for acetylation of a number of phenols with varying electronic properties and reactivities.

  2. Fabrication of interfacial functionalized porous polymer monolith and its adsorption properties of copper ions.

    PubMed

    Han, Jiaxi; Du, Zhongjie; Zou, Wei; Li, Hangquan; Zhang, Chen

    2014-07-15

    The interfacial functionalized poly (glycidyl methacrylate) (PGMA) porous monolith was fabricated and applied as a novel porous adsorbent for copper ions (Cu(2+)). PGMA porous material with highly interconnected pore network was prepared by concentrated emulsion polymerization template. Then polyacrylic acid (PAA) was grafted onto the interface of the porous monolith by the reaction between the epoxy group on PGMA and a carboxyl group on PAA. Finally, the porous monolith was interfacial functionalized by rich amount of carboxyl groups and could adsorb copper ions effectively. The chemical structure and porous morphology of the porous monolith were measured by Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the effects of pore size distribution, pH value, co-existing ions, contacting time, and initial concentrations of copper ions on the adsorption capacity of the porous adsorbents were studied.

  3. Polymer Coated Electrodes in Ambient Temperature Molten Salts.

    DTIC Science & Technology

    1983-08-01

    22Y4 , polyvinyl ferrocene and thionine ~ polymers have been investigated in basic, neutral and acidic melts. Behavior 9 is similar to that reported for...polyacetylenes, tn the fields of electrocatalysis , fuel cells polylpylles and others also appears to have photoelectrochemistry and batteries. Addition

  4. In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating.

    PubMed

    Ebbens, Stephen; Hodgkinson, Richard; Parnell, Andrew J; Dunbar, Alan; Martin, Simon J; Topham, Paul D; Clarke, Nigel; Howse, Jonathan R

    2011-06-28

    Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. Applications for such layers include photovoltaics and light-emitting diodes where performance relies upon the nanoscale phase separation morphology of the spun film. Furthermore, at micrometer scales, phase separation provides a route to produce self-organized structures for templating applications. Understanding the factors that determine the final phase-separated morphology in these systems is consequently an important goal. However, it has to date proved problematic to fully test theoretical models for phase separation during spin coating, due to the high spin speeds, which has limited the spatial resolution of experimental data obtained during the coating process. Without this fundamental understanding, production of optimized micro- and nanoscale structures is hampered. Here, we have employed synchronized stroboscopic illumination together with the high light gathering sensitivity of an electron-multiplying charge-coupled device camera to optically observe structure evolution in such blends during spin coating. Furthermore the use of monochromatic illumination has allowed interference reconstruction of three-dimensional topographies of the spin-coated film as it dries and phase separates with nanometer precision. We have used this new method to directly observe the phase separation process during spinning for a polymer blend (PS-PI) for the first time, providing new insights into the spin-coating process and opening up a route to understand and control phase separation structures.

  5. Plasma deposition of antimicrobial coating on organic polymer

    NASA Astrophysics Data System (ADS)

    Rżanek-Boroch, Zenobia; Dziadczyk, Paulina; Czajkowska, Danuta; Krawczyk, Krzysztof; Fabianowski, Wojciech

    2013-02-01

    Organic materials used for packing food products prevent the access of microorganisms or gases, like oxygen or water vapor. To prolong the stability of products, preservatives such as sulfur dioxide, sulfites, benzoates, nitrites and many other chemical compounds are used. To eliminate or limit the amount of preservatives added to food, so-called active packaging is sought for, which would limit the development of microorganisms. Such packaging can be achieved, among others, by plasma modification of a material to deposit on its surface substances inhibiting the growth of bacteria. In this work plasma modification was carried out in barrier discharge under atmospheric pressure. Sulfur dioxide or/and sodium oxide were used as the coating precursors. As a result of bacteriological studies it was found that sulfur containing coatings show a 16% inhibition of Salmonella bacteria growth and 8% inhibition of Staphylococcus aureus bacteria growth. Sodium containing coatings show worse (by 10%) inhibiting properties. Moreover, films with plasma deposited coatings show good sealing properties against water vapor. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  6. Natural gas purification using a porous coordination polymer with water and chemical stability.

    PubMed

    Duan, Jingui; Jin, Wanqin; Krishna, Rajamani

    2015-05-04

    Porous coordination polymers (PCPs), constructed by bridging the metals or clusters and organic linkers, can provide a functional pore environment for gas storage and separation. But the rational design for identifying PCPs with high efficiency and low energy cost remains a challenge. Here, we demonstrate a new PCP, [(Cu4Cl)(BTBA)8·(CH3)2NH2)·(H2O)12]·xGuest (PCP-33⊃guest), which shows high potential for purification of natural gas, separation of C2H2/CO2 mixtures, and selective removal of C2H2 from C2H2/C2H4 mixtures at ambient temperature. The lower binding energy of the framework toward these light hydrocarbons indicates the reduced net costs for material regeneration, and meanwhile, the good water and chemical stability of it, in particular at pH = 2 and 60 °C, shows high potential usage under some harsh conditions. In addition, the adsorption process and effective site for separation was unravelled by in situ infrared spectroscopy studies.

  7. Viscoelastic polymer flows and elastic turbulence in three-dimensional porous structures.

    PubMed

    Mitchell, Jonathan; Lyons, Kyle; Howe, Andrew M; Clarke, Andrew

    2016-01-14

    Viscoelastic polymer solutions flowing through reservoir rocks have been found to improve oil displacement efficiency when the aqueous-phase shear-rate exceeds a critical value. A possible mechanism for this enhanced recovery is elastic turbulence that causes breakup and mobilization of trapped oil ganglia. Here, we apply nuclear magnetic resonance (NMR) pulsed field gradient (PFG) diffusion measurements in a novel way to detect increased motion of disconnected oil ganglia. The data are acquired directly from a three-dimensional (3D) opaque porous structure (sandstone) when viscoelastic fluctuations are expected to be present in the continuous phase. The measured increase in motion of trapped ganglia provides unequivocal evidence of fluctuations in the flowing phase in a fully complex 3D system. This work provides direct evidence of elastic turbulence in a realistic reservoir rock - a measurement that cannot be readily achieved by conventional laboratory methods. We support the NMR data with optical microscopy studies of fluctuating ganglia in simple two-dimensional (2D) microfluidic networks, with consistent apparent rheological behaviour of the aqueous phase, to provide conclusive evidence of elastic turbulence in the 3D structure and hence validate the proposed flow-fluctuation mechanism for enhanced oil recovery.

  8. Synthesis of porous molecularly imprinted polymers for selective adsorption of glutathione

    NASA Astrophysics Data System (ADS)

    Song, Renyuan; Hu, Xiaoling; Guan, Ping; Li, Ji; Qian, Liwei; Wang, Chaoli; Wang, Qiaoli

    2015-03-01

    An effective approach overcome the classical deficiencies of biomolecules molecularly imprinted polymers (MIPs), that is, low binding capacity and slow mass transfer rate, is proposed. With glutathione (GSH) as target molecule, porous imprinted layers were fabricated according to our newly developed method the introduction of a mixture of acetontrile and dimethylsulfoxide as porogen in surface-initiated polymerization systems. The resultant MIPs particles exhibited a large surface area could remarkably improve the imprinting effect in relation to a significantly increased imprinting factor and mass transfer rate, compared to the MIPs prepared by using aqueous solution as solvent. The batch static binding tests were carried out to evaluate the adsorption kinetics, adsorption isotherms and selective recognition of the MIPs particles. The binding behavior followed the pseudo-second order kinetic model, revealing that the process was chemically carried out. Two binding isotherm models were applied to analyze equilibrium data, obtaining the best description by Langmuir isotherm model. In addition, the selective of separation and extraction of GSH from a mixture of GSH and its structural analogs could be achieved on the MIPs solid-phase extraction cartridge, indicating that the possibility for the separation and enrichment of the template from complicated matrices.

  9. Thiol-ol Chemistry for Grafting of Natural Polymers to Form Highly Stable and Efficacious Antibacterial Coatings.

    PubMed

    Li, Min; Mitra, Debirupa; Kang, En-Tang; Lau, Titus; Chiong, Edmund; Neoh, Koon Gee

    2017-01-18

    Bacterial contamination of surfaces and the associated infection risk is a significant threat to human health. Some natural antibacterial polymers with low toxicity are promising coating materials for alleviating pathogenic colonization on surfaces. However, widespread application of these polymers as antibacterial coatings is constrained by coating techniques which are not easily scalable due to stringent reaction conditions. Herein, thiol-ol reaction involving oxidative conjugation between thiol and hydroxyl groups is demonstrated as a facile technique to graft two natural polymer derivatives, agarose (AG) and quaternized chitosan (QCS), as antibacterial coatings on polymer and metal substrates. The substrate surfaces are first treated with oxygen plasma followed by UV-induced grafting of the polymers under atmospheric conditions. Dimercaprol, a FDA-approved drug, is used as both surface anchor and cross-linker of the polymer chains during grafting. The AG coating achieves >2 log reduction in Pseudomonas aeruginosa and Staphylococcus aureus biofilm formation, while the QCS coating reduces bacterial count from contaminated droplets on its surface by >95%. The coatings are noncytotoxic and exhibits a high degree of stability under conditions expected in their potential applications as antibacterial coating for biomedical devices (for AG), and for preventing pathogen transmission in the environment (for QCS).

  10. The effect of composition and thermodynamics on the surface morphology of durable superhydrophobic polymer coatings.

    PubMed

    Nahum, Tehila; Dodiuk, Hanna; Kenig, Samuel; Panwar, Artee; Barry, Carol; Mead, Joey

    2017-01-01

    Durable superhydrophobic coatings were synthesized using a system of silica nanoparticles (NPs) to provide nanoscale roughness, fluorosilane to give hydrophobic chemistry, and three different polymer binders: urethane acrylate, ethyl 2-cyanoacrylate, and epoxy. Coatings composed of different binders incorporating NPs in various concentrations exhibited different superhydrophobic attributes when applied on polycarbonate (PC) and glass substrates and as a function of coating composition. It was found that the substrate surface characteristics and wettability affected the superhydrophobic characteristics of the coatings. Interfacial tension and spreading coefficient parameters (thermodynamics) of the coating components were used to predict the localization of the NPs for the different binders' concentrations. The thermodynamic analysis of the NPs localization was in good agreement with the experimental observations. On the basis of the thermodynamic analysis and the experimental scanning electron microscopy, X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy results, it was concluded that localization of the NPs on the surface was critical to provide the necessary roughness and resulting superhydrophobicity. The durability evaluated by tape testing of the epoxy formulations was the best on both glass and PC. Several coating compositions retained their superhydrophobicity after the tape test. In summary, it was concluded that thermodynamic analysis is a powerful tool to predict the roughness of the coating due to the location of NPs on the surface, and hence can be used in the design of superhydrophobic coatings.

  11. The effect of composition and thermodynamics on the surface morphology of durable superhydrophobic polymer coatings

    PubMed Central

    Nahum, Tehila; Dodiuk, Hanna; Kenig, Samuel; Panwar, Artee; Barry, Carol; Mead, Joey

    2017-01-01

    Durable superhydrophobic coatings were synthesized using a system of silica nanoparticles (NPs) to provide nanoscale roughness, fluorosilane to give hydrophobic chemistry, and three different polymer binders: urethane acrylate, ethyl 2-cyanoacrylate, and epoxy. Coatings composed of different binders incorporating NPs in various concentrations exhibited different superhydrophobic attributes when applied on polycarbonate (PC) and glass substrates and as a function of coating composition. It was found that the substrate surface characteristics and wettability affected the superhydrophobic characteristics of the coatings. Interfacial tension and spreading coefficient parameters (thermodynamics) of the coating components were used to predict the localization of the NPs for the different binders’ concentrations. The thermodynamic analysis of the NPs localization was in good agreement with the experimental observations. On the basis of the thermodynamic analysis and the experimental scanning electron microscopy, X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy results, it was concluded that localization of the NPs on the surface was critical to provide the necessary roughness and resulting superhydrophobicity. The durability evaluated by tape testing of the epoxy formulations was the best on both glass and PC. Several coating compositions retained their superhydrophobicity after the tape test. In summary, it was concluded that thermodynamic analysis is a powerful tool to predict the roughness of the coating due to the location of NPs on the surface, and hence can be used in the design of superhydrophobic coatings. PMID:28243071

  12. High-temperature separation with polymer-coated fiber in packed capillary gas chromatography.

    PubMed

    Saito, Yoshihiro; Ogawa, Mitsuhiro; Imaizumi, Motohiro; Ban, Kazuhiro; Abe, Akira; Takeichi, Tsutomu; Wada, Hiroo; Jinno, Kiyokatsu

    2005-06-01

    High-temperature gas chromatographic separation of several synthetic polymer mixtures with Dexsil-coated fiber-packed columns was studied. A bundle of heat-resistant filaments, Zylon, was longitudinally packed into a short metal capillary, followed by the conventional coating process with Dexsil 300 material. Prior to the packing process the metal capillary was deactivated by the formation of a silica layer. The typical size of the resulting column was 0.3-mm i.d., 0.5-mm o.d., 1-m length, and packed with about 170 filaments of the Dexsil-coated Zylon. The column temperature could be elevated up to 450 degrees C owing to the good thermal stability of the fiber, Dexsil coating, and metal capillary; furthermore, this allowed the separation of low-volatile compounds to be studied.

  13. PEDOT polymer coatings facilitate smaller neural recording electrodes

    PubMed Central

    Ludwig, Kip A.; Langhals, Nicholas B.; Joseph, Mike D.; Richardson-Burns, Sarah M.; Hendricks, Jeffrey L.; Kipke, Daryl R.

    2012-01-01

    We investigated using poly(3,4-ethylenedioxythiophene) (PEDOT) to lower the impedance of small, gold recording electrodes with initial impedances outside of the effective recording range. Smaller electrode sites enable more densely packed arrays, increasing the number of input and output channels to and from the brain. Moreover, smaller electrode sizes promote smaller probe designs; decreasing the dimensions of the implanted probe has been demonstrated to decrease the inherent immune response, a known contributor to the failure of long-term implants. As expected, chronically implanted control electrodes were unable to record well-isolated unit activity, primarily as a result of a dramatically increased noise floor. Conversely, electrodes coated with PEDOT consistently recorded high-quality neural activity, and exhibited a much lower noise floor than controls. These results demonstrate that PEDOT coatings enable electrode designs 15 microns in diameter. PMID:21245527

  14. Trypsin coatings on electrospun and alcohol-dispersed polymer nanofibers for trypsin digestion column

    SciTech Connect

    Jun, Seung-Hyun; Chang, Mun Seock; Kim, Byoung Chan; An, Hyo Jin; Lopez-Ferrer, Daniel; Zhao, Rui; Smith, Richard D.; Lee, Sang-Won; Kim, Jungbae

    2010-09-15

    The construction of a trypsin reactor in a chromatography column for rapid and efficient protein digestion in proteomics is described. Electrospun and alcohol-dispersed polymer nanofibers were used for the fabrication of highly stable trypsin coating, which was prepared by a two-step process of covalent attachment and enzyme crosslinking. In a comparative study with the trypsin coatings on asspun and non-dispersed nanofibers, it has been observed that a simple step of alcohol dispersion improved not only the enzyme loading but also the performance of protein digestion. In-column digestion of enolase was successfully performed in less than twenty minutes. By applying the alcohol dispersion of polymer nanofibers, the bypass of samples was reduced by filling up the column with well-dispersed nanofibers, and subsequently, interactions between the protein and the enzymes were improved yielding more complete and reproducible digestions. Regardless of alcohol-dispersion or not, trypsin coating showed better digestion performance and improved performance stability under recycled uses than covalently-attached trypsin. The combination of highly stable trypsin coating and alcoholdispersion of polymer nanofibers has opened up a new potential to develop a trypsin column for on-line and automated protein digestion.

  15. Sol-gel metal oxide and metal oxide/polymer multilayers applied by meniscus coating

    SciTech Connect

    Britten, J.A.; Thomas, I.M.

    1993-10-01

    We are developing a meniscus coating process for manufacturing large-aperture dielectric multilayer high reflectors (HR`s) at ambient conditions from liquid suspensions. Using a lab-scale coater capable of coating 150 mm square substrates, we have produced several HR`s which give 99% + reflection with 24 layers and with edge effects confined to about 10 mm. In calendar 1993 we are taking delivery of an automated meniscus coating machine capable of coating substrates up to 400 mm wide and 600 mm long. The laser-damage threshold and failure stress of sol-gel thin films can be substantially increased through the use of soluble polymers which act as binders for the metal oxide particles comprising the deposited film. Refractive index control of the film is also possible through varying the polymer/oxide ratio. Much of our present effort present is in optimizing oxide particle/binder/solvent formulations for the high-index material. Films from colloidal zirconia strengthened with polyvinylpyrollidone (PVP) have given best results to date. An increase in the laser damage threshold (LDT) for single layers has been shown to significantly increase with increased polymer loading, but as yet the LDT for multilayer stacks remains low.

  16. Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating

    SciTech Connect

    Tavares, L.; Kjelstrup-Hansen, J.; Rubahn, H.-G.; Sturm, H.

    2010-05-15

    Para-hexaphenylene (p-6P) molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease in luminescence intensity upon UV light exposure, which could render the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiO{sub x} and Al{sub 2}O{sub 3}) were applied onto p-6P nanofibers. These treatments caused a reduction in the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings [a statistical copolymer of tetrafluoroethylene and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole, P(TFE-PDD), and poly(methyl methacrylate), PMMA] do not interfere with the luminescence spectrum from the p-6P but are not effective in stopping the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p-6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results in a significant reduction in bleaching without affecting significantly the emission spectrum from the nanofibers.

  17. Controlling cell-material interactions using coatings with advanced polymer architectures

    NASA Astrophysics Data System (ADS)

    Koegler, Peter; Pasic, Paul; Johnson, Graham; Bean, Penny; Lorenz, Guenter; Meagher, Laurence; Thissen, Helmut

    2011-12-01

    Polymeric coatings which allow the effective control of biointerfacial interactions and cellular responses are of increasing interest in a range of biomedical applications in vitro and in vivo such as cell culture tools, biosensors and implantable medical devices. A variety of coating strategies have been developed to gain control over cell-surface interactions but many of them are limited with respect to their function and transferability between different substrate materials. Here, our aim was to establish an easily transferable coating that reduces non-specific cell-surface interactions to a minimum while at the same time presenting functional groups which allow for the subsequent immobilisation of bioactive signals. To achieve this, we have applied an allylamine plasma polymer coating followed by the covalent immobilisation of a macro-initiator providing iniferter functional groups. Subsequent controlled free radical graft polymerisation using the monomers acrylamide and acrylic acid in different molar ratios resulted in highly uniform polymer coatings. Non-specific cell attachment was significantly reduced on coatings representing molar ratios of less than 10% acylic acid. At the same time, we have demonstrated the suitability of these coatings for the subsequent covalent binding of bioactive compounds carrying amine functional groups using the label 2,2,2-trifluoroethylamine. Successful surface modifications were confirmed by X-ray photoelectron spectroscopy (XPS) and profilometry. The cellular response was evaluated using HeLa cell attachment experiments for up to 24 hours. We expect that the coating platform established in this study will be translated into a number of biomedical applications, including applications in implantable devices and regenerative medicine.

  18. Coating flexible probes with an ultra fast degrading polymer to aid in tissue insertion

    PubMed Central

    Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B.; Kaplan, Hilton M.; Kohn, Joachim; Shreiber, David I.; Zahn, Jeffrey D.

    2016-01-01

    We report a fabrication process for coating neural probes with an ultrafast degrading polymer to create consistent and reproducible devices for neural tissue insertion. The rigid polymer coating acts as a probe insertion aid, but resorbs within hours post-implantation. Despite the feasibility for short term neural recordings from currently available neural prosthetic devices, most of these devices suffer from long term gliosis, which isolates the probes from adjacent neurons, increasing the recording impedance and stimulation threshold. The size and stiffness of implanted probes have been identified as critical factors that lead to this long term gliosis. Smaller, more flexible probes that match the mechanical properties of brain tissue could allow better long term integration by limiting the mechanical disruption of the surrounding tissue during and after probe insertion, while being flexible enough to deform with the tissue during brain movement. However, these small flexible probes inherently lack the mechanical strength to penetrate the brain on their own. In this work, we have developed a micromolding method for coating a non-functional miniaturized SU-8 probe with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)). Coated, non-functionalized probes of varying dimensions were reproducibly fabricated with high yields. The polymer erosion/degradation profiles of the probes were characterized in vitro. The probes were also mechanically characterized in ex vivo brain tissue models by measuring buckling and insertion forces during probe insertion. The results demonstrate the ability to produce polymer coated probes of consistent quality for future in vivo use, for example to study the effects of different design parameters that may affect tissue response during long term chronic intra-cortical microelectrode neural recordings. PMID:25681971

  19. Evaluating antibiotic release profiles as a function of polymer coating formulation - biomed 2011.

    PubMed

    Davidoff, Sherry N; Sevy, Justin O; Brooks, Benjamin D; Grainger, David W; Brooks, Amanda E

    2011-01-01

    To address persistent 1-3% infection rates associated with orthopedic implant surgeries, the next generation of bone graft filler materials will no longer pharmacologically silent being endowed as a local drug delivery vehicle to maintain locally high levels of antibiotic. Bone allograft material, used as a structural support to fill the avascular spaces in bone defects, revision surgeries, and traumatic injury, can be used as a drug depot to provide effective antibiotic delivery over the orthopedically relevant six-to-eight week time period. Passive antibiotic coatings, applied in the surgical theater, are quickly depleted from the site, inadvertently promoting the development of drug-resistance. Alternatively, many promising controlled-delivery strategies provide an initial burst release of antibiotic within 24 to 72 hours; however, this remains inadequate to combat the onslaught of ubiquitous pathogens that can persist only to reemerge once drug concentrations fall below the minimal inhibitory concentration (MIC). To improve the longevity of this strategy, a variety of coating techniques were evaluated in which clinically-accepted, FDA-recognized, degradable polycaprolactone (PCL) polymer acts as a rate-controlling membrane to retard the release of the antibiotic tobramycin from allograft bone. Using a combination of dipping and rapid drying, the drug-releasing polymer coating was applied concurrently maintaining the high surface area of the allograft bone; however, SEM imaging reveled an imperfect coating that negatively affected the release kinetics. Altering the drug-containing polymer formulation to incorporate water provided a smoother, more uniform coat and ultimately improved the drug-release profile and longevity out to 5 weeks using both bacteriostatic and bacteriocidal assays. Additionally, drug bioactivity was assessed and confirmed between 2 and 4 weeks in the absence of the water-containing polymer.

  20. Surface characteristics of a self-polymerized dopamine coating deposited on hydrophobic polymer films.

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhu, Baoku; Xu, Youyi

    2011-12-06

    This study aims to explore the fundamental surface characteristics of polydopamine (pDA)-coated hydrophobic polymer films. A poly(vinylidene fluoride) (PVDF) film was surface modified by dip coating in an aqueous solution of dopamine on the basis of its self-polymerization and strong adhesion feature. The self-polymerization and deposition rates of dopamine on film surfaces increased with increasing temperature as evaluated by both spectroscopic ellipsometry and scanning electronic microscopy (SEM). Changes in the surface morphologies of pDA-coated films as well as the size and shape of pDA particles in the solution were also investigated by SEM, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The surface roughness and surface free energy of pDA-modified films were mainly affected by the reaction temperature and showed only a slight dependence on the reaction time and concentration of the dopamine solution. Additionally, three other typical hydrophobic polymer films of polytetrafluoroethylene (PTFE), poly(ethylene terephthalate) (PET), and polyimide (PI) were also modified by the same procedure. The lyophilicity (liquid affinity) and surface free energy of these polymer films were enhanced significantly after being coated with pDA, as were those of PVDF films. It is indicated that the deposition behavior of pDA is not strongly dependent on the nature of the substrates. This information provides us with not only a better understanding of biologically inspired surface chemistry for pDA coatings but also effective strategies for exploiting the properties of dopamine to create novel functional polymer materials.

  1. Coating flexible probes with an ultra fast degrading polymer to aid in tissue insertion.

    PubMed

    Lo, Meng-chen; Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B; Kaplan, Hilton M; Kohn, Joachim; Shreiber, David I; Zahn, Jeffrey D

    2015-04-01

    We report a fabrication process for coating neural probes with an ultrafast degrading polymer to create consistent and reproducible devices for neural tissue insertion. The rigid polymer coating acts as a probe insertion aid, but resorbs within hours post-implantation. Despite the feasibility for short term neural recordings from currently available neural prosthetic devices, most of these devices suffer from long term gliosis, which isolates the probes from adjacent neurons, increasing the recording impedance and stimulation threshold. The size and stiffness of implanted probes have been identified as critical factors that lead to this long term gliosis. Smaller, more flexible probes that match the mechanical properties of brain tissue could allow better long term integration by limiting the mechanical disruption of the surrounding tissue during and after probe insertion, while being flexible enough to deform with the tissue during brain movement. However, these small flexible probes inherently lack the mechanical strength to penetrate the brain on their own. In this work, we have developed a micromolding method for coating a non-functional miniaturized SU-8 probe with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)). Coated, non-functionalized probes of varying dimensions were reproducibly fabricated with high yields. The polymer erosion/degradation profiles of the probes were characterized in vitro. The probes were also mechanically characterized in ex vivo brain tissue models by measuring buckling and insertion forces during probe insertion. The results demonstrate the ability to produce polymer coated probes of consistent quality for future in vivo use, for example to study the effects of different design parameters that may affect tissue response during long term chronic intra-cortical microelectrode neural recordings.

  2. Facile fabrication of ultrafine palladium nanoparticles with size- and location-control in click-based porous organic polymers.

    PubMed

    Li, Liuyi; Zhao, Huaixia; Wang, Jinyun; Wang, Ruihu

    2014-05-27

    Two click-based porous organic polymers (CPP-1 and CPP-2) are readily synthesized through a click reaction. Using CPP-1 and CPP-2 as supports, palladium nanoparticles (NPs) with uniform and dual distributions were prepared through H2 and NaBH4 reduction routes, respectively. Ultrafine palladium NPs are effectively immobilized in the interior cavities of polymers. The coordination of 1,2,3-triazolyl to palladium and the confinement effect of polymers on palladium NPs are verified by solid-state (13)C NMR and IR spectra, XPS analyses, EDX mapping, and computational calculation. The steric and electronic properties of polymers have a considerable influence on the interaction between polymers and palladium NPs, as well as the catalytic performances of NPs. The ultrafine palladium NPs with uniform distribution exhibit superior stability and recyclability over palladium NPs with dual distributions and palladium on charcoal in the hydrogenation of nitroarenes, and no obvious agglomeration and loss of catalytic activity were observed after recycling several times. The excellent performances mainly result from synergetic effects between palladium NPs and polymers.

  3. Solvent-free fabrication of porous polymer for tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxi

    Tissue engineering scaffold is one of the basic components of all tissue engineering approaches. Most of the existing fabrication techniques for tissue engineering scaffolds require the use of organic solvents that may never be fully removed, even after long processing hours. The residuals of these organic solvents reduce the ability of cells to form new tissues in vivo. In this research, a solvent-free approach to fabricating porous polymers was developed for potential tissue engineering applications. The method includes solid-state foaming and ultrasound treatment. PLA (Polylactic acid), one of the most popular materials in tissue engineering applications, was investigated. The PLA-CO2 system was characterized in this study for the solid-state foaming process with a particular goal of producing low density foams. The results show that low relative density foams (lower than 10%) could be achieved in a wide processing window. To better control the solid-state foaming process and tailor the material properties, a systematic study was carried out on the crystallization behavior of PLA at different stages of the solid-state foaming process. It is found that crystallinity increased linearly with the square root of the area strain of the porous structures. Ultrasound of 20 and 40 kHz was applied to the solid-state foams. Both dye diffusion tests and permeability measurements show that ultrasound could enhance the interconnectivity of solid-state foams. Effects of ultrasound processing time, ultrasound frequency, ultrasound power, bath temperature, and pore size were investigated. For PLA and PETG (Polyethylene Terephthalate Glycol) foams, interconnected microstructures were obtained, with permeability on the level of 10-12 m2 or higher for the pore sizes ranging from 230 mum to 430 mum. Ultrasound heating in the specimen was studied. The maximum temperature induced by the ultrasound heating was found to be below the Tg of PLA. It is proposed that ultrasound cavitation

  4. Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates

    NASA Astrophysics Data System (ADS)

    Kiviaho, Jenny K.; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa, Affc; Kostiainen, Mauri A.

    2016-06-01

    DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The

  5. Cell attachment to PET films coated with a thermo-sensitive block co-polymer with different chemical composition.

    PubMed

    Takamoto, Tomoaki; Yasuda, Kaori; Tsujino, Tomohiro; Sugihara, Shinji; Kanaoka, Shokyoku; Aoshima, Sadahito; Tabata, Yasuhiko

    2007-01-01

    This objective of this study is to characterize the surface of poly(ethylene terephthalate) (PET) films coated with the thermo-sensitive di-block co-polymers of 2-ethoxyethyl vinyl ether and 2-phenoxyethyl vinyl ether segments (EOVE-b-PhOVE) with a high polydispersity and evaluate the behavior of cell attachment on them at different temperatures. The EOVE segment possessed a low critical solution temperature at 20 degrees C while the hydrophobic PhOVE segment functioned as the site to allow the co-polymer to adsorb onto the PET films. X-ray photoelectron spectroscopy and contact angle measurements revealed that the PET film was coated with the EOVE-b-PhOVE co-polymers. The density of co-polymers coated increased with the concentration of co-polymers used for coating. Irrespective of the co-polymer type, 3T3L1 cells attached on the surface of coated films at 37 degrees C, while the cells showed a spread shape, which is similar to that of cells attached on the original non-coated film. However, when the temperature decreased from 37 to 4 degrees C, the cell shape changed to be round, in contrast to that of the original PET film. The percent increase of round cells depended on the coating density and the polymerization degree of EOVE segment.

  6. Stabilization of two-phase octanol/water flows inside poly(dimethylsiloxane) microchannels using polymer coatings.

    PubMed

    van der Linden, H J; Jellema, L C; Holwerda, M; Verpoorte, E

    2006-08-01

    In this paper we present our first results on the realization of stable water/octanol, two-phase flows inside poly(dimethylsiloxane) (PDMS) microchannels. Native PDMS microchannels were coated with high molecular weight polymers to change the surface properties of the microchannels and thus stabilize the laminar flow profile. The polymers poly(2-hydroxyethyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(ethylene glycol), and poly(vinyl alcohol) were assessed for their quality as stabilization coatings after deposition from flowing and stationary solutions. Additionally, the influence of coating the microchannels homogeneously with a single kind of polymer or heterogeneously with two different polymers was investigated. From the experimental observations, it can be concluded that homogeneous polymer coatings with poly(2-hydroxyethyl methacrylate) and poly(vinyl pyrrolidone) led to the effective stabilization of laminar water/octanol flows. Furthermore, heterogeneous coatings led to two-phase flows which had a better-defined and more stable interface over long distances (i.e., 40-mm-long microchannels). Finally, the partitioning of fuchsin dye in the coated microchannels was demonstrated, establishing the feasibility of the use of the polymer-coated PDMS microchannels for determination of logP values in laminar octanol/water flows.

  7. Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

    PubMed

    Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

    2017-02-27

    Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required.

  8. Organic matter induced mobilization of polymer-coated silver nanoparticles from water-saturated sand.

    PubMed

    Yang, Xinyao; Yin, Ziyi; Chen, Fangmin; Hu, Jingjing; Yang, Yuesuo

    2015-10-01

    Mobilization of polymer-coated silver nanoparticles (AgNPs) by anionic surfactant (sodium dodecylbenzenesulphonate: SDBS), amino acid derivative (N-acetylcysteine: NAC), and chelate (ethylenediaminetetraacetic acid: EDTA) in water-saturated sand medium was explored based on carefully designed column tests. Exposure experiments monitoring the size evolution of polyvinylpyrrolidone (PVP) coated AgNPs in organic solutions confirm the capacity of SDBS, NAC and EDTA to partly displace PVP. Single Pulse Column Experiment (SPCE) results show both the PVP polymer and the silver core controlled AgNP deposition while the effect of the PVP was dominant. Results of Co-injected Pulse Column Experiments (CPCEs) where AgNP and SDBS or NAC were co-injected into the column following a very short mixing (<1 s) disprove our hypothesis that coating-alternation by particle associated organic would mobilize irreversibly deposited particles from the uncoated sand, while surface charge modification by adsorbed NAC was identified as a potential mobilizing mechanism for AgNP from the iron-oxide-coated sand. Triple Pulse Column Experiment (TPCE) results confirm that such a charging effect of the adsorbed organic molecules may enable SDBS and NAC to mobilize AgNPs from the iron-oxide-coated sands. TPCE results with five distinct levels of SDBS indicate that concentration-stimulated change in the SDBS format from an individual to a micelle significantly increased the mobilizing efficiency and site blockage of SDBS. Although being an electrolyte, EDTA did not mobilize AgNPs, as the case with SDBS or NAC, as it dissolved the iron oxides which in turn prevented EDTA adsorption on sand. The findings have implications for better understanding the behavior of polymer-coated nanoparticles in organic-presented groundwater systems, i.e., detachment-associated uncertainty in exposure prediction of the nanomaterials.

  9. Novel Bio-functional Magnesium Coating on Porous Ti6Al4V Orthopaedic Implants: In vitro and In vivo Study

    PubMed Central

    Li, Xiaokang; Gao, Peng; Wan, Peng; Pei, Yifeng; Shi, Lei; Fan, Bo; Shen, Chao; Xiao, Xin; Yang, Ke; Guo, Zheng

    2017-01-01

    Titanium and its alloys with various porous structures are one of the most important metals used in orthopaedic implants due to favourable properties as replacement for hard tissues. However, surface modification is critical to improve the osteointegration of titanium and its alloys. In this study, a bioactive magnesium coating was successfully fabricated on porous Ti6Al4V by means of arc ion plating, which was proved with fine grain size and high film/substrate adhesion. The surface composition and morphology were characterized by X-ray diffraction and SEM equipped with energy dispersive spectroscopy. Furthermore, the in vitro study of cytotoxicity and proliferation of MC3T3-E1 cells showed that magnesium coated porous Ti6Al4V had suitable degradation and biocompatibility. Moreover, the in vivo studies including fluorescent labelling, micro-computed tomography analysis scan and Van-Gieson staining of histological sections indicated that magnesium coated porous Ti6Al4V could significantly promote bone regeneration in rabbit femoral condylar defects after implantation for 4 and 8 weeks, and has better osteogenesis and osteointegration than the bare porous Ti6Al4V. Therefore, it is expected that this bioactive magnesium coating on porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions can be used for orthopedic applications. PMID:28102294

  10. Versatile theranostics agents designed by coating ferrite nanoparticles with biocompatible polymers

    NASA Astrophysics Data System (ADS)

    Zahraei, M.; Marciello, M.; Lazaro-Carrillo, A.; Villanueva, A.; Herranz, F.; Talelli, M.; Costo, R.; Monshi, A.; Shahbazi-Gahrouei, D.; Amirnasr, M.; Behdadfar, B.; Morales, M. P.

    2016-06-01

    Three biocompatible polymers, polyethylene glycol (PEG), dextran and chitosan, have been used in this work to control the colloidal stability of magnetic nanoparticles (14 ± 5 nm in diameter) and to vary the aggregation state in order to study their effect on relaxometric and heating properties. Two different coating strategies have been deeply developed; one based on the formation of an amide bond between citric acid coated nanoparticles (NPs) and amine groups present on the polymer surface and the other based on the NP encapsulation. Relaxometric properties revealed that proton relaxation rates strongly depend on the coating layer hydrophilicity and the aggregation state of the particles due to the presence of magnetic interactions. Thus, while PEG coating reduces particle aggregation by increasing inter-particle spacing leading to reduction of both T1 and T2 relaxation, dextran and chitosan lead to an increase mainly in T2 values due to the aggregation of particles in bigger clusters where they are in close contact. Dextran and chitosan coated NPs have also shown a remarkable heating effect during the application of an alternating magnetic field. They have proved to be potential candidates as theranostic agents for cancer diagnosis and treatment. Finally, cytotoxicity of PEG conjugated NPs, which seem to be ideal for intravenous administration because of their small hydrodynamic size, was investigated resulting in high cell viability even at 0.2 mg Fe ml-1 after 24 h of incubation. This suspension can be used as drug/biomolecule carrier for in vivo applications.

  11. Development of superhydrophobicity in fluorosilane-treated diatomaceous earth polymer coatings

    NASA Astrophysics Data System (ADS)

    Sedai, Bhishma R.; Khatiwada, Bal K.; Mortazavian, Hamid; Blum, Frank D.

    2016-11-01

    Superhydrophobic coatings were prepared using 3-(heptafluoroisopropoxy)- propyltrimethoxysilane (HFIP-TMS) treated diatomaceous earth (DE) particles with high molecular mass polystyrene or poly(vinyl acetate) as polymer binders. DE is a highly hydrophilic material and treatment of the DE with HFIP-TMS turned it into superhydrophobic diatomaceous earth (HFIP-DE). Thermogravimetric analysis (TGA) was used to determine the amount of grafted fluorosilane on the surface of the DE particles. The results showed that approximately 1.8% of HFIP-TMS grafted onto the surface of DE particles resulted in superhydrophobicity with contact angles as high as 164° for the particles themselves and also in coatings. Fourier transformed infrared spectroscopy (FTIR) was used to confirm the presence of HFIP-TMS on the surface of DE particles. The development of the hydrophobicity in the coatings with either polystyrene (PS) or poly(vinyl acetate) (PVAc) as binders was followed as a function of the particle loading using contact angle measurements and scanning electron microscopy. It was found that for these model DE-binder systems, the contact angles of the coatings were independent of the polymers used as long as the particle loading was greater than a minimum amount (∼40% treated DE particles). It was also found that more treated DE particles moved to the air interface as the particle loadings in the coatings increased and then levelled off.

  12. Ultrathin, freestanding, stimuli-responsive, porous membranes from polymer hydrogel-brushes

    NASA Astrophysics Data System (ADS)

    Kang, Chengjun; Ramakrishna, Shivaprakash N.; Nelson, Adrienne; Cremmel, Clement V. M.; Vom Stein, Helena; Spencer, Nicholas D.; Isa, Lucio; Benetti, Edmondo M.

    2015-07-01

    The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had previously been patterned with polystyrene nanoparticles. Assembly parameters and particle sizes could be varied, in order to fabricate nanoporous hydrogel-brush membranes with tunable pore coverage and characteristics. Additionally, due to the presence of weak polyacid functions within the hydrogel, the membranes exhibited pH-dependent thickness in water and reversible opening/closing of the pores.The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had

  13. Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers

    DTIC Science & Technology

    1994-05-31

    T Code: 4132016 W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.KumarS.K. Dr. JoAnn Milliken Tripathy. 7. PHI-OUHMING OFH-NIZATION NAMIE(S) AND...Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers by W.H. Kim, B. Bihari, R. Moody, N. B. Kodali ...POLYMERS W. H. Kim, B. Bihari+, R. Moody+, N. B. Kodali , J. Kumar+, and S. K. Tripathy, University of Massachusetts-Lowell, Center for Advanced Materials

  14. Enhanced structural color generation in aluminum metamaterials coated with a thin polymer layer.

    PubMed

    Cheng, Fei; Yang, Xiaodong; Rosenmann, Daniel; Stan, Liliana; Czaplewski, David; Gao, Jie

    2015-09-21

    A high-resolution and angle-insensitive structural color generation platform is demonstrated based on triple-layer aluminum-silica-aluminum metamaterials supporting surface plasmon resonances tunable across the entire visible spectrum. The color performances of the fabricated aluminum metamaterials can be strongly enhanced by coating a thin transparent polymer layer on top. The results show that the presence of the polymer layer induces a better impedance matching for the plasmonic resonances to the free space so that strong light absorption can be obtained, leading to the generation of pure colors in cyan, magenta, yellow and black (CMYK) with high color saturation.

  15. Water Transport in the Micro Porous Layer and Gas Diffusion Layer of a Polymer Electrolyte Fuel Cell

    NASA Astrophysics Data System (ADS)

    Qin, C.; Hassanizadeh, S. M.

    2015-12-01

    In this work, a recently developed dynamic pore-network model is presented [1]. The model explicitly solves for both water pressure and capillary pressure. A semi-implicit scheme is used in updating water saturation in each pore body, which considerably increases the numerical stability at low capillary number values. Furthermore, a multiple-time-step algorithm is introduced to reduce the computational effort. A number of case studies of water transport in the micro porous layer (MPL) and gas diffusion layer (GDL) are conducted. We illustrate the role of MPL in reducing water flooding in the GDL. Also, the dynamic water transport through the MPL-GDL interface is explored in detail. This information is essential to the reduced continua model (RCM), which was developed for multiphase flow through thin porous layers [2, 3]. C.Z. Qin, Water transport in the gas diffusion layer of a polymer electrolyte fuel cell: dynamic pore-network modeling, J Electrochimical. Soci., 162, F1036-F1046, 2015. C.Z. Qin and S.M. Hassanizadeh, Multiphase flow through multilayers of thin porous media: general balance equations and constitutive relationships for a solid-gas-liquid three-phase system, Int. J. Heat Mass Transfer, 70, 693-708, 2014. C.Z. Qin and S.M. Hassanizadeh, A new approach to modeling water flooding in a polymer electrolyte fuel cell, Int. J. Hydrogen Energy, 40, 3348-3358, 2015.

  16. Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

    SciTech Connect

    Lytvynenko, Anton S.; Kiskin, Mikhail A.; Dorofeeva, Victoria N.; Mishura, Andrey M.; Titov, Vladimir E.; Kolotilov, Sergey V.; Eremenko, Igor L.; Novotortsev, Vladimir M.

    2015-03-15

    Linking of trinuclear pivalate Fe{sub 2}NiO(Piv){sub 6} (Piv=O{sub 2}CC(CH{sub 3}){sub 3}) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)·Solv, which was characterized in two forms: DMSO solvate Fe{sub 2}NiO(Piv){sub 6}(L)(DMSO)·2.5DMSO (1) or water solvate Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe{sub 2}NiO(Piv){sub 6}(L) was confirmed by the measurements of N{sub 2} and H{sub 2} adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics.

  17. Properties of Plasma Enhanced Chemical Vapor Deposition Barrier Coatings and Encapsulated Polymer Solar Cells

    NASA Astrophysics Data System (ADS)

    Qi, Lei; Zhang, Chunmei; Chen, Qiang

    2014-01-01

    In this paper, we report silicon oxide coatings deposited by plasma enhanced chemical vapor deposition technology (PECVD) on 125 μm polyethyleneterephthalate (PET) surfaces for the purpose of the shelf lifetime extension of sealed polymer solar cells. After optimization of the processing parameters, we achieved a water vapor transmission rate (WVTR) of ca. 10-3 g/m2/day with the oxygen transmission rate (OTR) less than 0.05 cc/m2/day, and succeeded in extending the shelf lifetime to about 400 h in encapsulated solar cells. And then the chemical structure of coatings related to the properties of encapsulated cell was investigated in detail.

  18. Assessment of Erosion Resistance of Coated Polymer Matrix Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Horan, Richard A.; Naik, Subhash K.; Cupp, Randall J.

    2004-01-01

    The erosion behavior of tungsten carbide-cobalt (WC-Co) coated and uncoated polymer matrix composites (PMCs) was examined with solid particle impingement using air jets. Erosion tests were conducted with Arizona road dust impinging at 20 degrees, 60 degrees, and 90 degrees angles at a velocity of 229 meters per second at both 294 and 366 K. Noncontact optical profilometry was used to measure the wear volume loss. Results indicate that the WC-Co coating enhanced erosion resistance and reduced erosion wear volume loss by a factor of nearly 2. This should contribute to longer wear lives, reduced related breakdowns, decreased maintenance costs, and increased product reliability.

  19. Enzyme precipitate coatings of lipase on polymer nanofibers.

    PubMed

    An, Hyo Jin; Lee, Hye-Jin; Jun, Seung-Hyun; Hwang, Sang Youn; Kim, Byoung Chan; Kim, Kwanghee; Lee, Kyung-Mi; Oh, Min-Kyu; Kim, Jungbae

    2011-09-01

    Lipase (LP) was immobilized on electrospun and ethanol-dispersed polystyrene-poly(styrene-co-maleic anhydride) (PS-PSMA) nanofibers (EtOH-NF) in the form of enzyme precipitate coatings (EPCs). LP precipitate coatings (EPCs-LP) were prepared in a three-step process, consisting of covalent attachment, LP precipitation, and crosslinking of precipitated LPs onto the covalently attached LPs via glutaraldehyde treatment. The LP precipitation was performed by adding various concentrations of ammonium sulfate (20-50%, w/v). EPCs-LP improved the LP activity and stability when compared to covalently attached LPs (CA-LP) and the enzyme coatings of LPs (EC-LP) without the LP precipitation. For example, the use of 40% (w/v) ammonium sulfate resulted in EPC40-LP with the highest activity, which was 4.0 and 3.6 times higher than those of CA-LP and EC-LP, respectively. After 165-day incubation under rigorous shaking at 200 rpm, the residual activities of EPC50-LP were 0.5 μM/min mg of EtOH-NF, representing 113 and 75 times higher than those of CA-LP and EC-LP, respectively. When LP was partially purified via a simple ammonium sulfate precipitation and dialysis, both activities and stabilities of EC-LP and EPC-LP could be marginally improved. It is anticipated that the improved LP activity and stability in the form of EPCs would allow for their potential applications in various bioconversion processes such as biodiesel production and ibuprofen resolution.

  20. Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.; Bakis, Charles; Williams, Tiffany S.; Johnston, James C.; Kuczmarski, Maria A.; Roberts, Gary D.

    2014-01-01

    Composite materials offer significant weight savings in many aerospace applications. The toughness of the interface of fibers crossing at different angles often determines failure of composite components. A method for toughening the interface in fabric and filament wound components using directly electrospun thermoplastic nanofiber on carbon fiber tow is presented. The method was first demonstrated with limited trials, and then was scaled up to a continuous lab scale process. Filament wound tubes were fabricated and tested using unmodified baseline towpreg material and nanofiber coated towpreg.

  1. Effects of poly (ε-caprolactone) coating on the properties of three-dimensional printed porous structures.

    PubMed

    Zhou, Zuoxin; Cunningham, Eoin; Lennon, Alex; McCarthy, Helen O; Buchanan, Fraser; Clarke, Susan A; Dunne, Nicholas

    2016-05-04

    Powder-based inkjet three-dimensional printing (3DP) to fabricate pre-designed 3D structures has drawn increasing attention. However there are intrinsic limitations associated with 3DP technology due to the weak bonding within the printed structure, which significantly compromises its mechanical integrity. In this study, calcium sulphate ceramic structures demonstrating a porous architecture were manufactured using 3DP technology and subsequently post-processed with a poly (ε-caprolactone) (PCL) coating. PCL concentration, immersion time, and number of coating layers were the principal parameters investigated and improvement in compressive properties was the measure of success. Interparticle spacing within the 3DP structures were successfully filled with PCL material. Consequently the compressive properties, wettability, morphology, and in vitro resorption behaviour of 3DP components were significantly augmented. The average compressive strength, Young׳s modulus, and toughness increased 217%, 250%, and 315%, following PCL coating. Addition of a PCL surface coating provided long-term structural support to the host ceramic material, extending the resorption period from less than 7 days to a minimum of 56 days. This study has demonstrated that application of a PCL coating onto a ceramic 3DP structure was a highly effective approach to addressing some of the limitations of 3DP manufacturing and allows this advanced technology to be potentially used in a wider range of applications.

  2. Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

    NASA Astrophysics Data System (ADS)

    Cho, Eunhae; Won, Jongok

    2016-12-01

    Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

  3. Three-dimensional culture of rat calvarial osteoblasts in porous biodegradable polymers

    NASA Technical Reports Server (NTRS)

    Ishaug-Riley, S. L.; Crane-Kruger, G. M.; Yaszemski, M. J.; Mikos, A. G.

    1998-01-01

    Neonatal rat calvarial osteoblasts were cultured in 90% porous, 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for up to 56 days to examine the effects of the cell seeding density, scaffold pore size, and foam thickness on the proliferation and function of the cells in this three-dimensional environment. Osteoblasts were seeded at either 11.1 x 10(5) or 22.1 x 10(5) cells per cm2 onto PLGA scaffolds having pore sizes in the range of 150-300 or 500-710 microm with a thickness of either 1.9 or 3.2 mm. After 1 day in culture, 75.6 and 68.6% of the seeded cells attached and proliferated on the 1.9 mm thick scaffolds of 150-300 microm pore size for the low and high seeding densities, respectively. The number of osteoblasts continued to increase throughout the study and eventually leveled off near 56 days, as indicated by a quantitative DNA assay. Osteoblast/foam constructs with a low cell seeding density achieved comparable DNA content and alkaline phosphatase (ALPase) activity after 14 days, and mineralization results after 56 days to those with a high cell seeding density. A maximum penetration depth of osseous tissue of 220+/-40 microm was reached after 56 days in the osteoblast/foam constructs of 150-300 microm pore size initially seeded with a high cell density. For constructs of 500-710 microm pore size, the penetration depth was 190+/-40 microm under the same conditions. Scaffold pore size and thickness did not significantly affect the proliferation or function of osteoblasts as demonstrated by DNA content, ALPase activity, and mineralized tissue formation. These data show that comparable bone-like tissues can be engineered in vitro over a 56 day period using different rat calvarial osteoblast seeding densities onto biodegradable polymer scaffolds with pore sizes in the range of 150-710 microm. When compared with the results of a previous study where similar polymer scaffolds were seeded and cultured with marrow stromal cells, this study

  4. Three-dimensional culture of rat calvarial osteoblasts in porous biodegradable polymers.

    PubMed

    Ishaug-Riley, S L; Crane-Kruger, G M; Yaszemski, M J; Mikos, A G

    1998-08-01

    Neonatal rat calvarial osteoblasts were cultured in 90% porous, 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for up to 56 days to examine the effects of the cell seeding density, scaffold pore size, and foam thickness on the proliferation and function of the cells in this three-dimensional environment. Osteoblasts were seeded at either 11.1 x 10(5) or 22.1 x 10(5) cells per cm2 onto PLGA scaffolds having pore sizes in the range of 150-300 or 500-710 microm with a thickness of either 1.9 or 3.2 mm. After 1 day in culture, 75.6 and 68.6% of the seeded cells attached and proliferated on the 1.9 mm thick scaffolds of 150-300 microm pore size for the low and high seeding densities, respectively. The number of osteoblasts continued to increase throughout the study and eventually leveled off near 56 days, as indicated by a quantitative DNA assay. Osteoblast/foam constructs with a low cell seeding density achieved comparable DNA content and alkaline phosphatase (ALPase) activity after 14 days, and mineralization results after 56 days to those with a high cell seeding density. A maximum penetration depth of osseous tissue of 220+/-40 microm was reached after 56 days in the osteoblast/foam constructs of 150-300 microm pore size initially seeded with a high cell density. For constructs of 500-710 microm pore size, the penetration depth was 190+/-40 microm under the same conditions. Scaffold pore size and thickness did not significantly affect the proliferation or function of osteoblasts as demonstrated by DNA content, ALPase activity, and mineralized tissue formation. These data show that comparable bone-like tissues can be engineered in vitro over a 56 day period using different rat calvarial osteoblast seeding densities onto biodegradable polymer scaffolds with pore sizes in the range of 150-710 microm. When compared with the results of a previous study where similar polymer scaffolds were seeded and cultured with marrow stromal cells, this study

  5. 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

  6. Bioactivity of dexamethasone-releasing coatings on polymer/magnesium composites.

    PubMed

    Bensiamar, Fátima; Olalde, Beatriz; Cifuentes, Sandra C; Argarate, Nerea; Atorrasagasti, Garbiñe; González-Carrasco, José L; García-Rey, Eduardo; Vilaboa, Nuria; Saldaña, Laura

    2016-10-07

    We developed biodegradable polymeric coatings loaded with increasing amounts of dexamethasone on composites based on polylactic acid and Mg particles for bone repair. Incorporation of Mg particles into the polymeric matrix improves the compressive behaviour of the polymer. Mg-containing composites release Mg(2+) ions into the culture medium and improve mesenchymal stem cell (MSC) viability, enhance their osteogenic potential and promote the release of angiogenic factors. Dexamethasone-loaded coatings deposited on composites delay Mg(2+) ion dissolution while releasing controlled amounts of the drug, which are highly dependent on initial payload. Release kinetic of dexamethasone from the coatings exhibits a fast initial release of the drug followed by a slower secondary release. Bioactivity of the released dexamethasone was explored by monitoring dose-dependent responses of MSCs and macrophages. Biological effects exerted by the released drug are similar to those observed in cells treated with solutions of the glucocorticoid, indicating that the method employed for inclusion of dexamethasone into the coatings does not impair its bioactive behaviour. Culturing MSCs on dexamethasone-releasing coatings enhances extracellular matrix production and initial induction to osteogenic commitment as a function of drug payload. Dexamethasone incorporated into the coatings presents anti-inflammatory activity, as shown by the decrease in the production of cytokines and angiogenic factors by macrophages and MSCs. Deposition of dexamethasone-releasing coatings on polymer/Mg composites appears to be a promising approach to delay composite degradation at the early stage of implantation and may be useful to attenuate inflammation and adverse foreign body reactions.

  7. A technique for thick polymer coating of inertial-confinement-fusion targets

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Feng, I.-A.; Wang, T. G.; Kim, H.-G.

    1983-01-01

    A technique to coat a stalk-mounted inertial-confinement fusion (ICF) target with a thick polymer layer has been successfully demonstrated. The polymer solution is first atomized, allowed to coalesce into a droplet, and positioned in a stable acoustic levitating field. The stalk-mounted ICF target is then moved into the acoustic field by manipulating a 3-D positioner to penetrate the surface membrane of the droplet, thus immersing the target in the levitated coating solution. The target inside the droplet is maintained at the center of the levitated liquid using the 3-D positional information provided by two orthogonally placed TV cameras until the drying process is completed. The basic components of the experimental apparatus, including an acoustic levitator, liquid sample deployment device, image acquisition instrumentation, and 3-D positioner, are briefly described.

  8. Self healing properties of Cu-Pt coated ionic polymer actuators

    NASA Astrophysics Data System (ADS)

    Johanson, Urmas; Punning, Andres; Kruusmaa, Maarja; Aabloo, Alvo

    2008-03-01

    Composite actuators consisting of sheets of the solid polymer electrolyte (similar to Nafion (R)) with Cu 2+ counter-ions inserted and coated with platinum and copper metal layers (so-called Ionomeric Polymer-Metal Composites; IPMCs) have been synthesised and their electromechanical performance upon actuation has been monitored. Resistance measurements on the electrodes show that the electrical conductivity of the membranes metal surface increases on the cathode side during the actuation process, contradictory to the situation when Cu is absent from the metal coating. This phenomenon is explained by the subsequent reduction of Cu 2+ ions on the cathode upon actuation; Cu layer growth in this side prevents it from cracking and decreases its electrode resistance. The phenomenon opens up for longer life-times for Cu-based IPMCs. However, additional problems with Cu layer oxidation and Cu dendrite growth on the electrodes should be considered.

  9. Investigations on the Mechanical Properties of Conducting Polymer Coating-Substrate Structures and Their Influencing Factors

    PubMed Central

    Wang, Xi-Shu; Tang, Hua-Ping; Li, Xu-Dong; Hua, Xin

    2009-01-01

    This review covers recent advances and work on the microstructure features, mechanical properties and cracking processes of conducting polymer film/coating- substrate structures under different testing conditions. An attempt is made to characterize and quantify the relationships between mechanical properties and microstructure features. In addition, the film cracking mechanism on the micro scale and some influencing factors that play a significant role in the service of the film-substrate structure are presented. These investigations cover the conducting polymer film/coating nucleation process, microstructure-fracture characterization, translation of brittle-ductile fractures, and cracking processes near the largest inherent macromolecule defects under thermal-mechanical loadings, and were carried out using in situ scanning electron microscopy (SEM) observations, as a novel method for evaluation of interface strength and critical failure stress. PMID:20054470

  10. A hierarchical polymer brush coating with dual-function antibacterial capability.

    PubMed

    Yan, Shunjie; Song, Lingjie; Luan, Shifang; Xin, Zhirong; Du, Shanshan; Shi, Hengchong; Yuan, Shuaishuai; Yang, Yuming; Yin, Jinghua

    2017-01-01

    Bacterial infections are problematic in many healthcare-associated devices. Antibacterial surfaces integrating the strength of bacteria repellent and bactericidal functions exhibit an encouraging efficacy in tackling this problem. Herein, a hierarchical dual-function antibacterial polymer brush coating that integrates an antifouling bottom layer with a bactericidal top layer is facilely constructed via living photograft polymerization. Excellent resistance to bacterial attachment is correlated with the antifouling components, and good bactericidal activity is afforded by the bactericidal components, and therefore the hierarchical coating shows an excellent long-term antibacterial capability. In addition, due to the presence of the hydrophilic background layer, the hierarchical surface has the greatly improved biocompatibility, as shown by the suppression of platelet adhesion and activation, the inhibition of erythrocyte adhesion and damage, and low toxicity against mammalian cells. The hierarchical polymer brush system provides the basis for the development of long-term antibacterial and biocompatible surfaces.

  11. Photoconductivity of organic polymer films doped with porous silicon nanoparticles and ionic polymethine dyes

    SciTech Connect

    Davidenko, N. A. Skrichevsky, V. A.; Ishchenko, A. A.; Karlash, A. Yu.; Mokrinskaya, E. V.

    2009-05-15

    Features of electrical conductivity and photoconductivity of polyvinylbutyral films containing porous silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with different ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of porous silicon nanoparticles. It is assumed that the electronic conductivity in porous silicon nanoparticles is higher in comparison with p-type conductivity.

  12. A capacitive technique for real-time monitoring polymer coating thickness on carbon filaments during prepregging process

    NASA Technical Reports Server (NTRS)

    Eftekhari, Abe; Chapman, John J.

    1989-01-01

    A technique for gauging the coating thickness during prepreg processing of carbon fibers was developed. It is based on the concept of measuring the capacitance of a cylindrical condenser through which a bundle of prepregged fibers is passed axially. Empirical results indicate the capacitance of this condenser element is linearly related to the polymer coating thickness on the fibers in the bundle. The capacitive transducer was successfully used to measure the polymer thickness on several test fiber bundles under static conditions.

  13. Fabrication of enzyme reactor utilizing magnetic porous polymer membrane for screening D-Amino acid oxidase inhibitors.

    PubMed

    Jiang, Jun Fang; Qiao, Juan; Mu, Xiao Yu; Moon, Myeong Hee; Qi, Li

    2017-04-01

    In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10mM, Vmax was 23.8mMmin(-1)) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors.

  14. Photochemical Reduction of Low Concentrations of CO2 in a Porous Coordination Polymer with a Ruthenium(II)-CO Complex.

    PubMed

    Kajiwara, Takashi; Fujii, Machiko; Tsujimoto, Masahiko; Kobayashi, Katsuaki; Higuchi, Masakazu; Tanaka, Koji; Kitagawa, Susumu

    2016-02-18

    Direct use of low pressures of CO2 as a C1 source without concentration from gas mixtures is of great interest from an energy-saving viewpoint. Porous heterogeneous catalysts containing both adsorption and catalytically active sites are promising candidates for such applications. Here, we report a porous coordination polymer (PCP)-based catalyst, PCP-Ru(II) composite, bearing a Ru(II) -CO complex active for CO2 reduction. The PCP-Ru(II) composite showed improved CO2 adsorption behavior at ambient temperature. In the photochemical reduction of CO2 the PCP-Ru(II) composite produced CO, HCOOH, and H2 . Catalytic activity was comparable with the corresponding homogeneous Ru(II) catalyst and ranks among the highest of known PCP-based catalysts. Furthermore, catalytic activity was maintained even under a 5 % CO2 /Ar gas mixture, revealing a synergistic effect between the adsorption and catalytically active sites within the PCP-Ru(II) composite.

  15. Selective CO2 adsorption in a robust and water-stable porous coordination polymer with new network topology.

    PubMed

    Nagarkar, Sanjog S; Chaudhari, Abhijeet K; Ghosh, Sujit K

    2012-01-02

    A robust and water-stable porous coordination polymer [Cd(NDC)(0.5)(PCA)]·G(x) (1) (H(2)NDC = 2,6-napthalenedicarboxylic acid, HPCA = 4-pyridinecarboxylic acid, G = guest molecules) with new network topology has been synthesized solvothermally. The framework is 3D porous material and forms a 1D channel along the c-axis, with the channel dimensions ~9.48 × 7.83 Å(2). The compound has high selectivity in uptake of CO(2) over other gases (H(2), O(2), Ar, N(2), and CH(4)). The framework is highly stable in presence of water vapor even at 60 °C. The high CO(2) selectivity over other gases and water stability makes the compound promising candidate for industrial postcombustion gas separation application.

  16. Coating carbon nanotubes with a polystyrene-based polymer protects against pulmonary toxicity

    PubMed Central

    2011-01-01

    Background carbon nanotubes (CNT) can have adverse effects on health. Therefore, minimizing the risk associated with CNT exposure is of crucial importance. The aim of this work was to evaluate if coating multi-walled CNT (MWCNT) with polymers could modify their toxicity, thus representing a useful strategy to decrease adverse health effects of CNT. We used industrially-produced MWCNT uncoated (NT1) or coated (50/50 wt%) with acid-based (NT2) or polystyrene-based (NT3) polymer, and exposed murine macrophages (RAW 264.7 cell line) or Balb/c mice by intratracheal administration. Biological experiments were performed both in vitro and in vivo, examining time- and dose-dependent effects of CNT, in terms of cytotoxicity, expression of genes and proteins related to oxidative stress, inflammation and tissue remodeling, cell and lung tissue morphology (optical and transmission electron microscopy), and bronchoalveolar lavage fluid content analysis. Results extensive physico-chemical characterization of MWCNT was performed, and showed, although similar dimensions for the 3 MWCNT, a much smaller specific surface area for NT2 and NT3 as compared to NT1 (54.1, 34 and 227.54 m2/g respectively), along with different surface characteristics. MWCNT-induced cytotoxicity, oxidative stress, and inflammation were increased by acid-based and decreased by polystyrene-based polymer coating both in vitro in murine macrophages and in vivo in lung of mice monitored for 6 months. Conclusions these results demonstrate that coating CNT with polymers, without affecting their intrinsic structure, may constitute a useful strategy for decreasing CNT toxicity, and may hold promise for improving occupational safety and that of general the user. PMID:21255417

  17. A novel composite of molecularly imprinted polymer-coated PdNPs for electrochemical sensing norepinephrine.

    PubMed

    Chen, Jianrong; Huang, Hong; Zeng, Yanbo; Tang, Huan; Li, Lei

    2015-03-15

    A novel composite of molecularly imprinted polymer-coated palladium nanoparticles (MIP-coated PdNPs) was synthesized by sol-gel method using norepinephrine as template, phenyl trimethoxysilane as functional monomer and tetramethoxysilane as crosslinker. The combination of PdNPs and silica-based MIP endowed the composite with good electrochemical catalytic property, large surface area and template selectivity. MIP-coated PdNPs were characterized by Fourier transform infrared spectroscopy and Transmission electron microscopy. Then MIP-coated PdNPs composite was used as a recognition element in the construction of an electrochemical sensor for norepinephrine. The properties of MIP-coated PdNPs sensor such as special binding, adsorption dynamics and selective recognition ability were evaluated by differential pulse voltammetry. The results demonstrated that MIP-coated PdNPs sensor not only possessed a short response time, but also high binding capacity for norepinephrine, which enabled the imprinted sensor with higher current response than that of non-imprinted material and MIP without PdNPs. In addition, the MIP-coated PdNPs sensor exhibited selectivity for norepinephrine in comparison to other analogs. The MIP-coated PdNPs sensor had a wide linear range over norepinephrine concentration from 0.5 to 80.0μM with a detection limit of 0.1μM. The MIP-coated PdNPs sensor was proved to be a suitable sensing tool for the fast, sensitive and selective determination of norepinephrine in injection and urine samples.

  18. Simple push coating of polymer thin-film transistors

    NASA Astrophysics Data System (ADS)

    Ikawa, Mitsuhiro; Yamada, Toshikazu; Matsui, Hiroyuki; Minemawari, Hiromi; Tsutsumi, Jun'ya; Horii, Yoshinori; Chikamatsu, Masayuki; Azumi, Reiko; Kumai, Reiji; Hasegawa, Tatsuo

    2012-11-01

    Solution processibility is a unique advantage of organic semiconductors, permitting the low-cost production of flexible electronics under ambient conditions. However, the solution affinity to substrate surfaces remains a serious dilemma; liquid manipulation is more difficult on highly hydrophobic surfaces, but the use of such surfaces is indispensable for improving device characteristics. Here we demonstrate a simple technique, which we call ‘push coating’, to produce uniform large-area semiconducting polymer films over a hydrophobic surface with eliminating material loss. We utilize a poly(dimethylsiloxane)-based trilayer stamp whose conformal contact with the substrate enables capillarity-induced wetting of the surface. Films are formed through solvent sorption and retention in the stamp, allowing the stamp to be peeled perfectly from the film. The planar film formation on hydrophobic surfaces also enables subsequent fine film patterning. The technique improves the crystallinity and field-effect mobility of stamped semiconductor films, constituting a major step towards flexible electronics production.

  19. Click Cross-Linking-Improved Waterborne Polymers for Environment-Friendly Coatings and Adhesives.

    PubMed

    Hu, Jianqing; Peng, Kaimei; Guo, Jinshan; Shan, Dingying; Kim, Gloria B; Li, Qiyao; Gerhard, Ethan; Zhu, Liang; Tu, Weiping; Lv, Weizhong; Hickner, Michael A; Yang, Jian

    2016-07-13

    Waterborne polymers, including waterborne polyurethanes (WPU), polyester dispersions (PED), and polyacrylate emulsions (PAE), are employed as environmentally friendly water-based coatings and adhesives. An efficient, fast, stable, and safe cross-linking strategy is always desirable to impart waterborne polymers with improved mechanical properties and water/solvent/thermal and abrasion resistance. For the first time, click chemistry was introduced into waterborne polymer systems as a cross-linking strategy. Click cross-linking rendered waterborne polymer films with significantly improved tensile strength, hardness, adhesion strength, and water/solvent resistance compared to traditional waterborne polymer films. For example, click cross-linked WPU (WPU-click) has dramatically improved the mechanical strength (tensile strength increased from 0.43 to 6.47 MPa, and Young's modulus increased from 3 to 40 MPa), hardness (increased from 59 to 73.1 MPa), and water resistance (water absorption percentage dropped from 200% to less than 20%); click cross-linked PED (PED-click) film also possessed more than 3 times higher tensile strength (∼28 MPa) than that of normal PED (∼8 MPa). The adhesion strength of click cross-linked PAE (PAE-click) to polypropylene (PP) was also improved (from 3 to 5.5 MPa). In addition, extra click groups can be preserved after click cross-linking for further functionalization of the waterborne polymeric coatings/adhesives. In this work, we have demonstrated that click modification could serve as a convenient and powerful approach to significantly improve the performance of a variety of traditional coatings and adhesives.

  20. Thin film deposition at atmospheric pressure using dielectric barrier discharges: Advances on three-dimensional porous substrates and functional coatings

    NASA Astrophysics Data System (ADS)

    Fanelli, Fiorenza; Bosso, Piera; Mastrangelo, Anna Maria; Fracassi, Francesco

    2016-07-01

    Surface processing of materials by atmospheric pressure dielectric barrier discharges (DBDs) has experienced significant growth in recent years. Considerable research efforts have been directed for instance to develop a large variety of processes which exploit different DBD electrode geometries for the direct and remote deposition of thin films from precursors in gas, vapor and aerosol form. This article briefly reviews our recent progress in thin film deposition by DBDs with particular focus on process optimization. The following examples are provided: (i) the plasma-enhanced chemical vapor deposition of thin films on an open-cell foam accomplished by igniting the DBD throughout the entire three-dimensional (3D) porous structure of the substrate, (ii) the preparation of hybrid organic/inorganic nanocomposite coatings using an aerosol-assisted process, (iii) the DBD jet deposition of coatings containing carboxylic acid groups and the improvement of their chemical and morphological stability upon immersion in water.