Science.gov

Sample records for micelle-forming polymeric surfactant

  1. Sorption of nonionic organic compounds in soil-water systems containing a micelle-forming surfactant

    SciTech Connect

    Sun, S.; Inskeep, W.P.; Boyd, S.A. |

    1994-12-31

    The solubility enhancement of nonionic organic compounds (NOCs) by surfactants may represent an important tool in chemical and biological remediation of contaminated soils. In aqueous systems, the presence of dissolved surfactant emulsions or micelles may enhance the solubility of NOCs by acting as a hydrophobic partitioning phase for the NOCs. However, most environmental remediation efforts involve soil-water or sediment-water systems, where surfactant molecules may also interact with the solid phase. An understanding of the effect of surfactants on the sorption and distribution of NOCs in soil or sediment environments will provide an essential basis for utilizing surfactants in environmental remediation. In this study, the authors examined the effect of a micelle-forming surfactant (Triton X-100) on the sorption of 2,2{prime},4,4{prime},5,5{prime}-PCB, 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (p,p{prime}-DDT) and 1,2,4-trichlorobenzene (1,2,4-TCB). A conceptual model, which accurately describes the functional dependence of K* on Triton X-100 concentration, was developed based on the partition coefficients of these NOCs by soil, soil-surfactant, surfactant monomer and surfactant micelle phases. This model can be further modified to provide quantitative prediction of K* of a given NOC at different surfactant concentrations.

  2. Growth Behavior, Geometrical Shape, and Second CMC of Micelles Formed by Cationic Gemini Esterquat Surfactants.

    PubMed

    Bergström, L Magnus; Tehrani-Bagha, Alireza; Nagy, Gergely

    2015-04-28

    Micelles formed by novel gemini esterquat surfactants have been investigated with small-angle neutron scattering (SANS). The growth behavior of the micelles is found to differ conspicuously depending on the length of the gemini surfactant spacer group. The gemini surfactant with a long spacer form rather small triaxial ellipsoidal tablet-shaped micelles that grow weakly with surfactant concentration in the entire range of measured concentrations. Geminis with a short spacer, on the other hand, form weakly growing oblates or tablets at low concentrations that start to grow much more strongly into polydisperse rodlike or wormlike micelles at higher concentrations. The latter behavior is consistent with the presence of a second CMC that marks the transition from the weakly to the strongly growing regime. It is found that the growth behavior in terms of aggregation number as a function of surfactant concentration always appear concave in weakly growing regimes, while switching to convex behavior in strongly growing regimes. As a result, we are able to determine the second CMC of the geminis with short spacer by means of suggesting a rather precise definition of it, located at the point of inflection of the growth curve that corresponds to the transition from concave to convex growth behavior. Our SANS results are rationalized by comparison with the recently developed general micelle model. In particular, this theory is able to explain and reproduce the characteristic appearances of the experimental growth curves, including the presence of a second CMC and the convex strongly growing regime beyond. By means of optimizing the agreement between predictions from the general micelle model and results from SANS experiments, we are able to determine the three bending elasticity constants spontaneous curvature, bending rigidity, and saddle-splay constant for each surfactant. PMID:25835031

  3. Study of the Formation and Solution Properties of Worm-Like Micelles Formed Using Both N-Hexadecyl-N-Methylpiperidinium Bromide-Based Cationic Surfactant and Anionic Surfactant

    PubMed Central

    Yan, Zhihu; Dai, Caili; Feng, Haishun; Liu, Yifei; Wang, Shilu

    2014-01-01

    The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB) with the anionic surfactant sodium laurate (SL) in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles. PMID:25296131

  4. Enhanced solubilization and desorption of organochlorine pesticides (OCPs) from soil by oil-swollen micelles formed with a nonionic surfactant.

    PubMed

    Zheng, Guanyu; Selvam, Ammaiyappan; Wong, Jonathan W C

    2012-11-01

    The effect of oil-swollen micelles formed with nonionic surfactant polyoxyethylene sorbitan monooleate (Tween 80), cosurfactant 1-pentanol, and linseed oil on the solubilization and desorption of organochlorine pesticides (OCPs) including DDT and γ-HCH from both loam soil and clay soil were investigated. Results showed that the solubilizing capacities of oil-swollen micelles were dependent on the critical micelle concentration (CMC) of Tween 80. Once the concentrations of oil-swollen micelles exceeded the CMC of Tween 80, the oil-swollen micelles exhibited much higher solubilizing capacity than empty Tween 80 micelles for the two OCPs. Desorption tests revealed that oil-swollen micelles could successfully enhance desorption of OCPs from both loam soil and clay soil. However, compared with the efficiencies achieved by empty Tween 80 micelles, oil-swollen micelles exhibited their superiority to desorb OCPs only in loam soil-water system while was less effective in clay soil-water system. Distribution of Tween 80, 1-pentanol and linseed oil in soil-water system revealed that the difference in the sorption behavior of linseed oil onto the two soils is responsible for the different effects of oil-swollen micelles on the desorption of OCPs in loam soil and clay soil systems. Therefore, oil-swollen micelles formed with nonionic surfactant Tween 80 are better candidates over empty micelle counterparts to desorb OCPs from soil with relatively lower sorption capacity for oil fraction, which may consequently enhance the availability of OCPs in soil environment during remediation processes of contaminated soil. PMID:22998366

  5. Extraction of lysozyme, alpha-chymotrypsin, and pepsin into reverse micelles formed using an anionic surfactant, isooctane, and water.

    PubMed

    Chang, Q; Liu, H; Chen, J

    1994-11-01

    The extraction of lysozyme, alpha-chymotrypsin, and pepsin from buffered salt solutions into reverse micelles was examined at different pH values and surfactant concentrations. The reverse micelles was formed by mixing aqueous buffer supplemented with KCl and an organic phase of isooctane(2,2,4-trimethylpentane), containing the anionic surfactant, Aerosol O. T. (dioctyl ester of sodium sulfosuccinic acid). The technique of dynamic laser scattering was used to measure the size of reverse micelles which were in equilibrium with the aqueous phase. It was found that the size of the reverse micelles decreased with increasing ionic strength but increased with increasing AOT concentration. In the process of extraction, the reverse micelles might have rearranged themselves to host the protein. The sizes of protein-filled and -unfilled reverse micelles were different, and an open equilibrium could be reached between them. Under the extraction conditions, only a small number of micelles were found to contain protein. PMID:7522474

  6. pH-sensitive polymeric micelles formed by doxorubicin conjugated prodrugs for co-delivery of doxorubicin and paclitaxel.

    PubMed

    Ma, Yakun; Fan, Xiaohui; Li, Lingbing

    2016-02-10

    A doxorubicin conjugated prodrug incorporated acid-sensitive linkage between drug and Pluronic F127-chitosan (F127-CS) polymer was successfully synthesized. Subsequently a pH-sensitive polymeric micelle system was designed based on the conjugated prodrugs (F127-CS-DOX) to co-deliver doxorubicin and paclitaxel. Paclitaxel (PTX) was physically entrapped in the hydrophobic inner core of the micelles simultaneously. The structures of conjugates were analyzed by means of (1)H NMR and UV-vis spectrum. Size distribution and morphology of the micelles were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results indicated that obtained micelles had good dispersity and the diameter was between 56.3 and 403.4 nm. The loading of PTX into the micelle increased with higher DOX content. DOX and PTX release from polymeric micelles followed an acid-triggered manner. Furthermore, in vivo pharmacokinetic study also showed that the area under the plasma concentration time curve (AUC0-∞) values of PTX and DOX for PTX-loaded F127-CS-DOX micelles in rats were 3.97 and 4.38-fold higher than those for PTX plus DOX solution. These results suggested the PTX-loaded F127-CS-DOX micelles would be a promising carrier for co-delivering DOX and PTX. PMID:26686101

  7. Polymeric cationic substituted acrylamide surfactants

    SciTech Connect

    Nieh, E.C.Y.

    1983-11-15

    A new composition of matter comprises a copolymer of a surface active quaternary ammonium monomer salt and from 50 to 97% by wt of acrylamide. The new copolymers can have molecular weights substantially greater than 10,000 and still remain water soluble and surface active. Copolymers are prepared by polymerization techniques known in the art. The quaternary ammonium monomer is dispersed under inert atmosphere in aqueous solution which may additionally contain dissolved therein a low molecular weight alcohol such as ethanol, isopropanol, and the like. Acidic polymerization initiator such as the azo initiators, organic peroxides, or redox initiators such as the sulfite- persulfate system is then added in an amount calculated to yield a polymer product of desired molecular weight. (14 claims.

  8. A light-responsive organofluid based on reverse worm-like micelles formed from an equi-charged, mixed, anionic gemini surfactant with an azobenzene spacer and a cationic conventional surfactant.

    PubMed

    Yang, Duoping; Zhao, Jianxi

    2016-05-01

    An equally-charged mixture of an anionic gemini surfactant, O,O'-bis(sodium 2-tetradecylcarboxylate)-p-azodiphendiol (G14-azo), and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), was dissolved in cyclohexane to form reverse worm-like micelles. Samples with different surfactant concentrations and amounts of added water were studied using rheological measurements. The amount of water, represented as the molar ratio of water to total surfactants W0, was c. 13 (at its minimum) in these equally charged systems of G14-azo (200 mmol L(-1))/CTAB. The low shear viscosity ηL of this system reached 4370 Pa s at W0 = 13 and the dynamic rheological result showed typical surfactant gel behaviour. Under UV-light irradiation, the transparent sample (G14-azo (300 mmol L(-1))/CTAB (600 mmol L(-1))) at W0 = 40 became turbid, during which ηL was rapidly reduced from the original 285 Pa s to 0.3 Pa s, indicating a transition of aggregate morphology from reverse worms into simple reverse micelles. Then the sample was returned to its original homogeneous state with c. 290 Pa s viscosity under visible light irradiation. However, this transition cannot be well achieved at low W0 due to the interior cores being too small. This limit has been attributed to both the Gemini type of surfactant molecule and to the inverted structure of aggregates. PMID:27021435

  9. Amphipols: Polymeric surfactants for membrane biology research.

    SciTech Connect

    Popot, J.-L.; Berry, E.A.; Charvolin, D.; Creuzenet, C.; Ebel, C.; Engelman, D.M.; Flotenmeyer, M.; Giusti, F.; Gohon, Y.; Hong, Q.; Lakey, J.H.; Leonard, K.; Shuman, H.A.; Timmins, P.; Warschawski, D.E.; Zito, F.; Zoonens, M.; Pucci, B.; Tribet, C.

    2003-06-20

    Membrane proteins classically are handled in aqueous solutions as complexes with detergents. The dissociating character of detergents, combined with the need to maintain an excess of them, frequently results in more or less rapid inactivation of the protein under study. Over the past few years, we have endeavored to develop a novel family of surfactants, dubbed amphipols (APs). APs are amphiphilic polymers that bind to the transmembrane surface of the protein in a noncovalent but, in the absence of a competing surfactant, quasi-irreversible manner. Membrane proteins complexed by APs are in their native state, stable, and they remain water soluble in the absence of detergent or free APs. An update is presented of the current knowledge about these compounds and their demonstrated or putative uses in membrane biology.

  10. Stabilization of emulsions using polymeric surfactants based on inulin.

    PubMed

    Tadros, Th F; Vandamme, A; Levecke, B; Booten, K; Stevens, C V

    2004-05-20

    The use of polymeric surfactants for stabilization of emulsions is described. A brief account of general classification and description of polymeric surfactants is given. This is followed by a description of the adsorption and conformation of polymeric surfactants at interfaces. The theoretical approaches for studying polymer adsorption are briefly described. This is followed by a section on the experimental techniques that can be applied to study adsorption and conformation of polymers at the interface. Examples are given to illustrate the experimental techniques. A section is devoted to the interaction between droplets containing adsorbed polymer layers (steric stabilization). The last section gives results on oil-in-water (O/W) emulsions stabilised with a novel graft copolymeric surfactant based on inulin that has been modified by introducing alkyl groups. Two oils were used, namely Isopar M (isoparaffinic oil) and cyclomethicone. Emulsions prepared using the inulin-based surfactant have large droplets, but this could be significantly reduced by addition of a cosurfactant in the oil phase, namely Span 20. The stability of the emulsions was investigated in water, in 0.5, 1.0, 1.5 and 2 mol dm(-3) NaCl and in 0.5, 1.0, 1.5 and 2 mol dm(-3) MgSO(4). These emulsions were stable for more than 1 year up to 50 degrees C in NaCl concentrations up to 2 mol dm(-3) and 1 mol dm(-3) MgSO(4). This high stability in high electrolyte concentrations could be attributed to the nature of the hydrophilic (stabilizing) polyfructose chain. This was confirmed using cloud point measurements, which showed high hydration of the polyfructose chain in such high electrolyte concentrations. This ensured the long-term physical stability resulting from the strong steric repulsion between the polyfructose chains. PMID:15072943

  11. Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes.

    PubMed

    Feng, Anchao; Yan, Qiang; Zhang, Huijuan; Peng, Liao; Yuan, Jinying

    2014-05-11

    The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies. PMID:24681929

  12. Morphology Control of Multicomponent Polymeric Surfactants Using Pressure

    NASA Astrophysics Data System (ADS)

    Cho, Junhan

    The development of nanoscale morphologies for a molten polymeric surfactant under pressure is investigated by using a recently formulated self-consistent field theory. A linear ABC block copolymer is taken as our model system that allows a disparity in the propensities for curved interfaces and pressure responses of ij-pairs. The interplay of those features lead the copolymer to new morphologies at a moderate segregation level and at ambient condition such as networks and pillars of 2-dimensional array. It is shown that pressure is an effective means of morphology control and identification for those new structures. The role of volume fluctuations in the development of those structures is discussed. J.C. acknowledges the support from Center for Photofunctional Energy Materials through Gyeonggi Regional Research Program.

  13. Foam, emulsion and wetting films stabilized by polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants.

    PubMed

    Khristov, Khr; Petkova, H; Alexandrova, L; Nedyalkov, M; Platikanov, D; Exerowa, D; Beetge, J

    2011-10-14

    This review explores three (A, B, C) polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants belonging to the group of star-like polymers. They have a similar structure, differing only in the number of polymeric branches (4, 6 and 9 in the mentioned order). The differences in these surfactants' ability to stabilize foam, o/w/o and w/o/w emulsion and wetting films are evaluated by a number of methods summarized in Section 2. Results from the studies indicate that differences in polymeric surfactants' molecular structure affect the properties exhibited at air/water, oil/water and water/solid interfaces, such as the value of surface tension, interfacial tension, critical micelle concentration, degree of hydrophobicity of solid surface, etc. Foam, emulsion and wetting films stabilized by such surfactants also show different behavior regarding some specific parameters, such as critical electrolyte concentration, surfactant concentration for obtaining a stable film, film thickness value, etc. These observations give reasons to believe that model studies can support a comprehensive understanding of how the change in polymeric surfactant structure can impact thin liquid films properties. This may enable a targeted design of the macromolecular architecture depending on the polymeric surfactants application purpose. PMID:21807358

  14. Studies on interfacial tension and contact angle of synthesized surfactant and polymeric from castor oil for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Babu, Keshak; Pal, Nilanjan; Bera, Achinta; Saxena, V. K.; Mandal, Ajay

    2015-10-01

    New synthesized polymeric surfactants have immensely attracted the researchers for further development of chemical enhanced oil recovery method particularly in surfactant flooding. Contact angle and interfacial tension measurement tests are the effective ways to identify proper chemicals/surfactants for enhanced oil recovery by chemical/surfactant flooding. In the present study a new polymeric surfactant was synthesized from pre-synthesized sodium methyl ester sulfonate (surfactant) and acrylamide for application in chemical enhanced oil recovery. The synthesized surfactant and polymeric surfactant were used to measure interfacial tension between their aqueous phase and crude oil phase to investigate the efficiency of the surfactants in reduction of interfacial tension. The synthesized polymeric surfactant has also ability to control the mobility because of its viscous nature in aqueous solution. Contact angles of solid-crude oil-surfactant interface were also measured to study the effect of the synthesized surfactant and polymeric surfactant on wettability alteration mechanism. Synergistic effect was studied by using NaCl and synthesized surfactants on interfacial tension. Dynamic interfacial tensions of the surfactant and polymeric surfactant solutions with crude oil were measured at different NaCl concentrations. Interfacial tension was found to be lowered up to 10-2 to 10-3 mN/m which is effective for oil recovery. Measurement of contact angle indicates the wettability change of the quartz surface. Comparative studies on efficiencies of synthesized sodium methyl ester sulfonate surfactant and polymeric surfactant were also carried out with respect to interfacial tension reduction and contact angle change.

  15. Nanoparticles of polystyrene latexes by semicontinuous microemulsion polymerization using mixed surfactants.

    PubMed

    Xu, Xiao-Jun; Chow, Pei-Yong; Quek, Chai-Hoon; Hng, Huey-Hoon; Gan, Leong-Ming

    2003-06-01

    Nanosized polystyrene (PS) latexes stabilized by the mixture of cationic/cationic, anionic/anionic, or anionic/cationic surfactants of various types with high weight ratios of PS to surfactant (ca. 10:1) have been successfully synthesized by a semicontinuous microemulsion polymerization process. For cationic or anionic systems, spherical latex particles with a weight-averaged diameter (Dw) ranging from about 22 to 53 nm were nearly linearly dependent on the weight ratio of the mixed surfactants with similar charges. Their particle size distributions were rather uniform (Dw/Dn < 1.20). For a system with oppositely charged surfactants at nonequimolar ratios, it could produce stable PS particles up to 94 nm in diameter. High molar masses (Mw) of PS ranging from 1.1 to 1.9 x 10(6) g/mol could easily be obtained for all three systems investigated. For both cationic/cationic and anionic/anionic surfactant systems, the number of PS particles per milliliter of latex (Np) generated in the very early stage of O/W' microemulsion remained rather constant throughout the polymerization. This was controlled by using only 1 wt% of mixed surfactants and the continuous addition of a small amount of styrene. The present polymerization method allows one to synthesize nanoparticles of PS or other polymers of high polymer/surfactant weight ratios at some particle sizes that are unable to achieve them with a single type of surfactant. PMID:14503408

  16. Enzymatic polymerizations using surfactant microstructures and the preparation of polymer-ferrite composites

    SciTech Connect

    Kommareddi, N.S.; Tata, M.; Karayigitoglu, C.

    1995-12-31

    Horseradish peroxidase has been used as a biocatalyst to synthesize a polymeric material from alkyl-substituted phenols. The synthesis is carried out in a surfactant-based microemulsion environment, with the monomer partitioned at the oil/water interface. The spherical nature of the microemulsion nanodroplets may be acting as a template for the polymer synthesis. The resultant polymer particles are spherical and typically in the submicron size range. The characteristics of the morphology development are described. The templating effect of the surfactant environment becomes more evident when the polymer particles are fully dissolved in a suitable solvent and refolded in the presence of surfactant. Interestingly, submicron-sized spherical particles are obtained only in the presence of surfactant, and particles of arbitrary morphology are seen in the absence of surfactant. Aspects of morphology development leading to the preparation of polymer-iron oxide composites are described.

  17. Preparation and Characterization of Polymeric Surfactants Based on Epoxidized Soybean Oil Grafted Hydroxyethyl Cellulose.

    PubMed

    Huang, Xujuan; Liu, He; Shang, Shibin; Rao, Xiaoping; Song, Jie

    2015-10-21

    Epoxidized soybean oil (ESO) grafted hydroxyethyl cellulose (HEC) was prepared via ring-opening polymerization, in which the hydroxyl groups of HEC acted as initiators and the polymeric ESO were covalently bonded to the HEC. Hydrolysis of ESO-grafted HEC (ESO-HEC) was performed with sodium hydroxide, and the hydrolyzed ESO-HEC (H-ESO-HEC) products were characterized via Fourier transform infrared (FT-IR) and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopies, high-temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The results indicated that ring-opening polymerization of ESO occurred with the hydroxyl groups of HEC as initiators. The molecular weights of the H-ESO-HEC products were varied by adjusting the mass ratio of HEC and ESO. Through neutralizing the carboxylic acid of H-ESO-HEC with sodium hydroxide, novel polymeric surfactants (H-ESO-HEC-Na) were obtained, and the effects of polymeric surfactants on the surface tension of water were investigated as a function of concentration of H-ESO-HEC-Na. The H-ESO-HEC-Na was effective at lowering the surface tension of water to 26.33 mN/m, and the critical micelle concentration (CMC) value decreased from 1.053 to 0.157 g/L with increases in molecular weights of the polymeric surfactants. Rheological measurements indicated that the H-ESO-HEC-Na solutions changed from pseudoplastic property to Newtonian with increasing shear rate. PMID:26416659

  18. Preparation of Surfactant-Resistant Polymersomes with Ultrathick Membranes through RAFT Dispersion Polymerization.

    PubMed

    Song, Ziyuan; Huang, Yinzhao; Prasad, Vikram; Baumgartner, Ryan; Zhang, Siyi; Harris, Keith; Katz, Joshua S; Cheng, Jianjun

    2016-07-13

    Surfactant-resistant polymersomes have substantial potential to be used as delivery vehicles in industrial applications. Herein, we report the preparation of poly(ethylene oxide)-block-polystyrene copolymers with ultrahigh hydrophobic-block molecular weights through RAFT dispersion polymerization, which allows the polymerization-induced self-assembly into well-defined polymersomes with ultrathick membranes up to ∼47 nm. These ultrathick membranes significantly enhance the resistance against surfactant solubilization of the vesicles, improving the vesicles' potential for use in industrial encapsulations. Vesicle-encapsulated actives are well retained in the presence of up to 40 wt % of various anionic and nonionic surfactants, with less than 7% active leakage being observed after 30 days. PMID:27367934

  19. Functional nanocomposites prepared by self-assembly and polymerization of diacetylene surfactants and silicic acid

    NASA Technical Reports Server (NTRS)

    Yang, Yi; Lu, Yunfeng; Lu, Mengcheng; Huang, Jinman; Haddad, Raid; Xomeritakis, George; Liu, Nanguo; Malanoski, Anthony P.; Sturmayr, Dietmar; Fan, Hongyou; Sasaki, Darryl Y.; Assink, Roger A.; Shelnutt, John A.; van Swol, Frank; Lopez, Gabriel P.; Burns, Alan R.; Brinker, C. Jeffrey

    2003-01-01

    Conjugated polymer/silica nanocomposites with hexagonal, cubic, or lamellar mesoscopic order were synthesized by self-assembly using polymerizable amphiphilic diacetylene molecules as both structure-directing agents and monomers. The self-assembly procedure is rapid and incorporates the organic monomers uniformly within a highly ordered, inorganic environment. By tailoring the size of the oligo(ethylene glycol) headgroup of the diacetylene-containing surfactant, we varied the resulting self-assembled mesophases of the composite material. The nanostructured inorganic host altered the diacetylene polymerization behavior, and the resulting nanocomposites show unique thermo-, mechano-, and solvatochromic properties. Polymerization of the incorporated surfactants resulted in polydiacetylene (PDA)/silica nanocomposites that were optically transparent and mechanically robust. Molecular modeling and quantum calculations and (13)C spin-lattice relaxation times (T(1)) of the PDA/silica nanocomposites indicated that the surfactant monomers can be uniformly organized into precise spatial arrangements prior to polymerization. Nanoindentation and gas transport experiments showed that these nanocomposite films have increased hardness and reduced permeability as compared to pure PDA. Our work demonstrates polymerizable surfactant/silica self-assembly to be an efficient, general approach to the formation of nanostructured conjugated polymers. The nanostructured inorganic framework serves to protect, stabilize, and orient the polymer, mediate its performance, and provide sufficient mechanical and chemical stability to enable integration of conjugated polymers into devices and microsystems.

  20. Thin liquid films from aqueous solutions of non-ionic polymeric surfactants.

    PubMed

    Exerowa, Dotchi; Platikanov, Dimo

    2009-01-01

    The conditions of formation and stability of foam, emulsion, and wetting films from aqueous solutions of non-ionic polymeric surfactants have been established. Two types of polymeric surfactants - PEO-PPO-PEO three-block copolymers (A-B-A type) and hydrophobically modified inulin graft polymer (AB(n) type) - have been explored. Information about surface forces and nanoscale phenomena in aqueous films containing polymeric surfactants was obtained using the micro-interferometric technique and the Thin Liquid Film-Pressure Balance Technique. Two types of surface forces, which determine the stability of the foam and emulsion films, have been distinguished, namely: DLVO-forces at low electrolyte concentrations and non-DLVO-forces at high electrolyte concentrations. Non-DLVO-forces are steric surface forces of the brush-to-brush and loop-to-loop interaction type according to De Gennes. A substantial difference in the behavior of these two film types has been established and in the case of O/W emulsion films transitions to Newton black film (NBF) have been observed. These films are very stable and so are the respective emulsions. In contrast the wetting films are relatively thicker compared to emulsion films, and their thickness depends on the concentration of the AB(n) polymeric surfactant. The steric repulsion of the loops and tails of the polymeric surfactant determine the film thickness of wetting films on a hydrophilic solid surface. For solid surfaces with different degrees of hydrophobicity the wetting films are stable only at high polymer concentrations and low degree of hydrophobicity. Otherwise the films are unstable and rupture. Two types of bilayer emulsion films have been distinguished for the first time. One type is related to the brush-to-brush or loop-to-loop interactions according to De Gennes. The other type is a NBF where the forces are also steric between strongly hydrated brush and loops but they are short-range forces acting in a two

  1. Synthesis of soybean oil-based polymeric surfactants in supercritical carbon dioxide and investigation of their surface properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports the preparation of polymeric surfactants (HPSO) via a two-step synthetic procedure: polymerization of soybean oil (PSO) in supercritical carbon dioxide and followed by hydrolysis of PSO with a base. HPSO was characterized and identified by using a combination of FTIR, 1H NMR, 13C...

  2. Extraction of oil from oil sands using thermoresponsive polymeric surfactants.

    PubMed

    Yang, Bingqing; Duhamel, Jean

    2015-03-18

    Several thermoresponsive block copolymers constituted of a poly(ethylene glycol) (PEG) and a poly(2-(2-methoxyethoxy) ethyl methacrylate) (PMEO2MA) block were prepared by atom transfer radical polymerization (ATRP) and their ability to extract oil from oil sands was evaluated. The chemical composition of the PEG113-b-PMEO2MAX block copolymers was determined by (1)H NMR and gel permeation chromatography (GPC) with X-values ranging between 48 and 80. Aqueous solutions of block copolymers showed a cloud point of 34 ± 1 °C as determined by turbidimetry and dynamic light scattering (DLS) measurements. DLS experiments indicated that these polymers formed stable block copolymer micelles due to association of the PMEO2MA blocks at temperatures greater than 45 °C with a unimodal distribution of hydrodynamic diameters. Since characterization of the block copolymer solutions as a function of temperature indicated the formation of hydrophobic domains in water for T > 45 °C, extractions of oil from oil sands with the block copolymers were conducted at T = 45 and 50 °C. At these temperatures, 15 mL of a 1 mg/mL PEG113-b-PMEO2MA77 aqueous solution extracted 100% of the oil trapped in 1 g of oil sand if 60 mg of toluene was added to the mixture. When the extraction was conducted under the same experimental conditions without block copolymer, a poor oil recovery of less than 30% was achieved. Starting with a 1 mg/mL block copolymer concentration, the block copolymer aqueous solution could be recycled up to five successive extractions while maintaining satisfying oil recovery. Each extraction cycle led to a 22% mass loss of block copolymer, certainly due to association with the toluene, oil, and sand particles. Together these experiments demonstrate that thermoresponsive block copolymers can be powerful aids to enhance the oil recovery of oil sands. PMID:25719623

  3. In situ X-ray polymerization: from swollen lamellae to polymer-surfactant complexes.

    PubMed

    Agzenai, Yahya; Lindman, Björn; Alfredsson, Viveka; Topgaard, Daniel; Renamayor, Carmen S; Pacios, Isabel E

    2014-01-30

    The influence of the monomer diallyldimethylammonium chloride (D) on the lamellar liquid crystal formed by the anionic surfactant aerosol OT (AOT) and water is investigated, determining the lamellar spacings by SAXS and the quadrupolar splittings by deuterium NMR, as a function of the D or AOT concentrations. The cationic monomer D induces a destabilization of the AOT lamellar structure such that, at a critical concentration higher than 5 wt %, macroscopic phase separation takes place. When the monomer, which is dissolved in the AOT lamellae, is polymerized in situ by X-ray initiation, a new collapsed lamellar phase appears, corresponding to the complexation of the surfactant with the resulting polymer. A theoretical model is employed to analyze the variation of the interactions between the AOT bilayers and the stability of the lamellar structure. PMID:24410395

  4. Theory of surface light scattering from a fluid-fluid interface with adsorbed polymeric surfactants

    NASA Astrophysics Data System (ADS)

    Buzza, D. M. A.; Jones, J. L.; McLeish, T. C. B.; Richards, R. W.

    1998-09-01

    We present a microscopic theory for the interfacial rheology of a fluid-fluid interface with adsorbed surfactant and calculate the effect of this on surface light scattering from the interface. We model the head and tail groups of the surfactant as polymer chains, a description that becomes increasingly accurate for large molecular weight surfactants, i.e., polymeric surfactants. Assuming high surface concentrations so that we have a double-sided polymer brush monolayer, we derive microscopic scaling expressions for the surface viscoelastic constants using the Alexander-deGennes model. Our results for the surface elastic constants agree with those in the literature, while the results for the viscous constants are new. We find that four elastic constants, i.e., γ (surface tension), ɛ (dilational elasticity), κ (bending modulus), λ (coupling constant), and three viscous constants, i.e., ɛ',κ',λ' (the viscous counterparts of ɛ, κ, and λ, respectively) are required for a general description of interfacial viscoelasticity (neglecting in-plane shear). In contrast to current phenomenological models, we find (1) there is no viscous counterpart to γ, i.e., γ'≡0; (2) there are two additional complex surface constants (i.e., λ+iωλ' and κ+iωκ') due to the finite thickness of the monolayer. Excellent agreement is found comparing our microscopic theory with measurements on diblock copolymer monolayers. We further derive the dispersion relation governing surface hydrodynamic modes and the power spectrum for surface quasielastic light scattering (SQELS) for a general interface parameterized by all the surface viscoelastic constants. Limiting results are presented for (1) liquid-air interfaces; (2) liquid-liquid interfaces with ultralow γ. The significant contribution of κ in the latter case opens up the possibility for a direct measurement of κ using SQELS for polymeric surfactant monolayers. Finally, we show that the coupling constant λ can lead to

  5. Biocatalytic synthesis of polymeric nanowires by micellar templates of ionic surfactants

    SciTech Connect

    Nazari, K.; Adhami, F.; Najjar-Safari, A.; Salmani, S.; Mahmoudi, A.

    2011-07-15

    Highlights: {yields} Soft-template production of polyguaiacol nanowire was done by peroxidase enzyme. {yields} Main advantage of this simple method is producing soluble encapsulated nanowires. {yields} Nanowire can be easily precipitated and separated by dilution with distilled water. {yields} Size tuned templates of sodium decyl sulfate (d = 2.7 nm) gave nanowires with d = 2-4 nm. {yields} Dried surfactant-coated wires recover freshly on specified and desired applications. -- Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV-Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM).

  6. Surface Rheological Data for a Polymeric Surfactant Using a Pulsed Drop Rheometer.

    PubMed

    Kitching; Johnson; Midmore; Herrington

    1996-01-15

    Measurements of dynamic interfacial tension of adsorbed layers of the oil-soluble polymeric surfactant E5 have been made using a pulsed drop rheometer. The pulsed drop rheometer is based on the instantaneous expansion of a water droplet in oil. After perturbation an interfacial relaxation occurs and is followed from the drop profile. The difference in pressure across a curved interface and the interfacial tension are directly related. The decay of pressure change, and hence the interfacial tension decay, is followed as a function of time using a sensitive pressure transducer. Concentrations of E5 above and below the CMC were investigated at the n-decane/water and Isopar M/water interfaces. The interfacial tension decays obtained were fitted to known relaxation mechanisms. Fourier transforms were calculated over a complete frequency spectrum to obtain the dilational elasticity and viscosity. Above the CMC, the interfacial relaxation of E5 at both the n-decane/water and Isopar M/water interfaces was shown to be due to the diffusion of micelles to the interface and the subsequent lowering of the interfacial tension. From the calculated diffusion coefficient and micelle size, the micellar aggregation number could be calculated. Below the CMC, both diffusion and reorientation contribute to the interfacial relaxation. It was not possible to determine the parameters for each process because the characteristic frequencies for the two processes are of similar magnitude. PMID:10479417

  7. Ionic Liquid-Based Polymer Electrolytes via Surfactant-Assisted Polymerization at the Plasma-Liquid Interface.

    PubMed

    Tran, Quoc Chinh; Bui, Van-Tien; Dao, Van-Duong; Lee, Joong-Kee; Choi, Ho-Suk

    2016-06-29

    We first report an innovative method, which we refer to as interfacial liquid plasma polymerization, to chemically cross-link ionic liquids (ILs). By this method, a series of all-solid state, free-standing polymer electrolytes is successfully fabricated where ILs are used as building blocks and ethylene oxide-based surfactants are employed as an assisted-cross-linking agent. The thickness of the films is controlled by the plasma exposure time or the ratio of surfactant to ILs. The chemical structure and properties of the polymer electrolyte are characterized by scanning electron microscopy (SEM), Fourier transformation infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS). Importantly, the underlying polymerization mechanism of the cross-linked IL-based polymer electrolyte is studied to show that fluoroborate or halide anions of ILs together with the aid of a small amount of surfactants having ethylene oxide groups are necessary to form cross-linked network structures of the polymer electrolyte. The ionic conductivity of the obtained polymer electrolyte is 2.28 × 10(-3) S·cm(-1), which is a relatively high value for solid polymer electrolytes synthesized at room temperature. This study can serve as a cornerstone for developing all-solid state polymer electrolytes with promising properties for next-generation electrochemical devices. PMID:27281115

  8. Nonaqueous Dispersion Formed by an Emulsion Solvent Evaporation Method Using Block-Random Copolymer Surfactant Synthesized by RAFT Polymerization.

    PubMed

    Ezaki, Naofumi; Watanabe, Yoshifumi; Mori, Hideharu

    2015-10-27

    As surfactants for preparation of nonaqueous microcapsule dispersions by the emulsion solvent evaporation method, three copolymers composed of stearyl methacrylate (SMA) and glycidyl methacrylate (GMA) with different monomer sequences (i.e., random, block, and block-random) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Despite having the same comonomer composition, the copolymers exhibited different functionality as surfactants for creating emulsions with respective dispersed and continuous phases consisting of methanol and isoparaffin solvent. The optimal monomer sequence for the surfactant was determined based on the droplet sizes and the stabilities of the emulsions created using these copolymers. The block-random copolymer led to an emulsion with better stability than obtained using the random copolymer and a smaller droplet size than achieved with the block copolymer. Modification of the epoxy group of the GMA unit by diethanolamine (DEA) further decreased the droplet size, leading to higher stability of the emulsion. The DEA-modified block-random copolymer gave rise to nonaqueous microcapsule dispersions after evaporation of methanol from the emulsions containing colored dyes in their dispersed phases. These dispersions exhibited high stability, and the particle sizes were small enough for application to the inkjet printing process. PMID:26421355

  9. Size controlled synthesis of sub-100 nm monodisperse poly(methylmethacrylate) nanoparticles using surfactant-free emulsion polymerization.

    PubMed

    Camli, Sevket Tolga; Buyukserin, Fatih; Balci, Oguz; Budak, Gurer Guven

    2010-04-15

    Surfactant-free emulsion polymerization (SFEP) is a well-known technique for the production of polymeric nanoparticles that does not require post-synthetic cleaning steps. Obtaining hydrophobic particles at sub-100 nm scale, however, is quite challenging with this polymerization method. Here, we demonstrate a single step synthetic approach that yields poly(methylmethacrylate) (PMMA) nanoparticles with controlled sub-100 nm size and relatively high resultant solid content. Dynamic light scattering (DLS) was used for the particle characterization. Spherical and uniformly sized nanoparticles were confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Acetone was used as a cosolvent in order to obtain monodisperse sub-100 nm diameter particles. Stable PMMA nanoparticle dispersions were obtained for all formulations where the persulfate initiator causes the negative charges on the particle surface. The effects of acetone, monomer and initiator concentration were studied to optimize average particle hydrodynamic diameter and polydispersity index of the final particles. Non-crosslinked monodisperse PMMA nanoparticles (polydispersity index less than 0.05) with diameters from 32 nm to 72 nm were synthesized by using this method. PMID:20138293

  10. Computational Investigation of Block Copolymer Surfactants for Stabilizing Fluctuation-Induced Polymeric Microemulsions

    NASA Astrophysics Data System (ADS)

    Delaney, Kris; Fredrickson, Glenn

    2013-03-01

    High molecular weight diblock copolymers introduced into a blend of immiscible homopolymers can act as a surfactant to suppress macroscopic two-fluid phase separation. With variation of block copolymer composition, the crossover between low-temperature ordering into microphase or macrophase separated states is marked by a mean-field isotropic Lifshitz multi-critical point. Strong fluctuations close to the Lifshitz point are observed to suppress the low-temperature ordering; a microemulsion state emerges, with large, co-continuous domains of segregated fluid lacking any long-range order. We study this phenomenon with fully fluctuating field-theoretic simulations based on complex Langevin sampling, and we attempt to design new block polymer surfactants that can produce the microemulsion state with a wider composition tolerance.

  11. Surfactants, not size or zeta-potential influence blood-brain barrier passage of polymeric nanoparticles.

    PubMed

    Voigt, Nadine; Henrich-Noack, Petra; Kockentiedt, Sarah; Hintz, Werner; Tomas, Jürgen; Sabel, Bernhard A

    2014-05-01

    Nanoparticles (NP) can deliver drugs across the blood-brain barrier (BBB), but little is known which of the factors surfactant, size and zeta-potential are essential for allowing BBB passage. To this end we designed purpose-built fluorescent polybutylcyanoacrylate (PBCA) NP and imaged the NP's passage over the blood-retina barrier - which is a model of the BBB - in live animals. Rats received intravenous injections of fluorescent PBCA-NP fabricated by mini-emulsion polymerisation to obtain various NP's compositions that varied in surfactants (non-ionic, anionic, cationic), size (67-464nm) and zeta-potential. Real-time imaging of retinal blood vessels and retinal tissue was carried out with in vivo confocal neuroimaging (ICON) before, during and after NP's injection. Successful BBB passage with subsequent cellular labelling was achieved if NP were fabricated with non-ionic surfactants or cationic stabilizers but not when anionic compounds were added. NP's size and charge had no influence on BBB passage and cell labelling. This transport was not caused by an unspecific opening of the BBB because control experiments with injections of unlabelled NP and fluorescent dye (to test a "door-opener" effect) did not lead to parenchymal labelling. Thus, neither NP's size nor chemo-electric charge, but particle surface is the key factor determining BBB passage. This result has important implications for NP engineering in medicine: depending on the surfactant, NP can serve one of two opposite functions: while non-ionic tensides enhance brain up-take, addition of anionic tensides prevents it. NP can now be designed to specifically enhance drug delivery to the brain or, alternatively, to prevent brain penetration so to reduce unwanted psychoactive effects of drugs or prevent environmental nanoparticles from entering tissue of the central nervous system. PMID:24607790

  12. Surfactant-induced ordering and wetting transitions of droplets of thermotropic liquid crystals "caged" inside partially filled polymeric capsules.

    PubMed

    Carlton, Rebecca J; Zayas-Gonzalez, Yashira M; Manna, Uttam; Lynn, David M; Abbott, Nicholas L

    2014-12-16

    We report a study of the wetting and ordering of thermotropic liquid crystal (LC) droplets that are trapped (or "caged") within micrometer-sized cationic polymeric microcapsules dispersed in aqueous solutions of surfactants. When they were initially dispersed in water, we observed caged, nearly spherical droplets of E7, a nematic LC mixture, to occupy ∼40% of the interior volume of the polymeric capsules [diameter of 6.7 ± 0.3 μm, formed via covalent layer-by-layer assembly of branched polyethylenimine and poly(2-vinyl-4,4-dimethylazlactone)] and to contact the interior surface of the capsule wall at an angle of ∼157 ± 11°. The internal ordering of LC within the droplets corresponded to the so-called bipolar configuration (distorted by contact with the capsule walls). While the effects of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) on the internal ordering of "free" LC droplets are similar, we observed the two surfactants to trigger strikingly different wetting and configurational transitions when LC droplets were caged within polymeric capsules. Specifically, upon addition of SDS to the aqueous phase, we observed the contact angles (θ) of caged LC on the interior surface of the capsule to decrease, resulting in a progression of complex droplet shapes, including lenses (θ ≈ 130 ± 10°), hemispheres (θ ≈ 89 ± 5°), and concave hemispheres (θ < 85°). The wetting transitions induced by SDS also resulted in changes in the internal ordering of the LC to yield states topologically equivalent to axial and radial configurations. Although topologically equivalent to free droplets, the contributions that surface anchoring, LC elasticity, and topological defects make to the free energy of caged LC droplets differ from those of free droplets. Overall, these results and others reported herein lead us to conclude that caged LC droplets offer a platform for new designs of LC-droplet-based responsive soft matter that cannot be

  13. Rotational reorientation dynamics of Aerosol-OT reverse micelles formed in near-critical propane

    SciTech Connect

    Heitz, M.P.; Bright, F.V.

    1996-06-01

    The rotational reorientation kinetics of two fluorescent solutes (rhodamine 6G, R6G, and rhodamine 101, R101) have been determined in sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol-OT, AOT) reverse micelles formed in liquid and near-critical propane. We show that the amount of water loading ([water]/[AOT], R), continuous phase density, and temperature all influence the solute rotational dynamics. In all cases, the decay of anisotropy data (i.e., frequency-dependent differential polarized phase angle and polarized modulation ratio) are well described by a bi-exponential decay law. We find that the faster rotational correlation times are similar to but slightly less than the values predicted for an individual AOT reverse micelle rotating in propane. The recovered rotational correlation times range from 200 to 500 ps depending on experimental conditions. This faster rotational process is explained in terms of lateral diffusion of the fluorophore along the water/headgroup interfacial region within the reverse micelle. The recovered values for the slower rotational correlation times range from 7 to 18 ns. These larger rotational reorientation times are assigned to varying micelle-micelle (i.e., tail-tail) interactions in the low-density, highly compressible fluid region. We also quantify the contribution of the reverse micellar {open_quotes}aggregate{close_quotes} to the total decay of anisotropy. {copyright} {ital 1996} {ital Society for Applied Spectroscopy}

  14. Polystyrene latex particles containing europium complexes prepared by miniemulsion polymerization using bovine serum albumin as a surfactant for biochemical diagnosis.

    PubMed

    Aikawa, Tatsuo; Mizuno, Akihiro; Kohri, Michinari; Taniguchi, Tatsuo; Kishikawa, Keiki; Nakahira, Takayuki

    2016-09-01

    Luminescent particles have been attracting significant attention because they can be used in biochemical applications, such as detecting and imaging biomolecules. In this study, luminescent polystyrene latex particles were prepared through miniemulsion polymerization of styrene with dissolved europium complexes in the presence of bovine serum albumin (BSA) and poly(ethylene glycol) monomethoxy methacrylate as surfactants. The solubility of the europium complex in styrene has a strong effect on the yield of the particle. Europium tris(2-thenoyl trifluoroacetonate) di(tri-n-octyl phosphine oxide), which has a high solubility in styrene, was sufficiently incorporated into the polystyrene particles compared to europium tris(2-thenoyl trifluoroacetonate), which has a low solubility in styrene. The luminescence property of the europium complex could remain intact even after its incorporation through the miniemulsion polymerization. In the aqueous dispersion, the resulting particles could emit strong luminescence, which is a characteristic of the europium complex. The antibody fragments were covalently attached to BSA-covered particles after a reaction with a bifunctional linker, N-(6-maleimidocaproyloxy)succinimide. The time-resolved fluoroimmunoassay technique showed that 3.3pg/mL of human α-fetoproteins (AFP) can be detected by using the resulting luminescent particles. An immunochromatographic assay using the resulting particles was also performed as a convenient method to qualitatively detect biomolecules. The detection limit of AFP measured by the immunochromatographic assay was determined to be 2000pg/mL. These results revealed that the luminescent particles obtained in this study can be utilized for the highly sensitive detection of biomolecules and in vitro biochemical diagnosis. PMID:27182649

  15. Equilibrium study of single-solute adsorption of anionic surfactants with polymeric XAD resins

    SciTech Connect

    Garcia-Delgado, R.A.; Cotoruelo-Minguez, L.M.; Rodriguez, J.J. )

    1992-06-01

    Equilibrium data for the adsorption of sodium lauryl sulfate (SLS) and sodium dodecylbenzene sulfonate (SDBS) from aqueous solutions by Amberlite XAD-4 and XAD-7 polymeric resins at temperatures in the 10-40C range have been obtained. The specific surface area of the resins plays a major role in adsorption, and thus the best results have been obtained with XAD-4 resin. A higher adsorption of SDBS over SLS was also observed. Several adsorption isotherm models have been used to fit the experimental data. The best results have been obtained with the Redlich-Peterson and Langmuir-Freundlich equations. Estimations of the isosteric heat of adsorption, free energy, and entropy of adsorption are also reported.

  16. Interfacial activity of polymeric surfactants at the polystyrene-carbon dioxide interface

    SciTech Connect

    Harrison, K.L.; Rocha, S.R.P. da; Yates, M.Z.; Johnston, K.P.; Canelas, D.; DeSimone, J.M.

    1998-11-24

    The reduction of the interfacial tension at the polystyrene (PS, M{sub n} = 1850)-supercritical CO{sub 2} interface is reported for poly(1,1-dihydroperfluorooctyl acrylate)(PFOA) and the block copolymers PS-b-PFOA(3.7K/27K) and PS-b-poly(dimethylsiloxane) (PDMS) (2K/16K, 500/10K) at 45 C. PS-b-PDMS (2K/16K) lowers the interfacial tension to 0.5 dyn/cm at 45 C and 238 bar, more than that of any of the other copolymers. On the basis of the dynamics of the lowering of the interfacial tension, the apparent diffusion coefficient of PS-b-PDMS (2K/16K) is 8 {times} 10{sup {minus}6} cm{sup 2}/s. The critical micelle concentration of PS-b-PFOA (3.7K/27K) is 9 {times} 10{sup {minus}4} wt %. Whereas both the PDMS- and PFOA-based copolymers studied adsorb on the PS surface, PS-b-PFOA is much more effective in stabilizing the PS emulsions. The difference in stabilization is discussed in terms of the surfactant adsorption and the interactions of the anchor and buoy blocks with CO{sub 2} and the PS surface.

  17. Surfactant-controlled polymerization of semiconductor clusters to quantum dots through competing step-growth and living chain-growth mechanisms.

    PubMed

    Evans, Christopher M; Love, Alyssa M; Weiss, Emily A

    2012-10-17

    This article reports control of the competition between step-growth and living chain-growth polymerization mechanisms in the formation of cadmium chalcogenide colloidal quantum dots (QDs) from CdSe(S) clusters by varying the concentration of anionic surfactant in the synthetic reaction mixture. The growth of the particles proceeds by step-addition from initially nucleated clusters in the absence of excess phosphinic or carboxylic acids, which adsorb as their anionic conjugate bases, and proceeds indirectly by dissolution of clusters, and subsequent chain-addition of monomers to stable clusters (Ostwald ripening) in the presence of excess phosphinic or carboxylic acid. Fusion of clusters by step-growth polymerization is an explanation for the consistent observation of so-called "magic-sized" clusters in QD growth reactions. Living chain-addition (chain addition with no explicit termination step) produces QDs over a larger range of sizes with better size dispersity than step-addition. Tuning the molar ratio of surfactant to Se(2-)(S(2-)), the limiting ionic reagent, within the living chain-addition polymerization allows for stoichiometric control of QD radius without relying on reaction time. PMID:23009216

  18. Giant rodlike reversed micelles formed by sodium bis(2-ethylhexyl) phosphate in n-heptane

    SciTech Connect

    Yu, Z.J.; Neuman, R.D. )

    1994-08-01

    The solution behaviors of sodium bis(2-ethylhexyl) phosphate (NaDEHP) in n-heptane were investigated by light-scattering and viscosity measurements. NaDEHP forms giant rodlike reversed micelles, with a radius of gyration as large as 53 nm, which violently contrasts with the literature view that the average micellar aggregation numbers in nonaqueous or apolar media are much smaller (seldom exceeding 20) than those in aqueous media. Significantly, a small amount of water plays the role of an antimicellar growth agent; i.e., the reversed micellar size decreases remarkably when [open quotes]dry[close quotes] solutions are exposed to humid air from which water vapor is absorbed or when bulk water is directly added - a behavior which is distinctly opposite to that for sodium bis(2-ethylhexyl) sulfosuccinate/apolar medium systems. Thus, the literature views that large micelles can only be found in aqueous media and that the surfactant headgroups in reversed micelles are linked together by hydrogen bonds are misleading. It is suggested that the primary contribution to the driving force for the growth of rodlike NaDEHP reversed micelles is long-range electrostatic interactions among the headgroups of the surfactant molecules and their counterions, and a possible mechanism for the effect of water is also discussed. 27 refs., 7 figs., 1 tab.

  19. Probing the internal dynamics of reverse micelles formed in highly compressible solvents: Aerosol-OT in near-critical propane

    SciTech Connect

    Zhang, J.; Bright, F.V.

    1992-10-29

    In normal liquids, the rate of water reorganization within the interior of AOT (sodium bis(2-ethylhexyl) sulfosuccinate or Aerosol-OT) reverse micelles in a strong function of water loading and temperature. In this report, we discuss our most recent efforts to understand the internal dynamics of reverse micelles maintained in highly compressible solvents (near-critical propane). By using steady-state and time-resolved fluorescence spectroscopy, we report the first evidence for pressure-assisted control of the rate of solvent relaxation within the core region of a reverse micelle maintained in a highly compressible fluid. Three factors are taken into account in this study: amount of water loading, temperature, and bulk fluid density. The key conclusion is that the continuous phase density can influence the rate of solvent reorientation within the interior of AOT micelles formed in near-critical propane. 58 refs., 10 figs., 3 tabs.

  20. Viscoelastic properties of polystyrene and poly(methyl methacrylate) dispersions sterically stabilized by hydrophobically modified inulin (polyfructose) polymeric surfactant.

    PubMed

    Nestor, Jérémie; Obiols-Rabasa, Marc; Esquena, Jordi; Solans, Conxita; Levecke, Bart; Booten, Karl; Tadros, Tharwat F

    2008-03-01

    Recently, steric repulsive forces induced by a new graft copolymer surfactant, which is based in inulin (polyfructose), have been described. Previous investigations by atomic force microscopy between solid surfaces covered with adsorbed surfactant indicated strong repulsive forces even at high electrolyte concentration, due to the steric repulsion produced by the surfactant hydration. In the present paper, the colloidal stabilization provided by this surfactant is studied by rheology. The measurements were carried out on sterically stabilized polystyrene (PS) and poly(methyl methacrylate) (PMMA) containing adsorbed surfactant (INUTEC SP1). Steady-state shear stress as a function of shear rate curves was established at various latex volume fractions. The viscosity volume fraction curves were compared with those calculated using the Doughtry-Krieger equation for hard sphere dispersions. From the experimental eta r-phi curves the effective volume fraction of the latex dispersions could be calculated and this was used to determine the adsorbed layer thickness Delta. The value obtained was 9.6 nm, which is in good agreement with that obtained using atomic force microscopy (AFM). Viscoelastic measurements of the various latex dispersions were carried out as a function of applied stress (to obtain the linear viscoelastic region) and frequency. The results showed a change from predominantly viscous to predominantly elastic response at a critical volume fraction (phi c). The effective critical volume fraction, phi eff, was calculated using the adsorbed layer thickness (Delta) obtained from steady-state measurements. For PS latex dispersions phi eff was found to be equal to 0.24 whereas for PMMA phi eff=0.12. These results indicated a much softer interaction between the latex dispersions containing hydrated polyfructose loops and tails when compared with latices containing poly(ethylene oxide) (PEO) layers. The difference could be attributed to the stronger hydration of the

  1. Surfactant-Induced Ordering and Wetting Transitions of Droplets of Thermotropic Liquid Crystals “Caged” Inside Partially Filled Polymeric Capsules

    PubMed Central

    2015-01-01

    We report a study of the wetting and ordering of thermotropic liquid crystal (LC) droplets that are trapped (or “caged”) within micrometer-sized cationic polymeric microcapsules dispersed in aqueous solutions of surfactants. When they were initially dispersed in water, we observed caged, nearly spherical droplets of E7, a nematic LC mixture, to occupy ∼40% of the interior volume of the polymeric capsules [diameter of 6.7 ± 0.3 μm, formed via covalent layer-by-layer assembly of branched polyethylenimine and poly(2-vinyl-4,4-dimethylazlactone)] and to contact the interior surface of the capsule wall at an angle of ∼157 ± 11°. The internal ordering of LC within the droplets corresponded to the so-called bipolar configuration (distorted by contact with the capsule walls). While the effects of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) on the internal ordering of “free” LC droplets are similar, we observed the two surfactants to trigger strikingly different wetting and configurational transitions when LC droplets were caged within polymeric capsules. Specifically, upon addition of SDS to the aqueous phase, we observed the contact angles (θ) of caged LC on the interior surface of the capsule to decrease, resulting in a progression of complex droplet shapes, including lenses (θ ≈ 130 ± 10°), hemispheres (θ ≈ 89 ± 5°), and concave hemispheres (θ < 85°). The wetting transitions induced by SDS also resulted in changes in the internal ordering of the LC to yield states topologically equivalent to axial and radial configurations. Although topologically equivalent to free droplets, the contributions that surface anchoring, LC elasticity, and topological defects make to the free energy of caged LC droplets differ from those of free droplets. Overall, these results and others reported herein lead us to conclude that caged LC droplets offer a platform for new designs of LC-droplet-based responsive soft matter that cannot

  2. Soy-based polymeric surfactants prepared in carbon dioxide media and influence of structure on their surface properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean oil (SO) and epoxidized soybean oil (ESO) were polymerized in the CO2 media (supercritical and sub-supercritical) by BF3•OEt2 catalyst. The resulting polymers (PSO and PESO) were hydrolyzed into polysoaps (HPSO) and (HPESO) with Na+, K+, or TEA+ (triethanolamine, ammonium salt) counter ions....

  3. A novel micelle-forming material used for preparing a theranostic vehicle exhibiting enhanced in vivo therapeutic efficacy.

    PubMed

    Chen, Hsiao-Ping; Chen, Ming-Hong; Tung, Fu-I; Liu, Tse-Ying

    2015-05-14

    A new micelle-forming material, folic acid-conjugated carboxymethyl lauryl chitosan (FA-CLC), and superparamagnetic iron oxide (SPIO) nanoparticles were used for preparing an imaging-guided drug vehicle (the FA-CLC/SPIO hybrid micelle) that demonstrates targeted delivery, imaging, and controlled release of hydrophobic agents. We found that the ratio of viable normal cells to tumor cells was increased prominently after delivery of camptothecin (CPT)-loaded FA-CLC/SPIO micelles and therapeutic sonication. In addition, a magnetic field could enhance the tumor-targeting effect of FA-CLC/SPIO micelles. Therefore, after sequential administration of magnetic attraction to CPT-loaded FA-CLC/SPIO micelles, and therapeutic sonication, the in vivo therapeutic efficacy of CPT was markedly enhanced. However, a nonfocused magnetic field could enhance the undesirable accumulation of iron-containing vehicles in the liver if the tumor (i.e., magnetic attraction site) is near the liver. We propose that magnetic attraction must be carefully applied, far from the liver. PMID:25933159

  4. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    NASA Astrophysics Data System (ADS)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  5. Admicellar polymerization of precipated silica

    SciTech Connect

    Reynolds, J.L.; Grady, B.P.; Harwell, J.H.

    1996-10-01

    The tendency of a surfactant molecule to adsorb at a solid-liquid interface is the basis for an in situ surface modification process, termed admicellar polymerization. The four-step admicellar polymerization process includes: (1) adsorption of surfactant at the solid-liquid interface, (2) adsolubilization of monomer into the surfactant bilayer, (3) polymerization using free-radical initiators and heat, (4) removal of excess surfactant to expose the polymer modified surface. The process is used to apply polymer to precipitated silica to enhance the compatibility of the silica when added to filled rubber. The adsorption isotherms were first determined for particular surfactant/silica combinations to find the surfactant concentration that would sufficiently adsolubilize the monomer, while remaining below the critical micelle concentration. A series of experiments were then devised for the polymerization reactions in which the surfactant and monomer amounts were varied over three levels to establish the optimal combination.

  6. Anticancer and antiangiogenic activity of surfactant-free nanoparticles based on self-assembled polymeric derivatives of vitamin E: structure-activity relationship.

    PubMed

    Palao-Suay, Raquel; Aguilar, María Rosa; Parra-Ruiz, Francisco J; Fernández-Gutiérrez, Mar; Parra, Juan; Sánchez-Rodríguez, Carolina; Sanz-Fernández, Ricardo; Rodrigáñez, Laura; Román, Julio San

    2015-05-11

    α-Tocopheryl succinate (α-TOS) is a well-known mitochondrially targeted anticancer compound, however, it is highly hydrophobic and toxic. In order to improve its activity and reduce its toxicity, new surfactant-free biologically active nanoparticles (NP) were synthesized. A methacrylic derivative of α-TOS (MTOS) was prepared and incorporated in amphiphilic pseudoblock copolymers when copolymerized with N-vinylpyrrolidone (VP) by free radical polymerization (poly(VP-co-MTOS)). The selected poly(VP-co-MTOS) copolymers formed surfactant-free NP by nanoprecipitation with sizes between 96 and 220 nm and narrow size distribution, and the in vitro biological activity was tested. In order to understand the structure-activity relationship three other methacrylic monomers were synthesized and characterized: MVE did not have the succinate group, SPHY did not have the chromanol ring, and MPHY did not have both the succinate group and the chromanol ring. The corresponding families of copolymers (poly(VP-co-MVE), poly(VP-co-SPHY), and poly(VP-co-MPHY)) were synthesized and characterized, and their biological activity was compared to poly(VP-co-MTOS). Both poly(VP-co-MTOS) and poly(VP-co-MVE) presented triple action: reduced cell viability of cancer cells with little or no harm to normal cells (anticancer), reduced viability of proliferating endothelial cells with little or no harm to quiescent endothelial cells (antiangiogenic), and efficiently encapsulated hydrophobic molecules (nanocarrier). The anticancer and antiangiogenic activity of the synthesized copolymers is demonstrated as the active compound (vitamin E or α-tocopheryl succinate) do not need to be cleaved to trigger the biological action targeting ubiquinone binding sites of complex II. Poly(VP-co-SPHY) and poly(VP-co-MPHY) also formed surfactant-free NP that were also endocyted by the assayed cells; however, these NP did not selectively reduce cell viability of cancer cells. Therefore, the chromanol ring of the

  7. Advances in reactive surfactants.

    PubMed

    Guyot, A

    2004-05-20

    The study of reactive surfactants and their applications in the synthesis of latexes for waterborne coatings has been recently boosted by two successive European programmes, involving all together eight academic and five industrial laboratories. The most significant results were obtained using surfactants derived from maleic and related anhydrides, or both nonionic and anionic reactive polymeric surfactants. Such surfactants are able to improve the stability of styrenic and acrylic latexes vs. various constraints, such as electrolyte addition, freeze-thawing tests or extraction with alcohol or acetone. The properties of films used in waterborne coatings are also improved in case of water exposure (less water uptake, dimensional stability), as well as improved weatherability, and blocking properties. Formulations for woodstain varnishes, metal coating of printing inks, based on the use of simple polymerizable surfactants, are now in the market. PMID:15072924

  8. Role of solubilized water in micelles formed by Triton X-100 in 1-butyl-3-methylimidazolium ionic liquids.

    PubMed

    Li, Na; Zhang, Shaohua; Ma, Hongchao; Zheng, Liqiang

    2010-06-15

    We demonstrate here the aggregation behavior of a nonionic surfactant Triton X-100 in two 1-butyl-3-methylimidazolium ionic liquids (the hydrophilic IL [bmim][BF(4)] and the hydrophobic IL [bmim][PF(6)]) by surface tension measurements. The effects of added water on the microstructure of Triton X-100 in ILs micelles are investigated. When small amounts of water are added to Triton X-100 in [bmim][PF(6)] micelles, the water molecules are first bound to the ethylene oxide (EO) units of Triton X-100 and then form the water pool in the core of the microemulsion. When water molecules are added to the Triton X-100 in [bmim][BF(4)] micelles, there is no microemulsion formed; these water molecules are first solubilized in [bmim][BF(4)]. When the solubilization is saturated, the water molecules start to bind to the EO group of Triton X-100; these results are confirmed by UV-vis, FTIR, and (1)H NMR spectra. PMID:20302278

  9. Sustainable polymerizations in recoverable microemulsions.

    PubMed

    Chen, Zhenzhen; Yan, Feng; Qiu, Lihua; Lu, Jianmei; Zhou, Yinxia; Chen, Jiaxin; Tang, Yishan; Texter, John

    2010-03-16

    Free radical and atom-transfer radical polymerizations were conducted in monomer/ionic liquid microemulsions. After the polymerization and isolation of the resultant polymers, the mixture of the catalyst and ionic liquids (surfactant and continuous phase) can be recovered and reused, thereby dramatically improving the environmental sustainability of such chemical processing. The addition of monomer to recovered ionic liquid mixtures regenerates transparent, stable microemulsions that are ready for the next polymerization cycle upon addition of initiator. The method combines the advantages of IL recycling and microemulsion polymerization and minimizes environmental disposable effects from surfactants and heavy metal ions. PMID:20170175

  10. Order-Disorder Transition (ODT) in Micelle-Forming A-B/A and A-B/B Diblock Copolymer/Homopolymer Blends

    NASA Astrophysics Data System (ADS)

    Dormidontova, Elena E.; Lodge, Timothy P.

    2002-03-01

    In the framework of strong segregation (Semenov-like) theory we consider the phase behavior and properties of solvent-free diblock copolymer/homopolymer blends. We consider the case in which the homopolymer is similar to either the A or B block of diblock copolymer. Addition of a homopolymer that is similar to the corona-forming block of the diblock copolymer decreases the ODT temperature and increases the temperature window corresponding to the stable disordered micelle state. Above some critical homopolymer concentration no ordered micelle state can be found. In the case that the added homopolymer is similar to the core-forming block macrophase separation plays an important role. In the framework of standard Flory-Huggins theory macrophase separation into ordered or disordered diblock copolymer micelle phase and pure homopolymer phase seems to be preferable to co-micellization of the homopolymers and diblock copolymers. In reality kinetic factors as well as surface interactions between co-existing phases can produce a metastable phase of ordered or disordered micelles formed by both diblock and homopolymers. We discuss the order-disorder and co-micellisation transitions for this case, the latter often having an anomalous character (very large initial miceller size) when the fraction of homopolymers is not too small.

  11. Mechanistic study of wettability alteration of oil-wet sandstone surface using different surfactants

    NASA Astrophysics Data System (ADS)

    Hou, Bao-feng; Wang, Ye-fei; Huang, Yong

    2015-03-01

    Different analytical methods including Fourier transform infrared (FTIR), atomic force microscopy (AFM), zeta potential measurements, contact angle measurements and spontaneous imbibition tests were utilized to make clear the mechanism for wettability alteration of oil-wet sandstone surface using different surfactants. Results show that among three types of surfactants including cationic surfactants, anionic surfactants and nonionic surfactants, the cationic surfactant CTAB demonstrates the best effect on the wettability alteration of oil-wet sandstone surface. The positively charged head groups of CTAB molecules and carboxylic acid groups from crude oil could interact to form ion pairs, which could be desorbed from the solid surface and solubilized into the micelle formed by CTAB. Thus, the water-wetness of the solid surface is improved. Nonionic surfactant TX-100 could be adsorbed on oil-wet sandstone surface through hydrogen bonds and hydrophobic interaction to alter the wettability of oil-wet solid surface. The wettability alteration of oil-wet sandstone surface using the anionic surfactant POE(1) is caused by hydrophobic interaction. Due to the electrostatic repulsion between the anionic surfactant and the negatively charged surface, POE(1) shows less effect on the wettability alteration of oil-wet sandstone surface.

  12. Lung surfactant.

    PubMed Central

    Rooney, S A

    1984-01-01

    Aspects of pulmonary surfactant are reviewed from a biochemical perspective. The major emphasis is on the lipid components of surfactant. Topics reviewed include surfactant composition, cellular and subcellular sites as well as pathways of biosynthesis of phosphatidylcholine, disaturated phosphatidylcholine and phosphatidylglycerol. The surfactant system in the developing fetus and neonate is considered in terms of phospholipid content and composition, rates of precursor incorporation, activities of individual enzymes of phospholipid synthesis and glycogen content and metabolism. The influence of the following hormones and other factors on lung maturation and surfactant production is discussed: glucocorticoids, thyroid hormone, estrogen, prolactin, cyclic AMP, beta-adrenergic and cholinergic agonists, prostaglandins and growth factors. The influence of maternal diabetes, fetal sex, stress and labor are also considered. Nonphysiologic and toxic agents which influence surfactant in the fetus, newborn and adult are reviewed. PMID:6145585

  13. The solubilization of fatty acids in systems based on block copolymers and nonionic surfactants

    NASA Astrophysics Data System (ADS)

    Mirgorodskaya, A. B.; Yatskevich, E. I.; Zakharova, L. Ya.

    2010-12-01

    The solubilizing action of micellar, microemulsion, and polymer-colloid systems formed on the basis of biologically compatible amphiphilic polymers and nonionic surfactants on capric, lauric, palmitic, and stearic acids was characterized quantitatively. Systems based on micelle forming oxyethyl compounds increased the solubility of fatty acids by more than an order of magnitude. Acid molecules incorporated into micelles increased their size and caused structural changes. Solubilization was accompanied by complete or partial destruction of intrinsic acid associates and an increase in their p K a by 1.5-2 units compared with water.

  14. Controlling colloid charge in nonpolar liquids with surfactants.

    PubMed

    Smith, Gregory N; Eastoe, Julian

    2013-01-14

    The formation of ions in nonpolar solvents (with relative permittivity ε(r) of approximately 2) is more difficult than in polar liquids; however, these charged species play an important role in many applications, such as electrophoretic displays. The low relative permittivities of these solvents mean that charges have to be separated by large distances to be stable (approximately 28 nm or 40 times that in water). The inverse micelles formed by surfactants in these solvents provide an environment to stabilize ions and charges. Common surfactants used are sodium dioctylsulfosuccinate (Aerosol OT or AOT), polyisobutylene succinimide, sorbitan oleate, and zirconyl 2-ethyl hexanoate. The behavior of charged inverse micelles has been studied on both the bulk and on the microscopic scale and can be used to determine the motion of the micelles, their structure, and the nature of the electrostatic double layer. Colloidal particles are only weakly charged in the absence of surfactant, but in the presence of surfactants, many types, including polymers, metal oxides, carbon blacks, and pigments, have been observed to become positively or negatively charged. Several mechanisms have been proposed as the origin of surface charge, including acid-base reactions between the colloid and the inverse micelle, preferential adsorption of charged inverse micelles, or dissolution of surface species. While most studies vary only the concentration of surfactant, systematic variation of the particle surface chemistry or the surfactant structure have provided insight into the origin of charging in nonpolar liquids. By carefully varying system parameters and working to understand the interactions between surfactants and colloidal surfaces, further advances will be made leading to better understanding of the origin of charge and to the development of more effective surfactants. PMID:23187453

  15. Novel gemini cationic surfactants based on N, N-dimethyl fatty hydrazide and 1,3-dibromopropane: synthesis, evaluation of surface and antimicrobial properties.

    PubMed

    Badr, E E; Kandeel, E M; El-Sadek, B M

    2010-01-01

    A fatty hydrazide based cationic gemini surfactants, 1,3-bis (N'-acyl-N,N-dimethylhydrazinium) propane dibromide which possess hydrolyzable amido moieties in the lipophilic portions, were prepared by reacting 1,3-bromopropane with N,N-dimethyl fatty hydrazide. The surface properties were explained and discussed based on the effect of their chemical structures. The micelle-forming ability, foaming ability, and foam stability were evaluated. The prepared surfactants also showed some antimicrobial activity against gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) but they were not active against gram negative bacteria (Escherichia coli, P. aeruginosa), yeast (Candida albicans), and molds (Aspergillus niger). PMID:21099142

  16. High Charge-Carrier Mobility of 2.5 cm(2) V(-1) s(-1) from a Water-Borne Colloid of a Polymeric Semiconductor via Smart Surfactant Engineering.

    PubMed

    Cho, Jangwhan; Cheon, Kwang Hee; Ahn, Hyungju; Park, Kwang Hun; Kwon, Soon-Ki; Kim, Yun-Hi; Chung, Dae Sung

    2015-10-01

    Semiconducting polymer nanoparticles dispersed in water are synthesized by a novel method utilizing non-ionic surfactants. By developing a smart surfactant engineering technique involving a selective post-removal process of surfactants, an unprecedentedly high mobility of 2.51 cm(2) V(-1) s(-1) from a water-borne colloid is demonstrated for the first time. PMID:26288123

  17. Polymerization of anionic wormlike micelles.

    PubMed

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles. PMID:16430253

  18. Polymeric Bicontinuous Microemulsions

    NASA Astrophysics Data System (ADS)

    Bates, Frank S.; Maurer, Wayne W.; Lipic, Paul M.; Hillmyer, Marc A.; Almdal, Kristoffer; Mortensen, Kell; Fredrickson, Glenn H.; Lodge, Timothy P.

    1997-08-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in mixtures containing a model diblock copolymer and two homopolymers. Although we attribute development of this equilibrium morphology to the effects of fluctuations, mean-field theory provides a quantitative strategy for preparing the bicontinuous state at blend compositions near an isotropic Lifshitz point.

  19. Influence of Corona Structure on Binding of an Ionic Surfactant in Oppositely Charged Amphiphilic Polyelectrolyte Micelles.

    PubMed

    Delisavva, Foteini; Uchman, Mariusz; Škvarla, Juraj; Woźniak, Edyta; Pavlova, Ewa; Šlouf, Miroslav; Garamus, Vasil M; Procházka, Karel; Štěpánek, Miroslav

    2016-04-26

    Interaction of polystyrene-block-poly(methacrylic acid) micelles (PS-PMAA) with cationic surfactant N-dodecylpyridinium chloride (DPCl) in alkaline aqueous solutions was studied by static and dynamic light scattering, SAXS, cryogenic transmission electron microscopy (cryo-TEM), isothermal titration calorimetry (ITC), and time-resolved fluorescence spectroscopy. ITC and fluorescence measurements show that there are two distinct regimes of surfactant binding in the micellar corona (depending on the DPCl content) caused by different interactions of DPCl with PMAA in the inner and outer parts of the corona. The compensation of the negative charge of the micellar corona by DPCl leads to the aggregation of PS-PMAA micelles, and the micelles form colloidal aggregates at a certain critical surfactant concentration. SAXS shows that the aggregates are formed by individual PS-PMAA micelles with intact cores and collapsed coronas interconnected with surfactant micelles by electrostatic interactions. Unlike polyelectrolyte-surfactant complexes formed by free polyelectrolyte chains, the PMAA/DPCl complex with collapsed corona does not contain surfactant micelles. PMID:27054848

  20. Surfactant Behavior of Sodium Dodecylsulfate in Deep Eutectic Solvent Choline Chloride/Urea.

    PubMed

    Arnold, T; Jackson, A J; Sanchez-Fernandez, A; Magnone, D; Terry, A E; Edler, K J

    2015-12-01

    Deep eutectic solvents (DES) resemble ionic liquids but are formed from an ionic mixture instead of being a single ionic compound. Here we present some results that demonstrate that surfactant sodium dodecyl sulfate (SDS) remains surface-active and shows self-assembly phenomena in the most commonly studied DES, choline chloride/urea. X-ray reflectivity (XRR) and small angle neutron scattering (SANS) suggest that the behavior is significantly different from that in water. Our SANS data supports our determination of the critical micelle concentration using surface-tension measurements and suggests that the micelles formed in DES do not have the same shape and size as those seen in water. Reflectivity measurements have also demonstrated that the surfactants remain surface-active below this concentration. PMID:26540438

  1. Atrazine and Diuron partitioning within a soil-water-surfactant system

    NASA Astrophysics Data System (ADS)

    Wang, P.; Keller, A.

    2006-12-01

    The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

  2. A spectral approach to determine location and orientation of azo dyes within surfactant aggregates

    NASA Astrophysics Data System (ADS)

    Karukstis, Kerry K.; Litz, Jonathan P.; Garber, Matthew B.; Angell, Laura M.; Korir, George K.

    2010-04-01

    The UV-vis absorption properties of azo dyes are known to exhibit a variation with the polarity and acidity of the dye environment. The spectral properties of a series of anionic azo dyes were characterized to further probe the interaction of these dyes with two types of surfactant aggregates: (1) the spherical micelles formed in aqueous solution by alkyltrimethylammonium bromide (C nTAB) surfactants with n = 10-16 and (2) the unilamellar vesicles spontaneously formed in water from binary mixtures of the oppositely-charged double-tailed surfactants cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium dioctylsulfosuccinate (Aerosol OT or AOT). The observed dye spectra reflect the solvatochromic behavior of the dyes and suggest the location and orientation of the dye within the surfactant aggregates. Deconvolution of the overall spectra into sums of Gaussian curves more readily displays any contributions of tautomeric forms of the azo dyes resulting from intramolecular hydrogen bonding. The rich variation in UV/vis absorption properties of these anionic azo dyes supports their use as sensitive tools to explore the nanostructures of surfactant aggregates.

  3. Surfactant compositions

    SciTech Connect

    Novakovic, M.; Abend, P.G.

    1987-09-29

    A surfactant composition is described for subsequent addition to a soap slurring comprising an acyloxy alkane sulfonate salt. The sulfonate salt is present in an amount by weight of about 44 percent of about 56 percent. The polyol is present in an amount by weight of about 2 percent to about 6 percent, and water is present in an amount by weight of 26 to 36 percent. The composition constituting a solid reversible solution at ambient temperature and having a solids content of about 58 to 72 percent, whereby subsequent addition of the surfactant composition to a soap slurry results in formation of a soap/detergent bar having a smooth texture, uniform wear properties and a lack of grittiness.

  4. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  5. Dielectric Analysis for the Spherical and Rodlike Micelle Aggregates Formed from a Gemini Surfactant: Driving Forces of Micellization and Stability of Micelles.

    PubMed

    Wang, Shanshan; Zhao, Kongshuang

    2016-08-01

    The self-aggregation behavior of Gemini surfactant 12-2-12 (ethanediyl-1,2-bis(dimethyldodecylammonium bromide)) in water was investigated by dielectric relaxation spectroscopy (DRS) over a frequency range from 40 Hz to 110 MHz. Dielectric determination shows that well-defined spherical micelles formed when the concentration of the surfactant was above a critical micelle concentration CMC1 of 3 mM and rodlike micelles formed above CMC2, 16 mM. The formation mechanism of the spherical micelles and their transition mechanism to clubbed micelles were proposed by calculating the degree of counterion binding of the micelles. The interactions between the head groups and the hydrophobic chains of the surfactant led to the formation of the micelles, whereas the transition is mainly attributed to the interaction among the hydrophobic chains. By analyzing the dielectric relaxation observed at about 10(7) Hz based on the interface polarization theory, the permittivity and conductivity of micelle aggregates (spherical and clubbed) and volume fraction of micelles were calculated theoretically as well as the electrical properties of the solution medium. Furthermore, we also calculated the electrokinetic parameters of the micelle particle surface, surface conductivity, surface charge density, and zeta potential, using the relaxation parameters and phase parameters. On the basis of these results, the balance of forces controlling morphological transitions, interfacial electrokinetic properties, and the stability of the micelle aggregates was discussed. PMID:27396495

  6. Solubilization of PAH mixtures by three different anionic surfactants.

    PubMed

    Chun, Chan Lan; Lee, Jung-Ju; Park, Jae-Woo

    2002-01-01

    Solubilization of naphthalene and phenanthrene into the micelles formed by three different anionic surfactants was investigated for single, binary, and ternary mixtures including pyrene. The three surfactants were sodium dodecylbenzene sulfonate (SDDBS), monoalkylated disulfonated diphenyl oxide (MADS-C12), and dialkylated disulfonated diphenyl oxide (DADS-C12). The order of increasing solubility enhancement of naphthalene and phenanthrene was SDDBS < MADS-C12 < < DADS-C12, which indicates that the hydrophobic chains in micellar core play more important role for the solubilization of polycyclic aromatic hydrocarbons (PAHs) than the benzene rings in palisade layer of a micelle. The solubility enhancement of naphthalene was slightly changed in PAH mixtures. The solubility of phenanthrene was greatly enhanced in presence of naphthalene but reduced in presence of pyrene. The explanation for these results could be that less hydrophobic compounds can be solubilized at the interfacial region of a hydrophobic core, which reduces the interfacial tension between the core and water, and then the reduced interfacial tension can support a larger core volume for the same interfacial energy. PMID:12009127

  7. Classifying surfactants with respect to their effect on lipid membrane order.

    PubMed

    Nazari, Mozhgan; Kurdi, Mustafa; Heerklotz, Heiko

    2012-02-01

    We propose classifying surfactants with respect to their effect on membrane order, which is derived from the time-resolved fluorescence anisotropy of DPH. This may help in understanding why certain surfactants, including biosurfactants such as antimicrobial lipopeptides and saponins, often show a superior performance to permeabilize and lyse membranes and/or a better suitability for membrane protein solubilization. Micelle-forming surfactants induce curvature stress in membranes that causes disordering and, finally, lysis. Typical detergents such as C(12)EO(8), octyl glucoside, SDS, and lauryl maltoside initiate membrane lysis after reaching a substantial, apparently critical extent of disordering. In contrast, the fungicidal lipopeptides surfactin, fengycin, and iturin from Bacillus subtilis QST713 as well as digitonin, CHAPS, and lysophosphatidylcholine solubilize membranes without substantial, overall disordering. We hypothesize they disrupt the membrane locally due to a spontaneous segregation from the lipid and/or packing defects and refer to them as heterogeneously perturbing. This may account for enhanced activity, selectivity, and mutual synergism of antimicrobial biosurfactants and reduced destabilization of membrane proteins by CHAPS or digitonin. Triton shows the pattern of a segregating surfactant in the presence of cholesterol. PMID:22325272

  8. Classifying Surfactants with Respect to Their Effect on Lipid Membrane Order

    PubMed Central

    Nazari, Mozhgan; Kurdi, Mustafa; Heerklotz, Heiko

    2012-01-01

    We propose classifying surfactants with respect to their effect on membrane order, which is derived from the time-resolved fluorescence anisotropy of DPH. This may help in understanding why certain surfactants, including biosurfactants such as antimicrobial lipopeptides and saponins, often show a superior performance to permeabilize and lyse membranes and/or a better suitability for membrane protein solubilization. Micelle-forming surfactants induce curvature stress in membranes that causes disordering and, finally, lysis. Typical detergents such as C12EO8, octyl glucoside, SDS, and lauryl maltoside initiate membrane lysis after reaching a substantial, apparently critical extent of disordering. In contrast, the fungicidal lipopeptides surfactin, fengycin, and iturin from Bacillus subtilis QST713 as well as digitonin, CHAPS, and lysophosphatidylcholine solubilize membranes without substantial, overall disordering. We hypothesize they disrupt the membrane locally due to a spontaneous segregation from the lipid and/or packing defects and refer to them as heterogeneously perturbing. This may account for enhanced activity, selectivity, and mutual synergism of antimicrobial biosurfactants and reduced destabilization of membrane proteins by CHAPS or digitonin. Triton shows the pattern of a segregating surfactant in the presence of cholesterol. PMID:22325272

  9. Dispersion behavior and aqueous foams in mixtures of a vesicle-forming surfactant and edible nanoparticles.

    PubMed

    Binks, Bernard P; Campbell, Shawn; Mashinchi, Saeed; Piatko, Michael P

    2015-03-17

    In an attempt to prepare ultrastable aqueous foams composed entirely of food-grade ingredients, we describe the foamability and foam stability of aqueous phases containing either calcium carbonate particles (CaCO3), sodium stearoyl lactylate surfactant (SSL), or their mixtures. Techniques including zeta potential measurements, adsorption isotherm determination, contact angles and optical and cryo-scanning electron microscopy are used to probe the interaction between particles and surfactant molecules. Aqueous dispersions of inherently hydrophilic cationic CaCO3 nanoparticles do not foam to any great extent. By contrast, aqueous dispersions of anionic SSL, which forms a lamellar phase/vesicles, foam progressively on increasing the concentration. Despite their foamability being low compared to that of micelle-forming surfactant sodium dodecyl sulfate, they are much more stable to collapse with half-lives (of up to 40 days) of around 2 orders of magnitude higher above the respective aggregation concentrations. We believe that, in addition to surfactant lamellae around bubbles, the bilayers within vesicles contain surfactant chains in a solidlike state yielding indestructible aggregates that jam the aqueous films between bubbles, reducing the drainage rate and both bubble coalescence and gas-transfer between bubbles. In mixtures of particles and surfactant, the adsorption of SSL monomers occurs on particle surfaces, leading to an increase in their hydrophobicity, promoting particle adsorption to bubble surfaces. Ultrastable foams result with half-lives of around an order of magnitude higher again at low concentrations and foams which lose only around 30% of their volume within a year at high concentrations. In the latter case, we evidence a high surface density of discrete surfactant-coated particles at bubble surfaces, rendering them stable to coalescence and disproportionation. PMID:25734773

  10. Online monitoring of polymerization reactions in inverse emulsions.

    PubMed

    Alb, Alina M; Farinato, Ray; Calbick, Joe; Reed, Wayne F

    2006-01-17

    Automatic continuous online monitoring of polymerization reactions (ACOMP) was adapted to the monitoring of acrylamide polymerization in inverse emulsions. This is the first application of ACOMP to heterogeneous phase polymerization. The conversion and reduced viscosity were monitored by continuously inverting and diluting the emulsion phase using a small reactor sample stream and a breaker surfactant solution, followed by UV absorption and viscometric detection. This inversion into a stable portion of the polymer/surfactant phase diagram is accomplished in tens of seconds, yielding dilute solutions containing acrylamide (Aam), polyacrylamide (PA), oil droplets, and small quantities of surfactant, initiator and other debris, and low molecular weight compounds. After establishing the means of making ACOMP measurements, a first application of the method is made to resolving some of the kinetic issues involved in emulsion polymerization, including the evolution of molecular mass, and the simultaneous action of an "intrinsic" initiator and an added chemical initiator. PMID:16401138

  11. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2009-11-24

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  12. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2006-04-04

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments and the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  13. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2009-09-29

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  14. Polymerization catalyst

    SciTech Connect

    Graves, V.

    1987-05-12

    A process is described for polymerizing at least one alpha olefin under conditions characteristic of Ziegler polymerization wherein the polymerization is conducted in the presence of a catalyst system which comprises: a supported catalyst prepared under anhydrous conditions by the sequential steps of: preparing a slurry of inert particulate support material; adding to the slurry a solution of an organomagnesium compound; adding to the slurry and reacting a solution of a zirconium halide compound, hafnium compound or mixtures thereof; adding to the slurry and reacting a halogenator; adding to the slurry and reacting a tetravalent titanium halide compound; and recovering solid catalyst.

  15. Polymerization catalyst

    SciTech Connect

    Graves, V.

    1986-10-21

    A process is described for polymerizing at least one alpha-olefin under conditions characteristic of Ziegler polymerization wherein the polymerization is conducted in the presence of a catalyst comprising: a supported catalyst prepared under anhydrous conditions by the steps of: (1) sequentially; (a) preparing a slurry of inert particulate support material; (b) adding to the slurry a solution of an organomagnesium compound; (c) adding to the slurry and reacting a solution of zirconium compound; and (2) thereafter; (d) adding to the slurry and reacting a halogenator; (e) adding to the slurry and reacting a tetravalent titanium compound; (f) recovering solid catalyst; and an organoaluminum compound.

  16. Polymerization in emulsion microdroplet reactors

    NASA Astrophysics Data System (ADS)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  17. Heteroepitaxial formation of aligned mesostructured silica films with large structural periodicities from mixed surfactant systems.

    PubMed

    Hayase, Saeko; Kanno, Yosuke; Watanabe, Masatoshi; Takahashi, Masahiko; Kuroda, Kazuyuki; Miyata, Hirokatsu

    2013-06-11

    Liquid-crystal phases consisting of cylindrical micelles of amphiphilic block copolymers and silica precursors are epitaxially built up on aligned surface micelles formed by an alkyl-PEO surfactant, Brij56, irrespective of the large difference in the intrinsic structural periodicities resulting in the formation of fully aligned mesostructured silica films with large lattice constants. Brij56 works as an alignment controlling agent on rubbing-treated polyimide through selective adsorption from a precursor solution containing the two surfactants, a block copolymer and Brij56, through strong hydrophobic interactions to form an anisotropic surface micelle structure. Aligned mesostructured silica layers with larger periodicities, which dominantly consist of block copolymers, form on these aligned surface micelles by gradually changing the vertical periodicity keeping the lateral intermicelle distance constant. This can be regarded as a kind of heteroepitaxy because the lattice constant at the surface is different from that of the bulk of the film. On the basis of this new concept, highly aligned mesostructured silica films with structural periodicities as large as 10 nm are successfully formed, which has never been achieved when the block copolymers are used alone as the structure-directing agent. The periodicity of the aligned films can precisely be controlled by an appropriate choice of block copolymers and the mixing ratio of the two surfactants, which increases the opportunity for applications of these films with highly anisotropic mesoscale structure. PMID:23721098

  18. Novel designed polyoxyethylene nonionic surfactant with improved safety and efficiency for anticancer drug delivery

    PubMed Central

    Li, Chang; Sun, Chunmeng; Li, Shasha; Han, Peng; Sun, Huimin; Ouahab, Ammar; Shen, Yan; Xu, Yourui; Xiong, Yerong; Tu, Jiasheng

    2014-01-01

    In order to limit the adverse reactions caused by polysorbate 80 in Taxotere®, a widely used formulation of docetaxel, a safe and effective nanocarrier for this drug has been developed based on micelles formed by a new class of well-defined polyoxyethylene sorbitol oleate (PSO) with sorbitol as the matrix in aqueous solution. The physicochemical properties of the amphiphilic surfactant and the resulting micelles can be easily fine-tuned by the homogeneous sorbitol matrix and pure oleic acid. Composition, critical micelle concentration, and entrapment efficiency were investigated by ultraviolet visible spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, fluorospectrophotometry, and high-performance liquid chromatography. In vitro and in vivo evaluation revealed that PSO had exceptionally low hemolysis and histamine release rates compared with commercial polysorbate 80. Moreover, the tumor targeting delivery of PSO was investigated by in vivo imaging in S180 tumor-bearing mice. The results suggest that this novel delivery system, PSO, provides an acceptable alternative to polysorbate 80 for delivery of docetaxel. Further, due to the hypoallergenic nature of PSO, the mechanism of pseudoallergy caused by the polyoxyethylene nonionic surfactant was investigated. Based on in vitro cell analysis, it was assumed that the initial contact of polyoxyethylene nonionic surfactant with mast cells provoked pseudoallergy via polyamine receptor-mediated endocytosis. PMID:24812509

  19. Novel designed polyoxyethylene nonionic surfactant with improved safety and efficiency for anticancer drug delivery.

    PubMed

    Li, Chang; Sun, Chunmeng; Li, Shasha; Han, Peng; Sun, Huimin; Ouahab, Ammar; Shen, Yan; Xu, Yourui; Xiong, Yerong; Tu, Jiasheng

    2014-01-01

    In order to limit the adverse reactions caused by polysorbate 80 in Taxotere(®), a widely used formulation of docetaxel, a safe and effective nanocarrier for this drug has been developed based on micelles formed by a new class of well-defined polyoxyethylene sorbitol oleate (PSO) with sorbitol as the matrix in aqueous solution. The physicochemical properties of the amphiphilic surfactant and the resulting micelles can be easily fine-tuned by the homogeneous sorbitol matrix and pure oleic acid. Composition, critical micelle concentration, and entrapment efficiency were investigated by ultraviolet visible spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, fluorospectrophotometry, and high-performance liquid chromatography. In vitro and in vivo evaluation revealed that PSO had exceptionally low hemolysis and histamine release rates compared with commercial polysorbate 80. Moreover, the tumor targeting delivery of PSO was investigated by in vivo imaging in S180 tumor-bearing mice. The results suggest that this novel delivery system, PSO, provides an acceptable alternative to polysorbate 80 for delivery of docetaxel. Further, due to the hypoallergenic nature of PSO, the mechanism of pseudoallergy caused by the polyoxyethylene nonionic surfactant was investigated. Based on in vitro cell analysis, it was assumed that the initial contact of polyoxyethylene nonionic surfactant with mast cells provoked pseudoallergy via polyamine receptor-mediated endocytosis. PMID:24812509

  20. Doxycycline and oxytetracycline loading of a zwitterionic amphoteric surfactant-gel and their controlled release.

    PubMed

    Cesaretti, A; Carlotti, B; Gentili, P L; Clementi, C; Germani, R; Elisei, F

    2014-11-14

    Oxytetracycline (OX) and doxycycline (DX) are antibiotics belonging to the family of tetracyclines. We present a UV-Visible steady state and time-resolved experimental study of OX and DX and their biologically active Mg(2+) complexes loaded within a hydrogel matrix. Hydrogels are a three dimensional network of worm-like micelles, mutually intertwined, forming a pattern of hydrophobic domains and water pools. We resorted to a hydrogel, made of a zwitterionic N-oxide surfactant (p-dodecyloxybenzyldimethylamine N-oxide, pDoAO), which showed promising features as a drug vehicle. The spectral and photophysical properties of the drugs are significantly altered by the inclusion in the hydrophobic domains of the gel and these variations are indicators of the permeation ratio of the drug in between the micelles forming the gel network. We thus get a clear picture of the distribution of the drug molecules and metal chelates into the two different kinds of environment, where the hydrophobic domains are also able to cause a gel-induced deprotonation of these two drugs. Furthermore, the amphoteric nature of the surfactant is responsible for its peculiar acid-base behaviour: under acidic pH conditions, the surfactant gets protonated and the stability of the gel network is damaged. This feature can be thus exploited for the pH controlled release of the tetracycline drugs. PMID:25251135

  1. Surfactant Uptake Dynamics in Mammalian Cells Elucidated with Quantitative Coherent Anti-Stokes Raman Scattering Microspectroscopy

    PubMed Central

    Okuno, Masanari; Kano, Hideaki; Fujii, Kenkichi; Bito, Kotatsu; Naito, Satoru; Leproux, Philippe; Couderc, Vincent; Hamaguchi, Hiro-o

    2014-01-01

    The mechanism of surfactant-induced cell lysis has been studied with quantitative coherent anti-Stokes Raman scattering (CARS) microspectroscopy. The dynamics of surfactant molecules as well as intracellular biomolecules in living Chinese Hamster Lung (CHL) cells has been examined for a low surfactant concentration (0.01 w%). By using an isotope labeled surfactant having CD bonds, surfactant uptake dynamics in living cells has been traced in detail. The simultaneous CARS imaging of the cell itself and the internalized surfactant has shown that the surfactant molecules is first accumulated inside a CHL cell followed by a sudden leak of cytosolic components such as proteins to the outside of the cell. This finding indicates that surfactant uptake occurs prior to the cell lysis, contrary to what has been believed: surface adsorption of surfactant molecules has been thought to occur first with subsequent disruption of cell membranes. Quantitative CARS microspectroscopy enables us to determine the molecular concentration of the surfactant molecules accumulated in a cell. We have also investigated the effect of a drug, nocodazole, on the surfactant uptake dynamics. As a result of the inhibition of tubulin polymerization by nocodazole, the surfactant uptake rate is significantly lowered. This fact suggests that intracellular membrane trafficking contributes to the surfactant uptake mechanism. PMID:24710120

  2. Surface shear inviscidity of soluble surfactants

    PubMed Central

    Zell, Zachary A.; Nowbahar, Arash; Mansard, Vincent; Leal, L. Gary; Deshmukh, Suraj S.; Mecca, Jodi M.; Tucker, Christopher J.; Squires, Todd M.

    2014-01-01

    Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 103–104 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants. PMID:24563383

  3. Cationic surfactants in the form of nanoparticles and micelles elicit different human neutrophil responses: a toxicological study.

    PubMed

    Hwang, Tsong-Long; Sung, Calvin T; Aljuffali, Ibrahim A; Chang, Yuan-Ting; Fang, Jia-You

    2014-02-01

    Cationic surfactants are an ingredient commonly incorporated into nanoparticles for clinical practicability; however, the toxicity of cationic surfactants in nanoparticles is not fully elucidated. We aimed to evaluate the inflammatory responses of cationic nanobubbles and micelles in human neutrophils. Soyaethyl morpholinium ethosulfate (SME) and hexadecyltrimethyl-ammonium bromide (CTAB) are the two cationic surfactants employed in this study. The zeta potential of CTAB nanobubbles was 80 mV, which was the highest among all formulations. Nanobubbles, without cationic surfactants, showed no cytotoxic effects on neutrophils in terms of inflammatory responses. Cationic nanobubbles caused a concentration-dependent cytotoxicity of degranulation (elastase release) and membrane damage (release of lactate dehydrogenase, LDH). Among all nanoparticles and micelles, CTAB-containing nanosystems showed the greatest inflammatory responses. A CTAB nanobubble diluent (1/150) increased the LDH release 80-fold. Propidium iodide staining and scanning electron microscopy (SEM) verified cell death and morphological change of neutrophils treated by CTAB nanobubbles. SME, in a micelle form, strengthened the inflammatory response more than SME-loaded nanobubbles. Membrane interaction and subsequent Ca(2+) influx were the mechanisms that triggered inflammation. The information obtained from this work is beneficial in designing nanoparticulate formulations for balancing clinical activity and toxicity. PMID:24246197

  4. Polymeric nanoparticles

    PubMed Central

    Bolhassani, Azam; Javanzad, Shabnam; Saleh, Tayebeh; Hashemi, Mehrdad; Aghasadeghi, Mohammad Reza; Sadat, Seyed Mehdi

    2014-01-01

    Nanocarriers with various compositions and biological properties have been extensively applied for in vitro/in vivo drug and gene delivery. The family of nanocarriers includes polymeric nanoparticles, lipid-based carriers (liposomes/micelles), dendrimers, carbon nanotubes, and gold nanoparticles (nanoshells/nanocages). Among different delivery systems, polymeric carriers have several properties such as: easy to synthesize, inexpensive, biocompatible, biodegradable, non-immunogenic, non-toxic, and water soluble. In addition, cationic polymers seem to produce more stable complexes led to a more protection during cellular trafficking than cationic lipids. Nanoparticles often show significant adjuvant effects in vaccine delivery since they may be easily taken up by antigen presenting cells (APCs). Natural polymers such as polysaccharides and synthetic polymers have demonstrated great potential to form vaccine nanoparticles. The development of new adjuvants or delivery systems for DNA and protein immunization is an expanding research field. This review describes polymeric carriers especially PLGA, chitosan, and PEI as vaccine delivery systems. PMID:24128651

  5. Investigation of Polymer-Surfactant and Polymer-Drug-Surfactant Miscibility for Solid Dispersion.

    PubMed

    Gumaste, Suhas G; Gupta, Simerdeep Singh; Serajuddin, Abu T M

    2016-09-01

    In a solid dispersion (SD), the drug is generally dispersed either molecularly or in the amorphous state in polymeric carriers, and the addition of a surfactant is often important to ensure drug release from such a system. The objective of this investigation was to screen systematically polymer-surfactant and polymer-drug-surfactant miscibility by using the film casting method. Miscibility of the crystalline solid surfactant, poloxamer 188, with two commonly used amorphous polymeric carriers, Soluplus® and HPMCAS, was first studied. Then, polymer-drug-surfactant miscibility was determined using itraconazole as the model drug, and ternary phase diagrams were constructed. The casted films were examined by DSC, PXRD and polarized light microscopy for any crystallization or phase separation of surfactant, drug or both in freshly prepared films and after exposure to 40°C/75% RH for 7, 14, and 30 days. The miscibility of poloxamer 188 with Soluplus® was <10% w/w, while its miscibility with HPMCAS was at least 30% w/w. Although itraconazole by itself was miscible with Soluplus® up to 40% w/w, the presence of poloxamer drastically reduced its miscibility to <10%. In contrast, poloxamer 188 had minimal impact on HPMCAS-itraconazole miscibility. For example, the phase diagram showed amorphous miscibility of HPMCAS, itraconazole, and poloxamer 188 at 54, 23, and 23% w/w, respectively, even after exposure to 40°C/75% RH for 1 month. Thus, a relatively simple and practical method of screening miscibility of different components and ultimately physical stability of SD is provided. The results also identify the HPMCAS-poloxamer 188 mixture as an optimal surface-active carrier system for SD. PMID:27301752

  6. Towards unravelling surfactant transport

    NASA Astrophysics Data System (ADS)

    Sellier, Mathieu; Panda, Satyananda

    2015-11-01

    Surfactant transport arises in many natural or industrial settings. Examples include lipid tear layers in the eye, pulmonary surfactant replacement therapy, or industrial coating flows. Flows driven by the surface tension gradient which arises as a consequence of surfactant concentration inhomogeneity, also known as Marangoni-driven flows, have attracted the attention of fluid dynamists for several decades and has led to the development of sophisticated models and the undeniable advancement of the understanding of such flows. Yet, experimental confirmation of these models has been hampered by the difficulty in reliably and accurately measuring the surfactant concentration and its temporal evolution. In this contribution, we propose a methodology which may help shed some light on surfactant transport at the surface of thin liquid films. The surface stress induced by surfactant concentration induces a flow at the free surface which is visible and measurable. In the context of thin film flows for which the lubrication approximation hold, we demonstrate how the knowledge of this free surface flow field provides sufficient information to reconstruct the surfactant tension field. From the surface tension and an assumed equation of state, the local surfactant concentration can also be calculated and other transport parameters such as the surfactant surface diffusivity indirectly inferred. In this contribution, the proposed methodology is tested with synthetic data generated by the forward solution of the governing partial differential equations in order to illustrate the feasibility of the algorithm and highlight numerical challenges.

  7. Genetics Home Reference: surfactant dysfunction

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions surfactant dysfunction surfactant dysfunction Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Surfactant dysfunction is a lung disorder that causes breathing ...

  8. Recent advances in polymeric micelles for anti-cancer drug delivery.

    PubMed

    Biswas, Swati; Kumari, Preeti; Lakhani, Prit Manish; Ghosh, Balaram

    2016-02-15

    Block co-polymeric micelles receive increased attention due to their ability to load therapeutics, deliver the cargo to the site of action, improve the pharmacokinetic of the loaded drug and reduce off-target cytotoxicity. While polymeric micelles can be developed with improved drug loading capabilities by modulating hydrophobicity and hydrophilicity of the micelle forming block co-polymers, they can also be successfully cancer targeted by surface modifying with tumor-homing ligands. However, maintenance of the integrity of the self-assembled system in the circulation and disassembly for drug release at the site of drug action remain a challenge. Therefore, stimuli-responsive polymeric micelles for on demand drug delivery with minimal off-target effect has been developed and extensively investigated to assess their sensitivity. This review focuses on discussing various polymeric micelles currently utilized for the delivery of chemotherapeutic drugs. Designs of various stimuli-sensitive micelles that are able to control drug release in response to specific stimuli, either endogenous or exogenous have been delineated. PMID:26747018

  9. SURFACTANTS AND SUBSURFACE REMEDIATION

    EPA Science Inventory

    Because of the limitations of pump-and-trat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. Surfactants have been studied for use in soil washing and enhanced oil recovery. Although similarities exist between the application...

  10. SURFACTANTS IN LUBRICATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants are one of the most widely applied materials by consumers and industry. The application areas for surfactants span from everyday mundane tasks such as cleaning, to highly complex processes involving the formulation of pharmaceuticals, foods, pesticides, lubricants, etc. Even though sur...

  11. Chain Reaction Polymerization.

    ERIC Educational Resources Information Center

    McGrath, James E.

    1981-01-01

    The salient features and importance of chain-reaction polymerization are discussed, including such topics as the thermodynamics of polymerization, free-radical polymerization kinetics, radical polymerization processes, copolymers, and free-radical chain, anionic, cationic, coordination, and ring-opening polymerizations. (JN)

  12. Polymerization in emulsion microdroplet reactors

    NASA Astrophysics Data System (ADS)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  13. Metathesis depolymerizable surfactants

    DOEpatents

    Jamison, Gregory M.; Wheeler, David R.; Loy, Douglas A.; Simmons, Blake A.; Long, Timothy M.; McElhanon, James R.; Rahimian, Kamyar; Staiger, Chad L.

    2008-04-15

    A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.

  14. Equilibrium surface tension, dynamic surface tension, and micellization properties of lactobionamide-type sugar-based gemini surfactants.

    PubMed

    Yoshimura, Tomokazu; Umezawa, Shin; Fujino, Akihiko; Torigoe, Kanjiro; Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko; Esumi, Kunio

    2013-01-01

    A sugar-based gemini surfactant N,N'-dialkyl-N,N'-dilactobionamideethylenediamine (2C(n)Lac, where n represents alkyl chain lengths of 8, 10, 12, and 14) was synthesized by reacting N,N'-dialkylethylenediamine with lactobionic acid. The adsorption properties of 2C(n)Lac were characterized by equilibrium and dynamic surface tension measurements. Their micellization properties were investigated by steady-state fluorescence using pyrene as a probe and dynamic light scattering (DLS) techniques. The dependence of these properties on the alkyl chain length and the number of sugars was determined through a comparison with the corresponding monomeric surfactants C(n)MLA and previously reported sugar-based gemini surfactants containing monosaccharide gluconamide or disaccharide lactobionamide groups with a hexanediamide spacer. The critical micelle concentration (cmc) and surface tension of 2C(n)Lac are both lower than those of C(n)MLA surfactants. These lower values indicate that the synthesized sugar-based gemini surfactants have excellent micelle-forming ability in solution and high adsorption ability at the air-water interface, which result from strong interactions of the hydrogen bonds between the hydroxyls in lactobionamide groups. When the alkyl chain length of 2C(n)Lac increases to 14, premicellar formation occurs in the solution along with adsorption at the air-water interface at concentrations below the cmc. Furthermore, 2C(n)Lac forms micelles measuring 4 to 12 nm in solution, with no dependence on the alkyl chain length, and their size slightly increases with increasing concentration. PMID:23728326

  15. Phosphine oxide surfactants revisited.

    PubMed

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. PMID:26869216

  16. Surfactant phospholipid metabolism.

    PubMed

    Agassandian, Marianna; Mallampalli, Rama K

    2013-03-01

    Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23026158

  17. Waterflooding employing amphoteric surfactants

    SciTech Connect

    Stournas, S.

    1980-08-05

    Process for the recovery of oil from a subterranean oil reservoir involving the injection into the reservoir of an aqueous solution of an amphoteric surfactant having an inner quaternary ammonium group linked to a terminal sulfonate or carboxylate group is described. The amphoteric surfactants may be employed in relatively low concentrations within the range of 0.0005 to 0.1% by weight and injected in a slug of at least 0.5 pv. The apparatus may be applied in situations in which the reservoir waters and/or the waters employed in formulating the surfactant solution contain relatively high amounts of divalent metal ions. Specifically described amphoteric surfactants include hydrocarby dialkyl or dihydroxyalkyl ammonium alkane sulfonates and carboxylates in which the hydrocarbyl group contains from 8 to 26 carbon atoms. 29 claims.

  18. Genetic disorders of surfactant homeostasis.

    PubMed

    Whitsett, Jeffrey A

    2006-01-01

    Pulmonary surfactant reduces surface tension at the air-liquid interface in the alveolus, thereby maintaining lung volumes during the respiratory cycle. In premature newborn infants, the lack of surfactant causes atelectasis and respiratory failure, characteristic of respiratory of distress syndrome. Surfactant is comprised of lipids and associated proteins that are required for surfactant function. Surfactant proteins B and C and a lamellar body associated transport protein, ABCA3 play critical roles in surfactant synthesis and function. Mutations in the genes encoding these proteins cause lethal respiratory distress in newborn infants. This review discusses the clinical and pathological findings associated with these inherited disorders of alveolar homeostasis. PMID:16798578

  19. Phase behavior of polyion-surfactant ion complex salts: effects of surfactant chain length and polyion length.

    PubMed

    Svensson, Anna; Norrman, Jens; Piculell, Lennart

    2006-06-01

    The aqueous phase behavior of a series of complex salts, containing cationic surfactants with polymeric counterions, has been investigated by visual inspection and small-angle X-ray scattering (SAXS). The salts were alkyltrimethylammonium polyacrylates, CxTAPAy, based on all combinations of five surfactant chain lengths (C6, C8, C10, C12, and C16) and two lengths of the polyacrylate chain (30 and 6 000 repeating units). At low water contents, all complex salts except C6TAPA6000 formed hexagonal and/or cubic Pm3n phases, with the hexagonal phase being favored by lower water contents. The aggregate dimensions in the liquid crystalline phases changed with the surfactant chain length. The determined micellar aggregation numbers of the cubic phases indicated that the micelles were only slightly aspherical. At high water contents, the C6TAPAy salts were miscible with water, whereas the other complex salts featured wide miscibility gaps with a concentrated phase in equilibrium with a (sometimes very) dilute aqueous solution. Thus, the attraction between oppositely charged surfactant aggregates and polyions decreases with decreasing surfactant chain length, and with decreasing polyion length, resulting in an increased miscibility with water. The complex salt with the longest surfactant chains and polyions gave the widest miscibility gap, with a concentrated hexagonal phase in equilibrium with almost pure water. A decrease in the attraction led to cubic-micellar and micellar-micellar coexistence in the miscibility gap and to an increasing concentration of the complex salt in the dilute phase. For each polyion length, the mixtures for the various surfactant chain lengths were found to conform to a global phase diagram, where the surfactant chain length played the role of an interaction parameter. PMID:16722736

  20. Anionic surfactant with hydrophobic and hydrophilic chains for nanoparticle dispersion and shape memory polymer nanocomposites.

    PubMed

    Iijima, Motoyuki; Kobayakawa, Murino; Yamazaki, Miwa; Ohta, Yasuhiro; Kamiya, Hidehiro

    2009-11-18

    An anionic surfactant comprising a hydrophilic poly(ethylene glycol) (PEG) chain, hydrophobic alkyl chain, and polymerizable vinyl group was synthesized as a capping agent of nanoparticles. TiO(2) nanoparticles modified by this surfactant were completely dispersible in various organic solvents with a wide range of polarities, such as nitriles, alcohols, ketones, and acetates. Furthermore, these particles were found to be dispersible in various polymers with different properties, such as thermosetting epoxy resins and radical polymerized poly(methylmethacrylate) (PMMA). A polymer composite of surface-modified TiO(2) nanoparticles in epoxy resins prepared by using the developed surfactant also possessed temperature-induced shape memory properties. PMID:19852463

  1. Rapid analysis of water- and fat-soluble vitamins by electrokinetic chromatography with polymeric micelle as pseudostationary phase.

    PubMed

    Ni, Xinjiong; Xing, Xiaoping; Cao, Yuhua; Cao, Guangqun

    2014-11-28

    A novel polymeric micelle, formed by random copolymer poly (stearyl methacrylate-co-methacrylic acid) (P(SMA-co-MAA)) has been used as pseudostationary phase (PSP) in electrokinetic chromatography (EKC) for simultaneous and rapid determination of 11 kinds of water- and fat-soluble vitamins in this work. The running buffer consisting of 1% (w/v) P(SMA-co-MAA), 10% (v/v) 1-butanol, 20% (v/v) acetonitrile, and 30 mM Palitzsch buffer solution (pH 9.2) was applied to improve the selectivity and efficiency, as well as to shorten analysis time. 1-Butanol and acetonitrile as the organic solvent modifiers played the most important roles for rapid separation of these vitamins. The effects of organic solvents on microstructure of the polymeric micelle were investigated. The organic solvents swell the polymeric micelle by three folds, lower down the surface charge density and enhance the microenviromental polarity of the polymeric micelle. The 11 kinds of water- and fat-soluble vitamins could be baseline separated within 13 min. The method was applied to determine water- and fat-soluble vitamins in commercial vitamin sample; the recoveries were between 93% and 111% with the relative standard derivations (RSDs) less than 5%. The determination results matched the label claim. PMID:25454151

  2. Characteristic of core materials in polymeric micelles effect on their micellar properties studied by experimental and dpd simulation methods.

    PubMed

    Cheng, Furong; Guan, Xuewa; Cao, Huan; Su, Ting; Cao, Jun; Chen, Yuanwei; Cai, Mengtan; He, Bin; Gu, Zhongwei; Luo, Xianglin

    2015-08-15

    Polymeric micelles are one important class of nanoparticles for anticancer drug delivery, but the impact of hydrophobic segments on drug encapsulation and release is unclear, which deters the rationalization of drug encapsulation into polymeric micelles. This paper focused on studying the correlation between the characteristics of hydrophobic segments and encapsulation of structurally different drugs (DOX and β-carotene). Poly(ϵ-caprolactone) (PCL) or poly(l-lactide) (PLLA) were used as hydrophobic segments to synthesize micelle-forming amphiphilic block copolymers with the hydrophilic methoxy-poly(ethylene glycol) (mPEG). Both blank and drug loaded micelles were spherical in shape with sizes lower than 50 nm. PCL-based micelles exhibited higher drug loading capacity than their PLLA-based counterparts. Higher encapsulation efficiency of β-carotene was achieved compared with DOX. In addition, both doxorubicin and β-carotene were released much faster from PCL-based polymeric micelles. Dissipative particle dynamics (DPD) simulation revealed that the two drugs tended to aggregate in the core of the PCL-based micelles but disperse in the core of PLLA based micelles. In vitro cytotoxicity investigation of DOX loaded micelles demonstrated that a faster drug release warranted a more efficient cancer-killing effect. This research could serve as a guideline for the rational design of polymeric micelles for drug delivery. PMID:26196277

  3. Antagonistic effects between magnetite nanoparticles and a hydrophobic surfactant in highly concentrated Pickering emulsions.

    PubMed

    Vílchez, Alejandro; Rodríguez-Abreu, Carlos; Menner, Angelika; Bismarck, Alexander; Esquena, Jordi

    2014-05-13

    Herein we present a systematic study of the antagonistic interaction between magnetite nanoparticles (Fe3O4) and nonionic hydrophobic surfactant in Pickering highly concentrated emulsions. Interfacial tension measurements, phase behavior, and emulsion stability studies, combined with electron microscopy observations in polymerized systems and magnetometry, are used to support the discussion. First, stable W/O highly concentrated emulsions were obtained using partially hydrophobized magnetite nanoparticles. These emulsions experienced phase separation when surfactant is added at concentrations as low as 0.05 wt %. Such phase separation arises from the preferential affinity of the surfactant for the nanoparticle surfaces, which remarkably enhances their hydrophobicity, leading to a gradual desorption of nanoparticles from the interface. W/O emulsions were obtained at higher surfactant concentrations, but in this case, these emulsions were mainly stabilized by surfactant molecules. Therefore, stable emulsions could be prepared in two separate ranges of surfactant concentrations. After polymerization, low-density macroporous polymers were obtained, and the adsorption and aggregation of nanoparticles was analyzed by transmission electron microscopy. The progressive displacement of the nanoparticles was revealed: from the oil-water interface, in which aggregated nanoparticles were adsorbed, forming dense layers, to the continuous phase of the emulsions, where small nanoparticle aggregates were randomly dispersed. Interestingly, the results also show that the blocking temperature of the iron oxide superparamagnetic nanoparticles embedded in the macroporous polymers could be modulated by appropriate control of the concentrations of both surfactant and nanoparticles. PMID:24738961

  4. Analysis of interfacial and micellar behavior of sodium dioctyl sulphosuccinate salt (AOT) with zwitterionic surfactants in aqueous media.

    PubMed

    Mahajan, Rakesh Kumar; Sharma, Rabia

    2011-11-01

    The interfacial and bulk properties of mixtures of the anionic surfactant (dioctyl sulphosuccinate sodium salt, AOT) with zwitterionic surfactants 3-(N,N-dimethyldodecylammonio) propane sulfonate (DPS), 3-(N,N-dimethyltetradecylammonio) propane sulfonate (TPS), 3-(N,N-dimethylhexadecylammonio) propane sulfonate (HPS) have been studied employing surface tension, fluorescence, and viscometric techniques in aqueous media at 25 °C. It is observed that these mixtures exhibit synergism and these synergistic interactions increase with the enhancement of the hydrocarbon chain of the zwitterionic surfactant. The various physicochemical properties such as critical micelle concentration (cmc), surface excess concentration (Г(max)), minimum area per molecule (A(min)), aggregation number (N(agg)), interaction parameters (β(σ), β(m)), and thermodynamic parameters such as standard Gibbs free energy of adsorption (ΔG(ads)(o)), excess free energy of micellization (ΔG(ex)), and standard Gibbs free energy of micellization (ΔG(m)(o)) have been evaluated. The negative values of ΔG(m)(o) and ΔG(ads)(o) show that the micelle formation and adsorption of surfactant at the air/solution interface is energetically favorable, while a negative value of ΔG(ex) ensures stability of the mixed micelles formed. The Regular Solution Approximation, Motomura and Rosen's approaches have been used to explain and compare the results. The packing parameter (p) ensures the formation of vesicles or bilayers for AOT+DPS/TPS mixtures, which can potentially be used as delivery agents for industrial applications. PMID:21843891

  5. Surfactant mixing rules applied to surfactant enhanced alkaline flooding

    SciTech Connect

    Taylor, K.C. )

    1992-01-01

    This paper discusses surfactant mixing rules which have been used to describe crude oil/alkali/surfactant phase behavior, using David Lloydminster crude oil and the surfactant Neodol 25-3S. It was found that at a fixed salinity and alkali concentration, a specific mole fraction of synthetic surfactant to petroleum soap was required to produce optimal phase behavior as the water-to-oil ratio varied. This methodology is useful in understanding the relationship between the variables of water-to-oil ratio and synthetic surfactant concentration in phase behavior systems that produce a petroleum soap.

  6. Surfactant loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30 1995

    SciTech Connect

    Casteel, J.

    1996-07-01

    The aim of this research project was to investigate mechanisms governing adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy have been determined. A multi-pronged approach consisting of micro & nano spectroscopy, electrokinetics, surface tension and wettability is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the three years contract period, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride were the surfactants studied. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes in interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amounts of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactants in mixed aggregate leads to shielding of the charge of ionic surfactants which in turn promotes aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution on adsorption as well as correlations between monomer concentration in mixtures and adsorption were revealed.

  7. Adsorption kinetics of surfactant mixtures from micellar solutions as studied by maximum bubble pressure technique.

    PubMed

    Frese, Ch; Ruppert, S; Sugár, M; Schmidt-Lewerkühne, H; Wittern, K P; Fainerman, V B; Eggers, R; Miller, R

    2003-11-15

    The adsorption kinetics of micellar solutions of anionic/cationic SDS/DATB mixtures with mixing ratios of 10/1 and 10/2, respectively, are studied experimentally by means of the maximum bubble pressure method. For long adsorption times the adsorption of the highly surface-active anionic/cationic complex leads to a decrease of dynamic surface tension in comparison to the single SDS system. However, the situation is the reverse for short adsorption times where the dynamic surface tension is increased by addition of the cationic surfactant, although the overall concentration is increased. This unexpected behavior is explained by partial solubilization of free SDS molecules into micelles formed by SDS/DTAB complexes. With increasing overall concentration, when eventually the CMC of SDS is reached, the anionic/cationic complex itself is solubilized by SDS micelles. Finally, no complex micelles, which for their part can solubilize an excess of SDS molecules, are present. Hence, the dynamic properties of the solution are no longer influenced by the depletion of SDS molecules and the mixture tends to behave like a pure SDS solution. PMID:14583225

  8. Surfactant-enhanced bioremediation

    SciTech Connect

    Churchill, P.F.; Dudley, R.J.; Churchill, S.A.

    1995-12-31

    This study was undertaken to examine the effect of three structurally related, non-ionic surfactants, Triton X-45, Triton X-100 and Triton X-165, as well as the oleophilic fertilizer, Inipol EAP 22, on the rate of biodegradation of phenanthrene by pure bacterial cultures. Each surfactant dramatically increased the apparent aqueous solubility of phenanthrene. Model studies were conducted to investigate the ability of these surfactants to enhance the rate of transport and uptake of polycyclic aromatic hydrocarbons into bacterial cells, and to assess the impact that increasing the aqueous solubility of hydrocarbons has on their rate of biodegradation. The results indicate that increasing the apparent aqueous solubility of hydrocarbons can lead to enhanced biodegradation rates by two Pseudomonas saccharophila strains. However, the experiments also suggest that some surfactants can inhibit aromatic hydrocarbon biodegradation by certain bacteria. The data also support the hypothesis that surface-active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental clean-up technology on Exxon Valdez crude oil-contaminated Alaskan beaches.

  9. Polymerization of perfluorobutadiene

    NASA Technical Reports Server (NTRS)

    Newman, J.; Toy, M. S.

    1970-01-01

    Diisopropyl peroxydicarbonate dissolved in liquid perfluorobutadiene is conducted in a sealed vessel at the autogenous pressure of polymerization. Reaction temperature, ratio of catalyst to monomer, and amount of agitation determine degree of polymerization and product yield.

  10. Diseases of Pulmonary Surfactant Homeostasis

    PubMed Central

    Whitsett, Jeffrey A.; Wert, Susan E.; Weaver, Timothy E.

    2015-01-01

    Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after birth. Mutations in genes regulating surfactant homeostasis have been associated with severe lung disease in neonates and older infants. Biophysical and transgenic mouse models have provided insight into the mechanisms underlying surfactant protein and alveolar homeostasis. These studies have provided the framework for understanding the structure and function of pulmonary surfactant, which has informed understanding of the pathogenesis of diverse pulmonary disorders previously considered idiopathic. This review considers the pulmonary surfactant system and the genetic causes of acute and chronic lung disease caused by disruption of alveolar homeostasis. PMID:25621661

  11. Diseases of pulmonary surfactant homeostasis.

    PubMed

    Whitsett, Jeffrey A; Wert, Susan E; Weaver, Timothy E

    2015-01-01

    Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after birth. Mutations in genes regulating surfactant homeostasis have been associated with severe lung disease in neonates and older infants. Biophysical and transgenic mouse models have provided insight into the mechanisms underlying surfactant protein and alveolar homeostasis. These studies have provided the framework for understanding the structure and function of pulmonary surfactant, which has informed understanding of the pathogenesis of diverse pulmonary disorders previously considered idiopathic. This review considers the pulmonary surfactant system and the genetic causes of acute and chronic lung disease caused by disruption of alveolar homeostasis. PMID:25621661

  12. Polymerization Reactor Engineering.

    ERIC Educational Resources Information Center

    Skaates, J. Michael

    1987-01-01

    Describes a polymerization reactor engineering course offered at Michigan Technological University which focuses on the design and operation of industrial polymerization reactors to achieve a desired degree of polymerization and molecular weight distribution. Provides a list of the course topics and assigned readings. (TW)

  13. Facile Directed Assembly of Hollow Polymer Nanocapsules within Spontaneously Formed Catanionic Surfactant Vesicles

    SciTech Connect

    Kim, Mariya D.; Dergunov, Sergey; Richter, Andrew; Durbin, Jeffrey; Shmakov, Sergey; Jia, Ying; Kenbeilova, Saltanat; Orazbekuly, Yerbolat; Kengpeiil, Aigerim; Lindner, Erno; Pingali, Sai Venkatesh; Urban, Volker S; Weigand, Steven; Pinkhassik, Eugene

    2014-01-01

    Surfactant vesicles containing monomers in the interior of the bilayer were used to template hollow polymer nanocapsules. This study investigated the formation of surfactant/monomer assemblies by two loading methods, concurrent loading and diffusion loading. The assembly process and the resulting aggregates were investigated with dynamic light scattering, small angle neutron scattering, and small-angle X-ray scattering. Acrylic monomers formed vesicles with a mixture of cationic and anionic surfactants in a broad range of surfactant ratios. Regions with predominant formation of vesicles were broader for compositions containing acrylic monomers compared with blank surfactants. This observation supports the stabilization of the vesicular structure by acrylic monomers. Diffusion loading produced monomer-loaded vesicles unless vesicles were composed from surfactants at the ratios close to the boundary of a vesicular phase region on a phase diagram. Both concurrent-loaded and diffusion-loaded surfactant/monomer vesicles produced hollow polymer nanocapsules upon the polymerization of monomers in the bilayer followed by removal of surfactant scaffolds.

  14. Dynamics of polymeric drop breakup in microchannels

    NASA Astrophysics Data System (ADS)

    Arratia, Paulo; Gollub, Jerry; Durian, Douglas

    2006-11-01

    The dynamics of drop formation of sheared polymeric and Newtonian fluids are investigated in a 50 μm microchannel. Inverse emulsions are obtained in a cross-like geometry by impinging a continuous oil phase (with surfactant) onto either a polymeric or a Newtonian aqueous solution. The viscosity ratio between the continuous and dispersed phases is kept close to unity, and both flow rates are varied. Solutions containing small amounts (100 ppm) of flexible polymers strongly affect the filament and drop breakup processes when compared to a Newtonian solution of similar viscosity. We find that the thinning of the filament for the Newtonian case is characterized by linear decline followed by a rapid approach to breakup. The polymeric case shows an initial Newtonian-like thinning followed by a slower, elasticity- dominated thinning. Consequently, the filament breakup time and length are considerably increased for the polymeric solutions. Also, larger primary drops and beads-on-string phenomena are found for the polymer solutions.

  15. pH-Dependent, Thermosensitive Polymeric Nanocarriers for Drug Delivery to Solid Tumors

    PubMed Central

    Chen, Ching-Yi; Kim, Tae Hee; Wu, Wen-Chung; Huang, Chi-Ming; Wei, Hua; Mount, Christopher W.; Tian, Yanqing; Jang, Sei-Hum; Pun, Suzie H.; Jen, Alex K-Y

    2013-01-01

    Polymeric micelles are promising carriers for anticancer agents due to their small size, ease of assembly, and versatility for functionalization. A current challenge in the use of polymeric micelles is the sensitive balance that must be achieved between stability during prolonged blood circulation and release of active drug at the tumor site. Stimuli-responsive materials provide a mechanism for triggered drug release in the acidic tumor and intracellular microenvironments. In this work, we synthesized a series of dual pH- and temperature-responsive block copolymers containing a poly(ε-caprolactone) (PCL) hydrophobic block with a poly(triethylene glycol) block that were copolymerized with an amino acid-functionalized monomer. The block copolymers formed micellar structures in aqueous solutions. An optimized polymer that was functionalized with 6-aminocaproic acid (ACA) possessed pH-sensitive phase transitions at mildly acidic pH and body temperature. Doxorubicin-loaded micelles formed from these polymers were stable at blood pH (~7.4) and showed increased drug release at acidic pH. In addition, these micelles displayed more potent anti-cancer activity than free doxorubicin when tested in a tumor xenograft model in mice. PMID:23498892

  16. Preparing polymeric matrix composites using an aqueous slurry technique

    NASA Technical Reports Server (NTRS)

    Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

    1993-01-01

    An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

  17. Effect of surfactant architecture on the properties of polystyrene-montmorillonite nanocomposites.

    PubMed

    Simons, Ranya; Qiao, Greg G; Powell, Clem E; Bateman, Stuart A

    2010-06-01

    A series of surfactants were designed and synthesized for use as clay modification reagents to investigate the impact of their chemical structure on the nanocomposites morphology obtained following polymerization. The behavior of the surfactant-modified clays at three different stages were investigated: after ion exchange, following dispersion in styrene monomer, and once polymerization was complete. The propensity of the styrene monomer to swell the surfactant-modified clay was observed to be a useful indicator of compatibility and predictor of the resultant polystyrene nanocomposite morphology which was directly observed using small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (TEM). It was found that the key components of surfactant design driving exfoliated morphologies were (1) the position of the ammonium group, (2) the inclusion of a polymerizable group, (3) the solubility of the surfactant in the monomer, (4) the length of the alkyl chain, and (5) sufficient concentration of surfactant used to exchange the clay. This understanding should lead to better design of clay modifications for use in polymer nanocomposites. PMID:20155983

  18. Surfactant studies for coal liquefaction

    SciTech Connect

    Hsu, G.C.

    1990-12-20

    Objectives of this project include: select economical/practical surfactants for use in coal liquefaction; screen surfactants for the proposed work through simple laboratory screening tests; and check the survivability of the selected surfactants at 350{degrees}C and 2000 psi using a 1-hour residence time for the thermal treatment in a stirred autoclave. Surfactant screening studies have shown the lignin sulfonate salt being the best candidate studied. Based upon the findings from the screening studies and practical considerations (e.g., potential cost, thermal survivability and recycling recovery), two surfactant choices in the anionic and nonionic categories were tested further in the autoclave reactor and engineering experiments at JPL. The goal of the autoclave work was to engineering experiments at JPL. The goal of the autoclave work was to determine the effects of surfactants on coal liquefaction performance and to test surfactant survivability. A eight of (8) autoclave experiments using 100 grams of as-received coal were performed. Two commercial surfactant choices were evaluated. They were: Sodium Lignin Sulfonate (LS) as a colloidal (heterogenous) surfactant of anionic type; and Triton X-100 (TRI) (trade name of a polyoxyethylated tert-octyphenol) as a liquid (homogenous) surfactant of nonionic type. Two additional reference tests were performed. 10 refs., 15 figs., 7 tabs.

  19. Polymeric bicontinuous microemulsions

    NASA Astrophysics Data System (ADS)

    Krishnan, Kasiraman

    Rheology of complex fluids has been a topic of considerable interest recently. Bicontinuous microemulsions (BmuE), made by mixing appropriate amounts of oil, water and a surfactant, form a unique class of complex fluids. They possess a characteristic nanostructure consisting of undulating surfaces with vanishingly small interfacial curvature. BmuEs can also be generated in polymers by mixing appropriate amounts of two homopolymers and their corresponding diblock copolymer. The main objective of the present research is to study effects of shear on a model polymeric BmuE. Scattering is used as a predominant tool with in situ flow devices, along with optical microscopy and rheology. The model BmuE consists of a ternary blend of poly(ethyl ethylene) (PEE), poly(dimethyl siloxane) (PDMS) and a PEE-PDMS diblock copolymer. Steady shear experiments reveal four regimes as a function of shear rate. At low shear rates (regime I), Newtonian behavior is observed; there is onset of shear thinning at higher rates (regime II). In regime III, the stress is independent of shear rate, whereas it increases with shear rate once again in regime IV. Morphological characterization was carried out for each of these four regimes using scattering and microscopy, the key result being the evidence for flow-induced phase separation in regime III. Transient rheological measurements were conducted for startup and step changes in shear rate, and the BmuE exhibits features similar to worm-like micellar colloidal systems. Time-resolved light scattering and microscopy also reveal interesting characteristics. Dynamic mechanical spectroscopy indicates similarities with neat block copolymers near the order-disorder transition. The equilibrium rheological behavior is intriguing and detailed comparisons are made with Landau-Ginzburg theoretical models. Other areas of research as a part of this thesis include study of structural dynamics of BmuEs with dynamic light scattering, and the rheological

  20. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants

    NASA Astrophysics Data System (ADS)

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-01

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using 19F and 31P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F6OPC. The lipid interactions of SMA(3 : 1) and F6OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F6OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research.Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and

  1. Polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant suitable for endovascular applications.

    PubMed

    Morral-Ruíz, Genoveva; Melgar-Lesmes, Pedro; García, María Luísa; Solans, Conxita; García-Celma, María José

    2014-01-30

    The design of new, safe and effective nanotherapeutic systems is an important challenge for the researchers in the nanotechnology area. This study describes the formation of biocompatible polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant formed from O/W nano-emulsions by polymerization at the droplet interfaces in systems composed by aqueous solution/Kolliphor(®) ELP/medium chain triglyceride suitable for intravenous administration. Initial nano-emulsions incorporating highly hydrophilic materials were prepared by the phase inversion composition (PIC) method. After polymerization, nanoparticles with a small particle diameter (25-55 nm) and low polydispersity index were obtained. Parameters such as concentration of monomer, O/S weight ratio as well as the polymerization temperature were crucial to achieve a correct formation of these nanoparticles. Moreover, FT-IR studies showed the full conversion of the monomer to polyurethane and polyurea polymers. Likewise the involvement of the surfactant in the polymerization process through their nucleophilic groups to form the polymeric matrix was demonstrated. This could mean a first step in the development of biocompatible systems formulated with polyoxyethylene castor oil derivative surfactants. In addition, haemolysis and cell viability assays evidenced the good biocompatibility of KELP polyurethane and polyurea nanoparticles thus indicating the potential of these nanosystems as promising drug carriers. PMID:24275445

  2. Surfactants and atherogenesis.

    PubMed

    Seely, S

    1977-01-01

    In previous publications (1,2) the hypothesis was put forward that atheroma is caused by some pathogen or metabolic fault which impairs the transportability of cholesterol in the plasma. The lipoproteins containing the faulty metabolites are assumed to be incapable of traversing the capillary endothelium and continue to circulate uselessly in the blood stream, possibly giving rise to hypercholesterolaemia, until captured by lipophages which, if they can successfully complete their journey, void them into the gall bladder. The present paper takes the argument a step further by pointing out that the types of substances most likely to cause the described impairment are surfactants. A surfactant finding its way into the plasma could separate cholesterol from its carrier protein and itself become its carrier. The complex would still be kept in suspension in the plasma, but unable to cross biological barriers like the capillary endothelium. An important argument in favour of the hypothesis is that it can offer an explanation of the long-standing medical mystery of the connection between atheroma and the hardness or softness of the water supply. Infant deaths from coronary occlusion present a similar enigma. The paper points out that surfactants can conceivably find their way into infants' feeding bottles. PMID:593183

  3. Clouding behaviour in surfactant systems.

    PubMed

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources. PMID:21296314

  4. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants.

    PubMed

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-28

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using (19)F and (31)P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F(6)OPC. The lipid interactions of SMA(3 : 1) and F(6)OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F(6)OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research. PMID:26599076

  5. Heterogeneous polymerizations in supercritical carbon dioxide continuous phases

    SciTech Connect

    DeSimone, J.M.; Maury, E.E.; Combes, J.R.; Menceloglu, Y.Z.

    1993-12-31

    Heterogeneous emulsion polymerizations are important industrial methods for the synthesis of various polymeric materials. These processes generally use water as the dispersing medium. The authors propose to utilize carbon dioxide as the dispersing medium which would make the polymer recovery easier and would circumvent the contamination of water. In CO{sub 2} - based emulsion process one can have either a hydrophilic dispersed phase (hydrophilic monomer) or a hydrophobic dispersed phase (hydrophobic monomer). The surfactant has to be designed to partition itself at the CO{sub 2} - monomer/polymer interface and the initiator has to be soluble in the dispersing medium. The design of the initiator and graft copolymer surfactants will be presented. One example of a graft copolymer is a copolymer of poly(ethylene oxide) macromonomer synthesized by living anionic polymerization and a fluoroacrylate monomer resulting in a graft copolymer having hydrophilic grafts and a {open_quotes}CO{sub 2}-philic{close_quotes} backbone (due to the fluorine chains). The phase behavior of these surfactants will be discussed at the meeting.

  6. Stimuli-responsive surfactant/phospholipid stabilized colloidal dispersions and their film formation.

    PubMed

    Lestage, David J; Yu, Min; Urban, Marek W

    2005-01-01

    Methyl methacrylate (MMA) and n-butyl acrylate (nBA) were copolymerized into stable colloidal particles in the presence of micelle forming sodium dioctyl sulfosuccinate (SDOSS) and liposome forming 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) in aqueous media that serve as thermodynamically stable loci for lipophilic monomers and nanostructured templates. These studies show for the first time that hollow colloidal particles may coalesce to form polymeric films and the combination of SDOSS and DLPC dispersing agents provides a stimuli-responsive environment during film formation through which individual surface stabilizing components can be driven to the film-air (F-A) or film-substrate (F-S) interface. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) of p-MMA/nBA colloidal dispersions revealed preferential and enhanced mobility of SDOSS and DLPC lipid rafts to the F-A and F-S interfaces in response to thermal, ionic, and enzymatic stimuli. PMID:15877379

  7. Surfactant and process for enhanced oil recovery

    SciTech Connect

    Stapp, P. R.

    1984-12-11

    A novel surfactant is formed by reacting maleic anhydride with either a petroleum sulfonate or an alkaryl sulfonate. A surfactant system containing the above surfactant useful in enhanced oil recovery processes is also provided.

  8. Synthesis and characterization of polyacrylonitrile nanoparticles by dispersion/emulsion polymerization process.

    PubMed

    Boguslavsky, Lior; Baruch, Sigal; Margel, Shlomo

    2005-09-01

    Polyacrylonitrile nanoparticles in sizes ranging from approximately 35 to 270 nm were prepared by dispersion/emulsion polymerization of acrylonitrile in a continuous aqueous phase in the presence of potassium persulfate as initiator and various alkyl-sulfate and sulfonate surfactants. The influence of various polymerization parameters (e.g., concentration of monomer and initiator, type and concentration of surfactant, temperature and time of polymerization, ionic strength, pH and co-solvent concentration) on the properties (e.g., size and size distribution, yield, stability, etc.) of the particles has been investigated. The polymerization of acrylonitrile may occur in two major locations: in the aqueous continuous phase (dispersion polymerization) and/or within the surfactant micelles (emulsion polymerization). A discussion concerning the role of these two mechanisms under different conditions, including comparison with previous literature, is also presented. Surface and bulk characterizations of the particles were performed by methods such as transmission and scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, zeta potential, and gravimetric measurements. PMID:16009219

  9. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    SciTech Connect

    Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

    1989-02-01

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs.

  10. Polyelectrolyte-Surfactant Complexes: A New Class of Organogelators

    NASA Astrophysics Data System (ADS)

    Cavicchi, Kevin; Liu, Yuqing; Guzman, Gustavo

    2011-03-01

    Polyelectrolyte-surfactant complexes (PE-SURFs) are a class of polymers generated by neutralizing a polyelectrolyte with an oppositely charged surfactant. It has been found that PE-SURFs composed of polystyrene sulfonate and long chain alkyl dimethyl amines act as good organogelators for a range of hydrophobic, organic solvents. Thermo-reversible organogels are formed by heating and cooling PE-SURF/solvent solutions. The gel transition temperature is influenced by the degree of polymerization, the length of the alkyl side-chain, the solubility parameter of the solvent, and the concentration of the gelator. Freeze-drying and scanning electron microscopy characterization of the resultant xerogels shows the formation of rod- and plate-like network morphologies depending on the system parameters. This behavior is consistent with gelation driven by the self-assembly of the amphiphilic PE-SURFs into micellar networks.

  11. Interaction of nonionic surfactant AEO9 with ionic surfactants*

    PubMed Central

    Zhang, Zhi-guo; Yin, Hong

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, α AEO9=0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ CMC), maximum surface excess concentration (Γ max) and minimum area per molecule at the air/solution interface (A min) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness. PMID:15909351

  12. Surfactant loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1993--September 30, 1994

    SciTech Connect

    Somasundaran, P.

    1995-06-01

    The aim of this project is to elucidate the mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effect of surfactant structure, surfactant combinations, other inorganic and polymeric species is being studied. A multi-pronged approach consisting of micro and nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability is used to achieve the goals. The results of this study should help in controlling surfactant loss in chemical flooding and also in developing optimum structures and conditions for efficient chemical flooding processes. During the second year of this three year contract, adsorption/desorption of single surfactants and select surfactant mixtures on alumina and silica was studied. Surfactants studied include the anionic sodium dodecyl sulfate (SDS), cationic tetradecyl trimethyl ammonium chloride (TTAC), nonionic pentadecylethoxylated nonyl phenol (NP-15) and the nonionic octaethylene glycol n-dodecyl ether (C{sub 12}EO{sub 8}) of varying hydrocarbon chain length. The microstructure of the adsorbed layer in terms of micropolarity and aggregation numbers was probed using fluorescence spectroscopy. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactant in the mixed aggregate led to shielding of the charge of the ionic surfactant which in-turn promoted aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution upon adsorption as well as correlations between monomer concentrations in mixtures and adsorption were revealed.

  13. Novel Approaches to Surfactant Administration

    PubMed Central

    Gupta, Samir; Donn, Steven M.

    2012-01-01

    Surfactant replacement therapy has been the mainstay of treatment for preterm infants with respiratory distress syndrome for more than twenty years. For the most part, surfactant is administered intratracheally, followed by mechanical ventilation. In recent years, the growing interest in noninvasive ventilation has led to novel approaches of administration. This paper will review these techniques and the associated clinical evidence. PMID:23243504

  14. Surfactant-assisted coal liquefaction

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.

    1977-01-01

    Improved process of coal liquefaction utilizing nonaqueous surfactant has increased oil yield from 50 to about 80%. Asphaltene molecule formation of colloid particles is prevented by surfactant. Separated molecules present more surface area for hydrogenation reaction. Lower requirements for temperature, pressure, and hydrogen lead to reduction in capital and operation costs.

  15. Surfactant monitoring by foam generation

    DOEpatents

    Mullen, Ken I.

    1997-01-01

    A device for monitoring the presence or absence of active surfactant or other surface active agents in a solution or flowing stream based on the formation of foam or bubbles is presented. The device detects the formation of foam with a light beam or conductivity measurement. The height or density of the foam can be correlated to the concentration of the active surfactant present.

  16. NATURAL SURFACTANTS IN PAPER RECYCLING

    EPA Science Inventory

    The objective of this project is to introduce new types of surfactants based on renewable materials (sugar surfactants) for use in ink removal from recycled paper. By applying green chemistry approaches we not only will solve an important industry and environmental problem but...

  17. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  18. On-line surfactant monitoring

    SciTech Connect

    Mullen, K.I.; Neal, E.E.; Soran, P.D.; Smith, B.

    1995-04-01

    This group has developed a process to extract metal ions from dilute aqueous solutions. The process uses water soluble polymers to complex metal ions. The metal/polymer complex is concentrated by ultrafiltration and the metals are recovered by a pH adjustment that frees the metal ions. The metal ions pass through the ultrafiltration membrane and are recovered in a concentrated form suitable for reuse. Surfactants are present in one of the target waste streams. Surfactants foul the costly ultrafiltration membranes. It was necessary to remove the surfactants before processing the waste stream. This paper discusses an on-line device the authors fabricated to monitor the process stream to assure that all the surfactant had been removed. The device is inexpensive and sensitive to very low levels of surfactants.

  19. Computer simulations of lung surfactant.

    PubMed

    Baoukina, Svetlana; Tieleman, D Peter

    2016-10-01

    Lung surfactant lines the gas-exchange interface in the lungs and reduces the surface tension, which is necessary for breathing. Lung surfactant consists mainly of lipids with a small amount of proteins and forms a monolayer at the air-water interface connected to bilayer reservoirs. Lung surfactant function involves transfer of material between the monolayer and bilayers during the breathing cycle. Lipids and proteins are organized laterally in the monolayer; selected species are possibly preferentially transferred to bilayers. The complex 3D structure of lung surfactant and the exact roles of lipid organization and proteins remain important goals for research. We review recent simulation studies on the properties of lipid monolayers, monolayers with phase coexistence, monolayer-bilayer transformations, lipid-protein interactions, and effects of nanoparticles on lung surfactant. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26922885

  20. Protein transfer through polyacrylamide hydrogel membranes polymerized in lyotropic phases.

    PubMed

    Monteiro, Michael J; Hall, Geoff; Gee, Sarah; Xie, Li

    2004-01-01

    A way to control the average pore size in cross-linked polyacrylamide-based membranes is by altering the ratio of cross-linker to acylamide monomer. Larger pore sizes are prepared with a minimum amount of cross-linker, resulting in membranes that are mechanically weak and have short lifetimes. The aim of this study was to prepare cross-linked polyacrylamide membranes with large pore sizes and with good mechanical integrity. The methodology was to carry out the polymerization in a template, formed from the self-aggregation of surfactant. Two surfactant templates were used, and their pore size was examined with proteins of different sizes. The surfactants chosen for this study were sodium dodecyl sulfate (SDS, ionic surfactant) and TERIC BL8 (nonionic surfactant), both of which have very different aggregation properties. The data showed that at 10% and greater of TERIC BL8, a very different and open gel structure is formed, in which the pore size was significantly increased. SDS seemed to have little effect on the pore size. The data suggests that the gel structures for both surfactants up to 4% (w/v) are similar and micellular, because SDS is known to favor a micelle structure. Above 4% (w/v), TERIC BL8 then goes through a change in its lyotropic phase, thus, producing membranes of a large pore size. In conclusion, the pore size and gel structure of polyacrylamide hydrogel membranes can be significantly increased using TERIC BL8 (nonionic) surfactant. This allows large-pore-size membranes with a high cross-link density and consequently high mechanical strength to be prepared for the separation of large biomolecules. PMID:15360267

  1. Surfactant induced autophobing.

    PubMed

    Bera, B; Duits, M H G; Cohen Stuart, M A; van den Ende, D; Mugele, F

    2016-05-18

    Surfactant adsorption in a three-phase system and its influence on wetting properties are relevant in various applications. Here, we report a hitherto not observed phenomenon, namely the retraction of an aqueous drop on hydrophilic solid substrates (which we refer to as 'autophobing') in ambient oil containing water-insoluble fatty acids, caused by the deposition of these fatty acids from the ambient oil onto the solid substrate. AFM measurements confirm that the surfactant is deposited on the solid by the moving contact line. This leads to a more hydrophobic substrate, the retraction of the contact line and a concomitant increase in the contact angle. The deposition process is enabled by the formation of a reaction product between deprotonated fatty acids and Ca(2+) ions at the oil/water interface. We investigate how the transition to a new equilibrium depends on the concentrations of the fatty acids, the aqueous solute, the chain lengths of the fatty acid, and the types of alkane solvent and silica or mica substrates. This phenomenon is observed on both substrates and for all explored combinations of fatty acids and solvents and thus appears to be generic. In order to capture the evolution of the contact angle, we develop a theoretical model in which the rate of adsorption at the oil-water interface governs the overall kinetics of autophobing, and transfer to the solid is determined by a mass flux balance (similar to a Langmuir Blodgett transfer). PMID:27102975

  2. Surfactant protein B deficiency: insights into surfactant function through clinical surfactant protein deficiency.

    PubMed

    Thompson, M W

    2001-01-01

    Surfactant protein B (SP-B) deficiency is a disorder of surfactant function with complete or transient absence of SP-B in term neonates. SP-B, 1 of 4 described surfactant-associated proteins, plays a key role in surfactant metabolism, particularly in intracellular packaging of surfactant components, formation of tubular myelin, and the presentation of the surfactant phospholipid monolayer to the air-fluid interface within the alveolus. Neonates with clinical SP-B deficiency best demonstrate the key role of SP-B in surfactant function. "Classic" deficiency results in severe respiratory failure in term infants and death unless lung transplantation is performed. Because the initial description of complete deficiency secondary to a homozygous frameshift mutation in codon 121 of the SP-B cDNA, partial deficiencies with differing genetic backgrounds and less severe clinical courses have been reported. These partial deficiency states may provide a clearer picture of genotype/phenotype relationships in SP-B function and surfactant metabolism. SP-B deficiency or dysfunction may be more common than once thought and may play a significant role in neonatal lung disease. PMID:11202476

  3. Polymeric Carbon Dioxide

    SciTech Connect

    Yoo, C-S.

    1999-11-02

    Synthesis of polymeric carbon dioxide has long been of interest to many chemists and materials scientists. Very recently we discovered the polymeric phase of carbon dioxide (called CO{sub 2}-V) at high pressures and temperatures. Our optical and x-ray results indicate that CO{sub 2}-V is optically non-linear, generating the second harmonic of Nd: YLF laser at 527 nm and is also likely superhard similar to cubic-boron nitride or diamond. CO{sub 2}-V is made of CO{sub 4} tetrahedra, analogous to SiO{sub 2} polymorphs, and is quenchable at ambient temperature at pressures above 1 GPa. In this paper, we describe the pressure-induced polymerization of carbon dioxide together with the stability, structure, and mechanical and optical properties of polymeric CO{sub 2}-V. We also present some implications of polymeric CO{sub 2} for high-pressure chemistry and new materials synthesis.

  4. Genetic disorders of surfactant homeostasis.

    PubMed

    Whitsett, Jeffrey A; Wert, Susan E; Xu, Yan

    2005-01-01

    Adaptation to air breathing at birth requires the precise orchestration of cellular processes to initiate fluid clearance, enhance pulmonary blood flow, and to synthesize and secrete pulmonary surfactant needed to reduce surface tension at the air-liquid interface in the alveoli. Genetic programs regulating the synthesis of the surfactant proteins and lipids required for the production and function of pulmonary surfactant are highly conserved across vertebrates, and include proteins that regulate the synthesis and packaging of pulmonary surfactant proteins and lipids. Surfactant proteins B and C (SP-B and -C) are small, uniquely hydrophobic proteins that play important roles in the stability and spreading of surfactant lipids in the alveolus. Deletion or mutations in SP-B and -C cause acute and chronic lung disease in neonates and infants. SP-B and -C are synthesized and packaged with surfactant phospholipids in lamellar bodies. Normal lamellar body formation requires SP-B and a member of the ATP-binding cassette (ABC) family of ATP-dependent membrane-associated transport proteins, ABCA3. Mutations in ABCA3 cause fatal respiratory disease in newborns and severe chronic lung disease in infancy. Expression of SP-B, -C, and ABCA3 are coregulated during late gestation by transcriptional programs influenced by thyroid transcription factor-1 and forkhead box a2, transcription factors that regulate both differentiation of the respiratory epithelium and transcription of genes required for perinatal adaptation to air breathing. PMID:15985750

  5. Surfactant and process for enhanced oil recovery

    SciTech Connect

    Stapp, P. R.

    1985-03-12

    A novel surfactant is formed by reacting maleic anhydride with a polynuclear aromatic compound having a molecular weight of at least 155. A novel surfactant system useful in enhanced oil recovery containing the above surfactant is also provided. In addition, an improved process for the enhanced recovery of oil is provided utilizing the novel surfactant system.

  6. Antioxidant poly(lactic-co-glycolic) acid nanoparticles made with α-tocopherol-ascorbic acid surfactant.

    PubMed

    Astete, Carlos E; Dolliver, Debra; Whaley, Meocha; Khachatryan, Lavrent; Sabliov, Cristina M

    2011-12-27

    The goal of the study was to synthesize a surfactant made of α-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC, and to use this surfactant to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and their physical properties (size, size distribution, morphology) were studied at different salt concentrations, surfactant concentrations, and polymer/surfactant ratios. EC surfactant was shown to form self-assembled nanostructures in water with a size of 22 to 138 nm in the presence of sodium chloride, or 12 to 31 nm when synthesis was carried out in sodium bicarbonate. Polymeric PLGA-EC nanoparticles presented a size of 90 to 126 nm for 40% to 120% mass ratio PLGA to surfactant. For the same mass ratios, the PLGA-Span80 formed particles measured 155 to 216 nm. Span80 formed bilayers, whereas EC formed monolayers at the interfaces. PLGA-EC nanoparticles and EC showed antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay measurements using UV and EPR techniques, antioxidant activity which is not characteristic to commercially available Span80. The thiobarbituric acid reactive substances (TBARS) assay for lipid peroxidation showed that PLGA nanoparticles with EC performed better as antioxidants than the EC nanoassembly or the free vitamin C. Nanoparticles were readily internalized by HepG2 cells and were localized in the cytoplasm. The newly synthesized EC surfactant was therefore found successful in forming uniform, small size polymeric nanoparticles of intrinsic antioxidant properties. PMID:22017172

  7. Encapsulation of the synthetic retinoids Am80 and LE540 into polymeric micelles and the retinoids' release control.

    PubMed

    Satoh, Taku; Higuchi, Yuriko; Kawakami, Shigeru; Hashida, Mitsuru; Kagechika, Hiroyuki; Shudo, Koichi; Yokoyama, Masayuki

    2009-06-19

    The objective of this study was to encapsulate two synthetic retinoids Am80 and LE540 into polymeric micelles and to control the retinoids' release rate in vitro. Highly efficient encapsulation yields of these retinoids were obtained for micelles forming from PEG-poly(benzyl aspartate) block copolymers in the wide range of the benzyl substitution degree. The in vitro release examination for LE540 indicated very stable encapsulation of this retinoid owing to its strongly hydrophobic nature. On the other hand, Am80 exhibited a rapid release in Dulbecco's phosphate buffer saline. An addition of a hydrophobic alkyl amine in the Am80-encapsulation process successfully led to significant retardation of the Am80 release rate. A mechanism of the retardation was considered an increase of Am80 hydrophobicity due to an ion-pairing with the alkyl amine. This paper is the first report on release control in the polymeric micelle carrier system through the ion-pairing between an encapsulated drug and an additive. PMID:19289148

  8. Pulmonary surfactant for neonatal respiratory disorders.

    PubMed

    Merrill, Jeffrey D; Ballard, Roberta A

    2003-04-01

    Surfactant therapy has revolutionized neonatal care and is used routinely for preterm infants with respiratory distress syndrome. Recent investigation has further elucidated the function of surfactant-associated proteins and their contribution toward surfactant and lung immune defense functions. As the field of neonatology moves away from intubation and mechanical ventilation of preterm infants at birth toward more aggressive use of nasal continuous positive airway pressure, the optimal timing of exogenous surfactant therapy remains unclear. Evidence suggests that preterm neonates with bronchopulmonary dysplasia and prolonged mechanical ventilation also experience surfactant dysfunction; however, exogenous surfactant therapy beyond the first week of life has not been well studied. Surfactant replacement therapy has been studied for use in other respiratory disorders, including meconium aspiration syndrome and pneumonia. Commercial surfactant preparations currently available are not optimal, given the variability of surfactant protein content and their susceptibility to inhibition. Further progress in the treatment of neonatal respiratory disorders may include the development of "designer" surfactant preparations. PMID:12640270

  9. Gold-loaded polymeric micelles for computed tomography-guided radiation therapy treatment and radiosensitization.

    PubMed

    Al Zaki, Ajlan; Joh, Daniel; Cheng, Zhiliang; De Barros, André Luís Branco; Kao, Gary; Dorsey, Jay; Tsourkas, Andrew

    2014-01-28

    Gold nanoparticles (AuNPs) have generated interest as both imaging and therapeutic agents. AuNPs are attractive for imaging applications since they are nontoxic and provide nearly three times greater X-ray attenuation per unit weight than iodine. As therapeutic agents, AuNPs can sensitize tumor cells to ionizing radiation. To create a nanoplatform that could simultaneously exhibit long circulation times, achieve appreciable tumor accumulation, generate computed tomography (CT) image contrast, and serve as a radiosensitizer, gold-loaded polymeric micelles (GPMs) were prepared. Specifically, 1.9 nm AuNPs were encapsulated within the hydrophobic core of micelles formed with the amphiphilic diblock copolymer poly(ethylene glycol)-b-poly(ε-capralactone). GPMs were produced with low polydispersity and mean hydrodynamic diameters ranging from 25 to 150 nm. Following intravenous injection, GPMs provided blood pool contrast for up to 24 h and improved the delineation of tumor margins via CT. Thus, GPM-enhanced CT imaging was used to guide radiation therapy delivered via a small animal radiation research platform. In combination with the radiosensitizing capabilities of gold, tumor-bearing mice exhibited a 1.7-fold improvement in the median survival time, compared with mice receiving radiation alone. It is envisioned that translation of these capabilities to human cancer patients could guide and enhance the efficacy of radiation therapy. PMID:24377302

  10. Surfactant-enhanced aquifier remediation

    SciTech Connect

    Fountain, J.C.

    1996-12-31

    Surfactants can be used to rapidly remove NAPL from contaminated aquifers. They are effective for virtually any organic contaminant. Use in LNAPL contaminated sites requires adequate hydraulic conductivity and control of flow using either hydraulic or physical methods. The presence of DNAPL requires consideration of vertical mobility; a competent confining layer (aquitard) is required if additional aquifers are present at greater depths. Surfactant processes, whether based upon mobilization or solubilization, can be effective at mass removal, but cannot be expected to provide resortation to drinking water standards. The fraction of mass removal, and the cost of remediation using surfactants are dependent upon a sites hydrogeology. Both minimization of cost and maximization of NAPL removal requires detailed characterization of sites contaminant distribution and hydrogeology. Assessment of the feasibility of surfactant-enhanced remediation is dependent upon a detailed site characterization.

  11. Protein recovery from surfactant precipitation.

    PubMed

    Cheng, Shu Ian; Stuckey, David C

    2011-01-01

    The recovery of lysozyme from an aqueous solution containing precipitated lysozyme-AOT complexes formed by the direct addition of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) to a lysozyme solution was studied using both solvents, and a counterionic surfactant. Ethanol,methanol and solvent mixtures dissolved the surfactant precipitate and recovered lysozyme as a solid. Recovery efficiency and protein stability varied with the type of solvent used. An entirely different method of recovery was also evaluated using a counterionic surfactant: tri-octylmethylammonium chloride (TOMAC) which bound to AOT releasing lysozyme into solution.Complete recovery (100%) of lysozyme was achieved at a molar ratio of 2:1(TOMAC:AOT), and the original protein activity was maintained in the final aqueous phase.The recovered lysozyme retained its secondary structure as observed in circular dichroism(CD) spectra. Specific activity studies show that counterionic surfactant extraction does not alter the biological activity of the enzyme. PMID:22235487

  12. A Computational Study of the Rheology and Structure of Surfactant Covered Droplets

    NASA Astrophysics Data System (ADS)

    Maia, Joao; Boromand, Arman

    Using different types of surface-active agents are ubiquitous in different industrial applications ranging from cosmetic and food industries to polymeric nano-composite and blends. This allows to produce stable multiphasic systems like foams and emulsions whose stability and shelf-life are directly determined by the efficiency and the type of the surfactant molecules. Moreover, presence and self-assembly of these species on an interface will display complex dynamics and structural evolution under different processing conditions. Analogous to bulk rheology of complex systems, surfactant covered interfaces will response to an external mechanical forces or deformation differently depends on the molecular configuration and topology of the system constituents. Although the effect of molecular configuration of the surface-active molecules on the planar interfaces has been studied both experimentally and computationally, it remains challenging from both experimental and computational aspects to track efficiency and effectiveness of different surfactant molecules with different molecular geometries on curved interfaces. Using Dissipative Particle Dynamics, we have studies effectiveness and efficiency of different surfactant molecules on a curved interface in equilibrium and far from equilibrium. Interfacial tension is calculated for linear and branched surfactant with different hydrophobic and hydrophilic tail and head groups with different branching densities. Deformation parameter and Taylor plots are obtained for individual surfactant molecules under shear flow.

  13. Synthesis, micellization behavior and alcohol induced amphipathic cellulose film of cellulose-based amphiphilic surfactant

    NASA Astrophysics Data System (ADS)

    Yang, Fang; Liu, Ya-nan; Yu, Jian-ling; Li, Hai-peng; Li, Gang

    2015-08-01

    This paper presented a novel preparation method of the cellulose-based amphiphilic surfactant, and the surfactant was used to prepare amphipathic cellulose membrane. The native cotton cellulose was tailored to cellulose segments in ionic liquid 1-butyl-3-methylimidazolium chloride. Then, the hydrophobic and hydrophilic modification of cellulose segments were carried out by esterification and graft polymerization of the ɛ-caprolactone (ɛ-CL) monomer onto the hydroxyl group of cellulose as well as sulphonation with sulfamic acid. The amphipathic cellulose membrane was made by cellulose-based amphiphilic surfactant cross-linking with glutaraldehyde. The molecular structure of amphipathic cellulose surfactant was confirmed by FT-IR, and its surface active properties were investigated by Wilhelmy plate method and Steady-state fluorescence probe method, respectively. Experimental results showed that cellulose-based amphiphilic surfactant caused low interfacial tension of 48.62 mN/m and its critical micelle concentration (cmc) value was 0.65 wt% when the grafting ratio of cellulose-g-PCL (poly-caprolactone) was 25.40%. The contact angle between a droplet of water and the surface of membrane was 90.84o, and the surface free energy of the alcohol induced cellulose membrane was 15.7 mJ/m2. This study may help increase using natural and biodegradable surface-activity materials with improved properties as surfactants.

  14. Effects of cationic ammonium gemini surfactant on micellization of PEO-PPO-PEO triblock copolymers in aqueous solution.

    PubMed

    Wang, Ruijuan; Tang, Yongqiang; Wang, Yilin

    2014-03-01

    Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) on the micellization of two triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), F127 (EO97PO69EO97) and P123 (EO20PO70EO20), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12-6-12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12-6-12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12-6-12 concentration increases and the ability of 12-6-12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12-6-12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12-6-12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12-6-12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12-6-12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12-6-12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12-6-12 micelles form with the increase of the 12-6-12 concentration. PMID:24528103

  15. Polymerization catalyst system

    SciTech Connect

    Graves, V.

    1986-03-25

    This patent describes a catalyst system for polymerizing at least one alpha-olefin under conditions characteristic of Ziegler polymerization. This system consists of: 1. a supported polymerization catalyst or mixture of polymerization catalysts prepared under anhydrous conditions by the sequential steps of: (a) preparing a slurry of inert particulate porous support material; (b) adding to the slurry a solution of an organomagnesium compound; (c) adding to the slurry and reacting a solution of a zirconium halide compound, hafnium compound or mixtures thereof; (d) adding to the slurry and reacting a halogenator; (e) adding to the slurry and reacting a tetravalent titanium halide compound; and (f) recovering solid catalyst component; 2. an organoaluminum compound; and 3. a promotor of chlorinated hydrocarbons having one to 20 carbon atoms.

  16. Pulmonary Surfactant: An Immunological Perspective

    PubMed Central

    Chroneos, Zissis C.; Sever-Chroneos, Zvjezdana; Shepherd, Virginia L.

    2009-01-01

    Pulmonary surfactant has two crucial roles in respiratory function; first, as a biophysical entity it reduces surface tension at the air water interface, facilitating gas exchange and alveolar stability during breathing, and, second, as an innate component of the lung's immune system it helps maintain sterility and balance immune reactions in the distal airways. Pulmonary surfactant consists of 90% lipids and 10% protein. There are four surfactant proteins named SP-A, SP-B, SP-C, and SP-D; their distinct interactions with surfactant phospholipids are necessary for the ultra-structural organization, stability, metabolism, and lowering of surface tension. In addition, SP-A and SP-D bind pathogens, inflict damage to microbial membranes, and regulate microbial phagocytosis and activation or deactivation of inflammatory responses by alveolar macrophages. SP-A and SP-D, also known as pulmonary collectins, mediate microbial phagocytosis via SP-A and SP-D receptors and the coordinated induction of other innate receptors. Several receptors (SP-R210, CD91/calreticulin, SIRPα, and toll-like receptors) mediate the immunological functions of SP-A and SP-D. However, accumulating evidence indicate that SP-B and SP-C and one or more lipid constituents of surfactant share similar immuno-regulatory properties as SP-A and SP-D. The present review discusses current knowledge on the interaction of surfactant with lung innate host defense. PMID:20054141

  17. Radical-Mediated Enzymatic Polymerizations

    PubMed Central

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  18. Radical-Mediated Enzymatic Polymerizations.

    PubMed

    Zavada, Scott R; Battsengel, Tsatsral; Scott, Timothy F

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes--catalytic proteins--owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol-ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  19. Hybrid surfactants decorated with copper ions: aggregation behavior, antimicrobial activity and anti-proliferative effect.

    PubMed

    Kaur, Gurpreet; Kumar, Sandeep; Dilbaghi, Neeraj; Bhanjana, Gaurav; Guru, Santosh Kumar; Bhushan, Shashi; Jaglan, Sundeep; Hassan, P A; Aswal, V K

    2016-09-14

    In the present study, the emphasis is laid on the self aggregation behavior of copper based inorganic-organic hybrids in aqueous media. The two complexes, cationic hexadecyl pyridinium trichloro cuprate (1 : 1), [Cp](+)[CuCl3](-), and bishexadecylpyridinium tetrachloro cuprate (2 : 1), [Cp2](2+)[CuCl4](2-), were synthesized using the ligand insertion method. The complexes were characterized using elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analysis. The copper complexes were found to be thermally stable, and in the solid state, they possessed the perovskite arrangement with [Cp2](2+)[CuCl4](2-) exhibiting superior stability and crystallinity. The self aggregation behavior of the prepared complexes was analyzed in solution phase (in aqueous medium) using surface tension, conductivity, XRD and small angle neutron scattering (SANS). The results show that the presence of copper as a co-ion in both the stoichiometries results in lower critical micellization concentrations than their precursor. Micellization was thermodynamically spontaneous and micelles formed were ellipsoidal in shape and underwent a prolate ellipsoidal growth with an increase in the concentration of metallosurfactant, as estimated from the SANS. Furthermore, these metallosurfactants were investigated for biocompatibility (using hemolytic assay), antimicrobial activity (fungus and bacteria) and cytotoxicity using human cancerous cells. The hemolysis activity was found to depend on the aggregated state of the metallosurfactants, displaying the highest activity in the monomeric state, and the minimum for post micellar concentrations. The surfactants were found to enhance the antibacterial activity by twofold or more, with the addition of metal in both the stoichiometries. On the contrary, for anticancer and antifungal activities, barely any regular trend or generalization could be obtained

  20. Amphiphilic Polymerizable Porphyrins Conjugated to a Polyglycerol Dendron Moiety as Functional Surfactants for Multifunctional Polymer Particles.

    PubMed

    Moriishi, Masako; Kitayama, Yukiya; Ooya, Tooru; Takeuchi, Toshifumi

    2015-12-01

    An amphiphilic polyglycerol dendron (PGD) conjugated porphyrin (PGP) bearing a polymerizable group was successfully synthesized. The PGP was used as an effective surfactant in emulsion and microsuspension polymerization systems to prepare styrene and methacrylate polymer particles, and the use of PGP provided the simple polymer particles with fluorescence derived from the metalloporphyrin and high colloidal stability due to the PGD. Furthermore, based on confocal laser scanning microscopy, we observed that the particles spontaneously formed a core-shell morphology with the PGP localized in the shell region during the polymerization and demonstrated drug loading in the shell region using rhodamine B as a model drug. The results indicate that the use of the functional surfactant PGP led to the preparation of multifunctional polymer particles from simple monomer species, and the resulting particles possessed high colloidal stability, fluorescence, and drug loading capability. PMID:26569154

  1. Biomimicry of surfactant protein C.

    PubMed

    Brown, Nathan J; Johansson, Jan; Barron, Annelise E

    2008-10-01

    Since the widespread use of exogenous lung surfactant to treat neonatal respiratory distress syndrome, premature infant survival and respiratory morbidity have dramatically improved. Despite the effectiveness of the animal-derived surfactant preparations, there still remain some concerns and difficulties associated with their use. This has prompted investigation into the creation of synthetic surfactant preparations. However, to date, no clinically used synthetic formulation is as effective as the natural material. This is largely because the previous synthetic formulations lacked analogues of the hydrophobic proteins of the lung surfactant system, SP-B and SP-C, which are critical functional constituents. As a result, recent investigation has turned toward the development of a new generation of synthetic, biomimetic surfactants that contain synthetic phospholipids along with a mimic of the hydrophobic protein portion of lung surfactant. In this Account, we detail our efforts in creating accurate mimics of SP-C for use in a synthetic surfactant replacement therapy. Despite SP-C's seemingly simple structure, the predominantly helical protein is extraordinarily challenging to work with given its extreme hydrophobicity and structural instability, which greatly complicates the creation of an effective SP-C analogue. Drawing inspiration from Nature, two promising biomimetic approaches have led to the creation of rationally designed biopolymers that recapitulate many of SP-C's molecular features. The first approach utilizes detailed SP-C structure-activity relationships and amino acid folding propensities to create a peptide-based analogue, SP-C33. In SP-C33, the problematic and metastable polyvaline helix is replaced with a structurally stable polyleucine helix and includes a well-placed positive charge to prevent aggregation. SP-C33 is structurally stable and eliminates the association propensity of the native protein. The second approach follows the same design

  2. Synthesis of Polymeric Microgels and their Characterization with Light Scattering

    NASA Astrophysics Data System (ADS)

    Gunder, Christian; Streletzky, Kiril A.; Freeman, Krista; Mino, Janna

    Polymeric microgels were synthesized in by chemically crosslinking hydroxypropylcellulose (HPC) chains in aqueous solutions of sodium hydroxide at temperatures above the low critical solution temperature (LCST) of HPC. In order to create a narrower size distribution of HPC microgels, surfactant was added. It was found that the LCST of the solution moved from 40C up to 80C with an increase in surfactant concentration from 0 to 12 g/l. Formed microgels were characterized by dynamic light scattering (DLS). Microgel solutions synthesized resulted in reasonably monodispersed nanoparticles with Rh of 90-150 nm below the transition, and Rh of 50-90 nm above the transition. The effect of synthesis temperature and crosslinker concentration on microgel size, polydispersity, and swelling ratio were also studied.

  3. Surfactant therapy and spontaneous diuresis.

    PubMed

    Bhat, R; John, E; Diaz-Blanco, J; Ortega, R; Fornell, L; Vidyasagar, D

    1989-03-01

    The effect of artificial surfactant therapy on renal function and the onset of spontaneous diuresis was prospectively evaluated in 19 infants with hyaline membrane disease in a double-blind, controlled study. Twelve infants were in the surfactant group; seven infants received placebo (0.9% saline solution). There was no difference in the time of onset of spontaneous diuresis (as defined by output greater than or equal to 80% of intake). The glomerular filtration rate, determined by endogenous creatinine clearance, was also similar in the surfactant- and placebo-treated infants during the first 3 days of life. The fractional excretion of sodium was significantly higher in the placebo group at 24 hours and 36 hours. Infants in the placebo group had a higher negative sodium balance than those in the surfactant group. Ventilatory status improved significantly soon after surfactant treatment, as evidenced by improvement in the alveolar/arterial oxygen pressure ratio and by a lower mean airway pressure. These data suggest that ventilatory status can be improved without diuresis; the factors that regulate diuresis are multiple and not fully understood. PMID:2646416

  4. Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30, 1993

    SciTech Connect

    Somasundaran, P.

    1994-07-01

    The aim of this research project is to investigate mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy will be determined. A multi-pronged approach consisting of micro & nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability; is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the first year of this three year contract, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Surfactants studied include alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amount of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed.

  5. Organocatalyzed Group Transfer Polymerization.

    PubMed

    Chen, Yougen; Kakuchi, Toyoji

    2016-08-01

    In contrast to the conventional group transfer polymerization (GTP) using a catalyst of either an anionic nucleophile or a transition-metal compound, the organocatalyzed GTP has to a great extent improved the living characteristics of the polymerization from the viewpoints of synthesizing structurally well-defined acrylic polymers and constructing defect-free polymer architectures. In this article, we describe the organocatalyzed GTP from a relatively personal perspective to provide our colleagues with a perspicuous and systematic overview on its recent progress as well as a reply to the curiosity of how excellently the organocatalysts have performed in this field. The stated perspectives of this review mainly cover five aspects, in terms of the assessment of the livingness of the polymerization, limit and scope of applicable monomers, mechanistic studies, control of the polymer structure, and a new GTP methodology involving the use of tris(pentafluorophenyl)borane and hydrosilane. PMID:27427399

  6. Polymer/surfactant transport in micellar flooding

    SciTech Connect

    Chiou, C.S.; Kellerhals, G.E.

    1981-10-01

    For the surfactant formulations used (particular surfactant concentration, surfactant type, cosolvent type, cosolvent concentration, etc.), the results show that surfactant systems containing polymer as a mobility control agent may exhibit adverse polymer transport behavior during flow through porous media. Polymer generally lagged behind the surfactant even though the two species were injected simultaneously in the surfactant slug. This poor polymer transport definitely could have a detrimental effect on the efficiency of a micellar flooding process in the field. Phase studies show that when some surfactant systems containing xanthan gum are mixed with crude oil at various salinities, a polymer-rich, gel-like phase forms. The polymer lag phenomenon in core tests can be related to phase separation due to divalent cations generated in situ as a result of ion exchange with the clays and the surfactant. 18 refs.

  7. CHARACTERISTICS OF SURFACTANTS IN TOXICITY IDENTIFICATION EVALUATIONS

    EPA Science Inventory

    The behavior of a number of anionic, nonionic and cationic surfactants in manipulations associated with toxicity identification evaluations was studied. t was found that toxicity of the surfactants could be removed from aqueous samples via aeration, apparently through sublation. ...

  8. Biofoams and natural protein surfactants

    PubMed Central

    Cooper, Alan; Kennedy, Malcolm W.

    2010-01-01

    Naturally occurring foam constituent and surfactant proteins with intriguing structures and functions are now being identified from a variety of biological sources. The ranaspumins from tropical frog foam nests comprise a range of proteins with a mixture of surfactant, carbohydrate binding and antimicrobial activities that together provide a stable, biocompatible, protective foam environment for developing eggs and embryos. Ranasmurfin, a blue protein from a different species of frog, displays a novel structure with a unique chromophoric crosslink. Latherin, primarily from horse sweat, but with similarities to salivary, oral and upper respiratory tract proteins, illustrates several potential roles for surfactant proteins in mammalian systems. These proteins, together with the previously discovered hydrophobins of fungi, throw new light on biomolecular processes at air–water and other interfaces. This review provides a perspective on these recent findings, focussing on structure and biophysical properties. PMID:20615601

  9. Removal of surfactants from hydrocarbons with alcohol

    SciTech Connect

    Aiello, R.P.; Poling, D.E.; Stefanidakis, G.

    1984-02-07

    A method is disclosed for removing hydrocarbon-soluble anionic surfactants from gasoline or kerosene boiling range hydrocarbons. The method comprises (a) contacting a hydrocarbon mixture containing surfactants with a lower alcohol which is miscible with the hydrocarbon mixture to extract the surfactants; (b) contacting the mixture with water or caustic solution to extract the lower alcohol and surfactants from the hydrocarbon mixture; (c) separating the water or caustic solution from the hydrocarbons; and (d) removing the hydrocarbons.

  10. Genetic Disorders of Surfactant Dysfunction

    PubMed Central

    Wert, Susan E.; Whitsett, Jeffrey A.; Nogee, Lawrence M.

    2010-01-01

    Mutations in the genes encoding the surfactant proteins B and C (SP-B and SP-C) and the phospholipid transporter, ABCA3, are associated with respiratory distress and interstitial lung disease in the pediatric population. Expression of these proteins is regulated developmentally, increasing with gestational age, and is critical for pulmonary surfactant function at birth. Pulmonary surfactant is a unique mixture of lipids and proteins that reduces surface tension at the air-liquid interface, preventing collapse of the lung at the end of expiration. SP-B and ABCA3 are required for the normal organization and packaging of surfactant phospholipids into specialized secretory organelles, known as lamellar bodies, while both SP-B and SP-C are important for adsorption of secreted surfactant phospholipids to the alveolar surface. In general, mutations in the SP-B gene SFTPB are associated with fatal respiratory distress in the neonatal period, and mutations in the SP-C gene SFTPC are more commonly associated with interstitial lung disease in older infants, children, and adults. Mutations in the ABCA3 gene are associated with both phenotypes. Despite this general classification, there is considerable overlap in the clinical and histologic characteristics of these genetic disorders. In this review, similarities and differences in the presentation of these disorders with an emphasis on their histochemical and ultrastructural features will be described, along with a brief discussion of surfactant metabolism. Mechanisms involved in the pathogenesis of lung disease caused by mutations in these genes will also be discussed. PMID:19220077

  11. Saponins: a renewable and biodegradable surfactant from its microwave-assisted extraction to the synthesis of monodisperse lattices.

    PubMed

    Schmitt, C; Grassl, B; Lespes, G; Desbrières, J; Pellerin, V; Reynaud, S; Gigault, J; Hackley, V A

    2014-03-10

    Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as biodegradable and renewable surfactants for emulsion polymerization. This chemical has been extracted from soapnuts by microwave assisted extraction and characterized in terms of surfactant properties prior to emulsion polymerization. The results in terms of particle size distribution and morphology control have been compared to those obtained with classical nonionic (NP40) or anionic (SDS) industrial surfactants. Microwave-extracted saponins were able to lead to latexes as stable as standard PS latex, as shown by the CMC and CCC measurements. The saponin-stabilized PS particles have been characterized in terms of particle size and distribution by Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation. Monomodal and monodispersed particles ranging from 250 to 480 nm in terms of diameter with a particle size distribution below 1.03 have been synthesized. PMID:24443771

  12. Formation of porous epoxy monolith via concentrated emulsion polymerization.

    PubMed

    Wang, Jianli; Zhang, Chen; Du, Zhongjie; Xiang, Aiming; Li, Hangquan

    2008-09-15

    Step polymerization was introduced into the concentrated emulsion templating method and was illustrated with the preparation of porous epoxy monolith. A solution of diglycidyl ether of bisphenol-A (DGEBA), its curing agent low molecular weight polyamide resin, and surfactant nonyl phenol polyoxyethylene ether in 4-methyl-2-pentanon as a solvent was used as the continuous phase, an aqueous suspension of colloidal silica as the dispersed phase of the concentrated emulsion. After the continuous phase polymerized and the dispersed phase removed, a porous material is obtained. The key point in this work is to find a compromise between the rates of curing and phase separating and thus achieve a kinetic stability of the concentrated emulsion. The effects of loading of colloidal silica, the pre-curing of the epoxy precursors, and the volume fraction of the dispersed phase were systematically investigated. PMID:18571192

  13. Agglutination of lung surfactant with glucan.

    PubMed Central

    De Lucca, A J; Brogden, K A; French, A D

    1992-01-01

    Respirable cotton dust, implicated in the pathogenesis of byssinosis, contains a number of bioactive compounds. These include lipopolysaccharide (LPS), tannins, bacterial peptides, byssinosin, iacinilene C, and 1,3-beta-D-glucan. The exact aetiological agent of byssinosis in such dust has not been definitively identified nor has its mechanism of action on lower lung surfaces been determined. In the present study 1,3-beta-D-glucan, Enterobacter agglomerans LPS, and ovine pulmonary surfactant were mixed in varying combinations. After incubation, their characteristics were determined by sucrose density centrifugation, TLC, and carbohydrate analysis. Precipitates were found in mixtures containing surfactant-glucan and surfactant-glucan-LPS, but not in surfactant-LPS. Precipitates were not seen in the surfactant, LPS, and glucan controls. The formation of a precipitate did not increase the density of the surfactant glucan mixture when compared by density gradient centrifugation with the surfactant control. The interaction between surfactant and glucan was analysed by molecular modelling. The energy of a surfactant-glucan complex (60.07 kcal/mol) was calculated to be much lower than the sum of glucan (47.09 kcal/mol) and surfactant (30.98 kcal/mol) when added separately. The results indicate that 1,3-beta-D-glucan does interact with surfactant and this complex may play a part in the pathogenesis of byssinosis by altering lung physiology maintained by pulmonary surfactant. Images PMID:1463675

  14. SURFACTANT ENHANCED AQUIFER REMEDIATION WITH SURFACTANT REGENERATION/REUSE

    EPA Science Inventory

    A demonstration of surfactant-enhanced aquifer remediation was conducted during the spring of 1999 at Marine Corps Base, Camp LeJeune, NC. A PCE-DNAPL zone was identified and delineated by extensive soil sampling in 1997, and was further characteized by a partitioning interwell t...

  15. Surfactant-Bound Monolithic Columns for Separation of Proteins in Capillary High Performance Liquid Chromatography

    PubMed Central

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Simmons, Robert; Shamsi, Shahab A.

    2011-01-01

    A surfactant bound monolithic stationary phase based on the co-polymerization of 11-acrylamino-undecanoic acid (AAUA) is designed for capillary high performance liquid chromatography (HPLC). Using D-optimal design, the effect of the polymerization mixture (concentrations of monomer, crosslinker and porogens) on the chromatographic performance (resolution and analysis time) of the AAUA-EDMA monolithic column was evaluated. The polymerization mixture was optimized using three proteins as model test solutes. The D-optimal design indicates a strong dependence of chromatographic parameters on the concentration of porogens (1,4-butanediol and water) in the polymerization mixture. Optimized solutions for fast separation and high resolution separation, respectively, were obtained using the proposed multivariate optimization. Differences less than 6.8% between the predicted and the experimental values in terms of resolution and retention time indeed confirmed that the proposed approach is practical. Using the optimized column, fast separation of proteins could be obtained in 2.5 min, and a tryptic digest of myoglobin was successfully separated on the high resolution column. The physical properties (i.e. morphology, porosity and permeability) of the optimized monolithic column were thoroughly investigated. It appears that this surfactant-bound monolith may have a great potential as a new generation of capillary HPLC stationary phase. PMID:20031139

  16. Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

    PubMed

    Tawfik, Salah M; Hefni, Hassan H

    2016-01-01

    New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant. PMID:26478092

  17. Variable Effect during Polymerization

    ERIC Educational Resources Information Center

    Lunsford, S. K.

    2005-01-01

    An experiment performing the polymerization of 3-methylthiophene(P-3MT) onto the conditions for the selective electrode to determine the catechol by using cyclic voltammetry was performed. The P-3MT formed under optimized conditions improved electrochemical reversibility, selectivity and reproducibility for the detection of the catechol.

  18. Polymerized and functionalized triglycerides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant oils are useful sustainable raw materials for the development of new chemical products. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a new method for polymerizing epoxidized triglycerides with the use of fluorosulfonic acid. Depending on the ...

  19. Programmable Supramolecular Polymerizations.

    PubMed

    van der Zwaag, Daan; de Greef, Tom F A; Meijer, E W

    2015-07-13

    Living large: Rational design of self-assembly pathways has been demonstrated in supramolecular polymers. By controlling the concentration of an aggregation-competent monomer through intramolecular interactions, living supramolecular polymerization conditions were achieved. This universal approach can be used to obtain aggregates of well-defined length and narrow dispersity, and allows access to new supramolecular polymer architectures. PMID:26095705

  20. Effective integrative supramolecular polymerization.

    PubMed

    Zhang, Qiwei; Tian, He

    2014-09-26

    Exercise control: By taking advantage of self-sorting processes among host-guest components, a controlled supramolecular polymerization can be realized, as demonstrated recently with the preparation of a cucurbit[n]uril-based supramolecular polymer. This method may be used for the design of more ordered supramolecular polymers from complex and discrete components. PMID:25080388

  1. Protein specific polymeric immunomicrospheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)

    1980-01-01

    Small, round, bio-compatible microspheres capable of covalently bonding proteins and having a uniform diameter below about 3500 A are prepared by substantially instantaneously initiating polymerization of an aqueous emulsion containing no more than 35% total monomer including an acrylic monomer substituted with a covalently bondable group such as hydroxyl, amino or carboxyl and a minor amount of a cross-linking agent.

  2. Surfactant and allergic airway inflammation.

    PubMed

    Winkler, Carla; Hohlfeld, Jens M

    2013-01-01

    Pulmonary surfactant is a complex mixture of unique proteins and lipids that covers the airway lumen. Surfactant prevents alveolar collapse and maintains airway patency by reducing surface tension at the air-liquid interface. Furthermore, it provides a defence against antigen uptake by binding foreign particles and enhancing cellular immune responses. Allergic asthma is associated with chronic airway inflammation and presents with episodes of airway narrowing. The pulmonary inflammation and bronchoconstriction can be triggered by exposure to allergens or pathogens present in the inhaled air. Pulmonary surfactant has the potential to interact with various immune cells which orchestrate allergen- or pathogen-driven episodes of airway inflammation. The complex nature of surfactant allows multiple sites of interaction, but also makes it susceptible to external alterations, which potentially impair its function. This duality of modulating airway physiology and immunology during inflammatory conditions, while at the same time being prone to alterations accompanied by restricted function, has stimulated numerous studies in recent decades, which are reviewed in this article. PMID:23896983

  3. Aerosol delivery of synthetic lung surfactant

    PubMed Central

    Hernández-Juviel, José M.; Waring, Alan J.

    2014-01-01

    Background. Nasal continuous positive airway pressure (nCPAP) is a widely accepted technique of non-invasive respiratory support in premature infants with respiratory distress syndrome due to lack of lung surfactant. If this approach fails, the next step is often intubation, mechanical ventilation (MV) and intratracheal instillation of clinical lung surfactant. Objective. To investigate whether aerosol delivery of advanced synthetic lung surfactant, consisting of peptide mimics of surfactant proteins B and C (SP-B and SP-C) and synthetic lipids, during nCPAP improves lung function in surfactant-deficient rabbits. Methods. Experimental synthetic lung surfactants were produced by formulating 3% Super Mini-B peptide (SMB surfactant), a highly surface active SP-B mimic, and a combination of 1.5% SMB and 1.5% of the SP-C mimic SP-Css ion-lock 1 (BC surfactant), with a synthetic lipid mixture. After testing aerosol generation using a vibrating membrane nebulizer and aerosol conditioning (particle size, surfactant composition and surface activity), we investigated the effects of aerosol delivery of synthetic SMB and BC surfactant preparations on oxygenation and lung compliance in saline-lavaged, surfactant-deficient rabbits, supported with either nCPAP or MV. Results. Particle size distribution of the surfactant aerosols was within the 1–3 µm distribution range and surfactant activity was not affected by aerosolization. At a dose equivalent to clinical surfactant therapy in premature infants (100 mg/kg), aerosol delivery of both synthetic surfactant preparations led to a quick and clinically relevant improvement in oxygenation and lung compliance in the rabbits. Lung function recovered to a greater extent in rabbits supported with MV than with nCPAP. BC surfactant outperformed SMB surfactant in improving lung function and was associated with higher phospholipid values in bronchoalveolar lavage fluid; these findings were irrespective of the type of ventilatory support

  4. Emulsion polymerization synthesis of cationic polymer latex in an ultrasonic field.

    PubMed

    Bradley, Melanie; Grieser, Franz

    2002-07-01

    Poly(methyl methacrylate) and poly(butyl acrylate) lattices have been synthesized under ultrasonic irradiation in the presence of a cationic surfactant, dodecyltrimethylammonium chloride. The polymerization of oil-in-water emulsions of monomeric species was carried out at 30 degrees C (+/-5 degrees C) in the absence of a chemical initiator. The lattices were formed as stable dispersions with particle diameters spanning the range of 40-150 nm and with polymer molecular weights greater than 10(6) g mol(-1). The results obtained strongly support a polymerization process involving a miniemulsion system, in which continuous nucleation of particles takes place throughout the monomer to polymer conversion reaction. PMID:16290704

  5. Preparation and spectral characterization of polymeric nanocapsules containing DR1 organic dye

    NASA Astrophysics Data System (ADS)

    Sharifimehr, Mohammad Reza; Ghanbari, Khadijeh; Ayoubi, Kazem; Mohajerani, Ezedin

    2015-07-01

    In order to provide necessary degree of freedom for organic dye molecules in optical applications and also for safety improvement, water insoluble Disperse Red 1 (DR1) dye molecules were placed inside the polymeric nanocapsules along with suitable surfactants and using controlled phase-separation method. TEM images were used to investigate the morphology of prepared nanocapsules. Total dye concentration for a solution consist of obtained polymeric nanocapsules was determined using decomposition of nanocapsules and a reference absorption spectrum. Absorption spectrum of a solution containing DR1 and dichloromethane was also compared with prepared nanocapsules at the same dye concentration, thereby a red-shift in absorption spectrum was detected.

  6. Interactions of surfactants with lipid membranes.

    PubMed

    Heerklotz, Heiko

    2008-01-01

    Surfactants are surface-active, amphiphilic compounds that are water-soluble in the micro- to millimolar range, and self-assemble to form micelles or other aggregates above a critical concentration. This definition comprises synthetic detergents as well as amphiphilic peptides and lipopeptides, bile salts and many other compounds. This paper reviews the biophysics of the interactions of surfactants with membranes of insoluble, naturally occurring lipids. It discusses structural, thermodynamic and kinetic aspects of membrane-water partitioning, changes in membrane properties induced by surfactants, membrane solubilisation to micelles and other phases formed by lipid-surfactant systems. Each section defines and derives key parameters, mentions experimental methods for their measurement and compiles and discusses published data. Additionally, a brief overview is given of surfactant-like effects in biological systems, technical applications of surfactants that involve membrane interactions, and surfactant-based protocols to study biological membranes. PMID:19079805

  7. An anionic surfactant for EOR applications

    NASA Astrophysics Data System (ADS)

    Sagir, Muhammad; Tan, Isa M.; Mushtaq, Muhammad

    2014-10-01

    This work is to investigate the new anionic surfactants for the Enhanced Oil Recovery (EOR) application. Sulfonated anionic surfactant was produced by attaching SO3 to an ethoxylated alcohol to increase the performance of the surfactant. Methallyl chloride and ethoxylated alcohol was reacted followed by the reaction with sodium bisulfite to produce anionic sulfonated surfactant in 80.3 % yield. The sulfonation reaction parameters such as reactants mole ratio, reaction temperature and catalyst amount were optimized. The generation and stability of foam from the synthesized surfactant is also tested and results are reported. The synthesized novel surfactant was further investigated for the effect on the CO2 mobility in porous media and the findings are presented here. This in house developed surfactant has a great potential for CO2- EOR applications.

  8. Synthesis of Hemoglobin Conjugated Polymeric Micelle: A ZnPc Carrier with Oxygen Self-Compensating Ability for Photodynamic Therapy.

    PubMed

    Wang, Shasha; Yuan, Fang; Chen, Kui; Chen, Gaojian; Tu, Kehua; Wang, Hongjun; Wang, Li-Qun

    2015-09-14

    Photodynamic therapy (PDT) is a promising singlet oxygen ((1)O2) mediated clinical treatment for many tumors. As the source of (1)O2, oxygen plays an important role in the curative effect of PDT. However, the facts of photochemical depletion of oxygen and the intrinsic hypoxic microenvironment of tumors remain the major challenges. In this work, a novel photosensitizer carrier with oxygen self-compensating ability was designed for PDT. It was synthesized via chemical conjugation of hemoglobin (Hb) to polymeric micelles formed by triblock copolymers of poly(ethylene glycol)-block-poly(acrylic acid)-block-polystyrene (PEG-b-PAA-b-PS). The PEG-b-PAA-b-PS and resultant micelles in aqueous solution were comprehensively characterized by means of FTIR, (1)H NMR, GPC, DLS, TEM, and fluorescence spectroscopy. The oxygen-binding capacity and antioxidative activity of the Hb conjugated micelles were evaluated via UV-vis spectroscopy. In addition, compared with the control micelles without Hb, the Hb conjugated photosensitizer carrier was able to generate more (1)O2 and exert greater photocytotoxicity on Hela cells in vitro. PMID:26207413

  9. Self-assembled polymeric nanoparticles as new, smart contrast agents for cancer early detection using magnetic resonance imaging

    PubMed Central

    Mouffouk, Fouzi; Simão, Teresa; Dornelles, Daniel F; Lopes, André D; Sau, Pablo; Martins, Jorge; Abu-Salah, Khalid M; Alrokayan, Salman A; Rosa da Costa, Ana M; dos Santos, Nuno R

    2015-01-01

    Early cancer detection is a major factor in the reduction of mortality and cancer management cost. Here we developed a smart and targeted micelle-based contrast agent for magnetic resonance imaging (MRI), able to turn on its imaging capability in the presence of acidic cancer tissues. This smart contrast agent consists of pH-sensitive polymeric micelles formed by self-assembly of a diblock copolymer (poly(ethyleneglycol-b-trimethylsilyl methacrylate)), loaded with a gadolinium hydrophobic complex (tBuBipyGd) and exploits the acidic pH in cancer tissues. In vitro MRI experiments showed that tBuBipyGd-loaded micelles were pH-sensitive, as they turned on their imaging capability only in an acidic microenvironment. The micelle-targeting ability toward cancer cells was enhanced by conjugation with an antibody against the MUC1 protein. The ability of our antibody-decorated micelles to be switched on in acidic microenvironments and to target cancer cells expressing specific antigens, together with its high Gd(III) content and its small size (35–40 nm) reveals their potential use for early cancer detection by MRI. PMID:25565804

  10. A COMPOSITE HOLLOW FIBER MEMBRANE-BASED PERVAPORATION PROCESS FOR SEPARATION OF VOCS FROM AQUEOUS SURFACTANT SOLUTIONS. (R825511C027)

    EPA Science Inventory

    The separation and recovery of VOCs from surfactant-containing aqueous solutions by a composite hollow fiber membrane-based pervaporation process has been studied. The process employed hydrophobic microporous polypropylene hollow fibers having a thin plasma polymerized silicon...

  11. The Role of Surfactant in Respiratory Distress Syndrome

    PubMed Central

    Ma, Christopher Cheng-Hwa; Ma, Sze

    2012-01-01

    The key feature of respiratory distress syndrome (RDS) is the insufficient production of surfactant in the lungs of preterm infants. As a result, researchers have looked into the possibility of surfactant replacement therapy as a means of preventing and treating RDS. We sought to identify the role of surfactant in the prevention and management of RDS, comparing the various types, doses, and modes of administration, and the recent development. A PubMed search was carried out up to March 2012 using phrases: surfactant, respiratory distress syndrome, protein-containing surfactant, protein-free surfactant, natural surfactant, animal-derived surfactant, synthetic surfactant, lucinactant, surfaxin, surfactant protein-B, surfactant protein-C. Natural, or animal-derived, surfactant is currently the surfactant of choice in comparison to protein-free synthetic surfactant. However, it is hoped that the development of protein-containing synthetic surfactant, such as lucinactant, will rival the efficacy of natural surfactants, but without the risks of their possible side effects. Administration techniques have also been developed with nasal continuous positive airway pressure (nCPAP) and selective surfactant administration now recommended; multiple surfactant doses have also reported better outcomes. An aerosolised form of surfactant is being trialled in the hope that surfactant can be administered in a non-invasive way. Overall, the advancement, concerning the structure of surfactant and its mode of administration, offers an encouraging future in the management of RDS. PMID:22859930

  12. Research on interfacial polymerization of pyrrole assist with Span80 system

    NASA Astrophysics Data System (ADS)

    Yang, Q. H.; Tu, Z. Y.; Zhao, N. Y.

    2016-07-01

    With assistance of surfactants, self-assembled Polypyrrole (PPy) film was prepared via oil / water interfacial polymerization. The chemical structure and morphologies of the obtained samples have been characterized by Fourier transform infrared (FT-IR) and Scanning Electron Microscope (SEM), respectively. The electrochemical performance recorded on an electrochemical workstation, mainly includes cyclic voltammetry (CV) tests. The prepared PPy film has its own extremely vesicular structures from results and indicates by using different concentration surfactant Span80. The PPy film prepared 25 °C with 3.32 g/L Span80 (surpass its critical micelle concentration) as a surfactant possess a supernal specific capacitance of 368.18 F/g at a scan rate 50 mV/s in 1 M NaNO3 aqueous solution at.

  13. Hydrophobic and high adhesive polyaniline layer of rectangular microtubes fabricated by a modified interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhou, Chuanqiang; Gong, Xiangxiang; Qu, Yun; Han, Jie

    2016-08-01

    A modified interfacial polymerization of aniline is developed to fabricate hydrophobic and adhesive polyaniline (PANI) layer of rectangular microtubes on the glass substrate. The modified method uses pentanol as an organic medium to dissolve aniline monomer, with the water film of oxidant and surfactant on the glass substrate as water phase. The effects of some synthetic parameters (such as monomer concentration, alcohol molecular structure and surfactant type) on the morphology of PANI layer are studied for better understanding the fabrication of PANI nanostructures on the film. The alcohol molecular structure plays key role for the supermolecular assembly of PANI chains into nanostructures, while the surfactant may direct the array and deposition of these nanostructures on the glass substrate. The formation reason of PANI rectangular sub-microtubes is roughly interpreted according to our previous works. Wettability experiment indicates that the as-prepared PANI layer exhibits excellent hydrophobicity and high adhesive properties to water drop.

  14. Hollow hybrid polymer-graphene oxide nanoparticles via Pickering miniemulsion polymerization.

    PubMed

    Thickett, Stuart C; Wood, Noriko; Ng, Yun Hau; Zetterlund, Per B

    2014-08-01

    The preparation of hybrid hollow capsules consisting of a cross-linked polymer shell and a coating of graphene oxide (GO) is demonstrated. The capsules are prepared by Pickering miniemulsion polymerization, exploiting the surface activity of GO for its use as a colloidal surfactant. This approach represents a simple and convenient route towards hollow carbon nanostructures for a variety of applications. The incorporation of surface-modified TiO2 nanoparticles into the interior of these capsules was also demonstrated. PMID:24976455

  15. Frontal Polymerization in Microgravity

    NASA Technical Reports Server (NTRS)

    Pojman, John A.

    1999-01-01

    Frontal polymerization systems, with their inherent large thermal and compositional gradients, are greatly affected by buoyancy-driven convection. Sounding rocket experiments allowed the preparation of benchmark materials and demonstrated that methods to suppress the Rayleigh-Taylor instability in ground-based research did not significantly affect the molecular weight of the polymer. Experiments under weightlessness show clearly that bubbles produced during the reaction interact very differently than under 1 g.

  16. Surface polymerization agents

    SciTech Connect

    Taylor, C.; Wilkerson, C.

    1996-12-01

    This is the final report of a 1-year, Laboratory-Directed R&D project at LANL. A joint technical demonstration was proposed between US Army Missile Command (Redstone Arsenal) and LANL. Objective was to demonstrate that an unmanned vehicle or missile could be used as a platform to deliver a surface polymerization agent in such a manner as to obstruct the filters of an air-breathing mechanism, resulting in operational failure.

  17. A study of the microstructural and diffusion properties of poly(vinyl alcohol) cryogels containing surfactant supramolecular aggregates.

    PubMed

    Tedeschi, Annamaria; Auriemma, Finizia; Ricciardi, Rosa; Mangiapia, Gaetano; Trifuoggi, Marco; Franco, Lorenzo; Rosa, Claudio De; Heenan, Richard K; Paduano, Luigi; D'Errico, Gerardino

    2006-11-23

    Surfactant-containing poly(vinyl alcohol) (PVA) cryogels have been prepared by drying and reswelling hydrogel patches, previously obtained by the freeze/thaw procedure, in decyltrimethylammonium bromide (C10TAB) aqueous solutions. The microstructural and diffusive properties of the resulting material have been characterized by a combined experimental strategy. Gravimetric measurements show that the cryogel maximum swelling is not affected by the surfactant. The surfactant concentration within the cryogel, measured by ion chromatography, is the same as that in the rehydrating surfactant solution. Electron paramagnetic resonance (EPR) spin-probe and small-angle neutron scattering (SANS) measurements show that surfactant self-aggregation in the gel is similar to that in water, occurring at the same critical concentration and resulting in the formation of micellar aggregates whose structure is not affected by the cryogel polymeric scaffold. However, both the micelle intradiffusion coefficients, measured by PGSE-NMR, and the spin-probe correlation times, measured by EPR, indicate that dynamic processes in the hydrogel are much slower than in bulk water. A quantitative analysis of these results suggests that the cryogel polymer-poor domains, in which surfactant molecules are solubilized, have an average dimension of approximately 0.1 microm. Interestingly the experimental data also show that the polymer-poor phase contains more polymer than expected, suggesting that the spinodal decomposition, which occurs during the freezing step of cryogel preparation, is not complete or prevented by ice formation. PMID:17107141

  18. Surfactant transport on viscous bilayers

    NASA Astrophysics Data System (ADS)

    Matar, Omar; Craster, Richard; Warner, Mark

    2001-11-01

    We model the external delivery of surfactant to pulmonary airways, an integral part of Surfactant Replacement Therapy (SRT), a method of treatment of Respiratory Distress Syndrome in neonates. We examine the spreading dynamics of insoluble surfactant by Marangoni stresses along the mucus-perciliary liquid bilayers that line the inside of airways. The bilayer is modelled as a thin highly viscous mucus surface film (mucus) overlying a much less viscous perciliary liquid layer (PCL); this is appropriate for small airways. By exploiting this large viscosity constrast, a variant of standard lubrication theory is adopted wherein terms, which would have otherwise been neglected in the lubrication approximation, are promoted in order to model correctly the presence of the mucus. Inclusion of van der Waals forces in the model permit the study of the effect of this mucus 'skin' on the possibility of bilayer rupture, a potential cause of failure of SRT. We find that increasing the viscosity contrast and initial mucus layer thickness delays the onset of rupture, while increasing the relative significance of Marangoni stresses leads to more marked thinning and rapid bilayer rupture [1]. [1] O. K. Matar, R. V. Craster and M. R. Warner, submitted to J. Fluid Mech. (2001).

  19. Hydrodynamic size of DNA/cationic gemini surfactant complex as a function of surfactant structure.

    PubMed

    Devínsky, Ferdinand; Pisárcik, Martin; Lacko, Ivan

    2009-06-01

    The present study deals with the determination of hydrodynamic size of DNA/cationic gemini surfactant complex in sodium bromide solution using the dynamic light scattering method. Cationic gemini surfactants with polymethylene spacer of variable length were used for the interaction with DNA. The scattering experiments were performed at constant DNA and sodium bromide concentrations and variable surfactant concentration in the premicellar and micellar regions as a function of surfactant spacer length. It was found that the DNA conformation strongly depends on the polymethylene spacer length as well as on the surfactant concentration relative to the surfactant critical micelle concentration. Gemini surfactant molecules with 4 methylene groups in the spacer were found to be the least efficient DNA compacting agent in the region above the surfactant cmc. Gemini molecules with the shortest spacer length (2 methylene groups) and the longest spacer length (8 methylene groups) investigated showed the most efficient DNA compaction ability. PMID:19592712

  20. Cationic additives in nanosystems activate cytotoxicity and inflammatory response of human neutrophils: lipid nanoparticles versus polymeric nanoparticles

    PubMed Central

    Hwang, Tsong-Long; Aljuffali, Ibrahim A; Lin, Chwan-Fwu; Chang, Yuan-Ting; Fang, Jia-You

    2015-01-01

    This report compares the effect of lipid and polymeric nanoparticles upon human neutrophils in the presence of cationic surfactants. Nanostructured lipid carriers and poly(lactic-co-glycolic) acid nanoparticles were manufactured as lipid and polymeric systems, respectively. Some cytotoxic and proinflammatory mediators such as lactate dehydrogenase (LDH), elastase, O2•−, and intracellular Ca2+ were examined. The nanoparticles showed a size of 170–225 nm. Incorporation of cetyltrimethylammonium bromide or soyaethyl morpholinium ethosulfate, the cationic surfactant, converted zeta potential from a negative to a positive charge. Nanoparticles without cationic surfactants revealed a negligible change on immune and inflammatory responses. Cationic surfactants in both nanoparticulate and free forms induced cell death and the release of mediators. Lipid nanoparticles generally demonstrated a greater response compared to polymeric nanoparticles. The neutrophil morphology observed by electron microscopy confirmed this trend. Cetyltrimethylammonium bromide as the coating material showed more significant activation of neutrophils than soyaethyl morpholinium ethosulfate. Confocal microscope imaging displayed a limited internalization of nanoparticles into neutrophils. It is proposed that cationic nanoparticles interact with the cell membrane, triggering membrane disruption and the following Ca2+ influx. The elevation of intracellular Ca2+ induces degranulation and oxidative stress. The consequence of these effects is cytotoxicity and cell death. Caution should be taken when selecting feasible nanoparticulate formulations and cationic additives for consideration of applicability and toxicity. PMID:25609950

  1. Cationic additives in nanosystems activate cytotoxicity and inflammatory response of human neutrophils: lipid nanoparticles versus polymeric nanoparticles.

    PubMed

    Hwang, Tsong-Long; Aljuffali, Ibrahim A; Lin, Chwan-Fwu; Chang, Yuan-Ting; Fang, Jia-You

    2015-01-01

    This report compares the effect of lipid and polymeric nanoparticles upon human neutrophils in the presence of cationic surfactants. Nanostructured lipid carriers and poly(lactic-co-glycolic) acid nanoparticles were manufactured as lipid and polymeric systems, respectively. Some cytotoxic and proinflammatory mediators such as lactate dehydrogenase (LDH), elastase, O2(•-), and intracellular Ca(2+) were examined. The nanoparticles showed a size of 170-225 nm. Incorporation of cetyltrimethylammonium bromide or soyaethyl morpholinium ethosulfate, the cationic surfactant, converted zeta potential from a negative to a positive charge. Nanoparticles without cationic surfactants revealed a negligible change on immune and inflammatory responses. Cationic surfactants in both nanoparticulate and free forms induced cell death and the release of mediators. Lipid nanoparticles generally demonstrated a greater response compared to polymeric nanoparticles. The neutrophil morphology observed by electron microscopy confirmed this trend. Cetyltrimethylammonium bromide as the coating material showed more significant activation of neutrophils than soyaethyl morpholinium ethosulfate. Confocal microscope imaging displayed a limited internalization of nanoparticles into neutrophils. It is proposed that cationic nanoparticles interact with the cell membrane, triggering membrane disruption and the following Ca(2+) influx. The elevation of intracellular Ca(2+) induces degranulation and oxidative stress. The consequence of these effects is cytotoxicity and cell death. Caution should be taken when selecting feasible nanoparticulate formulations and cationic additives for consideration of applicability and toxicity. PMID:25609950

  2. Formation of Worm-Like Micelles in Mixed N-Hexadecyl-N-Methylpyrrolidinium Bromide-Based Cationic Surfactant and Anionic Surfactant Systems

    PubMed Central

    Dai, Caili; Yan, Zhihu; You, Qing; Du, Mingyong; Zhao, Mingwei

    2014-01-01

    Through the descriptive and rheological characterization of worm-like micelles formed by N-hexadecyl-N-methylpyrrolidinium bromide and sodium laurate, the formation and properties of the worm-like micelles were affected by the concentrations of sodium laurate and temperature. Additionally, cryogenic transmission electron microscopy images further validated the formation of worm-like micelles. PMID:25019152

  3. Surfactant adsorption to soil components and soils.

    PubMed

    Ishiguro, Munehide; Koopal, Luuk K

    2016-05-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management. PMID

  4. Surfactant Therapy of ALI and ARDS

    PubMed Central

    Raghavendran, K; Willson, D; Notter, RH

    2011-01-01

    This article examines exogenous lung surfactant replacement therapy and its utility in mitigating clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). Biophysical research has documented that lung surfactant dysfunction can be reversed or mitigated by increasing surfactant concentration, and multiple studies in animals with ALI/ARDS have shown that respiratory function and pulmonary mechanics in vivo can be improved by exogenous surfactant administration. Exogenous surfactant therapy is a routine intervention in neonatal intensive care, and is life-saving in preventing or treating the neonatal respiratory distress syndrome (NRDS) in premature infants. In applications relevant for lung injury-related respiratory failure and ALI/ARDS, surfactant therapy has been shown to be beneficial in term infants with pneumonia and meconium aspiration lung injury, and in children up to age 21 with direct pulmonary forms of ALI/ARDS. However, extension of exogenous surfactant therapy to adults with respiratory failure and clinical ALI/ARDS remains a challenge. Coverage here reviews clinical studies of surfactant therapy in pediatric and adult patients with ALI/ARDS, particularly focusing on its potential advantages in patients with direct pulmonary forms of these syndromes. Also discussed is the rationale for mechanism-based therapies utilizing exogenous surfactant in combination with agents targeting other aspects of the multifaceted pathophysiology of inflammatory lung injury. Additional factors affecting the efficacy of exogenous surfactant therapy in ALI/ARDS are also described, including the difficulty of effectively delivering surfactants to injured lungs and the existence of activity differences between clinical surfactant drugs. PMID:21742216

  5. Intensification of evaporation processes using surfactants

    NASA Astrophysics Data System (ADS)

    Sharifullin, V. N.; Sharifullin, A. V.

    2015-06-01

    The effect of a group of low molecular surfactants on the evaporation rate during nucleate boiling of water is investigated. It is found that the vaporization rate and heat flux from the heater increase by 4-8% in an electric boiler with surfactants. The analysis of the process based on the model of the phase contact surface restoration made it possible to formulate the mechanism of the effect of considered surfactants.

  6. Acrylic esters in radiation polymerization

    SciTech Connect

    Fomina, N.V.; Khoromskaya, V.A.; Shiryaeva, G.V.

    1988-03-01

    The radiation behavior of (meth)acrylic esters of varying structure was studied. It was shown that in radiation polymerization, in contrast to thermal polymerization, the structure of the ester part can significantly affect the reaction rate and capacity for polymerization in the presence of oxygen. The experimental data are explained from the point of view of consideration of nonvalence effects of the substitutent on the reactivity of the double bond.

  7. Polymerization Evaluation by Spectrophotometric Measurements.

    ERIC Educational Resources Information Center

    Dunach, Jaume

    1985-01-01

    Discusses polymerization evaluation by spectrophotometric measurements by considering: (1) association degrees and molar absorptivities; (2) association degrees and equilibrium constants; and (3) absorbance and equilibrium constants. (JN)

  8. Cholesterol-mediated surfactant dysfunction is mitigated by surfactant protein A.

    PubMed

    Hiansen, Joshua Qua; Keating, Eleonora; Aspros, Alex; Yao, Li-Juan; Bosma, Karen J; Yamashita, Cory M; Lewis, James F; Veldhuizen, Ruud A W

    2015-03-01

    The ability of pulmonary surfactant to reduce surface tension at the alveolar surface is impaired in various lung diseases. Recent animal studies indicate that elevated levels of cholesterol within surfactant may contribute to its inhibition. It was hypothesized that elevated cholesterol levels within surfactant inhibit human surfactant biophysical function and that these effects can be reversed by surfactant protein A (SP-A). The initial experiment examined the function of surfactant from mechanically ventilated trauma patients in the presence and absence of a cholesterol sequestering agent, methyl-β-cyclodextrin. The results demonstrated improved surface activity when cholesterol was sequestered in vitro using a captive bubble surfactometer (CBS). These results were explored further by reconstitution of surfactant with various concentrations of cholesterol with and without SP-A, and testing of the functionality of these samples in vitro with the CBS and in vivo using surfactant depleted rats. Overall, the results consistently demonstrated that surfactant function was inhibited by levels of cholesterol of 10% (w/w phospholipid) but this inhibition was mitigated by the presence of SP-A. It is concluded that cholesterol-induced surfactant inhibition can actively contribute to physiological impairment of the lungs in mechanically ventilated patients and that SP-A levels may be important to maintain surfactant function in the presence of high cholesterol within surfactant. PMID:25522687

  9. Continuous polymerization reactor

    SciTech Connect

    Wilt, M.S.

    1986-05-06

    A method is described for contacting olefinic monomer and initiator in a continuous polymerization process comprising of the steps of: creating three turbulent zones in a vessel; introducing the olefinic monomer into a first part of the periphery of each one of the three turbulent zones; introducing the initiator into a second part of the periphery of each one of the three turbulent zones, wherein the first part of the periphery of each one of the three turbulent zones is substantially diametrically opposed to the second part of the periphery of each one of the three turbulent zones respectively.

  10. Bimorphic polymeric photomechanical actuator

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey S. (Inventor); Curley, Michael J. (Inventor); Adamovsky, Grigory (Inventor); Sarkisov, Jr., Sergey S. (Inventor); Fields, Aisha B. (Inventor)

    2006-01-01

    A bimorphic polymeric photomechanical actuator, in one embodiment using polyvinylidene fluoride (PVDF) as a photosensitive body, transmitting light over fiber optic cables, and controlling the shape and pulse duration of the light pulse to control movement of the actuator. Multiple light beams are utilized to generate different ranges of motion for the actuator from a single photomechanical body and alternative designs use multiple light beams and multiple photomechanical bodies to provide controlled movement. Actuator movement using one or more ranges of motion is utilized to control motion to position an actuating element in three dimensional space.

  11. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Bauman, Robert

    2006-11-14

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  12. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Baumann, Robert

    2003-08-26

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  13. Living olefin polymerization processes

    DOEpatents

    Schrock, R.R.; Baumann, R.

    1999-03-30

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  14. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Baumann, Robert

    1999-01-01

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  15. Smart pH-sensitive and temporal-controlled polymeric micelles for effective combination therapy of doxorubicin and disulfiram.

    PubMed

    Duan, Xiaopin; Xiao, Jisheng; Yin, Qi; Zhang, Zhiwen; Yu, Haijun; Mao, Shirui; Li, Yaping

    2013-07-23

    The combination of a chemotherapeutic drug with a multidrug resistance (MDR) modulator has emerged as a promising strategy for treating MDR cancer. To ensure two drugs could be simultaneously delivered to tumor region at the optimum ratio, and the MDR modulator could be released earlier and faster than the chemotherapeutic drug to inactivate P-glycoprotein (P-gp) and subsequently inhibit the pumping out of the chemotherapeutic drug, a smart pH-sensitive polymeric micelles system with high drug loading and precise drug ratio was designed and prepared by conjugating doxorubicin (DOX) to poly(styrene-co-maleic anhydride) (SMA) derivative with adipic dihydrazide (ADH) through a acid-cleavable hydrazone bond, and then encapsulating disulfiram (DSF), a P-gp inhibitor as well as an apoptosis inducer, into the micelles formed by the self-assembly of SMA-ADH-DOX (SAD) conjugate. The pH-sensitive polymeric micelles system enabled a temporal release of two drugs: encapsulated DSF was released fast to inhibit the activity of P-gp and restore cell apoptotic signaling pathways, while conjugated DOX was released in a sustained and pH-dependent manner and highly accumulated in drug resistant cells to exert therapeutic effect, due to the inactivation of P-gp by DSF. The smart co-delivery system was very effective in enhancing the cytotoxicity by increasing the intracellular accumulation of DOX and promoting the apoptotic response, and showed the most effective inhibitory effect on the growth of drug-resistant breast cancer xenografts as compared to other combinations of both drugs. In a word, this smart co-delivery system has significant promise for the clinical therapy of MDR cancer. PMID:23734880

  16. Surfactant-Bound Monolithic Columns for Capillary Electrochromatography

    PubMed Central

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Shamsi, Shahab A.

    2010-01-01

    A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid (AAUA) is designed for capillary electrochromatography (CEC). The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) was evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes (ABs) and seven alkyl phenyl ketones (APKs) as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of AAUA monomer and porogen (water) in the polymerization mixture. A difference of 6%, 8% and 13% RSD between the predicted and the experimental values in terms of efficiency, resolution, and retention time, respectively, indeed confirmed that the proposed approach is practical. The physical (i.e., morphology, porosity and permeability) and chromatographic properties of the monolithic columns were thoroughly investigated. With the optimized monolithic column, high efficiency separation of N-methylcarbamates (NMCs) pesticides and positional isomers was successfully achieved. It appears that this type of mixed-mode monolith (containing both chargeable and hydrophobic sites) may have a great potential as a new generation of CEC stationary phase. PMID:19885887

  17. Platinum nanoparticles from size adjusted functional colloidal particles generated by a seeded emulsion polymerization process.

    PubMed

    Vogel, Nicolas; Ziener, Ulrich; Manzke, Achim; Plettl, Alfred; Ziemann, Paul; Biskupek, Johannes; Weiss, Clemens K; Landfester, Katharina

    2011-01-01

    The benefits of miniemulsion and emulsion polymerization are combined in a seeded emulsion polymerization process with functional seed particles synthesized by miniemulsion polymerization. A systematic study on the influence of different reaction parameters on the reaction pathway is conducted, including variations of the amount of monomer fed, the ratio of initiator to monomer and the choice of surfactant and composition of the continuous phase. Critical parameters affecting the control of the reaction are determined. If carefully controlled, the seeded emulsion polymerization with functional seed particles yields monodisperse particles with adjustable size and functionalities. Size-adjusted platinum-acetylacetonate containing latex particles with identical seed particles and varied shell thicknesses are used to produce arrays of highly ordered platinum nanoparticles with different interparticle distances but identical particle sizes. For that, a self-assembled monolayer of functional colloids is prepared on a solid substrate and subsequently treated by oxygen plasma processing in order to remove the organic constituents. This step, however, leads to a saturated state of a residual mix of materials. In order to determine parameters influencing this saturation state, the type of surfactant, the amount of precursor loading and the size of the colloids are varied. By short annealing at high temperatures platinum nanoparticles are generated from the saturated state particles. Typically, the present fabrication method delivers a maximum interparticle distance of about 260 nm for well-defined crystalline platinum nanoparticles limited by deformation processes due to softening of the organic material during the plasma applications. PMID:22003452

  18. Polymers for use in controlled release systems: the effect of surfactants on their swelling properties.

    PubMed

    Vlachou, M; Hani, N; Efentakis, M; Tarantili, P A; Andreopoulos, A G

    2000-07-01

    The effect of an ampholytic surfactant on the swelling properties of polymeric materials was studied, using various swelling liquids. Tablets were prepared consisting of hydroxypropyl methylcellulose, poly(oxyethylene) and sodium alginate. Tego betain was the non-ionic surfactant used as an additive in a series of samples made of the above polymers. Those tablets were immersed in distilled water, phosphate buffer and 0.1 N HCl, and their weight uptake was recorded as a function of time, in order to assess the swelling process. Measurements of the contact angle of the above systems were also carried out for estimating their wetting properties. The results of this study showed a selectivity among polymers, surfactant and surrounding liquid. Clearly, an enhancement of the swelling capacity of hydroxypropyl methylcellulose tablets due to the surfactant was recorded. An unclear effect was observed in the case of poly(oxyethylene), whereas for sodium alginate, the dominant factor is its water solubility that controls swelling behaviour. PMID:10972160

  19. Vesicles formed by mixed catanionic surfactants as novel pseudostationary phase in electrokinetic chromatography.

    PubMed

    Lu, Jie; Ni, Xinjiong; Cao, Yuhua; Ma, Xinyu; Cao, Guangqun

    2014-09-12

    In this paper, a novel pseudostationary phase (PSP), the vesicle formed from octyltriethylammonium bromide (C8NE3Br) and sodium dodecyl benzene sulfonate (SDBS), has been developed in electrokinetic chromatography (EKC). Physicochemical parameters of the mixture of catanionic surfactants such as ζ potential and size of the aggregates were characterized as the molar ratio of C8NE3Br to SDBS varied from 2:8 to 8:2 and total concentration of surfactants fixed at 20mM. At any ratio mentioned above, ζ potential of mixture of catanionic surfactants remained negative. The absolute values of ζ potential were even larger than in only SDBS system as the molar ratio of C8NE3Br to SDBS less than 4:6, and they decreased as increasing the ratio of cationic surfactants. The size of the aggregates became smaller as the ratio was close to 1. Unexpectedly, the size was smallest at ratio of 3:7 and 6:4, instead of at 5:5. Notably, coagulation did not occur in the catanionic system at any proportion of each other. TEM testified the formation of vesicles. The performance of the vesicle as PSP was evaluated by separating eight kinds of corticosteroids with EKC, these analytes were separated completely without any additives. Compared with SDS microemulsion modified with ionic liquid (IL) and polymeric micelle, the novel vesicle PSP had better separation performances. PMID:25064530

  20. Bicontinuous Polymeric Microemulsions from Polydisperse Diblock Copolymers

    SciTech Connect

    Ellison, Christopher J.; Meuler, Adam J.; Qin, Jian; Evans, Christopher M.; Wolf, Lynn M.; Bates, Frank S.

    2009-06-12

    Polymeric bicontinuous microemulsions are thermodynamically stable structures typically formed by ternary blends of immiscible A and B homopolymers and a macromolecular surfactant such as an AB diblock copolymer. Investigations of these bicontinuous morphologies have largely focused on model systems in which all components have narrow molecular weight distributions. Here we probe the effects of AB diblock polydispersity in ternary blends of polystyrene (PS), polyisoprene (PI), and poly(styrene-b-isoprene) (PS-PI). Three series of blends were prepared using the same PS and PI homopolymers; two of them contain nearly monodisperse components while the third includes a polydisperse PS-PI diblock. The PS and PI homopolymers and two of the PS-PI diblocks were prepared by anionic polymerization using sec-butyllithium and have narrow molecular weight distributions. The polydisperse PS-PI diblock was prepared by anionic polymerization using the functional organolithium 3-tert-butyldimethylsilyloxy-1-propyllithium; this diblock has a polydisperse PS block (M{sub w}/M{sub n} = 1.57) and a nearly monodisperse PI block (Mw/Mn < 1.1). The phase behavior of the three series of blends was probed using a combination of dynamic mechanical spectroscopy, small-angle X-ray scattering, and cloud point measurements, and a bicontinuous microemulsion channel was identified in each system. These results prove that monodisperse components are not required to form bicontinuous microemulsions and highlight the utility of polydispersity as a tool to tune polymer blend phase behavior. The random-phase approximation, originally advanced by de Gennes, and self-consistent field theory are used to provide a theoretical supplement to the experimental work. These theories are able to predict the directions of the polydispersity-driven shifts in domain spacing, order-disorder transition temperatures, and the location of the microemulsion channel. Self-consistent field theory is also used in conjunction

  1. Organometallic Polymeric Conductors

    NASA Technical Reports Server (NTRS)

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. The highest conductivities reported (approximately 4/Scm) were achieved with polythiophene in a polystyrene host polymer. The best films using a polyamide as base polymer were four orders of magnitude less conductive than the polystyrene films. The authors suggested that this was because polyimides were unable to swell sufficiently for infiltration of monomer as in the polystyrene. It was not clear, however, if the different conductivities obtained were merely the result of differing oxidation conditions. Oxidation time, temperature and oxidant concentration varied widely among the studies.

  2. Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-01-12

    Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms. PMID:26653971

  3. Hemolysis by surfactants--A review.

    PubMed

    Manaargadoo-Catin, Magalie; Ali-Cherif, Anaïs; Pougnas, Jean-Luc; Perrin, Catherine

    2016-02-01

    An overview of the use of surfactants for erythrocyte lysis and their cell membrane action mechanisms is given. Erythrocyte membrane characteristics and its association with the cell cytoskeleton are presented in order to complete understanding of the erythrocyte membrane distortion. Cell homeostasis disturbances caused by surfactants might induce changes starting from shape modification to cell lysis. Two main mechanisms are hypothesized in literature which are osmotic lysis and lysis by solubilization even if the boundary between them is not clearly defined. Another specific mechanism based on the formation of membrane pores is suggested in the particular case of saponins. The lytic potency of a surfactant is related to its affinity for the membrane and the modification of the lipid membrane curvature. This is to be related to the surfactant shape defined by its hydrophobic and hydrophilic moieties but also by experimental conditions. As a consequence, prediction of the hemolytic potency of a given surfactant is challenging. Several studies are focused on the relation between surfactant erythrolytic potency and their physico-chemical parameters such as the critical micellar concentration (CMC), the hydrophile-lipophile balance (HLB), the surfactant membrane/water partition coefficient (K) or the packing parameter (P). The CMC is one of the most important factors considered even if a lytic activity cut-off effect points out that the only consideration of CMC not enough predictive. The relation K.CMC must be considered in addition to the CMC to predict the surfactant lytic capacity within the same family of non ionic surfactant. Those surfactant structure/lytic activity studies demonstrate the requirement to take into account a combination of physico-chemical parameters to understand and foresee surfactant lytic potency. PMID:26687805

  4. Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Quarterly technical progress report, January 1, 1993--March 31, 1993

    SciTech Connect

    Somasundaran, P.

    1993-05-01

    The aim of this project is to elucidate the mechanisms of adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effect of surfactant structure, surfactant combinations and other inorganic and polymeric species will be determined using solids of relevant mineralogy. A multi-pronged approach consisting of micro & nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability win be used to achieve the goals. The results of this study should help in controlling surfactant loss in chemical flooding and also in developing optimum structures and conditions for efficient chemical flooding processes. Adsorption of selected individual surfactants on oxide minerals was studied. The aim was to determine the effect of structure on surfactant adsorption at the solid-liquid as well as at the liquid-air interface. Nonionic polyethoxylated alkyl phenols and anionic meta xylene sulfonates (MXS) were the surfactants studied. Electrokinetic behavior was also determined along with adsorption in order to determine the role of electrostatic forces in determining the adsorption. In addition, the effect of varying the number of ethylene oxide groups on the adsorption of polyethoxylated alkyl phenols on silica was determined since the ethoxyl groups offer unique opportunities to control adsorption as well as wettability. Effect of pH was studied both because it is a parameter with first order effect and also because pH effects can help in developing mechanisms.

  5. Coating of plasma polymerized film

    NASA Technical Reports Server (NTRS)

    Morita, S.; Ishibashi, S.

    1980-01-01

    Plasma polymerized thin film coating and the use of other coatings is suggested for passivation film, thin film used for conducting light, and solid body lubrication film of dielectrics of ultra insulators for electrical conduction, electron accessories, etc. The special features of flow discharge development and the polymerized film growth mechanism are discussed.

  6. Oil recovery by fluorochemical surfactant waterflooding

    SciTech Connect

    Cooke, T.W.

    1984-07-17

    The instant invention relates to the recovery of oil from subterranean oil reservoirs involving the injection of an aqueous based liquid containing a fluorochemical surfactant possessing an oleophobic-hydrophobic fluoroaliphatic group, a hydrophilic group and an oleophilic group, optionally in conjugation with a conventional enhanced oil recovery surfactant.

  7. SURFACTANT ENHANCED PHOTO-OXIDATION OF WASTEWATERS

    EPA Science Inventory

    Initial research projects using the nonionic surfactant Brij-35 established that this surfactant could successfully adsolublize aromatic organic pollutants such as anthracene, naphthalene, benzoic acid, chlorophenol, and benzene onto the surface of TiO2 par...

  8. Surfactant Adsorption: A Revised Physical Chemistry Lab

    ERIC Educational Resources Information Center

    Bresler, Marc R.; Hagen, John P.

    2008-01-01

    Many physical chemistry lab courses include an experiment in which students measure surface tension as a function of surfactant concentration. In the traditional experiment, the data are fit to the Gibbs isotherm to determine the molar area for the surfactant, and the critical micelle concentration is used to calculate the Gibbs energy of micelle…

  9. Measuring surfactant concentration in plating solutions

    DOEpatents

    Bonivert, William D.; Farmer, Joseph C.; Hachman, John T.

    1989-01-01

    An arrangement for measuring the concentration of surfactants in a electrolyte containing metal ions includes applying a DC bias voltage and a modulated voltage to a counter electrode. The phase angle between the modulated voltage and the current response to the modulated voltage at a working electrode is correlated to the surfactant concentration.

  10. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  11. Surfactant effects on soil aggregate tensile strength

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  12. A surfactant film spreading regime

    SciTech Connect

    Nikishov, V.I.

    1984-06-01

    Interest has recently increased in the study of the mechanisms whereby oil spills spread over sea and ocean surfaces. In the later stages of this process, when the petroleum film thickness becomes sufficiently small, the main forces determining the growth of its horizontal dimensions are surface tension and viscosity. In this case the flow characteristics do not depend on total quantity of spreading substance nor its surface concentration distribution. However, in the final stages of the spreading process the film becomes so thin that it is necessary to consider the effect of surface concentration distribution of the material on the process. Similar problems occur in the study of the spreading of a surfactant in the case where the total quantity of material is small and the surface tension regime sets in quickly. Therefore, the author examines here the spreading of a film in a regime wherein it is necessary to consider the total quantity of surfactant present, initially located on the surface of a viscous incompressible liquid.

  13. Fibrinogen stability under surfactant interaction.

    PubMed

    Hassan, Natalia; Barbosa, Leandro R S; Itri, Rosangela; Ruso, Juan M

    2011-10-01

    Differential scanning calorimetry (DSC), circular dichroism (CD), difference spectroscopy (UV-vis), Raman spectroscopy, and small-angle X-ray scattering (SAXS) measurements have been performed in the present work to provide a quantitatively comprehensive physicochemical description of the complexation between bovine fibrinogen and the sodium perfluorooctanoate, sodium octanoate, and sodium dodecanoate in glycine buffer (pH 8.5). It has been found that sodium octanoate and dodecanoate act as fibrinogen destabilizer. Meanwhile, sodium perfluorooctanoate acts as a structure stabilizer at low molar concentration and as a destabilizer at high molar concentration. Fibrinogen's secondary structure is affected by all three studied surfactants (decrease in α-helix and an increase in β-sheet content) to a different extent. DSC and UV-vis revealed the existence of intermediate states in the thermal unfolding process of fibrinogen. In addition, SAXS data analysis showed that pure fibrinogen adopts a paired-dimer structure in solution. Such a structure is unaltered by sodium octanoate and perfluoroctanoate. However, interaction of sodium dodecanoate with the fibrinogen affects the protein conformation leading to a complex formation. Taken together, all results evidence that both surfactant hydrophobicity and tail length mediate the fibrinogen stability upon interaction. PMID:21722913

  14. Well-defined hollow nanochanneled-silica nanospheres prepared with the aid of sacrificial copolymer nanospheres and surfactant nanocylinders

    NASA Astrophysics Data System (ADS)

    Kim, Young Yong; Hwang, Bora; Song, Sungjin; Ree, Brian J.; Kim, Yongjin; Cho, Seo Yeon; Heo, Kyuyoung; Kwon, Yong Ku; Ree, Moonhor

    2015-08-01

    A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then followed by selective thermal decomposition of the polymeric core and the surfactant cylinder domains in the shell, producing the hollow nanochanneled-silica nanospheres. Comprehensive, quantitative structural analyses collectively confirm that the obtained nanoparticles are structurally well defined with a hollow core and a shell composed of cylindrical nanochannels that provide facile accessibility to the hollow interior space. Overall, the hollow nanochanneled-silica nanoparticles have great potential for applications in various fields.A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then

  15. Physical Properties and Biological Activity of Poly(butyl acrylate–styrene) Nanoparticle Emulsions Prepared with Conventional and Polymerizable Surfactants

    PubMed Central

    Garay-Jimenez, Julio C.; Gergeres, Danielle; Young, Ashley; Dickey, Sonja; Lim, Daniel V.; Turos, Edward

    2009-01-01

    Recent efforts in our laboratory have explored the use of polyacrylate nanoparticles in aqueous media as stable emulsions for potential applications in treating drug-resistant bacterial infections. These emulsions are made by emulsion polymerization of acrylated antibiotic compounds in a mixture of butyl acrylate and styrene (7:3 w:w) using sodium dodecyl sulfate (SDS) as a surfactant. Prior work in our group established that the emulsions required purification to remove toxicity associated with extraneous surfactant present in the media. This paper summarizes our investigations of poly(butyl acrylate-styrene) emulsions made using anionic, cationic, zwitterionic, and non-charged (amphiphilic) surfactants, as well as attachable surfactant monomers (surfmers), comparing the cytotoxicity and microbiological activity levels of the emulsion both before and after purification. Our results show that the attachment of a polymerizable surfmer onto the matrix of the nanoparticle neither improves nor diminishes cytotoxic or antibacterial effects of the emulsion, regardless of whether the emulsions are purified or not, and that the optimal properties are associated with the use of the non-ionic surfactants versus those carrying anionic, cationic, or zwitterionic charge. Incorporation of an N-thiolated β-lactam antibacterial agent onto the nanoparticle matrix via covalent attachment endows the emulsion with antibiotic properties against pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), without changing the physical properties of the nanoparticles or their emulsions. PMID:19523413

  16. Preparation of poly(NIPAAm)-Pluronic F68 as a thermosensitive surfactant for a controlled drug release.

    PubMed

    Choi, Sung-Wook; Lee, Hye Min; Park, Tae-Joon; Kim, Jung-Hyun

    2011-04-01

    This paper describes the synthesis of thermosensitive surfactants by polymerizing N-isopropylacrylamide (NIPAAm) into the Pluronic F68 surfactant and their application for a controlled drug release. Poly(NIPAAm)-Pluronic surfactants with different lengths of the NIPAAm block were synthesized by activating two hydroxyl groups of poly(ethylene oxide) (PEO) at the end of Pluronic F68 using cerium ammonium nitrate (CAN, redox initiator), followed by adding the NIPAAm monomer into a reactor. The resultant poly(NIPAAm)-Pluronic surfactants were characterized by FT-IR and gel filtration chromatography (GPC). It was observed that their critical micellar concentrations increased with an increase in the length of the poly(NIPAAm) block. In addition, poly(D,L-lactide-co-glycolide) (PLGA) microparticles was prepared by an oil-in-water emulsion and solvent evaporation method using the poly(NIPAAm)-Pluronic surfactants in an aqueous continuous phase. At 37°C, nile red (model dye) was released from the PLGA microparticles in a more sustained manner when the length of poly(NIPAAm) was longer due to a thicker layer of shrunken poly(NIPAAm) at the surface of the microparticles. PMID:23071926

  17. Sequential treatments of premature lambs with an artificial surfactant and natural surfactant.

    PubMed Central

    Ikegami, M; Jobe, A; Jacobs, H; Jones, S J

    1981-01-01

    To test an artificial surfactant in vivo, six 120-d gestational age lambs were treated at birth with a mixture of a 9:1 M ratio of [14C]dipalmitoyl phosphatidylcholine (DPC) and phosphatidylglycerol at a dose of 100 mg DPC/kg. Nine other lambs were not treated. The mean PO2 values of the lambs treated with artificial surfactant were 65.7 +/- 11 mm Hg vs. 24.8 +/- 1.6 mm Hg for the untreated lambs (P less than 0.001). All lambs then were treated with 50 mg/natural surfactant lipid per kg, which promptly improved PO2 in all lambs. The PO2 values of those lambs previously treated with artificial surfactant remained greater than 100 mm Hg for 2.5 +/- 0.5 h vs. 0.9 +/- 0.3 h for lambs untreated with artificial surfactant (P less than 0.01). The pH and PCO2 values were not strikingly different between the two groups of lambs. Airway samples taken from lambs treated with artificial surfactant before treatment with natural surfactant had minimal surface tensions of 32 +/- 2.9 dyn/cm, whereas the artificial surfactant reisolated from these samples by centrifugation had minimum surface tension of 0 dyn/cm. The minimum surface tension of artificial surfactant was inhibited by fetal lung fluid from the premature lambs, whereas the minimum surface tension of natural surfactant was much less sensitive to inhibition. Artificial surfactant did not improve the pressure-volume characteristics of unventilated premature lung, whereas natural surfactant did. The change in specific activity of [14C]DPC following treatment with natural surfactant indicated that approximately 50% of the DPC initially administered was no longer associated with the airways. PMID:6790576

  18. Micellar Effects on Photoinduced Electron Transfer in Aqueous Solutions Revisited: Dramatic Enhancement of Cage Escape Yields in Surfactant Ru(II) Diimine Complex/[Ru(NH3)6](2+) Systems.

    PubMed

    Adams, Rebecca E; Schmehl, Russell H

    2016-08-30

    The effect of cationic micelle incorporation on light induced electron transfer, charge separation and back electron transfer between an aqueous electron donor, [Ru(NH3)6](2+), and a series of Ru(II) diimine complex chromophores/acceptors, is presented. The chromophores have the general formula [(bpy)2Ru(LL)](2+) (LL = bpy; 4-R-4'-methyl-2,2'-bpy, R = pentyl (MC5), terdecyl (MC13), heptadecyl (MC17); 4,4'-di(heptadecyl)-2,2'-bpy (DC17)). Of the five chromophores, the MC13, MC17, and DC17 complexes associate with the added micelle forming surfactant, cetyltrimethylammonium bromide (CTAB). Quenching of the luminescence of the bpy and MC5 complexes by [Ru(NH3)6](2+) is unaffected by addition of surfactant, while rate constants for quenching of the MC13 and MC17 complexes are decreased. Cage escape yields following photoinduced electron transfer to generate [(bpy)2Ru(LL)](+) and [Ru(NH3)6](3+) are approximately 0.1 for all the water-soluble chromophores (excluding DC17) in the absence of added CTAB. In the presence of surfactant, the cage escape yields dramatically increase for the MC13 (0.4) and MC17 (0.6) complexes, while remaining unchanged for [Ru(bpy)3](2+) and the MC5 complex. Back electron transfer of the solvent separated ions is also strongly influenced by the presence of surfactant. For the MC13 and MC17 complexes, back electron transfer rate constants decrease by factors of 270 and 190, respectively. The MC5 complex exhibits two component back electron transfer, with the fast component having a rate constant close to that in the absence of surfactant and a slow component nearly 200 times smaller. Results are interpreted in terms of the partitioning of the 2+ and 1+ forms of the chromophores between aqueous and micellar phases. The extended lifetimes of the radical ions may prove useful in coupling the strong reductants formed to kinetically facile catalysts for reduction of water to hydrogen. PMID:27486891

  19. Production of monodisperse, polymeric microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Rhim, Won-Kyu (Inventor); Hyson, Michael T. (Inventor); Chang, Manchium (Inventor)

    1990-01-01

    Very small, individual polymeric microspheres with very precise size and a wide variation in monomer type and properties are produced by deploying a precisely formed liquid monomer droplet, suitably an acrylic compound such as hydroxyethyl methacrylate into a containerless environment. The droplet which assumes a spheroid shape is subjected to polymerizing radiation such as ultraviolet or gamma radiation as it travels through the environment. Polymeric microspheres having precise diameters varying no more than plus or minus 5 percent from an average size are recovered. Many types of fillers including magnetic fillers may be dispersed in the liquid droplet.

  20. Melting line of polymeric nitrogen

    NASA Astrophysics Data System (ADS)

    Yakub, L. N.

    2013-05-01

    We made an attempt to predict location of the melting line of polymeric nitrogen using two equations for Helmholtz free energy: proposed earlier for cubic gauche-structure and developed recently for liquid polymerized nitrogen. The P-T relation, orthobaric densities and latent heat of melting were determined using a standard double tangent construction. The estimated melting temperature decreases with increasing pressure, alike the temperature of molecular-nonmolecular transition in solid. We discuss the possibility of a triple point (solid-molecular fluid-polymeric fluid) at ˜80 GPa and observed maximum of melting temperature of nitrogen.

  1. Prevention of Metastasis in a 4T1 Murine Breast Cancer Model by Doxorubicin Carried by Folate Conjugated pH Sensitive Polymeric Micelles

    PubMed Central

    Gao, Zhong-Gao; Tian, Li; Hu, Jun; Park, In-Suh; Bae, You Han

    2011-01-01

    This study primarily focused on the anti-metastatic activity of doxorubicin (DOX) loaded in a pH-sensitive mixed polymeric micelle formed from two block polymers: poly(L-lactide) (PLLA) (Mn 3000)-b-poly(ethylene glycol) (PEG) (Mn 2000)-folate and poly(L-histidine) (PHis) (Mn 4700)-b-PEG (Mn 2000). Tumor formation and metastasis in mice were examined using a murine mammary carcinoma cell of 4T1 which is one of the most aggressive metastatic cancer cell lines. The efficacy was evaluated by tumor size, body weight change, survival rate, dorsal skin fold window chamber model, and histological observation of the lung, heart, liver and spleen after treatment with various DOX formulations. When the tumor reached 50–100 mm3 in size, the mice were treated by 4 times at a 3-day interval at a dose of 10 mg DOX/kg. The mixed micelle formulation resulted in retarded tumor growth, no weight loss, and no death for 4–5 weeks. In another set of the in vivo test for histological evaluation of the organs, the mice were similarly treated but the formulations were injected one day after 4T1 cell inoculation. The treatment by DOX loaded mixed micelle showed no apparent metastasis till 28 days. However, significant metastasis to the lung and heart was observed on Day 28 when the mice were treated with DOX carried by PBS, PLLA-b-PEG micelle and PHis-b-PEG micelle. PMID:21295088

  2. High temperature structural, polymeric foams from high internal emulsion polymerization

    SciTech Connect

    Hoisington, M.A.; Duke, J.R.; Apen, P.G.

    1996-02-01

    In 1982, a high internal phase emulsion (HIPE) polymerization process to manufacture microcellular, polymeric foam systems was patented by Unilever. This patent discloses a polymerization process that occurs in a water-in-oil emulsion in which the water represents at least 76% of the emulsion by volume. The oil phase consists of vinyl monomers such as styrene and acrylates that are crosslinked by divinyl monomers during polymerization. After polymerization and drying to remove the water phase, the result is a crosslinked polymer foam with an open cell microstructure that is homogeneous throughout in terms of morphology, density, and mechanical properties. Since 1982, numerous patents have examined various HIPE polymerized foam processing techniques and applications that include absorbents for body fluids, cleaning materials, and ion exchange systems. All the published HIPE polymerized foams have concentrated on materials for low temperature applications. Copolymerization of styrene with maleic anhydride and N-substituted maleimides to produce heat resistant thermoplastics has been studied extensively. These investigations have shown that styrene will free radically copolymerize with N-substituted maleimides to create an alternating thermoplastic copolymer with a Tg of approximately 200{degrees}C. However, there are many difficulties in attempting the maleimide styrene copolymerization in a HIPE such as lower polymerization temperatures, maleimide solubility difficulties in both styrene and water, and difficulty obtaining a stable HIPE with a styrene/maleimide oil phase. This work describes the preparation of copolymer foams from N-ethylmaleimide and Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane with styrene based monomers and crosslinking agents.

  3. Surface active properties of polyoxyethylene macromonomers and their role in radical polymerization in disperse systems.

    PubMed

    Capek, I

    2000-12-26

    Conventional dispersion polymerization and copolymerization of low-molecular weight (conventional) unsaturated monomers allows preparation of monodisperse and micronsize polymer particles. A similar behavior can be found in the surfactant-free dispersion polymerization of non-traditional vinyl monomers, unsaturated macromonomers. The latter systems allow preparation of random, comb-like, star-like and graft copolymers as well. An interesting alternative arises with the use of amphiphilic reactive macromonomers that contain a polymerizable group and aggregate into an organized structure -- a micelle. Under such conditions the high rate of polymerization and ultrafine (microparticles) polymer dispersions are generated. Thus, the surface-active macromonomers promote the formation of micelles and polymer growth within the main reaction loci -- polymer particles. Furthermore, the surface-active compounds can be formed during the copolymerization of hydrophilic macromonomer and hydrophobic low-molecular weight comonomer. The reactive surface-active oligomeric radicals are incorporated into the polymer matrix or the particle surface layer, which prevents them from subsequent migration. Besides, the covalently bound surface-active groups at the particle surface strongly increase the colloidal stability of final polymer dispersion. This article presents a review of the current literature in the field of the surfactant-free dispersion polymerization of the polyoxyethylene unsaturated macromonomers. Besides a short introduction into some kinetic aspects of radical polymerization of traditional monomers in homogeneous and disperse systems, we mainly focus on the organized aggregation of amphiphilic polyoxyethylene macromonomers, the characterization of amphiphilic graft copolymers and their aggregation properties, and radical copolymerization of polyoxyethylene macromonomers. We discuss the birth and growth of chains, the transfer of reaction loci from the continuous phase to

  4. Rhamnolipids--next generation surfactants?

    PubMed

    Müller, Markus Michael; Kügler, Johannes H; Henkel, Marius; Gerlitzki, Melanie; Hörmann, Barbara; Pöhnlein, Martin; Syldatk, Christoph; Hausmann, Rudolf

    2012-12-31

    The demand for bio-based processes and materials in the petrochemical industry has significantly increased during the last decade because of the expected running out of petroleum. This trend can be ascribed to three main causes: (1) the increased use of renewable resources for chemical synthesis of already established product classes, (2) the replacement of chemical synthesis of already established product classes by new biotechnological processes based on renewable resources, and (3) the biotechnological production of new molecules with new features or better performances than already established comparable chemically synthesized products. All three approaches are currently being pursued for surfactant production. Biosurfactants are a very promising and interesting substance class because they are based on renewable resources, sustainable, and biologically degradable. Alkyl polyglycosides are chemically synthesized biosurfactants established on the surfactant market. The first microbiological biosurfactants on the market were sophorolipids. Of all currently known biosurfactants, rhamnolipids have the highest potential for becoming the next generation of biosurfactants introduced on the market. Although the metabolic pathways and genetic regulation of biosynthesis are known qualitatively, the quantitative understanding relevant for bioreactor cultivation is still missing. Additionally, high product titers have been exclusively described with vegetable oil as sole carbon source in combination with Pseudomonas aeruginosa strains. Competitive productivity is still out of reach for heterologous hosts or non-pathogenic natural producer strains. Thus, on the one hand there is a need to gain a deeper understanding of the regulation of rhamnolipid production on process and cellular level during bioreactor cultivations. On the other hand, there is a need for metabolizable renewable substrates, which do not compete with food and feed. A sustainable bioeconomy approach should

  5. Organometallic Polymeric Conductors

    NASA Technical Reports Server (NTRS)

    Youngs, Wiley J.

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for

  6. Novel functionalized fluorescent polymeric nanoparticles for immobilization of biomolecules

    NASA Astrophysics Data System (ADS)

    Jain, Swati; Chattopadhyay, Sruti; Jackeray, Richa; Abid, C. K. V. Zainul; Singh, Harpal

    2013-07-01

    Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable, monodisperse, spherical nano sized particles exhibiting high luminescence properties. Particles with 1% SLS (S1) showed good dispersion stability and fluorescence intensity and were chosen as ideal candidates for further immobilization studies. Steady state fluorescence studies showed 10 times higher fluorescence intensity of S1 nanoparticles than that of pyrene solution in solvent-toluene at the same concentration. Environmental factors such as pH, ionic strength and time were found to have no effect on fluorescence intensity of FPNPs. Surface β-di-ketone groups were utilized for the covalent immobilization of enzyme conjugated antibodies without any activation or pre-treatment of nanoparticles.Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable

  7. A study of surfactant-assisted waterflooding

    SciTech Connect

    Scamehorn, J F; Harwell, J H

    1990-09-01

    In surfactant-assisted waterflooding, a surfactant slug is injected into a reservoir, followed by a brine spacer, followed by second surfactant slug. The charge on the surfactant in the first slug has opposite sign to that in the second slug. When the two slugs mix in the reservoir, a precipitate or coacervate is formed which plugs the permeable region of the reservoir. Subsequently injected water or brine is forced through the low permeability region of the reservoir, increasing sweep efficiency of the waterflood, compared to a waterflood not using surfactants. In this part of the work, two major tasks are performed. First, core floods are performed with oil present to demonstrate the improvement in incremental oil production, as well as permeability modification. Second, a reservoir simulation model will be proposed to further delineate the optimum strategy for implementation of the surfactant-assisted waterflooding, as well as indicate the reservoir types for which it would be most effective. Surfactants utilized were sodium dodecyl sulfate and dodecyl pyridinium chloride. 44 refs., 17 figs., 3 tabs.

  8. Pinchoff dynamics of surfactant covered viscous threads

    NASA Astrophysics Data System (ADS)

    Papageorgiou, Demetrios; Matar, Omar; Craster, Richard

    2001-11-01

    We study the breakup of a viscous thread covered with insoluble surfactant. One-dimensional evolution equations for the interface location, surfactant concentration and axial velocity are derived in the long wavelength approximation. The effect of surfactant is parameterized by its initial concentration, its strength and the Schmidt number, Sc, the ratio of kinematic viscosity to surface diffusion. Numerical solutions suggest that the presence of surfactant, which gives rise to Marangoni stresses, affect drastically the transient dynamics. The effective radius of the satellite formed during breakup decreases with increasing initial concentration and surfactant strength. For Sc > 10, increasing Sc has little effect on satellite effective radius [1]. These numerical solutions also show that the self-similar breakup dynamics of a surfactant-free viscous thread in the vicinity of the pinchoff region [2] are preserved even in the presence of surfactant. [1] R. V. Craster, O. K. Matar and D. T. Papageorgiou, submitted to Phys. Fluids (2001). [2] J. Eggers, Phys. Rev. Lett., 71, 3458 (1993).

  9. DNA compaction by azobenzene-containing surfactant

    NASA Astrophysics Data System (ADS)

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina; Santer, Svetlana

    2011-08-01

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  10. DNA compaction by azobenzene-containing surfactant

    SciTech Connect

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana

    2011-08-15

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  11. Tunable, antibacterial activity of silicone polyether surfactants.

    PubMed

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

    2015-08-01

    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. PMID:26057244

  12. Adsorption of dimeric surfactants in lamellar silicates

    NASA Astrophysics Data System (ADS)

    Balcerzak, Mateusz; Pietralik, Zuzanna; Domka, Ludwik; Skrzypczak, Andrzej; Kozak, Maciej

    2015-12-01

    The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay - hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1‧-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d001) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH2 and CH3 groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  13. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    NASA Astrophysics Data System (ADS)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  14. Surfactants tailored by the class Actinobacteria

    PubMed Central

    Kügler, Johannes H.; Le Roes-Hill, Marilize; Syldatk, Christoph; Hausmann, Rudolf

    2015-01-01

    Globally the change towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application. PMID:25852670

  15. Preparation and characterization of zwitterionic surfactant-modified montmorillonites.

    PubMed

    Zhu, Jianxi; Qing, Yanhong; Wang, Tong; Zhu, Runliang; Wei, Jingming; Tao, Qi; Yuan, Peng; He, Hongping

    2011-08-15

    A series of zwitterionic surfactant-modified montmorillonites (ZSMMs) were synthesized using montmorillonite and three zwitterionic surfactants with different alkyl chain lengths at different concentrations [0.2-4.0 cation exchange capacity (CEC)]. These ZSMMs were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis and differential thermo-gravimetric (TG/DTG) analyses. The zwitterionic surfactant could be intercalated into the interlayer spaces of montmorillonites and causing interlayer space-swelling. From XRD measurements, the amount of the surfactants loaded and the basal spacing increased with surfactant concentration and alkyl chain length. One endothermic DTG peak occurred at ~390 °C, which was assigned to the decomposition of the zwitterionic surfactant on the organo-montmorillonites from 0.2 to 0.6 CEC. When the surfactant loading was increased, a new endothermic peak appeared at ~340 °C. From the microstructures of these ZSMMs, the mechanism of zwitterionic surfactant adsorption was proposed. At relatively low loadings of the zwitterionic surfactant, most of surfactants enter the spacing by an ion-exchange mechanism and are adsorbed onto the interlayer cation sites. When the concentration of the zwitterionic surfactant exceeds the CEC of montmorillonite, the surfactant molecules then adhere to the surface-adsorbed surfactant. Some surfactants enter the interlayers, whereas the others are attached to the clay surface. When the concentration of surfactant increases further beyond 2.0 CEC, the surfactants may occupy the inter-particle space within the house-of-cards aggregate structure. PMID:21575956

  16. Surfactant-Assisted Coal Liquefaction

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory S.; Sharma, Pramod K.

    1993-01-01

    Obtaining liquid fuels from coal which are economically competitive with those obtained from petroleum based sources is a significant challenge for the researcher as well as the chemical industry. Presently, the economics of coal liquefaction are not favorable because of relatively intense processing conditions (temperatures of 430 degrees C and pressures of 2200 psig), use of a costly catalyst, and a low quality product slate of relatively high boiling fractions. The economics could be made more favorable by achieving adequate coal conversions at less intense processing conditions and improving the product slate. A study has been carried out to examine the effect of a surfactant in reducing particle agglomeration and improving hydrodynamics in the coal liquefaction reactor to increase coal conversions...

  17. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    DOE PAGESBeta

    Luo, Hongmei; Lin, Qianglu; Baber, Stacy; Naalla, Mahesh

    2010-01-01

    We demore » monstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta 2 O 5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses.« less

  18. Precipitation of mixtures of anionic and cationic surfactants; 3: Effect of added nonionic surfactant

    SciTech Connect

    Shiau, B.J.; Harwell, J.H.; Scamehorn, J.F. . Inst. for Applied Surfactant Research)

    1994-10-15

    The precipitation of an anionic surfactant by a cationic surfactant in the presence of a nonionic surfactant is examined. The precipitation domains for sodium dodecyl sulfate/dodecyl-pyridinium chloride were measured over a wide range of surfactant concentrations as a function of nonylphenol polyethoxylate concentration. Increasing the nonylphenol polyethoxylate concentration decreases the tendency for precipitation to occur. A model for predicting precipitation domains in ternary surfactant mixtures has been developed and verified experimentally. The model allows the nonionic surfactant to affect the precipitation behavior only by lowering the critical micelle concentration of the mixture. Small deviations between theory and experiments along part of the anionic-rich micelle boundary result from adsorption of SDS on the precipitate which gives the microcrystals a negative charge and prevents their growth to a visible size.

  19. Kinetics of silica polymerization

    SciTech Connect

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  20. Influence of surfactant charge on antimicrobial efficacy of surfactant-stabilized thyme oil nanoemulsions.

    PubMed

    Ziani, Khalid; Chang, Yuhua; McLandsborough, Lynne; McClements, David Julian

    2011-06-01

    Thyme oil-in-water nanoemulsions stabilized by a nonionic surfactant (Tween 80, T80) were prepared as potential antimicrobial delivery systems (pH 4). The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by incorporating ≥75% of corn oil (a hydrophobic material with a low water solubility) into the nanoemulsion droplets. The electrical characteristics of the droplets in the nanoemulsions were varied by incorporating ionic surfactants with different charges after homogenization: a cationic surfactant (lauric arginate, LAE) or an anionic surfactant (sodium dodecyl sulfate, SDS). The antifungal activity of nanoemulsions containing positive, negative, or neutral thymol droplets was then conducted against four strains of acid-resistant spoilage yeasts: Zygosaccharomyces bailli, Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Brettanomyces naardenensis. The antifungal properties of the three surfactants (T80, LAE, SDS) were also tested in the absence of thymol droplets. Both ionic surfactants showed strong antifungal activity in the absence of thymol droplets, but no antimicrobial activity in their presence. This effect was attributed to partitioning of the antimicrobial surfactant molecules between the oil droplet and microbial surfaces, thereby reducing the effective concentration of active surfactants available to act as antimicrobials. This study shows oil droplets may decrease the efficacy of surfactant-based antimicrobials, which has important consequences for formulating effective antimicrobial agents for utilization in emulsion-based food and beverage products. PMID:21520914

  1. Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

    PubMed

    Fukuzawa, Taku; Ishida, Junji; Kato, Akira; Ichinose, Taro; Ariestanti, Donna Maretta; Takahashi, Tomoya; Ito, Kunitoshi; Abe, Jumpei; Suzuki, Tomohiro; Wakana, Shigeharu; Fukamizu, Akiyoshi; Nakamura, Nobuhiro; Hirose, Shigehisa

    2013-01-01

    Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+) and Ig-Hepta(-/-) mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i) balanced synthesis of surfactant lipids and proteins and (ii) surfactant secretion, and (iii) a stimulating effect on recycling (uptake) in response to elevated levels of Sp-D in alveolar space. PMID:23922714

  2. Interfacial/free radical polymerization microencapsulation: kinetics of particle formation.

    PubMed

    Mahabadi, H K; Ng, T H; Tan, H S

    1996-01-01

    Microcapsules containing pigment and polymer were prepared by dispersing a viscous mixture of pigment, core monomers, initiators and oil-soluble shell monomer in an aqueous solution of surfactants, forming oil-in-water droplets. Subsequently, a water-soluble shell monomer was added to these droplets, encapsulating them via interfacial (IF) polycondensation. These microcapsules were then heated for free radical (FR) polymerization of the core monomers. Effects of primary variables, such as the shearing time during particle formation, surfactant concentration, organic phase concentration, and mode of water-soluble shell monomer addition, were studied. The results indicated that polyvinylalcohol (PVOH), used as the surfactant/stabilizer, reacted with the oil-soluble shell monomers. The depletion of PVOH, especially when PVOH concentration was low, resulted in rapid growth of particle size and, eventually, suspension failure. The kinetic data revealed a particle formation mechanism which consists of two processes. The first process is the formation of an equilibrium particle size by the equilibrium process of particle breakage due to the mechanical shearing force and coalescence due to collisions among particles and surface tension forces. The second process is the reaction between PVOH and oil-soluble shell monomer which leads to the depletion of PVOH and consequently causes more coalescence of particles and a significant increase in the equilibrium particle size. The net effect of these two processes shows an optimum shearing time where the smallest particle size can be attained, and this optimum time is a function of several primary variables. Methods to prevent the reaction and therefore the depletion of PVOH are proposed. PMID:8864993

  3. Preparation of amphiphilic glycopolymers with flexible long side chain and their use as stabilizer for emulsion polymerization.

    PubMed

    Alvárez-Paino, Marta; Juan-Rodríguez, Rafael; Cuervo-Rodríguez, Rocío; Muñoz-Bonilla, Alexandra; Fernández-García, Marta

    2014-03-01

    A glycomonomer was synthesized from poly(ethylene glycol) methacrylate (PEGMA). The terminal hydroxyl moieties were activated with ester groups and subsequently the glucosamine was incorporated forming urethane linkages. The obtained glycomonomer was copolymerized with methyl acrylate by free radical polymerization varying the initial feed composition to produce different amphiphilic glycopolymers. The glycopolymers were then characterized and compared with the homologous glycopolymers based on 2-{[(D-glucosamin-2-N-yl)carbonyl]oxy}ethyl methacrylate. Both series of glycopolymers were used in emulsion polymerization of methyl acrylate as stabilizers without the addition of any cosurfactant. Although high conversions were not achieved with any of the employed surfactant, the glycopolymers provide good colloidal stability, spherical, monodisperse and small latex particles in comparison with the surfactant-free emulsion polymerization. The latex particles stabilized with the glycosurfactant based on PEGMA, containing a flexible spacer between the backbone and the glucosamine, lead to smooth films whereas the short side chain surfactant from 2-hydroxyethyl methacrylate (HEMA), with higher glass transition temperature, restricts the coalescence of particles and, therefore, the film formation. Moreover, the surface bioactivity of these polymer coatings was examined by analyzing their specific interaction with the lectin, Concanavalin A, Canavalia ensiformis. The specific and successful binding to the Concanavalin A was demonstrated by fluorescence microscopy for both series being more intense with increasing amount of glycounits in the glycopolymer stabilizers. Interestingly, the incorporation of a flexible spacer in the glycopolymer structures enhances the binding activity. PMID:24407696

  4. Functionalized lipids and surfactants for specific applications.

    PubMed

    Kepczynski, Mariusz; Róg, Tomasz

    2016-10-01

    Synthetic lipids and surfactants that do not exist in biological systems have been used for the last few decades in both basic and applied science. The most notable applications for synthetic lipids and surfactants are drug delivery, gene transfection, as reporting molecules, and as support for structural lipid biology. In this review, we describe the potential of the synergistic combination of computational and experimental methodologies to study the behavior of synthetic lipids and surfactants embedded in lipid membranes and liposomes. We focused on select cases in which molecular dynamics simulations were used to complement experimental studies aiming to understand the structure and properties of new compounds at the atomistic level. We also describe cases in which molecular dynamics simulations were used to design new synthetic lipids and surfactants, as well as emerging fields for the application of these compounds. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26946243

  5. Fluorescence studies of polymer surfactant association

    NASA Astrophysics Data System (ADS)

    Miguel, M. da G.; Burrows, H. D.; Formosinho, S. J.; Lindman, B.

    2001-05-01

    Fluorescence spectroscopy has been successfully used for the study of central issues of solutions of surfactants and associating polymers. Different fluorescence techniques and methods are uniquely adapted to investigate problems in this field and can, by using extrinsic or intrinsic probes, provide information on molecular association, microstructure and molecular dynamics. This constitutes an important contribution to the understanding and control of macroscopic properties, as well as to their biological functions and technical applications. Important aspects of these mixed systems, related to their self-assembly, are: formation of micelles and hydrophobic microdomains in general; size and shape of surfactant molecular aggregates; formation and stability of vesicles; intra- vs. intermolecular association in polymers; conformational changes in polymers as affected by polymer-surfactant association; surfactant organization in adsorbed layers; kinetic aspects of the formation and disintegration of self-assembly structures; residence times of molecules in microdomains and migration of active molecules. Some of these issues will be addressed in this paper.

  6. Solar energy storage using surfactant micelles

    NASA Astrophysics Data System (ADS)

    Srivastava, R. C.; Marwadi, P. R.; Latha, P. K.; Bhise, S. B.

    1982-09-01

    The results of experiments designed to test the soluble reduced form of thionine dye as a suitable solar energy storage agent inside the hydrophobic core of surfactant micelles are discussed. Aqueous solutions of thionine, methylene blue, cetyl pyridinium bromide, sodium lauryl sulphate, iron salts, and iron were employed as samples of anionic, cationic, and nonionic surfactants. The solutions were exposed to light until the dye disappeared, and then added drop-by-drop to surfactant solutions. The resultant solutions were placed in one cell compartment while an aqueous solution with Fe(2+) and Fe(3+) ions were placed in another, with the compartments being furnished with platinum electrodes connected using a saturated KCl-agar bridge. Data was gathered on the short circuit current, maximum power, and internal resistance encountered. Results indicate that dye-surfactant systems are viable candidates for solar energy storage for later conversion to electrical power.

  7. Aggregation of sulfosuccinate surfactants in water

    SciTech Connect

    Magid, L.J.; Daus, K.A.; Butler, P.D.; Quincy, R.B.

    1983-12-22

    The aggregation of sodium di-n-alkyl sulfosuccinates in water (H/sub 2/O and D/sub 2/O at 45/sup 0/C) has been investigated. A self-consistent picture of the dependence of sodium ion binding on surfactant concentration is obtained from emf measurements, conductimetry, and small-angle neutron scattering (SANS) measurements. The concentration dependence of the micellar agregation number for the sulfosuccinates and related double-tailed surfactants depends markedly on surfactant solubility. A sphere-to-disk transition in micellar shape, which might have been expected as a precursor to formation of a lamellar mesophase, was not observed as the surfactant concentration was increased. 8 figures, 2 tables.

  8. Polymeric materials in Space

    NASA Astrophysics Data System (ADS)

    Skurat, Vladimir

    Paper of short review type. It is the continuation of and addition to previous review papers "V. E. Skurat. Polymers in Space. In: Encyclopedia of aerospace engineering, vol. 4, Wiley and sons, 2010; Ibid., 2012 (on line)". Following topics are considered: (1) Destruction of polymers by solar radiation with various wavelengths in different spectral regions (visible-UV, vacuum UV (VUV), deep UV, soft and hard X-rays) are discussed. In difference with common polymer photochemistry induced by UV radiation, directions of various routs of polymer phototransformations and their relative yields are greatly dependent on wavelength of light (photon energy) during illuminations in VUV, deep UV and X-ray regions. During last twenty years, intensive spacecraft investigations of solar spectrum show great periodic and spontaneous variations of radiation intensities in short-wavelengths regions - up to one - two decimal orders of magnitude for X-rays. As a result, during solar flares the absorbed dose on the polymer surfaces from X-rays can be compared with absorbed dose from VUV radiation. (2) Some new approaches to predictions of reaction efficiencies of fast orbital atomic oxygen in their interaction with polymeric materials are considered. (3) Some aspects of photocatalitic destruction of polymers in vacuum conditions by full-spectrum solar radiation are discussed. This process can take place in enamels containing semiconducting particles (TiO2, ZnO) as pigments. (4) Contamination of spacecraft surfaces from intrinsic outer atmosphere play important role not only from the point of view of deterioration of optical and thermophysical properties. Layers of SiO2 contaminations with nanometer thicknesses can greatly diminish mass losses from perfluorinated polymers under VUV irradiation.

  9. Polymeric materials for neovascularization

    NASA Astrophysics Data System (ADS)

    DeVolder, Ross John

    Revascularization therapies have emerged as a promising strategy to treat various acute and chronic wounds, cardiovascular diseases, and tissue defects. It is common to either administer proangiogenic growth factors, such as vascular endothelial growth factor (VEGF), or transplant cells that endogenously express multiple proangiogenic factors. Additionally, these strategies utilize a wide variety of polymeric systems, including hydrogels and biodegradable plastics, to deliver proangiogenic factors in a sophisticated manner to maintain a sustained proangiogenic environment. Despite some impressive results in rebuilding vascular networks, it is still a challenging task to engineer mature and functional neovessels in target tissues, because of the increasing complexities involved with neovascularization applications. To resolve these challenges, this work aims to design a wide variety of proangiogenic biomaterial systems with tunable properties used for neovascularization therapies. This thesis describes the design of several biomaterial systems used for the delivery of proangiogenic factors in neovascularization therapies, including: an electrospun/electrosprayed biodegradable plastic patch used for directional blood vessel growth (Chapter 2), an alginate-g-pyrrole hydrogel system that biochemically stimulates cellular endogenous proangiogenic factor expression (Chapter 3), an enzyme-catalyzed alginate-g-pyrrole hydrogel system for VEGF delivery (Chapter 4), an enzyme-activated alginate-g-pyrrole hydrogel system with systematically controllable electrical and mechanical properties (Chapter 5), and an alginate-g-pyrrole hydrogel that enables the decoupled control of electrical conductivity and mechanical rigidity and is use to electrically stimulate cellular endogenous proangiogenic factor expression (Chapter 6). Overall, the biomaterial systems developed in this thesis will be broadly useful for improving the quality of a wide array of molecular and cellular based

  10. Surfactant improves irrigant penetration into unoperated sinuses

    PubMed Central

    Rohrer, Joseph W.; Dion, Greg R.; Brenner, Pryor S.; Abadie, Wesley M.; McMains, Kevin C.; Thomas, Roy F.

    2012-01-01

    Background: Saline irrigations are proving to be a valuable intervention in the treatment of chronic sinusitis. The use of surfactants is a well established additive to topical treatments known to reduce surface tension and may prove to be a simple, nonoperative intervention to improve intrasinus douching penetration. Methods: Six 30-mL, flat-bottomed medicine cups with circular holes cut through the bottom center and varying in diameter from 1 to 6 mm were created with punch biopsies. Water, saline, saline/dye, and saline/dye/surfactant were compared for maximum holding pressure via these modeled ostia. Holding pressures also were determined for cups with septal mucosa fused to the bottom with holes ranging from 1 to 6 mm. In addition, analysis was carried out with blood and blood/surfactant. Finally, five thawed, fresh-frozen cadaver heads were evaluated before any sinus surgery with water/dye and water/dye/surfactant for intrasinus penetration. Results: Surfactant significantly improved the ability of all solutions to penetrate ostia in both the plastic cup and fused septal mucosa model. All nonsurfactant-containing solutions were not statistically different from one another, nor did surfactant change the ostial penetration of blood. Surfactant significantly improved the ability of sinus irrigant to penetrate unoperated sinus cavities (3.12 vs 3.5, p = .021). Conclusions: The addition of surfactant to saline irrigation improves ostial penetration in undissected and undiseased cadavers. This has practical implications for unoperated patients seeking care for sinus-related symptoms in that we have now described a method for improving topical treatment of target sinus mucosa prior to surgical intervention. PMID:22643945

  11. Hydrophobic surfactant proteins and their analogues.

    PubMed

    Walther, Frans J; Waring, Alan J; Sherman, Mark A; Zasadzinski, Joseph A; Gordon, Larry M

    2007-01-01

    Lung surfactant is a complex mixture of phospholipids and four surfactant-associated proteins (SP-A, SP-B, SP-C and SP-D). Its major function in the lung alveolus is to reduce surface tension at the air-water interface in the terminal airways by the formation of a surface-active film enriched in surfactant lipids, hence preventing cellular collapse during respiration. Surfactant therapy using bovine or porcine lung surfactant extracts, which contain only polar lipids and native SP-B and SP-C, has dramatically improved the therapeutic outcomes of preterm infants with respiratory distress syndrome (RDS). One important goal of surfactant researchers is to replace animal-derived therapies with fully synthetic preparations based on SP-B and SP-C, produced by recombinant technology or peptide synthesis, and reconstituted with selected synthetic lipids. Here, we review recent research developments with peptide analogues of SP-B and SP-C, designed using either the known primary sequence and three-dimensional (3D) structure of the native proteins or, alternatively, the known 3D structures of closely homologous proteins. Such SP-B and SP-C mimics offer the possibility of studying the mechanisms of action of the respective native proteins, and may allow the design of optimized surfactant formulations for specific pulmonary diseases (e.g., acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)). These synthetic surfactant preparations may also be a cost-saving therapeutic approach, with better quality control than may be obtained with animal-based treatments. PMID:17575474

  12. Spatial and Temporal Control of Surfactant Systems

    PubMed Central

    Liu, Xiaoyang; Abbott, Nicholas L.

    2011-01-01

    This paper reviews some recent progress on approaches leading to spatial and temporal control of surfactant systems. The approaches revolve around the use of redox-active and light-sensitive surfactants. Perspectives are presented on experiments that have realized approaches for active control of interfacial properties of aqueous surfactant systems, reversible control of microstructures and nanostructures formed within bulk solutions, and in situ manipulation of the interactions of surfactants with polymers, DNA and proteins. A particular focus of this review is devoted to studies of amphiphiles that contain the redox-active group ferrocene – reversible control of the oxidation state of ferrocene leads to changes in the charge/hydrophobicity of these amphiphiles, resulting in substantial changes in their self-assembly. Light-sensitive surfactants containing azobenzene, which undergo changes in shape/polarity upon illumination with light, are a second focus of this review. Examples of both redox-active and light-sensitive surfactants that lead to large (> 20mN/m) and spatially localized (~mm) changes in surface tensions on a time scale of seconds are presented. Systems that permit reversible transformations of bulk solution nanostructures – such as micelle-to-vesicle transitions or monomer-to-micelle transitions – are also described. The broad potential utility of these emerging classes of amphiphiles are illustrated by the ability to drive changes in functional properties of surfactant systems, such as rheological properties and reversible solubilization of oils, as well as the ability to control interactions of surfactants with biomolecules to modulate their transport into cells. PMID:19665723

  13. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2004-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Anionic surfactants (SS-6656, Alfoterra 35, 38, 63,65,68) have been identified which can change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil in the presence of Na{sub 2}CO{sub 3}. All the carbonate surfaces (Lithographic Limestone, Marble, Dolomite and Calcite) show similar behavior with respect to wettability alteration with surfactant 4-22. Anionic surfactants (5-166, Alfoterra-33 and Alfoterra-38 and Alfoterra-68), which lower the interfacial tension with a West Texas crude oil to very low values (<10{sup -2} nM/m), have also been identified. Plans for the next quarter include conducting wettability, mobilization, and imbibition studies.

  14. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate wettability. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  15. Surfactant mediated polyelectrolyte self-assembly

    SciTech Connect

    Goswami, Monojoy; Borreguero Calvo, Jose M.; Pincus, Phillip A.; Sumpter, Bobby G.

    2015-11-25

    Self-assembly and dynamics of polyelectrolyte (PE) surfactant complex (PES) is investigated using molecular dynamics simulations. The complexation is systematically studied for five different PE backbone charge densities. At a fixed surfactant concentration the PES complexation exhibits pearl-necklace to agglomerated double spherical structures with a PE chain decorating the surfactant micelles. The counterions do not condense on the complex, but are released in the medium with a random distribution. The relaxation dynamics for three different length scales, polymer chain, segmental and monomer, show distinct features of the charge and neutral species; the counterions are fastest followed by the PE chain and surfactants. The surfactant heads and tails have the slowest relaxation due to their restricted movement inside the agglomerated structure. At the shortest length scale, all the charge and neutral species show similar relaxation dynamics confirming Rouse behavior at monomer length scales. Overall, the present study highlights the structure-property relationship for polymer-surfactant complexation. These results will help improve the understanding of PES complex and should aid in the design of better materials for future applications.

  16. Surfactant mediated polyelectrolyte self-assembly

    DOE PAGESBeta

    Goswami, Monojoy; Borreguero Calvo, Jose M.; Pincus, Phillip A.; Sumpter, Bobby G.

    2015-11-25

    Self-assembly and dynamics of polyelectrolyte (PE) surfactant complex (PES) is investigated using molecular dynamics simulations. The complexation is systematically studied for five different PE backbone charge densities. At a fixed surfactant concentration the PES complexation exhibits pearl-necklace to agglomerated double spherical structures with a PE chain decorating the surfactant micelles. The counterions do not condense on the complex, but are released in the medium with a random distribution. The relaxation dynamics for three different length scales, polymer chain, segmental and monomer, show distinct features of the charge and neutral species; the counterions are fastest followed by the PE chain andmore » surfactants. The surfactant heads and tails have the slowest relaxation due to their restricted movement inside the agglomerated structure. At the shortest length scale, all the charge and neutral species show similar relaxation dynamics confirming Rouse behavior at monomer length scales. Overall, the present study highlights the structure-property relationship for polymer-surfactant complexation. These results will help improve the understanding of PES complex and should aid in the design of better materials for future applications.« less

  17. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2005-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Imbibition in an originally oil-wet 2D capillary is the fastest in the case of Alf-38 and slowest in the case of DTAB (among the surfactants studied). Force of adhesion studies and contact angle measurements show that greater wettability alteration is possible with these anionic surfactants than the cationic surfactant studied. The water imbibition rate does not increase monotonically with an increase in the surfactant concentration. A numerical model has been developed that fits the rate of imbibition. Plans for the next quarter include conducting simulation and imbibition studies.

  18. SURFACTANT - POLYMER INTERACTION FOR IMPROVED OIL RECOVERY

    SciTech Connect

    Unknown

    1998-10-01

    The goal of this research is to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, adsorption and mobility control. Surfactant--polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation high adsorption and viscous/heterogeneity fingering. A mixture comprising a ''pseudo oil'' with appropriate surfactant and polymer has been selected to study micellar-polymer chemical flooding. The physical properties and phase behavior of this system have been determined. A surfactant-polymer slug has been designed to achieve high efficiency recovery by improving phase behavior and mobility control. Recovery experiments have been performed on linear cores and a quarter 5-spot. The same recovery experiments have been simulated using a commercially available simulator (UTCHEM). Good agreement between experimental data and simulation results has been achieved.

  19. Turbulent drag reduction in nonionic surfactant solutions

    NASA Astrophysics Data System (ADS)

    Tamano, Shinji; Itoh, Motoyuki; Kato, Katsuo; Yokota, Kazuhiko

    2010-05-01

    There are only a few studies on the drag-reducing effect of nonionic surfactant solutions which are nontoxic and biodegradable, while many investigations of cationic surfactant solutions have been performed so far. First, the drag-reducing effects of a nonionic surfactant (AROMOX), which mainly consisted of oleyldimethylamineoxide, was investigated by measuring the pressure drop in the pipe flow at solvent Reynolds numbers Re between 1000 and 60 000. Second, we investigated the drag-reducing effect of a nonionic surfactant on the turbulent boundary layer at momentum-thickness Reynolds numbers Reθ from 443 to 814 using two-component laser-Doppler velocimetry and particle image velocimetry systems. At the temperature of nonionic surfactant solutions, T =25 °C, the maximum drag reduction ratio for AROMOX 500 ppm was about 50%, in the boundary layer flow, although the drag reduction ratio was larger than 60% in pipe flow. Turbulence statistics and structures for AROMOX 500 ppm showed the behavior of typical drag-reducing flow such as suppression of turbulence and modification of near-wall vortices, but they were different from those of drag-reducing cationic surfactant solutions, in which bilayered structures of the fluctuating velocity vectors were observed in high activity.

  20. Surfactant-Templated Synthesis of Polypyrrole Nanocages as Redox Mediators for Efficient Energy Storage

    PubMed Central

    Ahn, Ki-Jin; Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Im, Kyungun; Noh, Seonmyeong; Yoon, Hyeonseok

    2015-01-01

    Preparation of conducting-polymer hollow nanoparticles with different diameters was accomplished by surfactant templating. An anionic surfactant, namely sodium dodecylbenzenesulfonate, formed vesicles to template with the pyrrole monomer. Subsequent chemical oxidative polymerization of the monomer yielded spherical polypyrrole (PPy) nanoparticles with hollow interiors. The diameter of the hollow nanoparticles was easily controlled by adjusting the concentration of the surfactant. Subsequently, the size-dependent electrochemical properties of the nanoparticles, including redox properties and charge/discharge behavior, were examined. By virtue of the structural advantages, the specific capacitance (max. 326 F g−1) of PPy hollow nanoparticles was approximately twice as large as that of solid PPy nanospheres. The hollow PPy nanostructure can easily be used as a conductive substrate for the preparation of metal/polymer nanohybrids through chemical and electrochemical deposition. Two different pseudocapacitive metal-oxide clusters were readily deposited on the inner and outer surfaces of the hollow nanoparticles, which resulted in an increase in the specific capacitance to 390 F g−1. In addition, the hollow nanoparticles acted as a nanocage to prevent metal ion leaching during charge/discharge, thus allowing an excellent capacitance retention of ca. 86%, even following 10,000 cycles. PMID:26373685

  1. Effects of Surfactants on the Improvement of Sludge Dewaterability Using Cationic Flocculants

    PubMed Central

    Zhai, Jun; Teng, Houkai; Zhao, Chun; Zhao, Chuanliang; Liao, Yong

    2014-01-01

    The effects of the cationic surfactant (cationic cetyl trimethyl ammonium bromide, CTAB) on the improvement of the sludge dewaterability using the cationic flocculant (cationic polyacrylamide, CPAM) were analyzed. Residual turbidity of supernatant, dry solid (DS) content, extracellular polymeric substances (EPS), specific resistance to filtration (SRF), zeta potential, floc size, and settling rate were investigated, respectively. The result showed that the CTAB positively affected the sludge conditioning and dewatering. Compared to not using surfactant, the DS and the settling rate increased by 8%–21.2% and 9.2%–15.1%, respectively, at 40 mg·L−1 CPAM, 10×10−3 mg·L−1 CTAB, and pH 3. The residual turbidities of the supernatant and SRF were reduced by 14.6%–31.1% and 6.9%–7.8% compared with turbidities and SRF without surfactant. Furthermore, the release of sludge EPS, the increases in size of the sludge flocs, and the sludge settling rate were found to be the main reasons for the CTAB improvement of sludge dewatering performance. PMID:25347394

  2. Surfactant-Templated Synthesis of Polypyrrole Nanocages as Redox Mediators for Efficient Energy Storage

    NASA Astrophysics Data System (ADS)

    Ahn, Ki-Jin; Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Im, Kyungun; Noh, Seonmyeong; Yoon, Hyeonseok

    2015-09-01

    Preparation of conducting-polymer hollow nanoparticles with different diameters was accomplished by surfactant templating. An anionic surfactant, namely sodium dodecylbenzenesulfonate, formed vesicles to template with the pyrrole monomer. Subsequent chemical oxidative polymerization of the monomer yielded spherical polypyrrole (PPy) nanoparticles with hollow interiors. The diameter of the hollow nanoparticles was easily controlled by adjusting the concentration of the surfactant. Subsequently, the size-dependent electrochemical properties of the nanoparticles, including redox properties and charge/discharge behavior, were examined. By virtue of the structural advantages, the specific capacitance (max. 326 F g-1) of PPy hollow nanoparticles was approximately twice as large as that of solid PPy nanospheres. The hollow PPy nanostructure can easily be used as a conductive substrate for the preparation of metal/polymer nanohybrids through chemical and electrochemical deposition. Two different pseudocapacitive metal-oxide clusters were readily deposited on the inner and outer surfaces of the hollow nanoparticles, which resulted in an increase in the specific capacitance to 390 F g-1. In addition, the hollow nanoparticles acted as a nanocage to prevent metal ion leaching during charge/discharge, thus allowing an excellent capacitance retention of ca. 86%, even following 10,000 cycles.

  3. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.

    PubMed

    Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A; Gerlich, Daniel W

    2016-07-14

    Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization. PMID:27362226

  4. A Computational Study of the Rheology and Structure of Surfactant Covered Droplets

    NASA Astrophysics Data System (ADS)

    Maia, Joao; Boromand, Arman; Jamali, Safa

    2015-11-01

    The use of different types of surface-active agents is ubiquitous practice in different industrial applications ranging from cosmetic and food industries to polymeric nano-composite and blends. This allows stable multiphasic systems like foams and emulsions to be produced. Stability and shelf-life of those products are directly determined by the efficiency of the surfactant molecules. Although the effect of molecular configuration of the surface-active molecules on the planar interfaces has been studied both experimentally and computationally, it remains challenging to track the efficiency and effectiveness of different surfactant molecules on curved interfaces. In this study we address this gap by using Dissipative Particle Dynamics, to study the effectiveness and efficiency of different surfactant molecules (linear vs. branched) on a curved interface in equilibrium and far from equilibrium. In particular, we are interested to relate interfacial properties of the surface covered droplets and its dynamics to the molecular configuration of the surface active molecules under equilibrium and far from equilibrium condition.

  5. Effects of surfactants on the improvement of sludge dewaterability using cationic flocculants.

    PubMed

    Sun, Yongjun; Zheng, Huaili; Zhai, Jun; Teng, Houkai; Zhao, Chun; Zhao, Chuanliang; Liao, Yong

    2014-01-01

    The effects of the cationic surfactant (cationic cetyl trimethyl ammonium bromide, CTAB) on the improvement of the sludge dewaterability using the cationic flocculant (cationic polyacrylamide, CPAM) were analyzed. Residual turbidity of supernatant, dry solid (DS) content, extracellular polymeric substances (EPS), specific resistance to filtration (SRF), zeta potential, floc size, and settling rate were investigated, respectively. The result showed that the CTAB positively affected the sludge conditioning and dewatering. Compared to not using surfactant, the DS and the settling rate increased by 8%-21.2% and 9.2%-15.1%, respectively, at 40 mg·L-1 CPAM, 10×10-3 mg·L-1 CTAB, and pH 3. The residual turbidities of the supernatant and SRF were reduced by 14.6%-31.1% and 6.9%-7.8% compared with turbidities and SRF without surfactant. Furthermore, the release of sludge EPS, the increases in size of the sludge flocs, and the sludge settling rate were found to be the main reasons for the CTAB improvement of sludge dewatering performance. PMID:25347394

  6. DNA interaction with cis- and trans- isomers of photosensitive surfactant

    NASA Astrophysics Data System (ADS)

    Unksov, I. N.; Kasyanenko, N. A.

    2014-12-01

    Interaction between DNA and photosensitive cationic surfactant in a solution is studied. Studies were conducted to examine the impact of the surfactant in its cis- conformation on the size of DNA molecule and also to investigate the phase behavior of the system depending on DNA and surfactant concentration. We conclude that trans- isomer of surfactant requires its smaller concentration to reach the DNA compaction compared with cis- isomer received by UV radiation of solutions. Studies of DNA-surfactant systems were performed by means of spectrophotometry and viscometry. Variation of surfactant concentration enables us to determine the precipitation zone on phase diagram. From the viscosity study it can be indicated that precipitation zone is narrower for UV-radiated surfactant and it shifts to higher surfactant concentration. Also we examine the reversibility of DNA compaction in systems with the surfactant in its trans- form.

  7. Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer via covalent immobilization of nonionic sugar-based Gemini surfactants.

    PubMed

    Xin, Zhirong; Du, Binbin; Yan, Shunjie; Du, Shanshan; Ding, Jiaotong; Yang, Zongfeng; Ren, Wanzhong

    2014-07-01

    Gemini surfactants (GS) with sugar-containing head-groups and different alkyl chains were successfully prepared. Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer was grafted with glycidyl methacrylate (GMA) by means of UV-induced graft polymerization, and then the pGMA-grafted film was chemically immobilized with the GS. The surface graft polymerization was confirmed by ATR-FTIR and XPS. The wettability and hemocompatibility of the modified surface were characterized by means of water contact angle, protein adsorption, and platelet adhesion assays. The results showed that amphiphilic surfactant-containing polymer surfaces presented protein-resistant behavior and anti-platelet adhesion after functionalization with GS, GS1 and GS2. Besides, the hemocompatibility of the modified surface deteriorated as the length of hydrophobic chain of GS increased. PMID:24854325

  8. Synthesis of berberine loaded polymeric nanoparticles by central composite design

    NASA Astrophysics Data System (ADS)

    Mehra, Meenakshi; Sheorain, Jyoti; Kumari, Santosh

    2016-04-01

    Berberine is an isoquinoline alkaloid which is extracted from bark and roots of Berberis vulgaris plant. It has been used in ayurvedic medicine as it possess antimicrobial, antidiabetic, anticancer, antioxidant properties etc. But poor solubility of berberine leads to poor stability and bioavailability in medical formulations decreasing its efficacy. Hence nanoformulations of berberine can help in removing the limiting factors of alkaloid enhancing its utilization in pharmaceutical industry. Sodium alginate polymer was used to encapsulate berberine within nanoparticles by emulsion solvent evaporation method using tween 80 as a surfactant. Two factors and three level in central composite design was used to study the formulation. The optimized formulation (1% v/v of Tween 80 and 0.01% w/v of sodium alginate) of polymeric nanoparticles was taken for further evaluations. The size of synthesized nanoparticles was found to be 71.18 nm by particle size analysis (PSA). The berberine loaded polymeric nanoparticles showed better antibacterial activity compared to aqueous solution of berberine by well diffusion assay.

  9. Interactions of organic contaminants with mineral-adsorbed surfactants

    USGS Publications Warehouse

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  10. Stereospecific olefin polymerization catalysts

    DOEpatents

    Bercaw, John E.; Herzog, Timothy A.

    1998-01-01

    A metallocene catalyst system for the polymerization of .alpha.-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula ##STR1## wherein: R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ; R.sup.5 is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E.sup.1, E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; and the ligand may have C.sub.S or C.sub.1 -symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from .alpha.-olefin monomers.

  11. Stereospecific olefin polymerization catalysts

    DOEpatents

    Bercaw, J.E.; Herzog, T.A.

    1998-01-13

    A metallocene catalyst system is described for the polymerization of {alpha}-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula shown wherein: R{sup 1}, R{sup 2}, and R{sup 3} are independently selected from the group consisting of hydrogen, C{sub 1} to C{sub 10} alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C{sub 1} to C{sub 10} alkyls as a substituent, C{sub 6} to C{sub 15} aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R{sup 8}){sub 3} where R{sup 8} is selected from the group consisting of C{sub 1} to C{sub 10} alkyl, C{sub 6} to C{sub 15} aryl or C{sub 3} to C{sub 10} cycloalkyl; R{sup 4} and R{sup 6} are substituents both having van der Waals radii larger than the van der Waals radii of groups R{sup 1} and R{sup 3}; R{sup 5} is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E{sup 1}, E{sup 2} are independently selected from the group consisting of Si(R{sup 9}){sub 2}, Si(R{sup 9}){sub 2}--Si(R{sup 9}){sub 2}, Ge(R{sup 9}){sub 2}, Sn(R{sup 9}){sub 2}, C(R{sup 9}){sub 2}, C(R{sup 9}){sub 2}--C(R{sup 9}){sub 2}, where R{sup 9} is C{sub 1} to C{sub 10} alkyl, C{sub 6} to C{sub 15} aryl or C{sub 3} to C{sub 10} cycloalkyl; and the ligand may have C{sub S} or C{sub 1}-symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from {alpha}-olefin monomers.

  12. Anionic surfactant - Biogenic amine interactions: The role of surfactant headgroup geometry.

    PubMed

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun

    2016-03-15

    Oligoamines and biogenic amines (naturally occurring oligoamines) are small flexible polycations. They interact strongly with anionic surfactants such as sodium dodecyl sulfate, SDS. This results in enhanced adsorption and the formation of layered structures and the formation of layered structures at the air-water interface which depends on surfactant concentration and solution pH. The effect of changing the surfactant headgroup geometry on that interaction and subsequent adsorption is reported here. Neutron reflectivity, NR, results for the surface adsorption of the anionic surfactant sodium diethylene glycol monododecyl ether sulfate, SLES, with the biogenic amine, spermine, are presented, and contrasted with previous data for SDS/spermine mixtures. The enhancement in the adsorption of the surfactant at the air-water interface where monolayer adsorption occurs is similar for both surfactants. However the regions of surfactant concentration and solution pH where surface multilayer adsorption occurs is less extensive for the SLES/spermine mixtures, and occurs only at low pH. The results show how changing the headgroup geometry by the introduction of the ethylene oxide linker group between the alkyl chain and sulfate headgroup modifies the polyamine - surfactant interaction. The increased steric constraint from the polyethylene oxide group disrupts the conditions for surface multilayer formation at the higher pH values. This has important consequences for applications where the modification or manipulation of the surface properties are required. PMID:26724704

  13. Surfactant Delivery into the Lung

    NASA Astrophysics Data System (ADS)

    Grotberg, James; Filoche, Marcel

    2014-11-01

    We have developed a multiscale, compartmentalized model of surfactant and liquid delivery into the lung. Assuming liquid plug propagation, the airway compartment accounts for the plug's volume deposition (coating) on the airway wall, while the bifurcation compartment accounts for plug splitting from the parent airway to the two daughter airways. Generally the split is unequal due to gravity and geometry effects. Both the deposition ratio RD (deposition volume/airway volume), and the splitting ratio, RS, of the daughters volumes are solved independently from one another. Then they are used in a 3D airway network geometry to achieve the distribution of delivery into the lung. The airway geometry is selected for neonatal as well as adult applications, and can be advanced from symmetric, to stochastically asymmetric, to personalized. RD depends primarily on the capillary number, Ca, while RS depends on Ca, the Reynolds number, Re, the Bond number, Bo, the dose volume, VD, and the branch angles. The model predicts the distribution of coating on the airway walls and the remaining plug volume delivered to the alveolar region at the end of the tree. Using this model, we are able to simulate and test various delivery protocols, in order to optimize delivery and improve the respiratory function.

  14. Branching mechanisms in surfactant micelles

    NASA Astrophysics Data System (ADS)

    Dhakal, Subas; Sureshkumar, Radhakrishna

    The mechanisms of branch formation in surfactant micelles of cetyltrimethylammonium chloride (CTAC) in presence of sodium salicylate (NaSal) counter ions in water are studied using molecular dynamics simulations. The curvature energy associated with the formation of micelle branches and the effect of branching on the solution viscosity are quantified. Highly curved surfaces are energetically stabilized by a higher density of binding counter ions near the branch points. Simulations show that micellar branches result in a significant reduction in the solution viscosity as observed in experiments [Dhakal & Sureshkumar, J. Chem. Phys. 143, 024905 (2015)]. This reduction in viscosity has long been attributed to the sliding motion of micelle branches across the main chain. However, to date, such dynamics of micelle branches have never been visualized in either experiments or simulations. Here, we explicitly illustrate and quantify, for the first time, how branches slide along the micelle contour to facilitate stress relaxation. We acknowledged the computational resources provided by XSEDE which is supported by NSF Grant Number OCI-1053575 and the financial support by National Science Foundation under Grants 1049489 and 1049454.

  15. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  16. Size-controlled starch nanoparticles prepared by self-assembly with different green surfactant: The effect of electrostatic repulsion or steric hindrance.

    PubMed

    Li, Xiaojing; Qin, Yang; Liu, Chengzhen; Jiang, Suisui; Xiong, Liu; Sun, Qingjie

    2016-05-15

    To study the control effect of surfactants in the process of formation of starch nanoparticles by self-assembly, different surfactants (sodium dodecyl sulfate (SDS), polysorbate 80 (Tween 80), and sorbitan monooleate (Span 80) were added during the fabrication of waxy corn starch nanoparticles (WCSNPs) and potato starch nanoparticles (PSNPs), and their characteristics were determined and compared. The results showed that WCSNPs with SDS and Tween 80 had smaller particle size (28-35 nm and 15-24 nm, respectively) than that of WCSNPs (50-120 nm). The surfactants significantly increased the dispersion and thermal stability of nanoparticles. Short-chain amylose debranched from waxy corn starch had a lower degree of polymerization than that debranched from potato starch and were easier to retrograde, resulting in higher gelatinization enthalpy of WCSNPs. However, PSNPs were smaller in size and achieved better stability than WCSNPs due to stronger electrostatic repulsion caused by a higher absolute value of zeta potential. PMID:26775982

  17. Selection of surfactant in remediation of DDT-contaminated soil by comparison of surfactant effectiveness.

    PubMed

    Guo, Ping; Chen, Weiwei; Li, Yueming; Chen, Tao; Li, Linhui; Wang, Guanzhu

    2014-01-01

    With an aim to select the most appropriate surfactant for remediation of DDT-contaminated soil, the performance of nonionic surfactants Tween80, TX-100, and Brij35 and one anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in enhancement of DDT water solubility and desorption of DDT from contaminated soil and their adsorption onto soil and ecotoxicities were investigated in this study. Tween80 had the highest solubilizing and soil-washing ability for DDT among the four experimental surfactants. The adsorption loss of surfactants onto soil followed the order of TX-100 > Tween80 > Brij35 > SDBS. The ecotoxicity of Tween80 to ryegrass (Lolium perenne L.) was lowest. The overall performance considering about the above four aspects suggested that Tween80 should be selected for the remediation of DDT-contaminated soil, because Tween80 had the greatest solubilizing and soil-washing ability for DDT, less adsorption loss onto soil, and the lowest ecotoxicity in this experiment. PMID:23900948

  18. Surfactant-enhanced low-pH alkaline flooding

    SciTech Connect

    Peru, D.A. and Co., Columbia, MD . Research Div.); Lorenz, P.B. )

    1990-08-01

    This paper reports sodium bicarbonate investigated as a potential alkaline agent in surfactant-enhanced alkaline flooding because it has very little tendency to dissolve silicate minerals. In experiments performed with Wilmington, CA, crude oil and three types of surfactants, the bicarbonate/surfactant combination caused a marked lowering of interfacial tension (IFT). Bicarbonate protected the surfactant against divalent cations and reduced adsorption of surfactant and polymer on various minerals. Coreflood test confirm that sodium bicarbonate plus surfactant can be an effective alternative to the high-pH flooding process.

  19. Growing Characteristics of Fine Ice Particles in Surfactant Solution

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nakayama, Kosuke; Komoda, Yoshiyuki; Usui, Hiromoto; Okada, Kazuto; Fujisawa, Ryo

    Time variation characteristics of ice particles in a surfactant solution have been investigated. The effect of surfactants on corrosion characteristics was also studied. The results were compared with those treated with poly(vinyl alcohol). From the results, the present surfactant, cetyl dimethyl betaine was not found to be effective on preventing Ostward ripening of ice particles as poly(vinyl alcohol) showed. Then, it was concluded some effective technology has to be installed with surfactants when this surfactant treatment is realized. On the corrosion characteristics, it was found that the present surfactant shows the same level as tap water.

  20. Synthesis of polymer nanostructures via the use of surfactant surface aggregates as templates

    NASA Astrophysics Data System (ADS)

    Marquez, Maricel

    The subject of this work is the synthesis of polymer nanostructures via the use of surfactant surface aggregates as templates, also termed Template Assisted Admicellar Polymerization (TAAP). The first chapter reviews some of the most current nanopatterning techniques (including both top-down and bottom-up approaches), with particular emphasis on the fabrication of organic and inorganic patterned nanostructures via particle lithography. In chapter 2, highly ordered hexagonal arrays of latex spheres were prepared on highly ordered pyrolytic graphite (HOPG) from a variation of the Langmuir Blodgett technique, using an anionic surfactant (SDS), and a low molecular weight (ca. 10000) polyacrylamide as spreading agents. When a nonionic polyethoxylated (EO = 9) surfactant was used as the spreading agent, no ordered arrays were observed. Based on the correlation found between the surface tension in the presence of the latex particles and the critical concentration at which hexagonal arrangements of latex spheres occurs; a model was proposed to explain the role of the spreading agent in forming stable monolayers at the air/liquid interface, which in turn are necessary for the formation of well-ordered monolayers on a solid substrate from the LB technique. According to this model, solid-like regions of small numbers of latex spheres form at the liquid-air interface, which are then transferred to the substrate. These ordered regions then act as nuclei for the formation of 2D arrays of latex spheres on the surface upon water evaporation. The role of other factors such as relative humidity, substrate and solvent choice, and pulling vs. compression speed were also found to affect the quality of the monolayers formed. Finally, a simple, easy to automate, yet effective surface tension method was proposed to predict the optimal conditions for the formation of ordered monolayers using a variation of the LB deposition method from any monodisperse set of spheres. In chapter 3, a novel

  1. Isolation of Surfactant-Resistant Bacteria from Natural, Surfactant-Rich Marine Habitats▿

    PubMed Central

    Plante, Craig J.; Coe, Kieran M.; Plante, Rebecca G.

    2008-01-01

    Environmental remediation efforts often utilize either biodegradative microbes or surfactants, but not in combination. Coupling both strategies holds the potential to dramatically increase the rate and extent of remediation because surfactants can enhance the bioavailability of contaminants to microbes. However, many surfactants permeabilize bacterial cell membranes and are effective disinfectants. An important goal then is to find or genetically modify microorganisms that possess both desirable degradative capabilities and the ability to thrive in the presence of surfactants. The guts of some marine invertebrates, particularly deposit feeders, have previously been shown to contain high levels of biosurfactants. Our primary aim was to mine these natural, surfactant-rich habitats for surfactant-resistant bacteria. Relative to sediment porewaters, the gut contents of two polychaete deposit feeders, Nereis succinea and Amphitrite ornata, exhibited a significantly higher ratio of bacteria resistant to both cationic and anionic surfactants. In contrast, bacteria in the gut fluids of a holothuroid, Leptosynapta tenuis, showed surfactant susceptibility similar to that of bacteria from sediments. Analyses of 16S rRNA gene sequences revealed that the majority of surfactant-resistant isolates were previously undescribed species of the genus Vibrio or were of a group most closely related to Spongiobacter spp. We also tested a subset of resistant bacteria for the production of biosurfactants. The majority did produce biosurfactants, as demonstrated via the oil-spreading method, but in all cases, production was relatively weak under the culture conditions employed. Novel surfactant-resistant, biosurfactant-producing bacteria, and the habitats from which they were isolated, provide a new source pool for potential microorganisms to be exploited in the in situ bioremediation of marine sediments. PMID:18586977

  2. Direct spectrophotometric determination of alkylphenol polyethoxylate nonionic surfactants in wastewater.

    PubMed

    Zhu, Zhenzhong; Li, Zaijun; Hao, Zhuoli; Chen, Jian

    2003-11-01

    A new spectrophotometric method is proposed for direct determination of alkylphenol polyethoxylate, RO(CH(2)CH(2)O)(n)H (where R is alkylphenyl and n is the degree of polymerization), in wastewater. The method is based on the formation of ternary complex, Pb(II)-meso-tetra-(3,5-dibromo-4-hydrooxyphenyl)-Porphyrin (T(DBHP)P)-alkylphenol polyethoxylate (APE). Under optimum reaction conditions, T(DBHP)P reacts with lead(II) and APE to form a yellow ternary complex with the maximum absorption peak at 479 nm. The color reaction is rapidly completed and the absorbance remains stable for at least 24h under room temperature. The apparent molar absorption coefficients were 0.4-4.3 x 10(4) L mol(-1) cm(-1) for n=5-50. As little as 0.02 microg mL(-1) of APE can be detected. The effects of various substances on the determination of APE were also investigated in detail. It was found that all the studied co-existing substances, especially cationic and anionic surfactants, which always seriously interfere in some reported methods, could be tolerated in considerable amounts. The method offered the advantages of simplicity, rapidity, sensitivity and selectivity without any prior separation or extraction. PMID:14511721

  3. Group transfer polymerization. Mechanism revisted

    SciTech Connect

    Sogah, D.Y.

    1993-12-31

    Group Transfer Polymerization (GTP) is a living polymerization technique that allows control of characteristics of vinyl polymers, especially those derived from methacrylate monomers. Several mechanistic pathways have been proposed by different research groups. This presentation will examine the most plausible mechanisms and the evidence supporting each one. The dependence of the reaction on the type, nature and concentrations of catalysts, other additives, initiators and monomers will be discussed. The crucial role that chiral organosilicon reagents may play will be examined using a novel cyclic initiator containing 2,2`-dialkylsilyl-1,1`-binaphthyl.

  4. Deactivator for olefin polymerization catalyst

    SciTech Connect

    Rekers, L.J.; Speca, A.N.; Mayhew, H.W.

    1987-03-10

    A method is described comprising deactivating an olefin polymerization catalyst selected from the group consisting of Ziegler-Natta transition element catalysts and catalysts based on transition metal oxides by contacting the catalyst with a copolymer. The copolymer consists of an alpha-olefin having from 2 to about 12 carbon atoms and an unsaturated ester of a carboxylic acid. The deactivating copolymer is present in an amount such that the molar ratio of the unsaturated ester thereof to the sum of the transition element component of the polymerization catalyst and a cocatalyst for the transition element catalyst is in the range of between about 0.1 and about 6.

  5. On-demand photoinitiated polymerization

    DOEpatents

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  6. On-demand photoinitiated polymerization

    DOEpatents

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2015-01-13

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  7. Counterion specificity of surfactants based on dicarboxylic amino acids.

    PubMed

    Bordes, Romain; Tropsch, Jürgen; Holmberg, Krister

    2009-10-15

    The behavior in solution of a series of amino acid-based surfactants having two carboxyl groups separated by a spacer of one, two, or three carbon atoms has been investigated. All three surfactants precipitated on addition of acid, but the aspartate surfactant (with a two-carbon spacer) was considerably more resistant to precipitation than the aminomalonate surfactant (one-carbon spacer) and the glutamate surfactant (three-carbon spacer). The interactions with the monovalent counterions lithium, sodium, and potassium were investigated by conductivity. It was found that lithium ions bound the strongest and potassium ions the weakest to the surfactant micelles. These results were interpreted using the hard and soft acid-base theory. Comparing the three surfactants with respect to binding of one specific counterion, sodium, showed that the aminomalonate surfactant, which has the shortest spacer, bound sodium ions the strongest and the glutamate surfactant, which has the longest spacer, had the lowest affinity for the counterion. Also that could be explained by the hard and soft acid-base concept. The glutamate surfactant was found to be considerably more resistant to calcium ions than the two other surfactants. This was attributed to this surfactant forming an intermolecular complex with the calcium ion at the air-water interface while the aminomalonate and the aspartate surfactants, with shorter distance between the carboxylate groups could form six- and seven-membered intramolecular calcium complexes. PMID:19608191

  8. Synthesis of PEG-PCL-based polyurethane nanoparticles by miniemulsion polymerization.

    PubMed

    Valério, Alexsandra; Conti, Denise S; Araújo, Pedro H H; Sayer, Claudia; da Rocha, Sandro R P

    2015-11-01

    In this work biocompatible polyurethane nanoparticles for future application as noninvasive polymeric nanocarriers using propellant-based inhalers in the treatment of respiratory diseases were prepared by miniemulsion interfacial polymerization derived from isophorone diisocyanate, poly(ϵ-caprolactone), and poly(ethylene glycol). The effects of the surfactant type, nonionic Tween 80 and Brij 35, anionic sodium dodecyl sulfate, and cationic cetyltrimethyl ammonium bromide, and poly(ethylene glycol) molar mass on the stability, size and morphology of nanoparticles were evaluated. In addition, the ability of cells to proliferate in contact with polyurethane nanoparticles was assessed by MTS ([(3-(4,5-dimethylthiazole-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium, inner salt]) assay using human lung adenocarcinoma A549 cells, an in vitro model of Type II alveolar epithelium. PMID:26241914

  9. CO2-responsive polymeric materials: synthesis, self-assembly, and functional applications.

    PubMed

    Darabi, Ali; Jessop, Philip G; Cunningham, Michael F

    2016-08-01

    CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications. PMID:27284587

  10. New amphiphilic diblock copolymers: surfactant properties and solubilization in their micelles.

    PubMed

    Garnier, Sébastien; Laschewsky, André

    2006-04-25

    Several series of amphiphilic diblock copolymers are investigated as macrosurfactants in comparison to reference low-molar-mass and polymeric surfactants. The various copolymers share poly(butyl acrylate) as a common hydrophobic block but are distinguished by six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) with various compositions. Dynamic light scattering experiments indicate the presence of micelles over the whole concentration range from 10(-4) to 10 g x L(-1). Accordingly, the critical micellization concentrations are very low. Still, the surface tension of aqueous solutions of block copolymers decreases slowly but continuously with increasing concentration, without exhibiting a plateau. The longer the hydrophobic block, the shorter the hydrophilic block, and the less hydrophilic the monomer of the hydrophilic block is, the lower the surface tension is. However, the effects are small, and the copolymers reduce the surface tension much less than standard low-molar-mass surfactants. Also, the copolymers foam much less and even act as anti-foaming agents in classical foaming systems composed of standard surfactants. The copolymers stabilize O/W emulsions made of methyl palmitate as equally well as standard surfactants but are less efficient for O/W emulsions made of tributyrine. However, the copolymer micelles exhibit a high solubilization power for hydrophobic dyes, probably at their core-corona interface, in dependence on the initial geometry of the micelles and the composition of the block copolymers. Whereas micelles of copolymers with strongly hydrophilic blocks are stable upon solubilization, solubilization-induced micellar growth is observed for copolymers with moderately hydrophilic blocks. PMID:16618143

  11. Aqueous Self-Assembly of Non-Ionic Bottlebrush Block Copolymer Surfactants with Tunable Molecular Shapes

    NASA Astrophysics Data System (ADS)

    Rzayev, Javid

    2015-03-01

    Polymer amphiphiles provide a robust and versatile platform for the fabrication of nanostructured soft matter. In this research, we explore a new class of polymer surfactants based on comb-like bottlebrush architecture as highly tunable molecular building blocks for aqueous self-assembly. Excluded volume interactions between densely grafted polymer side chains in the bottlebrush architecture are alleviated by backbone stretching, which leads to the formation of shape-persistent cylindrical macromolecules whose molecular dimensions can be precisely tailored during chemical synthesis. Amphiphilic bottlebrush block copolymers containing hydrophobic polylactide (PLA) and hydrophilic poly(oligoethylene oxide methacrylate) (PEO) side chains of various lengths were synthesized by a combination of controlled radical and ring-opening polymerizations. In dilute aqueous solutions, bottlebrush surfactants rapidly assembled into spherical, cylindrical and bilayer aggregates, as visualized by cryogenic transmission electron microscopy (cryo-TEM). Depending on the compositional side chain asymmetry, the formation of spherical micelles with different sizes and dispersities was observed. The molecular shape-dependent assembly was analyzed with help of a packing parameter (p) computed from the molecular composition data akin to small molecule surfactants, with most uniform spherical aggregates observed for bottlebrush amphiphiles with p close to 0.3. The formation of highly uniform micelles and the presence of a rich morphological diagram with relatively narrow compositional windows were attributed to the lack of conformational freedom in bottlebrush surfactants. Similarly, the unusual formation of cylindrical micelles with long aspect ratios for such high molecular weight amphiphiles was attributed to their inability to stabilize morphological defects, such as Y-junctions, with large deviations from mean curvature. Financial support for this work was provided by the National

  12. Self-Assembly of Gemini Surfactants

    NASA Astrophysics Data System (ADS)

    Yethiraj, Arun; Mondal, Jagannath; Mahanthappa, Mahesh

    2013-03-01

    The self-assembly behavior of Gemini (dimeric or twin-tail) dicarboxylate disodium surfactants is studied using molecular dynamics simulations. This gemini architecture, in which two single tailed surfactants are joined through a flexible hydrophobic linker, has been shown to exhibit concentration-dependent aqueous self-assembly into lyotropic phases including hexagonal, gyroid, and lamellar morphologies. Our simulations reproduce the experimentally observed phases at similar amphiphile concentrations in water, including the unusual ability of these surfactants to form gyroid phases over unprecedentedly large amphiphile concentration windows. We demonstrate quanitative agreement between the predicted and experimentally observed domain spacings of these nanostructured materials. Through careful conformation analyses of the surfactant molecules, we show that the gyroid phase is electrostatically stabilized related to the lamellar phase. By starting with a lamellar phase, we show that decreasing the charge on the surfactant headgroups by carboxylate protonation or use of a bulkier tetramethyl ammonium counterion in place of sodium drives the formation of a gyroid phase.

  13. 2-DE using hemi-fluorinated surfactants.

    PubMed

    Starita-Geribaldi, Mireille; Thebault, Pascal; Taffin de Givenchy, Elisabeth; Guittard, Frederic; Geribaldi, Serge

    2007-07-01

    The synthesis of hemi-fluorinated zwitterionic surfactants was realized and assessed for 2-DE, a powerful separation method for proteomic analysis. These new fluorinated amidosulfobetaine (FASB-p,m) were compared to their hydrocarbon counterparts amidosulfobetaine (ASB-n) characterized by a hydrophilic polar head, a hydrophobic and lipophilic tail, and an amido group as connector. The tail of these FASB surfactants was in part fluorinated resulting in the modulation of its lipophilicity (or oleophobicity). Their effect on the red blood cell (RBC) membrane showed a specific solubilization depending on the length of the hydrophobic part. A large number of polypeptide spots appeared in the 2-DE patterns by using FASB-p,m. The oleophobic character of these surfactants was confirmed by the fact that Band 3, a highly hydrophobic transmembrane protein, was not solubilized by these fluorinated structures. The corresponding pellet was very rich in Band 3 and could then be solubilized by using a strong detergent such as amidosulfobetaine with an alkyl tail containing 14 carbon atoms (ASB-14). Thus, these hemi-fluorinated surfactants appeared as powerful tools when used at the first step of a two-step solubilization strategy using a hydrocarbon homologous surfactant in the second step. PMID:17577887

  14. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2004-03-31

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Anionic surfactants (Alfoterra 35, 38) recover more than 40% of the oil in about 50 days by imbibition driven by wettability alteration in the core-scale. Anionic surfactant, Alfoterra-68, recovers about 28% of the oil by lower tension aided gravity-driven imbibition in the core-scale. Residual oil saturation showed little capillary number dependence between 10{sup -5} and 10{sup -2}. Wettability alteration increases as the number of ethoxy groups increases in ethoxy sulfate surfactants. Plans for the next quarter include conducting mobilization, and imbibition studies.

  15. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2004-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Simulation studies indicate that both wettability alteration and gravity-driven flow play significant role in oil recovery from fractured carbonates. Anionic surfactants (Alfoterra 35, 38) recover about 55% of the oil in about 150 days by imbibition driven by wettability alteration and low tension in the core-scale. Anionic surfactant, Alfoterra-68, recovers about 40% of the oil by lower tension aided gravity-driven imbibition in the core-scale. Cationic surfactant, DTAB recovers about 35% of the oil. Plans for the next quarter include conducting simulation and imbibition studies.

  16. SURFACTANT - POLYMER INTERACTION FOR IMPROVED OIL RECOVERY

    SciTech Connect

    Unknown

    1997-09-01

    The goal of this research is to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, adsorption and mobility control. Surfactant--polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation, high adsorption and viscous/heterogeneity fingering. This report contains data concerning selection of appropriate fluids for use in laboratory experiments and numerical simulations. A mixture comprising a ''pseudo oil'' with appropriate surfactant and polymer is proposed. The properties of this system has been determined. The experimental set-up has been conditioned for use and experiments involving the aforementioned system have already started. A commercial simulator has been acquired for use in reproducing the experiments. A graduate student has been trained in its use. Linear stability analysis equations have been developed and phase maps for one and two-dimensions are currently computed.

  17. Rheology of Natural Lung Surfactant Films

    NASA Astrophysics Data System (ADS)

    Alonso, Coralie; Waring, Alan; Zsadzinski, Joseph

    2004-03-01

    The lung surfactant (LS) is a lipoprotein mixture lining the inside of the pulmonary alveoli which has the ability to lower the surface tension of the air-liquid hypophase interface to value near zero thus reducing the work of breathing and which also prevents the alveolar collapse. A lack or malfunction of lung surfactant, as it is often the case for premature infants, leads to respiratory distress syndrome. RDS can be treated by supplying replacement LS to the infants and several medications derived from natural sources, are now widely used. The lung surfactant is adsorbed at the air-liquid interface and is subjected to incessant compression expansion cycles therefore Langmuir monolayers provide a suitable model to investigate the physical properties of lung surfactant films. Using a magnetic needle rheometer, we measured the shear viscosity of natural lung surfactant spread at the air-liquid interface upon compression and expansion cycles for three different formulations. The shear viscosity of Survanta changes by orders of magnitude along one cycle while for Curosurf samples it changes only slightly and for Infasurf films it remains constant. These different behaviors can be explained by differences in composition between the three formulations leading to different organizations on the molecular scale.

  18. Analysis of supercooling activities of surfactants.

    PubMed

    Kuwabara, Chikako; Terauchi, Ryuji; Tochigi, Hiroshi; Takaoka, Hisao; Arakawa, Keita; Fujikawa, Seizo

    2014-08-01

    Supercooling-promoting activities (SCAs) of 25 kinds of surfactants including non-ionic, anionic, cationic and amphoteric types were examined in solutions (buffered Milli-Q water, BMQW) containing the ice nucleation bacterium (INB) Erwinia ananas, silver iodide (AgI) or BMQW alone, which unintentionally contained unidentified ice nucleators, by a droplet freezing assay. Most of the surfactants exhibited SCA in solutions containing AgI but not in solutions containing the INB E. ananas or BMQW alone. SCAs of many surfactants in solutions containing AgI were very high compared with those of previously reported supercooling-promoting substances. Cationic surfactants, hexadecyltrimethylammonium bromide (C16TAB) and hexadecyltrimethylammonium chloride (C16TAC), at concentrations of 0.01% (w/v) exhibited SCA of 11.8 °C, which is the highest SCA so far reported. These surfactants also showed high SCAs at very low concentrations in solutions containing AgI. C16TAB exhibited SCA of 5.7 °C at a concentration of 0.0005% (w/v). PMID:24792543

  19. Interaction forces in thin liquid films stabilized by hydrophobically modified inulin polymeric surfactant. 2. Emulsion films.

    PubMed

    Exerowa, D; Gotchev, G; Kolarov, T; Khristov, Khr; Levecke, B; Tadros, Th

    2007-02-13

    The interaction forces in emulsion films stabilized using hydrophobically modified inulin (INUTEC SP1) were investigated by measuring the disjoining pressure of a microscopic horizontal film between two macroscopic emulsion drops of isoparaffinic oil (Isopar M). A special measuring cell was used for this purpose whereby the disjoining pressure Pi was measured as a function of the equivalent film thickness hw. The latter was determined using an interferometric method. In this way Pi-hw curves were established at a constant INUTEC SP1 concentration of 2x10(-5) mol.dm-3 and at various NaCl concentrations. At a constant disjoining pressure of 36 Pa, a constant temperature of 22 degrees C, and a film radius of 100 microm, hw decreased with an increase in the NaCl concentration, Cel, and reached a constant value of 11 nm at Cel=5x10(-2) mol.dm-3. This reduction in film thickness is due to the compression of the electrical double layer, and at the above critical NaCl concentration any electrostatic repulsion is removed and only steric interaction remains. This critical electrolyte concentration represents the transition from electrostatic to steric interaction. At a NaCl concentration of 2x10(-4) mol.dm-3 the Pi-hw isotherms showed a gradual decrease in hw with an increase in capillary pressure, after which there was a jump in hw from approximately 30 to approximately 7.2 nm when Pi reached a high value of 2-5.5 kPa. This jump is due to the formation of a Newton black film (NBF), giving a layer thickness of the polyfructose loops of approximately 3.6 nm. The film thickness did not change further when the pressure reached 45 kPa, indicating the high stability of the film. Pi-hw isotherms were obtained at various NaCl concentrations, namely, 5x10(-2), 5x10(-1), 1.0, and 2.0 mol.dm-3. The initial thicknesses are within the range 9-11 nm, after which a transition zone starts, corresponding to a pressure of about 0.5 kPa. In this zone all films transform to an NBF with a jump, after which the thickness remains constant with a further increase in the disjoining pressure up to 45 kPa, with no film rupture. This indicates the very high stability of the NBF in the presence of high electrolyte concentrations. The high emulsion film stability (due to strong steric repulsions between the strongly hydrated loops of polyfructose) is correlated with the bulk emulsion stability. PMID:17279648

  20. Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

    NASA Technical Reports Server (NTRS)

    Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

    1999-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  1. Probing nanoparticle effect in protein-surfactant complexes

    NASA Astrophysics Data System (ADS)

    Mehan, Sumit; Aswal, V. K.; Kohlbrecher, J.

    2015-06-01

    SANS experiments have been carried to probe the role of anionic silica nanoparticles in the anionic BSA protein-cationic DTAB surfactant complexes. In protein-surfactant complex, surfactant molecules aggregate to form micelle-like clusters along the unfolded polypeptide chains of the protein. The nanoparticle aggregation mediated by oppositely charged protein-surfactant complex coexists with the free protein-surfactant complexes in the nanoparticle-protein-surfactant system. There is rearrangement of micelles in adsorbed protein-surfactant complex on nanoparticles in leading to their (nanoparticle) aggregation. On the other hand, the unfolding of protein in free protein-surfactant complex is found to be significantly enhanced in presence of nanoparticles.

  2. Fullerene surfactants and their use in polymer solar cells

    SciTech Connect

    Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

    2015-12-15

    Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

  3. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    EPA Science Inventory

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  4. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1993-10-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  5. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsoodi, S.; Pang, Y.

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6]/hv.

  6. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsooodi, S; Yi Pang.

    1993-10-19

    A polymeric material is described which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6].

  7. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  8. Low vibration polymeric composite engine

    NASA Astrophysics Data System (ADS)

    Guimond, David P.; Muench, Rolf K.

    1994-12-01

    An internal combustion engine is constructed with metallic parts in its regions which are subjected to high stress (temperature, pressure) during combustion and polymeric materials in its regions which are subjected to relatively lower stresses. The integrated construction helps realize increased power densities and reductions on engine noise without compromising engine performance. V-configuration Diesel engines particularly benefit from this construction.

  9. Novel polymeric materials from triglycerides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Triglycerides are good platforms for new polymeric products that can substitute for petroleum-based materials. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a number of reactions in efforts to produce a wide range of value-added products. In this ...

  10. Supramolecular polymerization: Living it up

    NASA Astrophysics Data System (ADS)

    Würthner, Frank

    2014-03-01

    Protein fibril formation is involved in many human diseases and thus has been mechanistically elucidated in the context of understanding -- and in turn treating -- them. This biological phenomenon has now also inspired the design of a supramolecular system that undergoes living polymerization.

  11. The Viscosity of Polymeric Fluids.

    ERIC Educational Resources Information Center

    Perrin, J. E.; Martin, G. C.

    1983-01-01

    To illustrate the behavior of polymeric fluids and in what respects they differ from Newtonian liquids, an experiment was developed to account for the shear-rate dependence of non-Newtonian fluids. Background information, procedures, and results are provided for the experiment. Useful in transport processes, fluid mechanics, or physical chemistry…

  12. The absorption of polymeric composites

    NASA Astrophysics Data System (ADS)

    Řídký, R.; Popovič, M.; Rolc, S.; Drdlová, M.; Krátký, J.

    2016-06-01

    An absorption capacity of soft, viscoelastic materials at high strain rates is important for wide range of practical applications. Nowadays there are many variants of numerical models suitable for this kind of analysis. The main difficulty is in selection of the most realistic numerical model and a correct setup of many unknown material constants. Cooperation between theoretical simulations and real testing is next crucial point in the investigation process. Standard open source material database offer material properties valid for strain rates less than 250 s-1. There are experiments suitable for analysis of material properties with strain rates close to 2000 s-1. The high strain-rate characteristics of a specific porous blast energy absorbing material measured by modified Split Hopkinson Pressure Bar apparatus is presented in this study. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. One of the possible solution leads to complex and frequency depended Young modulus of testing bars material. This testing technique was applied to materials composed of porous glass/ceramic filler and polymeric binder, with density of 125 - 300 kg/m3 and particle size in range of 50 µm - 2 mm. The achieved material model was verified in practical application of sandwich structure includes polymeric composites under a blast test.

  13. POLYMERIC INTERFACES FOR STACK MONITORING

    EPA Science Inventory

    Research has been performed on the use of polymeric interfaces for in situ continuous stack monitoring of gaseous pollutants. Permeabilities of candidate interface materials to SO2 were measured at temperatures from ambient to 200C, and the results were used to design interfaces ...

  14. Surfactant mediated liquid phase exfoliation of graphene

    NASA Astrophysics Data System (ADS)

    Narayan, Rekha; Kim, Sang Ouk

    2015-10-01

    Commercialization of graphene based applications inevitably requires cost effective mass production. From the early days of research on graphene, direct liquid phase exfoliation (LPE) of graphite has been considered as the most promising strategy to produce high-quality mono or few-layer graphene sheets in solvent dispersion forms. Substantial success has been achieved thus far in the LPE of graphene employing numerous solvent systems and suitable surfactants. This invited review article principally showcase the recent research progress as well as shortcomings of surfactant assisted LPE of graphene. In particular, a comprehensive assessment of the quality and yield of the graphene sheets produced by different categories of the surfactants are summarized. Future direction of LPE methods is also proposed for the eventual success of commercial applications.

  15. Nanotube Dispersions Made With Charged Surfactant

    NASA Technical Reports Server (NTRS)

    Kuper, Cynthia; Kuzma, Mike

    2006-01-01

    Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant(s) and carbon nanotubes derived from the HiPco(TradeMark) (or equivalent) process. Among reagents known to be made from HiPco(TradeMark)(or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

  16. Natural surfactants used in cosmetics: glycolipids.

    PubMed

    Lourith, N; Kanlayavattanakul, M

    2009-08-01

    Cosmetic surfactant performs detergency, wetting, emulsifying, solubilizing, dispersing and foaming effects. Adverse reactions of chemical synthesis surfactant have an effect on environment and humans, particularly severe in long term. Biodegradability, low toxicity and ecological acceptability which are the benefits of naturally derived surfactant that promises cosmetic safety are, therefore, highly on demand. Biosurfactant producible from microorganisms exhibiting potential surface properties suitable for cosmetic applications especially incorporate with their biological activities. Sophorolipids, rhamnolipids and mannosylerythritol lipids are the most widely used glycolipids biosurfactant in cosmetics. Literatures and patents relevant to these three glycolipids reviewed were emphasizing on the cosmetic applications including personal care products presenting the cosmetic efficiency, efficacy and economy benefits of glycolipids biosurfactant. PMID:19496839

  17. Surfactant studies for bench-scale operation

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory S.; Sharma, Pramod K.

    1992-01-01

    A phase 2 study was initiated to investigate surfactant-assisted coal liquefaction, with the objective of quantifying the enhancement in liquid yields and product quality. This publication covers the first quarter of work. The major accomplishments were: the refurbishment of the high-pressure, high-temperature reactor autoclave, the completion of four coal liquefaction runs with Pittsburgh #8 coal, two each with and without sodium lignosulfonate surfactant, and the development of an analysis scheme for the product liquid filtrate and filter cake. Initial results at low reactor temperatures show that the addition of the surfactant produces an improvement in conversion yields and an increase in lighter boiling point fractions for the filtrate.

  18. Surfactant studies for bench-scale operation

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory S.; Sharma, Pramod K.

    1993-01-01

    A phase 2 study has been initiated to investigate surfactant-assisted coal liquefaction, with the objective of quantifying the enhancement in liquid yields and product quality. This report covers the second quarter of work. The major accomplishments were: completion of coal liquefaction autoclave reactor runs with Illinois number 6 coal at processing temperatures of 300, 325, and 350 C, and pressures of 1800 psig; analysis of the filter cake and the filtrate obtained from the treated slurry in each run; and correlation of the coal conversions and the liquid yield quality to the surfactant concentration. An increase in coal conversions and upgrading of the liquid product quality due to surfactant addition was observed for all runs.

  19. A study of the thermodynamic properties of surfactant mixtures: Mixed micelle formation and mixed surfactant adsorption

    SciTech Connect

    Lopata, J.J.

    1992-12-31

    The volumetric mixing in anionic/nonionic, cationic/nonionic, and anionic/cationic mixed micelles was determined by examining the total surfactant apparent molar volumes at total surfactant concentrations much greater than the mixture critical micelle concentration. The mixed surfactant systems investigated were: sodium dodecyl sulfate and a polyethoxylated nonylphenol, at 0.15 M NaCl and with no added NaCl; cetyl pyridinium chloride and polyethoxylated nonylphenol, at 0.03 M NaCl; and sodium dodecyl sulfate and dodecyl pyridinium chloride, at 0.15 M NaCl. The results of this study suggest that the electrostatic interactions in the mixed micelles do no significantly effect the molar volume of the mixed micelle. Therefore, the micelle hydrophobic core dominates the volumetric mixing in mixed micelles. The adsorption of sodium dodecyl sulfate and a polyethoxylated nonylphenol and well defined mixtures thereof was measured on gamma alumina. A pseudo-phase separation model to describe mixed anionic/nonionic admicelle (adsorbed surfactant aggregate) formation was developed. In this model, regular solution theory was used to describe the anionic/nonionic surfactant interactions in the mixed admicelle and a patch-wise adsorption model was used to describe surfactant adsorption on a heterogeneous surface. Regular solution theory was tested on specific homogeneous surface patches by examining constant total surfactant adsorption levels. For the adsorption of binary surfactant mixtures adsorbing at total equilibrium concentrations above the mixture critical micelle concentration, simultaneous solution of the pseudo-phase separation models for mixed admicelle and mixed micelle formation predicts that the surfactant compositions in the monomer, micelle, and admicelle pseudo-phases are constant at a constant total adsorption level.

  20. When do water-insoluble polyion-surfactant ion complex salts "redissolve" by added excess surfactant?

    PubMed

    dos Santos, Salomé; Gustavsson, Charlotte; Gudmundsson, Christian; Linse, Per; Piculell, Lennart

    2011-01-18

    The redissolution of water-insoluble polyion-surfactant ion complexes by added excess of surfactant has systematically been investigated in experimental and theoretical phase equilibrium studies. A number of stoichiometric polyion-surfactant ion "complex salts" were synthesized and they consisted of akyltrimethylammonium surfactant ions of two different alkyl chain lengths (C(12)TA(+) and C(16)TA(+)) combined with homopolyions of polyacrylate of two different lengths (PA(-)(25) and PA(-)(6000)) or copolyions of acrylate and the slightly hydrophobic nonionic comonomers N-isopropylacrylamide (PA(-)-co-NIPAM) or N,N-dimethylacrylamide (PA(-)-co-DAM). The complex salts were mixed with water and excess alkyltrimethylammonium surfactant with either bromide or acetate counterions (C(n)TABr or C(n)TAAc). Factors promoting efficient redissolution were (i) very short polyions, (ii) a large fraction of NIPAM or DAM comonomers, and (iii) acetate, rather than bromide, as the surfactant counterion. Added C(12)TAAc gave an efficient redissolution of C(12)TAPA(25) but virtually no redissolution of C(12)TAPA(6000). A very efficient redissolution by added C(12)TAAc was obtained for PA(-)-co-NIPAM with 82 mol % of NIPAM. The C(12)TAPA-co-NIPAM/C(12)TAAc/H(2)O ternary phase diagram closely resembled the corresponding diagram for the much-studied pair cationic hydroxyethyl cellulose-(sodium) dodecyl sulfate. The simple Flory-Huggins theory adopted for polyelectrolyte systems successfully reproduced the main features of the experimental phase diagrams for the homopolyion systems, including the effect of the surfactant counterion. The efficient redissolution found for certain copolyion systems was explained by the formation of soluble polyion-surfactant ion complexes carrying an excess of surfactant ions through an additional hydrophobic attraction. PMID:21166446

  1. Polarity Reversal in Homologous Series of Surfactant-Free Janus Nanoparticles: Toward the Next Generation of Amphiphiles.

    PubMed

    Wu, Dalin; Chew, Jia Wei; Honciuc, Andrei

    2016-06-28

    The ability to finely tune the amphiphilic balance of Janus nanoparticles (JNPs) could represent a step forward toward creating the next generation of solid-state amphiphiles with significant potential for applications. The inherent amphiphilicity of JNPs stemming from an intrinsic polarity contrast between two surface regions is well-acknowledged, but remained difficult to demonstrate experimentally in the absence of surfactants and stabilizers. We have designed two homologous series of surfactant-free polymeric JNPs starting from polystyrene (PS) seed nanoparticles (NPs) on which we grew Janus lobes of different sizes via seed polymerization and phase separation of the 3-(triethoxysilyl)propyl-methacrylate (3-TSPM) monomer. The two series differ only by the radical initiator used in the seed polymerization: polar ionic ammonium persulfate (APS) vs nonpolar oil-soluble 2,2'-azobis(2-methylpropionitrile) (AIBN). To compare the two series, we employed them in the emulsification of water with heptane or molten paraffin wax. A polarity reversal of the JNPs within AIBN-JNP series could be observed from the catastrophic and transitional emulsion phase inversions and occurred when the more polar lobe was larger than the nonpolar seed PS lobe. Furthermore, the AIBN-JNPs appeared to be amphiphilic and adopt preferred orientation within the monolayer at the oil/water interface. We therefore demonstrated that in the absence of surfactants the amphiphilicity of the JNPs depends not only on the relative size of the lobes, but also on the surface polarity contrast, which can be tuned by changing the nature of radical initiator. PMID:27283348

  2. Surfactant-Polymer Interaction for Improved Oil Recovery

    SciTech Connect

    Gabitto, Jorge; Mohanty, Kishore K.

    2002-01-07

    The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering.

  3. Adhesion of latex films. Influence of surfactants

    SciTech Connect

    Charmeau, J.Y.; Kientz, E.; Holl, Y.

    1996-12-31

    In the applications of film forming latexes in paint, paper, coating, adhesive, textile industries, one of the most important property of latex films is adhesion onto a support. From the point of view of adhesion, latex films have two specificities. The first one arises from the particular structure of the film which is usually not homogeneous but retains to a certain extent the memory of the particles it was made from. These structure effects are clearly apparent when one compares mechanical or adhesion properties of pure latex films and of films of the same polymers but prepared from a solution. Latex films show higher Young`s moduli and lower adhesion properties than solution films. The second specificity of latex films comes from the presence of the surfactant which was used in the synthesis and as stabilizer for the latex. Most industrial latexes contain low amounts of surfactant, typically in the range 0.1 to 2-3 wt%. However, being usually incompatible with the polymer, the surfactant is not homogeneously distributed in the film. It tends to segregate towards the film-air or film-support interfaces or to form domains in the bulk of the film. Distribution of surfactants in latex films has been studied by several authors. The influence of the surfactant on adhesion, as well as on other properties, is thus potentially very important. This article presents the results of the authors investigation of surfactant effects on adhesion properties of latex films. To the authors knowledge, there is no other example, in the open literature, of this kind of study.

  4. Glycine Polymerization on Oxide Minerals

    NASA Astrophysics Data System (ADS)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2016-07-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 + group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  5. Instantaneous Directional Growth of Block Copolymer Nanowires During Heterogeneous Radical Polymerization (HRP).

    PubMed

    Lu, Chunliang; Urban, Marek W

    2016-04-13

    Polymeric nanowires that consist of ultrahigh molecular weight block copolymers were instantaneously prepared via one-step surfactant-free heterogeneous radical polymerization (HRP). Under heterogeneous reaction and initiator-starvation conditions, the sequential copolymerization of hydrophilic and hydrophobic monomers facilitates the formation of amphiphilic ultrahigh molecular weight block copolymers, which instantaneously assemble to polymeric nanowires. As polymerization progresses, initially formed nanoparticles exhibit the directional growth due to localized repulsive forces of hydrophilic blocks and confinement of the hydrophobic blocks that adopt favorable high aspect ratio nanowire morphologies. Using one-step synthetic approach that requires only four ingredients (water as a solvent, two polymerizable monomers (one hydrophilic and one hydrophobic), and water-soluble initiator), block copolymer nanowires ∼70 nm in diameter and hundreds of microns in length are instantaneously grown. For example, when 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and styrene (St) were copolymerized, high aspect ratio nanowires consist of ultrahigh (>10(6) g/mol) molecular weight pDMAEMA-b-St block copolymers and the presence of temperature responsive pDMAEMA blocks facilitates nanowire diameter changes as a function of temperature. These morphologies may serve as structural components of the higher order biological constructs at micro and larger length scales, ranging from single strand nanowires to engineered biomolecular networks capable of responding to diverse and transient environmental signals, and capable of dimensional changes triggered by external stimuli. PMID:27002238

  6. Effects of selected surfactants on soil microbial activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants (surface-active agents) facilitate and accentuate the emulsifying, dispersing, spreading, and wetting properties of liquids. Surfactants are used in industry to reduce the surface tension of liquid and to solubilize compounds. For agricultural pest management, surfactants are an import...

  7. Surfactant Dynamics: Spreading and Wave Induced Dynamics of a Monolayer

    NASA Astrophysics Data System (ADS)

    Strickland, Stephen Lee

    Material adsorbed to the surface of a fluid - for instance crude oil in the ocean, biological surfactant on ocular or pulmonary mucous, or emulsions - can form a 2-dimensional mono-molecular layer. These materials, called surfactants, can behave like a compressible viscous 2-dimensional fluid, and can generate surface stresses that influence the sub-fluid's bulk flow. Additionally, the sub-fluid's flow can advect the surfactant and generate gradients in the surfactant distribution and thereby generate gradients in the interfacial properties. Due to the difficulty of non-invasive measurements of the spatial distribution of a molecular monolayer at the surface, little is known about the dynamics that couple the surface motion and the evolving density field. In this dissertation, I will present a novel method for measuring the spatiotemporal dynamics of the surfactant surface density through the fluorescence emission of NBD-tagged phosphatidylcholine, a lipid, and we will compare the surfactant dynamics to the dynamics of the surface morphology.With this method, we will consider the inward and outward spreading of a surfactant on a thin fluid film as well as the advection of a surfactant by linear and non-linear gravity-capillary waves. These two types of surfactant coupled fluid flows will allow us to probe well-accepted assumptions about the coupled fluid-surfactant dynamics. In chapter 1, we review the models used for understanding the spreading of a surfactant on a thin fluid film and the motion of surfactant on a linear gravity-capillary wave. In chapter 2, we will present the experimental methods used in this dissertation. In chapter 3, we will study the outward spreading of a localized region of surfactant and show that the spreading of a monolayer is considerably different from the spreading of thicker-layered surfactant. In chapter 4, we will investigate the inward spreading of a surfactant into a circular surfactant-free region and show that hole closure and

  8. Adsorption of Anionic or Cationic Surfactants in Polyanionic Brushes and Its Effect on Brush Swelling and Fouling Resistance during Emulsion Filtration.

    PubMed

    Yang, Zhefei; Tarabara, Volodymyr V; Bruening, Merlin L

    2015-11-01

    Atom transfer radical polymerization of ionic monomers from membrane surfaces yields polyelectrolyte brushes that swell in water and repel oil droplets to resist fouling during filtration of oil-in-water emulsions. However, surfactant adsorption to polyelectrolyte brushes may overcome this fouling resistance. This work examines adsorption of cationic and anionic surfactants in polyanionic brushes and the effect of these surfactants on emulsion filtration. In situ ellipsometry with films on flat surfaces shows that brushes composed of poly(3-sulfopropyl methacrylate salts) (pSPMK) swell 280% in water and do not adsorb sodium dodecyl sulfate (SDS). pSPMK-modified microfiltration membranes reject >99.9% of the oil from SDS-stabilized submicron emulsions, and the specific flux through these modified membranes is comparable to that through NF270 nanofiltration membranes. Moreover, the brush-modified membranes show no decline in flux over a 12 h filtration, whereas the flux through NF270 membranes decreases by 98.7%. In contrast, pSPMK brushes adsorb large quantities of cetyltrimethylammonium bromide (CTAB), and at low chain densities the brushes collapse in the presence of this cationic surfactant. Filtration of CTAB-stabilized emulsions through pSPMK-modified membranes gives minimal oil rejection, presumably due to the brush collapse. Thus, the fouling resistance of polyelectrolyte brush-modified membranes clearly depends on the surfactant composition in a particular emulsion. PMID:26442835

  9. Coalescence of surfactant covered drops in extensional flows: Effects of the interfacial diffusivity

    NASA Astrophysics Data System (ADS)

    Vannozzi, Carolina

    2012-08-01

    Boundary integral simulations and scaling theory were employed to study the effects of insoluble surfactant surface diffusivity Ds and concentration Γ on the coalescence process of two equal-sized viscous drops. The drops underwent head-on collisions in a biaxial extensional flow, in the Stokes flow limit and low capillary numbers. The simulations were compared with the drainage time experiments of Yoon et al. [Phys. Fluids 19, 023102 (2007), 10.1063/1.2409735] concerned with a polymeric system, polybutadiene (PBd) drops in a polydimethylsyloxane (PDMS) matrix, stabilized by block-copolymers acting as insoluble surfactants to explain the mechanism underneath their findings. An ad hoc equation of state, derived by mean field theory, specific for the block-copolymers in the experiments of Yoon et al., able to match the experimental surface tension data without fitting parameters, was used. We were able to reproduce the experimental drainage time data, although an additional attractive force, besides the usual van der Waals interactions, had to be introduced for high block-copolymer concentrations, probably as a result of the entropic attraction between the two facing dry brushes formed in the thin film between the two drops. According to simulations, the puzzling experimental drainage time transition for low surfactant concentrations, from high drainage time to low drainage time as Ca increases, was a consequence of the oscillating behavior of the minimum film thickness, which takes place for Marangoni numbers Ma < 5 and surface Peclet number Pes > 60. In this regard, a master curve was obtained for the scaled relative minimum film thickness attained during the oscillation as a function of Ma. This enabled to determine both the minimum value of the dimensionless attractive forces to avoid coalescence for each concentration studied and the range of Ma that favors early coalescence. The coalescence process was found very sensitive to Pes and for Pes O(100-1000) even

  10. Surfactant replacement therapy for adult respiratory distress syndrome in children.

    PubMed

    Evans, D A; Wilmott, R W; Whitsett, J A

    1996-05-01

    Surfactant replacement therapy may have a role in the treatment of ARDS in children. The current studies suggest that rapid instillation of exogenous surfactant is more effective than slow tracheal instillation or aerosolized delivery. Studies suggest that exogenous surfactant given early in the development of ARDS is more effective than therapy provided late in the course of the disease. Natural surfactants appear to be more effective than artificial surfactants due to the presence of SP-B and SP-C, which prevent inhibition of the exogenous surfactant by the protein leakage into the alveolus that is characteristic of ARDS. Exogenous surfactant replacement therapy appears to be safe and well tolerated. A surfactant that can be delivered by aerosol would be useful since this is more easily tolerated by the patients, requires less surfactant, and would be more cost effective when compared with tracheal instillation. Aerosolized surfactant could be given to patients who have not yet required mechanical ventilation, thus potentially preventing the progression of the acute lung injury to respiratory failure. The recent failure of a large multi-center trial of aerosolized Exosurf for the treatment of sepsis-related ARDS72 may have been due to the failure of the delivery system as opposed to the surfactant used in the trial; therefore, further research into aerosol delivery systems is needed. There may be different responses to exogenous surfactant therapy by patients with ARDS of different etiologies, such as aspiration pneumonia, sepsis, or trauma. Well-planned placebo-controlled trials will be required to determine these differences. The data supporting the role of surfactant replacement for the treatment of ARDS in children is growing. However, before widespread use of surfactant is considered, a multi-center, placebo-controlled trial will be required to establish the safety and efficacy of surfactant replacement in such patients. PMID:8726159

  11. Pulmonary surfactant proteins and polymer combinations reduce surfactant inhibition by serum.

    PubMed

    Lu, Karen W; Pérez-Gil, Jesús; Echaide, Mercedes; Taeusch, H William

    2011-10-01

    Acute respiratory distress syndrome (ARDS) is an inflammatory condition that can be associated with capillary leak of serum into alveoli causing inactivation of surfactant. Resistance to inactivation is affected by types and concentrations of surfactant proteins, lipids, and polymers. Our aim was to investigate the effects of different combinations of these three components. A simple lipid mixture (DPPC/POPG) or a more complex lipid mixture (DPPC/POPC/POPG/cholesterol) was used. Native surfactant proteins SP-B and SP-C obtained from pig lung lavage were added either singly or combined at two concentrations. Also, non-ionic polymers polyethylene glycol and dextran and the anionic polymer hyaluronan were added either singly or in pairs with hyaluronan included. Non-ionic polymers work by different mechanisms than anionic polymers, thus the purpose of placing them together in the same surfactant mixture was to evaluate if the combination would show enhanced beneficial effects. The resulting surfactant mixtures were studied in the presence or absence of serum. A modified bubble surfactometer was used to evaluate surface activities. Mixtures that included both SP-B and SP-C plus hyaluronan and either dextran or polyethylene glycol were found to be the most resistant to inhibition by serum. These mixtures, as well as some with either SP-B or SP-C with combined polymers were as or more resistant to inactivation than native surfactant. These results suggest that improved formulations of lung surfactants are possible and may be useful in reducing some types of surfactant inactivation in treating lung injuries. PMID:21741354

  12. Determination of surfactants by capillary electrophoresis.

    PubMed

    Heinig, K; Vogt, C

    1999-10-01

    Capillary electrophoresis has been increasingly used during the past few years for the separation and determination of surfactants. These substances are applied in many household and industrial products such as laundry detergents, cosmetics and pharmaceuticals, often as homologous and isomeric mixtures. Product development and control as well as toxicological and environmental analyses require selective and sensitive analytical methods. This review presents capillary electrophoretic techniques to determine important representatives of cationic, anionic, and neutral surfactants. The application of different buffer additives such as organic solvents, cyclodextrins or micelles to enhance the resolution of complex mixtures is discussed. Besides direct and indirect UV and fluorescence detection, examples for conductivity and mass spectrometric detection are also given. Derivatization procedures to improve the detectability and implement charge in neutral analytes are described. The successful use of capillary electrophoresis for surfactant determinations has proven that it can serve as a routine technique in many real-world applications. Robust, validated methods for the quantitation of single compounds, such as alkylbenzene sulfonates, sodium dodecyl sulfate and benzalkonium salts, are now available. Characteristic peak patterns (fingerprint analysis) can be used for the identification of surfactants in multicomponent formulations (e.g. ethoxylates and phosphonates). PMID:10596832

  13. Biodegradation potential of photocatalyzed surfactant washwater.

    PubMed

    Maillacheruvu, K; Buck, L; Lee, E

    2001-01-01

    Enhanced release of hydrophobic compounds from a soil matrix can be achieved by use of soil-washing or soil-flushing using various surfactants. However, the surfactants used in achieving the desorption of organic contaminants may also cause a problem in subsequent removal/disposal of these contaminants. UV radiation in the presence of TiO2 as a pre-treatment step to achieve initial (or partial) breakdown of naphthalene and Sodium Dodecyl Sulfate (SDS) using batch experiments indicated that 56% to 88% naphthalene degradation occurred within 30 minutes to one hour. Preliminary results on the estimate of the batch aerobic biodegradation potential of photocatalyzed washwater containing naphthalene and SDS suggested that SDS was the major carbon and energy source for an activated sludge enrichment culture and an enrichment culture obtained from microorganisms at a contaminated site. Continuous-flow stirred tank reactors (CSTRs) with with a solids retention time (SRT) of 4 days were not effective, but an SRT of 8 days was successful in biodegrading the naphthalene and surfactant. These results indicated that photocatalytic treatment as a pre-treatment step followed by a biodegradation step may offer potential in cleaning up surfactant washwaters containing organic contaminants. PMID:11501312

  14. Surfactants treatment of crude oil contaminated soils.

    PubMed

    Urum, Kingsley; Pekdemir, Turgay; Copur, Mehmet

    2004-08-15

    This study reports experimental measurements investigating the ability of a biological (rhamnolipid) and a synthetic (sodium dodecyl sulfate, SDS) surfactant to remove the North Sea Ekofisk crude oil from various soils with different particle size fractions under varying washing conditions. The washing parameters and ranges tested were as follows: temperature (5 to 50 degrees C), time (5 to 20 min), shaking speed (80 to 200 strokes/min), volume (5 to 20 cm3), and surfactant concentration (0.004 to 5 mass%). The contaminated soils were prepared in the laboratory by mixing crude oil and soils using a rotating cylindrical mixer. Two contamination cases were considered: (1) weathered contamination was simulated by keeping freshly contaminated soils in a fan assisted oven at 50 degrees C for 14 days, mimicking the weathering effect in a natural hot environment, and (2) nonweathered contamination which was not subjected to the oven treatment. The surfactants were found to have considerable potential in removing crude oil from different contaminated soils and the results were comparable with those reported in literature for petroleum hydrocarbons. The removal of crude oil with either rhamnolipid or SDS was within the repeatability range of +/-6%. The most influential parameters on oil removal were surfactant concentration and washing temperature. The soil cation exchange capacity and pH also influenced the removal of crude oil from the individual soils. However, due to the binding of crude oil to soil during weathering, low crude oil removal was achieved with the weathered contaminated soil samples. PMID:15271574

  15. Photosensitive surfactants: Micellization and interaction with DNA

    NASA Astrophysics Data System (ADS)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-01

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  16. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  17. SURFACTANT FLUSH: HOW WELL DID IT WORK?

    EPA Science Inventory

    The Oklahoma Corporation Commission through a contract with Surbec-Art, Inc. of Norman Oklahoma has remediated TPH contamination at a gasoline spill at Golden, Oklahoma. Residual gasoline was removed from the subsurface using a flush of surfactant, followed by in situ bioremedia...

  18. SIMULATION OF SURFACTANT-ENHANCED AQUIFER REMEDIATION

    EPA Science Inventory

    Surfactant-enhanced aquifer remediation (SEAR) is currently under active investigation as one of the most promising alternatives to conventional pump-and-treat remediation for aquifers contaminated by dense nonaqueous phase organic liquids. An existing three-dimensional finite-di...

  19. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2005-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the best hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (35-62% OOIP) for initially oil-wet cores through wettability alteration and IFT reduction. Core-scale simulation results match those of the experiments. Initial capillarity-driven imbibition gives way to a final gravity-driven process. As the matrix block height increases, surfactant alters wettability to a lesser degree, or permeability decreases, oil production rate decreases. The scale-up to field scale will be further studied in the next quarter.

  20. Potential commercial applications of microbial surfactants.

    PubMed

    Banat, I M; Makkar, R S; Cameotra, S S

    2000-05-01

    Surfactants are surface-active compounds capable of reducing surface and interfacial tension at the interfaces between liquids, solids and gases, thereby allowing them to mix or disperse readily as emulsions in water or other liquids. The enormous market demand for surfactants is currently met by numerous synthetic, mainly petroleum-based, chemical surfactants. These compounds are usually toxic to the environment and non-biodegradable. They may bio-accumulate and their production, processes and by-products can be environmentally hazardous. Tightening environmental regulations and increasing awareness for the need to protect the ecosystem have effectively resulted in an increasing interest in biosurfactants as possible alternatives to chemical surfactants. Biosurfactants are amphiphilic compounds of microbial origin with considerable potential in commercial applications within various industries. They have advantages over their chemical counterparts in biodegradability and effectiveness at extreme temperature or pH and in having lower toxicity. Biosurfactants are beginning to acquire a status as potential performance-effective molecules in various fields. At present biosurfactants are mainly used in studies on enhanced oil recovery and hydrocarbon bioremediation. The solubilization and emulsification of toxic chemicals by biosurfactants have also been reported. Biosurfactants also have potential applications in agriculture, cosmetics, pharmaceuticals, detergents, personal care products, food processing, textile manufacturing, laundry supplies, metal treatment and processing, pulp and paper processing and paint industries. Their uses and potential commercial applications in these fields are reviewed. PMID:10855707

  1. Surfactants on cleanup detail in paper mills

    SciTech Connect

    Longhini, D.

    1996-06-01

    From pulp production to paper coating, surfactants are involved in almost every facet of pulp and paper manufacturing. Within the industry, the role of surface-active agents is growing every larger with the demand for recycled paper. In the US, for example, The American Forest and Paper Assn. has established an ambitious goal of recovering 50% of the paper used in the US by 2000. By then, paper producers in North America are expected to have invested more than $10 billion in recycling equipment, and be spending more than $300 million/yr on drinking chemicals, including surfactants. Surfactants will also serve the industry indirectly, as additives in the production and formulation of products sold to the paper industry, including biocides, retention aids and water-treatment polymers. Providing higher-quality paper while reducing dependence on virgin pulp, requires manufacturing technologies and process chemicals that can restore wastepaper to its original state. Achieving those goals will depend on the development of novel surfactants through close collaboration with mill customers, and pioneering research in surface science, polymer engineering and organic chemistry.

  2. Synthesis of Novel Organosilicon Gemini Surfactants

    NASA Astrophysics Data System (ADS)

    Zhu, H.; Li, L. J.; Wang, E. F.

    A series of organosilicon gemini surfactants was synthesized from γ-(2. 3-epoxypropoxy) propytrimethoxysilane. hexametliyldisiloxane and polyethylene glycol. The target compounds were confirmed by IR. 1H NMR. Surface properties of the target compounds were measured. The critical micelle concentration values of 1-3 were 8mmol, 5mmol, and 3 mmol, respectively.

  3. Thermally stable surfactants and compositions and methods of use thereof

    DOEpatents

    Chaiko, David J.

    2008-09-02

    There are provided novel thermally stable surfactants for use with fillers in the preparation of polymer composites and nanocomposites. Typically, surfactants of the invention are urethanes, ureas or esters of thiocarbamic acid having a hydrocarbyl group of from 10 to 50 carbons and optionally including an ionizable or charged group (e.g., carboxyl group or quaternary amine). Thus, there are provided surfactants having Formula I: ##STR00001## wherein the variables are as defined herein. Further provided are methods of making thermally stable surfactants and compositions, including composites and nanocomposites, using fillers coated with the surfactants.

  4. Structural study of surfactant-dependent interaction with protein

    SciTech Connect

    Mehan, Sumit; Aswal, Vinod K.; Kohlbrecher, Joachim

    2015-06-24

    Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

  5. Surfactant loss: Effects of temperature, salinity, and wettability

    SciTech Connect

    Noll, L.A.; Gall, B.L.; Crocker, M.E.; Olsen, D.K.

    1989-05-01

    Adsorption of sodium dodecylsulfate, Triton X-100, decyltrimethylammonium bromide surfactants onto silica gel and Berea sandstone mineral surfaces has been studied as a function of temperature, solution salt concentration, and mineral surface wettability. Adsorption studies using a flow calorimeter were conducted using pure surfactants and minerals. The studies were then extended to the adsorption of one type of commercial surfactant onto both consolidated and crushed Berea sandstone using column techniques. This has allowed the comparison of different methods to evaluate surfactant losses from flowing rather than static surfactant solutions. 20 refs., 15 figs., 37 tabs.

  6. Polymeric Nanofibers in Tissue Engineering

    PubMed Central

    Dahlin, Rebecca L.; Kasper, F. Kurtis

    2011-01-01

    Polymeric nanofibers can be produced using methods such as electrospinning, phase separation, and self-assembly, and the fiber composition, diameter, alignment, degradation, and mechanical properties can be tailored to the intended application. Nanofibers possess unique advantages for tissue engineering. The small diameter closely matches that of extracellular matrix fibers, and the relatively large surface area is beneficial for cell attachment and bioactive factor loading. This review will update the reader on the aspects of nanofiber fabrication and characterization important to tissue engineering, including control of porous structure, cell infiltration, and fiber degradation. Bioactive factor loading will be discussed with specific relevance to tissue engineering. Finally, applications of polymeric nanofibers in the fields of bone, cartilage, ligament and tendon, cardiovascular, and neural tissue engineering will be reviewed. PMID:21699434

  7. Metal containing polymeric functional microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1979-01-01

    Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing. After collection of the labeled cells, the magnetic field is discontinued and the labeled sub-cell population recovered.

  8. Concurrent Covalent and Supramolecular Polymerization.

    PubMed

    Hou, Xisen; Ke, Chenfeng; Zhou, Yu; Xie, Zhuang; Alngadh, Ahmed; Keane, Denis T; Nassar, Majed S; Botros, Youssry Y; Mirkin, Chad A; Stoddart, J Fraser

    2016-08-22

    Covalent and supramolecular polymerizations, both of which offer their own unique advantages, have emerged as popular strategies for making artificial materials. Herein, we describe a concurrent covalent and supramolecular polymerization strategy-namely, one which utilizes 1) a bis-azide-functionalized diazaperopyrenium dication that undergoes polymeriation covalently with a bis-alkyne-functionalized biphenyl derivative in one dimension as a result of a rapid and efficient β-cyclodextrin(CD)-accelerated, cucurbit[6]uril(CB)-templated azide-alkyne cycloaddition, while 2) the aromatic core of the dication is able to dimerize in a criss-cross fashion by dint of π-π interactions, enabling simultaneous supramolecular assembly, resulting in an extended polymer network in an orthogonal dimension. PMID:27338246

  9. Controlled Bulk Properties of Composite Polymeric Solutions for Extensive Structural Order of Honeycomb Polysulfone Membranes

    PubMed Central

    Gugliuzza, Annarosa; Perrotta, Maria Luisa; Drioli, Enrico

    2016-01-01

    This work provides additional insights into the identification of operating conditions necessary to overcome a current limitation to the scale-up of the breath figure method, which is regarded as an outstanding manufacturing approach for structurally ordered porous films. The major restriction concerns, indeed, uncontrolled touching droplets at the boundary. Herein, the bulk of polymeric solutions are properly managed to generate honeycomb membranes with a long-range structurally ordered texture. Water uptake and dynamics are explored as chemical environments are changed with the intent to modify the hydrophilic/hydrophobic balance and local water floatation. In this context, a model surfactant such as the polyoxyethylene sorbitan monolaurate is used in combination with alcohols at different chain length extents and a traditional polymer such as the polyethersufone. Changes in the interfacial tension and kinematic viscosity taking place in the bulk of composite solutions are explored and examined in relation to competitive droplet nucleation and growth rate. As a result, extensive structurally ordered honeycomb textures are obtained with the rising content of the surfactant while a broad range of well-sized pores is targeted as a function of the hydrophilic-hydrophobic balance and viscosity of the composite polymeric mixture. The experimental findings confirm the consistency of the approach and are expected to give propulsion to the commercially production of breath figures films shortly. PMID:27196938

  10. Controlled Bulk Properties of Composite Polymeric Solutions for Extensive Structural Order of Honeycomb Polysulfone Membranes.

    PubMed

    Gugliuzza, Annarosa; Perrotta, Maria Luisa; Drioli, Enrico

    2016-01-01

    This work provides additional insights into the identification of operating conditions necessary to overcome a current limitation to the scale-up of the breath figure method, which is regarded as an outstanding manufacturing approach for structurally ordered porous films. The major restriction concerns, indeed, uncontrolled touching droplets at the boundary. Herein, the bulk of polymeric solutions are properly managed to generate honeycomb membranes with a long-range structurally ordered texture. Water uptake and dynamics are explored as chemical environments are changed with the intent to modify the hydrophilic/hydrophobic balance and local water floatation. In this context, a model surfactant such as the polyoxyethylene sorbitan monolaurate is used in combination with alcohols at different chain length extents and a traditional polymer such as the polyethersufone. Changes in the interfacial tension and kinematic viscosity taking place in the bulk of composite solutions are explored and examined in relation to competitive droplet nucleation and growth rate. As a result, extensive structurally ordered honeycomb textures are obtained with the rising content of the surfactant while a broad range of well-sized pores is targeted as a function of the hydrophilic-hydrophobic balance and viscosity of the composite polymeric mixture. The experimental findings confirm the consistency of the approach and are expected to give propulsion to the commercially production of breath figures films shortly. PMID:27196938

  11. Macrovoid Defect Growth during Evaporative Casting of Polymeric Membranes

    NASA Technical Reports Server (NTRS)

    Greenberg, A. R.; Khare, V. P.; Zartman, J.; Krantz, W. B.; Todd, P.

    2003-01-01

    Macrovoid (MV) formation is a significant problem in evaporatively cast polymeric membranes. MVs are large, elongated or teardrop-shaped pores (10-50 micron) that can impair membrane structural integrity. Although MVs have been extensively studied, there is no general agreement on the mechanisms governing MV growth. Recently, our research group has formulated the solutocapillary convection (SC) hypothesis, which contends that MV growth involves three principal forces: a Marangoni force generated by surface tension gradients within the MV interface, a viscous drag force, and a gravitationally induced body force. Two sets of complementary experiments were conducted to test the SC hypothesis. Ground-based videomicroscopy flow-visualization (VMFV) was utilized to measure the flow velocities at the MV-casting solution interface and deep within the casting solution. The measurements were performed with casting solutions containing 10 wt% cellulose acetate (CA), 30 wt% H2O, 60 wt% acetone, and 200- ppm TiO2 particles for flow visualization, and the surface tension was controlled by surfactant addition. Qualitatively, the experiments indicated that MV growth occurs in three distinct phases: (1) a very rapid initial growth period, (2) a much slower growth phase, and (3) absorption of selected MVs into the expanding demixed region. The presence of tracer particles inside the MVs suggests the presence of a convective flow, which transfers the particles from the bulk solution to the MV interior. Although the VMFV experiments did not establish any surfactant effect on the interfacial velocities, a statistically significant effect on the MV number density was observed. In the second set of experiments, membranes were cast aboard a KC-135 aircraft under 0-g and 2-g conditions. Despite careful attention to the design and fabrication of the membrane casting apparatus (MCA), several problems were encountered, the most significant of which was the contamination of the casting

  12. Radiation-hardened polymeric films

    DOEpatents

    Arnold, C. Jr.; Hughes, R.C.; Kepler, R.G.; Kurtz, S.R.

    1984-07-16

    The radiation-induced conductivity of polymeric dielectrics with low electronic mobility is reduced by doping with electron donor or electron acceptor compounds at a level of 10/sup 15/ to 10/sup 21/ molecules of dopant/cm/sup 3/. Polyesters, polyolefins, perfluoropolyolefins, vinyl polymers, vinylidene polymers, polycarbonates, polysulfones and polyimides can benefit from such a treatment. Usable dopants include 2,4,7-trinitro-9-fluorenone, tetracyanethylene, 7,7,8,8-tetracyanoquinodimethane, m-dinitrobenzene, 2-isopropylcarbazole, and triphenylamine.

  13. Electrochemical polymerization of pyrrole derivatives

    SciTech Connect

    Inagaki, T.; Hunter, M.; Yang, X.Q.; Skotheim, T.A.; Lee, H.S.; Okamoto, Y.

    1988-01-01

    Electrochemical copolymerization of pyrrole and 3-(6-ferrocenyl-6-hydroxyhexyl)pyrrole (P-Fc) yields a ferrocene functionalized polypyrrole with a controlled amount of ferrocene functionalization. Similarly, copolymers of pyrrole and 3-(4-(2,5- dimethoxyphenyl)butyl)pyrrole (P-MP) can be made by electrochemical polymerization and converted to the copolymers containing pH dependent electroactive hydroquinone moieties. 16 refs., 6 figs.

  14. Radiation-hardened polymeric films

    DOEpatents

    Arnold, Jr., Charles; Hughes, Robert C.; Kepler, R. Glen; Kurtz, Steven R.

    1986-01-01

    The radiation-induced conductivity of polymeric dielectrics with low electronic mobility is reduced by doping with electron donor or electron acceptor compounds at a level of 10.sup.15 to 10.sup.21 molecules of dopant/cm.sup.3. Polyesters, polyolefins, perfluoropolyolefins, vinyl polymers, vinylidene polymers, polycarbonates, polysulfones and polyimides can benefit from such a treatment. Usable dopants include 2,4,7-trinitro-9-fluorenone, tetracyanethylene, 7,7,8,8-tetracyanoquinodimethane, m-dinitrobenzene, 2-isopropylcarbazole, and triphenylamine.

  15. Alcohol polymerization using electron emission

    NASA Astrophysics Data System (ADS)

    Matsuura, Hiroshi; Tanikawa, Tamio; Takaba, Hiromitsu; Fujiwara, Yutaka

    2004-04-01

    We report a means of instantaneous alcohol polymerization using electron emission at room temperature. We selected 1-butanol as a source of alcohol polymer. A 1-butanol molecule has a simple molecular structure and is a good candidate for analyzing reaction mechanisms. Direct electron emission onto the surface of volatile 1-butanol prevented intense discharge and gently composed 1-butanol-polymer at room temperature in air. The strategy enabled exciting liquids and instantaneously composing new materials at room temperature.

  16. Comparative study of clinical pulmonary surfactants using atomic force microscopy

    PubMed Central

    Zhang, Hong; Fan, Qihui; Wang, Yi E.; Neal, Charles R.; Zuo, Yi Y.

    2016-01-01

    Clinical pulmonary surfactant is routinely used to treat premature newborns with respiratory distress syndrome, and has shown great potential in alleviating a number of neonatal and adult respiratory diseases. Despite extensive study of chemical composition, surface activity, and clinical performance of various surfactant preparations, a direct comparison of surfactant films is still lacking. In this study, we use atomic force microscopy to characterize and compare four animal-derived clinical surfactants currently used throughout the world, i.e., Survanta, Curosurf, Infasurf and BLES. These modified-natural surfactants are further compared to dipalmitoyl phosphatidylcholine (DPPC), a synthetic model surfactant of DPPC:palmitoyl-oleoyl phosphatidylglycerol (POPG) (7:3), and endogenous bovine natural surfactant. Atomic force microscopy reveals significant differences in the lateral structure and molecular organization of these surfactant preparations. These differences are discussed in terms of DPPC and cholesterol contents. We conclude that all animal-derived clinical surfactants assume a similar structure of multilayers of fluid phospholipids closely attached to an interfacial monolayer enriched in DPPC, at physiologically relevant surface pressures. This study provides the first comprehensive survey of the lateral structure of clinical surfactants at various surface pressures. It may have clinical implications on future application and development of surfactant preparations. PMID:21439262

  17. Lung injury and surfactant metabolism after hyperventilation of premature lambs.

    PubMed

    Ikegami, M; Kallapur, S; Michna, J; Jobe, A H

    2000-03-01

    We asked whether lung injury and surfactant metabolism differed in preterm lambs after a 1-h period of hyperventilation to P(CO2) values of 25-30 mm Hg. The lambs then were surfactant treated and conventionally ventilated (CV) or high-frequency oscillatory ventilated (HFOV) for an additional 1 or 8 h. The results were compared with lambs that were not hyperventilated or surfactant treated but were ventilated with CV or HFOV. The 1-h hyperventilation resulted in increased alveolar protein, increased recovery of intravascular [131I]albumin in the lungs, and an increase in tumor necrosis factor-alpha mRNA. There were no differences between CV or HFOV in alveolar or total lung recoveries of saturated phosphatidylcholine (Sat PC), tracer doses of [14C]Sat PC and [125I]surfactant protein-B, or in percent Sat PC in large aggregate surfactant in surfactant-treated lambs. The lambs not hyperventilated or treated with surfactant had lower large aggregate pools and lower recoveries of [14C]Sat PC and [125I]surfactant protein-B in total lungs than for the surfactant-treated lungs, but there were no differences between the CV and HFOV groups. Hyperventilation followed by surfactant treatment resulted in a mild injury, but the subsequent use of CV or HFOV did not result in differences in surfactant metabolism. PMID:10709742

  18. Pulmonary surfactants and their role in pathophysiology of lung disorders.

    PubMed

    Akella, Aparna; Deshpande, Shripad B

    2013-01-01

    Surfactant is an agent that decreases the surface tension between two media. The surface tension between gaseous-aqueous interphase in the lungs is decreased by the presence of a thin layer of fluid known as pulmonary surfactant. The pulmonary surfactant is produced by the alveolar type-II (AT-II) cells of the lungs. It is essential for efficient exchange of gases and for maintaining the structural integrity of alveoli. Surfactant is a secretory product, composed of lipids and proteins. Phosphatidylcholine and phosphatidylglycerol are the major lipid constituents and SP-A, SP-B, SP-C, SP-D are four types of surfactant associated proteins. The lipid and protein components are synthesized separately and are packaged into the lamellar bodies in the AT-II cells. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. The synthesis, secretion and recycling of the surfactant lipids and proteins is regulated by complex genetic and metabolic mechanisms. The lipid-protein interaction is very important for the structural organization of surfactant monolayer and its functioning. Alterations in surfactant homeostasis or biophysical properties can result in surfactant insufficiency which may be responsible for diseases like respiratory distress syndrome, lung proteinosis, interstitial lung diseases and chronic lung diseases. The biochemical, physiological, developmental and clinical aspects of pulmonary surfactant are presented in this article to understand the pathophysiological mechanisms of these diseases. PMID:23441475

  19. Lung surfactants and different contributions to thin film stability.

    PubMed

    Hermans, Eline; Bhamla, M Saad; Kao, Peter; Fuller, Gerald G; Vermant, Jan

    2015-11-01

    The surfactant lining the walls of the alveoli in the lungs increases pulmonary compliance and prevents collapse of the lung at the end of expiration. In premature born infants, surfactant deficiency causes problems, and lung surfactant replacements are instilled to facilitate breathing. These pulmonary surfactants, which form complex structured fluid-fluid interfaces, need to spread with great efficiency and once in the alveolus they have to form a thin stable film. In the present work, we investigate the mechanisms affecting the stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with the phospholipid dipalmitoylphosphatidylcholine (DPPC), are used. The surface of the dome can be covered with human alveolar epithelial cells and experiments are conducted at the physiological temperature. Drainage is slowed down due to the presence of all the different lung surfactant replacements and therefore the thin films show enhanced stability. However, a scaling analysis combined with visualization experiments demonstrates that different mechanisms are involved. For Curosurf and Infasurf, Marangoni stresses are essential to impart stability and interfacial shear rheology does not play a role, in agreement with what is observed for simple surfactants. Survanta, which was historically the first natural surfactant used, is rheologically active. For DPPC the dilatational properties play a role. Understanding these different modes of stabilization for natural surfactants can benefit the design of effective synthetic surfactant replacements for treating infant and adult respiratory disorders. PMID:26307946

  20. Surfactant therapy: the current practice and the future trends

    PubMed Central

    Altirkawi, Khalid

    2013-01-01

    The efficacy of surfactant preparations used in the prevention and treatment of respiratory distress syndrome (RDS) is a well known fact; however, many controversies remain. The debate over which surfactant to be used, when and what is the best mode of delivery is still raging. Currently, animal-derived surfactants are preferred and clearly recommended by various practice guidelines, but new synthetic surfactants containing peptides that mimic the action of surfactant proteins are emerging and they seem to have a comparable efficacy profile to the natural surfactants. It is hoped that with further improvements, they will outperform their natural counterparts in terms of reliability and cost-effectiveness. Early surfactant administration was shown to further reduce the risk of RDS and its complications. However, as nasal continuous positive airway pressure (nCPAP) is becoming increasingly the preferred first-line therapy for RDS, the less invasive approaches of respiratory support along with early selective surfactant administration (e.g. INSURE) appears to provide a better option. Although neonatal RDS is still the main indication of surfactant therapy, other pathological processes received considerable attention and major research has been dedicated to explore the role of surfactant in their management, Meconium aspiration syndrome (MAS) and congenital pneumonia are two worthy examples. The most updated practice guidelines do recommend the use of endotracheal instillation as the preferred mode of surfactant delivery. However, aerosolization and other non-invasive methods are being investigated with some success; nonetheless, further improvements are very much in need. PMID:27493353

  1. Hydrophobic surfactant proteins strongly induce negative curvature.

    PubMed

    Chavarha, Mariya; Loney, Ryan W; Rananavare, Shankar B; Hall, Stephen B

    2015-07-01

    The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism. PMID:26153706

  2. Surfactant-enhanced alkaline flooding field project

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  3. Two Photon Polymerization of Ormosils

    NASA Astrophysics Data System (ADS)

    Matei, A.; Zamfirescu, M.; Jipa, F.; Luculescu, C.; Dinescu, M.; Buruiana, E. C.; Buruiana, T.; Sima, L. E.; Petrescu, S. M.

    2010-10-01

    In this work, 3D structures of hybrid polymers—ORMOSILS (organically modified silicates) were produced via Two Photon Polymerization (2PP) of hybrid methacrylates based on silane derivates. Synthetic routes have been used to obtain series of hybrid monomers, their structure and purity being checked by NMR Spectroscopy and Fourier Transform Infrared Spectroscopy. Two photon polymerization method (a relatively new technology which allows fast micro and nano processing of three-dimensional structures with application in medical devices, tissue scaffolds, photonic crystals etc) was used for monomers processing. As laser a Ti: Sapphire laser was used, with 200 fs pulse duration and 2 kHz repetition rate, emitting at 775 nm. A parametric study on the influence of the processing parameters (laser fluence, laser scanning velocity, photo initiator) on the written structures was carried out. The as prepared polymeric scaffolds were tested in mesenchymal stem cells and fibroblasts cell cultures, with the aim of further obtaining bone and dermal grafts. Cells morphology, proliferation, adhesion and alignment were analyzed for different experimental conditions.

  4. Atomic force microscopy analysis of rat pulmonary surfactant films.

    PubMed

    Jiao, Xiujun; Keating, Eleonora; Tadayyon, Seyed; Possmayer, Fred; Zuo, Yi Y; Veldhuizen, Ruud A W

    2011-10-01

    Pulmonary surfactant facilitates breathing by forming a surface tension reducing film at the air-liquid interface of the alveoli. The objective was to characterize the structure of surfactant films using endogenous rat surfactant. Solid-support surfactant films, at different surface pressures, were obtained using a Langmuir balance and were analyzed using atomic force microscopy. The results showed a lipid film structure with three distinct phases: liquid expanded, liquid ordered and liquid condensed. The area covered by the liquid condensed domains increased as surface pressure increased. The presence of liquid ordered phase within these structures correlated with the cholesterol content. At a surface pressure of 50 mN/m, stacks of bilayers appeared. Several structural details of these films differ from previous observations made with goat and exogenous surfactants. Overall, the data indicate that surfactant films demonstrate phase separation at low surface pressures and multilayer formation at higher pressure, features likely important for normal surfactant function. PMID:21704443

  5. Status of surfactants as penetration enhancers in transdermal drug delivery

    PubMed Central

    Som, Iti; Bhatia, Kashish; Yasir, Mohd.

    2012-01-01

    Surfactants are found in many existing therapeutic, cosmetic, and agro-chemical preparations. In recent years, surfactants have been employed to enhance the permeation rates of several drugs via transdermal route. The application of transdermal route to a wider range of drugs is limited due to significant barrier to penetration across the skin which is associated with the outermost stratum corneum layer. Surfactants have effects on the permeability characteristics of several biological membranes including skin. They have the potential to solubilize lipids within the stratum corneum. The penetration of the surfactant molecule into the lipid lamellae of the stratum corneum is strongly dependent on the partitioning behavior and solubility of surfactant. Surfactants ranging from hydrophobic agents such as oleic acid to hydrophilic sodium lauryl sulfate have been tested as permeation enhancer to improve drug delivery. This article reviews the status of surfactants as permeation enhancer in transdermal drug delivery of various drugs. PMID:22368393

  6. SURFACTANT BASED ENHANCED OIL RECOVERY AND FOAM MOBILITY CONTROL

    SciTech Connect

    George J. Hirasaki; Clarence A. Miller; Gary A. Pope; Richard E. Jackson

    2004-02-01

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactant structures makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. Also, the addition of an alkali such as sodium carbonate makes possible in situ generation of surfactant and significant reduction of surfactant adsorption. In addition to reduction of interfacial tension to ultra-low values, surfactants and alkali can be designed to alter wettability to enhance oil recovery. An alkaline surfactant process is designed to enhance spontaneous imbibition in fractured, oil-wet, carbonate formations. It is able to recover oil from dolomite core samples from which there was no oil recovery when placed in formation brine.

  7. Synthesis, characterization, and application of polysodium N-alkylenyl α-d-glucopyranoside surfactants for micellar electrokinetic chromatography-tandem mass spectrometry.

    PubMed

    Liu, Yijin; Wu, Baolin; Wang, Peng; Shamsi, Shahab A

    2016-04-01

    Sugar-based ionic surfactants forming micelles are known to suppress ESI of various compounds due to decrease in surface tension upon micelle formation . For the first time, poly (sodium N-undecylenyl-α-d-glucopyranoside 4,6-hydrogen phosphate, (poly-α-d-SUGP) based surfactants with different chain lengths and head groups have been successfully synthesized, characterized, and applied as compatible chiral selector for MEKC-ESI-MS/MS. First, the effect of polymerization concentration of the monomer, α-d-SUGP, was evaluated by enantioseparation of one anionic compound (1,1'-binaphthyl-2,2'diyl-hydrogen phosphate) and one zwitterionic compound (dansylated phenylalanine) in MEKC-UV to find the optimum molar surfactant concentration for polymerization. Next, MEKC-UV and MEKC-MS were compared for the enantioseparation of 1,1'-binaphthyl-2,2'diyl-hydrogen phosphate. The influence of polymeric glucopyranoside based surfactant head groups and carbon chain lengths on chiral Rs was evaluated for two classes of cationic drugs (ephedrine alkaloids and β-blockers). Finally, enantioselective MEKC-MS of ephedrine alkaloids and β-blockers were profiled at their optimum pH 5.0 and 7.0, respectively, using 20 mM NH4 OAc, 25 mM poly-α-d-SUGP at 30 kV and 25°C under optimum spray chamber conditions. The LOD for most of the enantiomers ranges from 10 to 100 ng/mL with S/N of at least ≥3.0. PMID:26763089

  8. Polymerizable vesicles based on a single-tailed fatty acid surfactant: a simple route to robust nanocontainers.

    PubMed

    Lee, Jae-Ho; Danino, Dganit; Raghavan, Srinivasa R

    2009-02-01

    Vesicles with polymerizable bilayers have attracted interest because of their increased robustness, which is advantageous for applications. However, to prepare such vesicles, lipids with polymerizable moieties usually need to be synthesized, and this often involves cumbersome, multistep reactions. Here, we present an alternative, simpler approach based on a commercially available, single-tailed surfactant, viz. 10-undecenoic acid (UDA), a fatty acid with a terminal double bond. Previously, the polymerization of UDA micelles in water has been studied. We show that UDA can also be induced to form vesicles by adjusting the pH: vesicles form at intermediate pH (6-8), whereas at higher pH (>11), the vesicles are transformed into micelles. The presence of UDA vesicles in the pH 6-8 range is confirmed using small-angle neutron scattering (SANS) and cryotransmission electron microscopy (cryo-TEM). Subsequent thermal polymerization of UDA bilayers is done using 2,2-dimethoxy-2-phenylacetophenone (DMPA) as initiator. A partial polymerization of the bilayers is achieved, and polymerized UDA vesicles resist disruption into micelles when the solution pH is increased. To make the bilayers more robust, the vesicles are copolymerized with divinylbenzene (DVB), a hydrophobic cross-linker that partitions into the bilayer. DVB-cross-linked UDA vesicles are very stable and cannot be disrupted by detergents like Triton X-100. PMID:19138066

  9. Ultrasound-Mediated Polymeric Micelle Drug Delivery.

    PubMed

    Xia, Hesheng; Zhao, Yue; Tong, Rui

    2016-01-01

    The synthesis of multi-functional nanocarriers and the design of new stimuli-responsive means are equally important for drug delivery. Ultrasound can be used as a remote, non-invasive and controllable trigger for the stimuli-responsive release of nanocarriers. Polymeric micelles are one kind of potential drug nanocarrier. By combining ultrasound and polymeric micelles, a new modality (i.e., ultrasound-mediated polymeric micelle drug delivery) has been developed and has recently received increasing attention. A major challenge remaining in developing ultrasound-responsive polymeric micelles is the improvement of the sensitivity or responsiveness of polymeric micelles to ultrasound. This chapter reviews the recent advance in this field. In order to understand the interaction mechanism between ultrasound stimulus and polymeric micelles, ultrasound effects, such as thermal effect, cavitation effect, ultrasound sonochemistry (including ultrasonic degradation, ultrasound-initiated polymerization, ultrasonic in-situ polymerization and ultrasound site-specific degradation), as well as basic micellar knowledge are introduced. Ultrasound-mediated polymeric micelle drug delivery has been classified into two main streams based on the different interaction mechanism between ultrasound and polymeric micelles; one is based on the ultrasound-induced physical disruption of the micelle and reversible release of payload. The other is based on micellar ultrasound mechanochemical disruption and irreversible release of payload. PMID:26486348

  10. An overview of pulmonary surfactant in the neonate: genetics, metabolism, and the role of surfactant in health and disease.

    PubMed

    Nkadi, Paul O; Merritt, T Allen; Pillers, De-Ann M

    2009-06-01

    Pulmonary surfactant is a complex mixture of phospholipids (PL) and proteins (SP) that reduce surface tension at the air-liquid interface of the alveolus. It is made up of about 70-80% PL, mainly dipalmitoylphosphatidylcholine (DPPC), 10% SP-A, B, C and D, and 10% neutral lipids, mainly cholesterol. Surfactant is synthesized, assembled, transported and secreted into the alveolus where it is degraded and then recycled. Metabolism of surfactant is slower in newborns, especially preterm, than in adults. Defective pulmonary surfactant metabolism results in respiratory distress with attendant morbidity and mortality. This occurs due to accelerated breakdown by oxidation, proteolytic degradation, inhibition or inherited defects of surfactant metabolism. Prenatal corticosteroids, surfactant replacement, whole lung lavage and lung transplantation have yielded results in managing some of these defects. Gene therapy could prove valuable in treating inherited defects of surfactant metabolism. PMID:19299177

  11. Structure and Conformational Dynamics of DMPC/Dicationic Surfactant and DMPC/Dicationic Surfactant/DNA Systems

    PubMed Central

    Pietralik, Zuzanna; Krzysztoń, Rafał; Kida, Wojciech; Andrzejewska, Weronika; Kozak, Maciej

    2013-01-01

    Amphiphilic dicationic surfactants, known as gemini surfactants, are currently studied for gene delivery purposes. The gemini surfactant molecule is composed of two hydrophilic “head” groups attached to hydrophobic chains and connected via molecular linker between them. The influence of different concentrations of 1,5-bis (1-imidazolilo-3- decyloxymethyl) pentane chloride (gemini surfactant) on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers with and without the presence of DNA was investigated using Fourier transformed infrared (FTIR) and circular dichroism (CD) spectroscopies, small angle scattering of synchrotron radiation and differential scanning calorimetry. With increasing concentration of surfactant in DMPC/DNA systems, a disappearance of pretransition and a decrease in the main phase transition enthalpy and temperature were observed. The increasing intensity of diffraction peaks as a function of surfactant concentration also clearly shows the ability of the surfactant to promote the organisation of lipid bilayers in the multilayer lamellar phase. PMID:23571492

  12. Langmuir-Blodgett films of a pyrrole and ferrocene mixed surfactant system

    SciTech Connect

    Samuelson, L.; Rahman, A.K.M.; Clough, S.; Tripathy, S.; Hale, P.D.; Inagaki, T.; Skotheim, T.A.; Okamoto, Y. . Dept. of Chemistry; Brookhaven National Lab., Upton, NY; Polytechnic Univ., Brooklyn, NY . Dept. of Chemistry)

    1989-01-01

    The Langmuir-Blodgett technique was used to study the molecular organization of a mixed 3-hexadecyl pyrrole (3HDP) and ferrocene-derivatized pyrrole (Fc-Py) surfactant system. It has been determined that stable monolayer films of the mixed system could be formed at the air-water interface. The growth and assembly process led to polypyrrole 2-D lattices with heretofore unsurpassed order. In fact, the process of template polymerization, it appears, leads to a new crystal phase for the polypyrrole component of the thin film structure. Various monolayer and multilayer films were prepared on platinum coated substrates for surface spectroscopic characterization. Near Edge X-Ray Absorption Fine Structure (NEXAFS) studies revealed that highly ordered multilayer structures are being formed. Electrochemical studies have been initiated to determine the feasibility of these films in molecular electronic device applications. 13 refs., 6 figs., 1 tab.

  13. Polymerization rate and mechanism of ultrasonically initiated emulsion polymerization of n-butyl acrylate.

    PubMed

    Xia, Hesheng; Wang, Qi; Liao, Yongqin; Xu, Xi; Baxter, Steven M; Slone, Robert V; Wu, Shuguang; Swift, Graham; Westmoreland, David G

    2002-07-01

    The factors affecting the induction period and polymerization rate in ultrasonically initiated emulsion polymerization of n-butyl acrylate (BA) were investigated. The induction period takes only an instant in ultrasonically initiated emulsion polymerization of BA without any added initiator by enhancing the N2 flow rate. Increasing temperature, power output and SDS concentration, decreasing the monomer concentration results in further decreasing induction period and enhanced polymerization rate. Under optimized reaction conditions the conversion of BA reaches 92% in 11 min. The polymerization rate can be controlled by varying reaction parameters. The apparatus of ultrasonically initiated semi-continuous and continuous emulsion polymerization were set up and the feasibility was first studied. Based on the experimental results, a free radical polymerization mechanism for ultrasonically initiated emulsion polymerization was proposed, including the sources of the radicals, the process of radical formation, the locus of polymerization and the polymerization process. Compared with conventional emulsion polymerization, where the radicals come from thermal decomposition of a chemical initiator, ultrasonically initiated emulsion polymerization has attractive features such as no need for a chemical initiator, lower reaction temperature, faster polymerization rate, and higher molecular weight of the polymer prepared. PMID:12154689

  14. Surfactant Based Enhanced Oil Recovery and Foam Mobility Control

    SciTech Connect

    George J. Hirasaki; Clarence A. Miller

    2006-09-09

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactant structures makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. A mixture of two surfactants was found to be particularly effective for application in carbonate formations at low temperature. The mixture is single phase for higher salinity or calcium concentrations than that for either surfactant used alone. This makes it possible to inject the surfactant slug with polymer close to optimal conditions and yet be single phase. A formulation has been designed for a particular field application. It uses partially hydrolyzed polyacrylamide for mobility control. The addition of an alkali such as sodium carbonate makes possible in situ generation of naphthenic soap and significant reduction of synthetic surfactant adsorption. The design of the process to maximize the region of ultra-low IFT takes advantage of the observation that the ratio of soap to synthetic surfactant is a parameter in the conditions for optimal salinity. Even for a fixed ratio of soap to surfactant, the range of salinity for low IFT was wider than that reported for surfactant systems in the literature. Low temperature, forced displacement experiments in dolomite and silica sandpacks demonstrate that greater than 95% recovery of the waterflood remaining oil is possible with 0.2% surfactant concentration, 0.5 PV surfactant slug, with no alcohol. Compositional simulation of the displacement process demonstrates the role of soap/surfactant ratio on passage of the profile through the ultralow IFT region, the importance of a wide salinity range of low IFT, and the importance of the viscosity of the surfactant slug. Mobility control is essential for surfactant EOR. Foam is evaluated to improve the sweep efficiency of surfactant injected into fractured reservoirs as well as a

  15. LNAPL Removal from Unsaturated Porous Media using Surfactant Infiltration

    SciTech Connect

    Zhong, Lirong; Oostrom, Martinus

    2012-11-19

    A series of unsaturated column experiments was performed to evaluate light non-aqueous phase liquid (LNAPL) fate and removal during surfactant solution infiltration. Surfactant-LNAPL phase behavior tests were conducted to optimize the remedial solutions. Packed sand and site sediment columns were first processed to establish representative LNAPL smear zone under unsaturated conditions. Infiltration of low-concentration surfactant was then applied in a stepwise flush mode, with 0.3 column pore volume (PV) of solution in each flush. The influence of infiltrated surfactant solution volume and pH on LNAPL removal was assessed. A LNAPL bank was observed at the very front of the first surfactant infiltration in each column, indicating that a very low surfactant concentration is needed to reduce the LNAPL-water interfacial tension sufficiently enough to mobilize trapped LNAPL under unsaturated conditions. More LNAPL was recovered as additional steps of surfactant infiltration were applied. Up to 99% LNAPL was removed after six infiltration steps, with less than 2.0 PV of total surfactant solution application, suggesting surfactant infiltration may be an effective method for vadose zone LNAPL remediation. The influence of pH tested in this study (3.99~10.85) was insignificant because the buffering capacity of the sediment kept the pH in the column higher than the zero point charge, pHzpc, of the sediment and therefore the difference between surfactant sorption was negligible.

  16. Pulmonary surfactant adsorption is increased by hyaluronan or polyethylene glycol.

    PubMed

    Taeusch, H William; Dybbro, Eric; Lu, Karen W

    2008-04-01

    In acute lung injuries, inactivating agents may interfere with transfer (adsorption) of pulmonary surfactants to the interface between air and the aqueous layer that coats the interior of alveoli. Some ionic and nonionic polymers reduce surfactant inactivation in vitro and in vivo. In this study, we tested directly whether an ionic polymer, hyaluronan, or a nonionic polymer, polyethylene glycol, enhanced adsorption of a surfactant used clinically. We used three different methods of measuring adsorption in vitro: a modified pulsating bubble surfactometer; a King/Clements device; and a spreading trough. In addition we measured the effects of both polymers on surfactant turbidity, using this assay as a nonspecific index of aggregation. We found that both hyaluronan and polyethylene glycol significantly increased the rate and degree of surfactant material adsorbed to the surface in all three assays. Hyaluronan was effective in lower concentrations (20-fold) than polyethylene glycol and, unlike polyethylene glycol, hyaluronan did not increase apparent aggregation of surfactant. Surfactant adsorption in the presence of serum was also enhanced by both polymers regardless of whether hyaluronan or polyethylene glycol was included with serum in the subphase or added to the surfactant applied to the surface. Therefore, endogenous polymers in the alveolar subphase, or exogenous polymers added to surfactant used as therapy, may both be important for reducing inactivation of surfactant that occurs with various lung injuries. PMID:18065212

  17. Cycle-Induced Flow and Surfactant Transport in an Alveolus

    NASA Astrophysics Data System (ADS)

    Wei, H. H.

    2002-11-01

    The flow and transport in an alveolus are of fundamental importance to partial liquid ventilation, surfactant transport, pulmonary drug administration, cell-cell signaling pathways and gene therapy. We model the system in which an alveolus is partially filled with liquid in the presence of surfactants. Assuming a circular interface due to sufficiently strong surface tension, we can apply two-dimensional bipolar coordinates to describe the system. We then combine analytical and numerical techniques to solve the Stokes flow and the surfactant concentration. In the absence of surfactants, there is no steady streaming because of reversibility of the Stokes flow. The presence of surfactants however induces a non-trivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns (e.g., number of vortices) depend on the parameters, especially on the ratio of inspiration to expiration periods (I:E ratio). Either smaller or larger I:E ratio exhibits two primary vortices but the direction of primary vortices for small I:E is opposite to large I:E. Extension to soluble surfactants is also discussed. For sufficiently high surfactant bulk concentration, the surfactant transport is sorption-controlled and soluble surfactants diminish the size of steady vortices near the alveolar opening. For the estimated steady velocity u 10-5 cm/s, the corresponding Peclet number is 10-7/ D_m. Therefore, for Dm <= 10-7 cm^2/s, the convective transport dominates.

  18. Role of Silicone Surfactant in Flexible Polyurethane Foam.

    PubMed

    Zhang; Macosko; Davis; Nikolov; Wasan

    1999-07-15

    Grafted copolymers which consist of a polydimethylsiloxane backbone and polyethylene oxide-co-propylene oxide pendant groups are used as surfactants to stabilize the foam cells in the flexible polyurethane foaming process. The mechanical properties of the cured polyurethane foam such as air permeability and foam cell size are affected significantly by the structure of the silicone surfactant used in the formulation. It is shown that silicone surfactant has an important impact on both the bubble generation and the cell window stabilization stage. A series of silicone surfactants with different structures was tested. Surfactants with higher silicone content will provide lower surface tension and thus help increase the number of air bubbles introduced during mixing. These air bubbles serve as the starting point for foam cell growth. As a result, the cured polyurethane foam made with higher silicone content surfactant has a smaller bubble size. It is also shown that silicone surfactant can reduce the cell window drainage rate due to the surface tension gradient along the cell window. The Gibbs film elasticity, the dynamic film elasticity, and the film drainage rate were measured for the first time versus surfactant composition. Surfactants with longer siloxane backbones are shown to give higher film elasticity. Using the vertical film drainage and foam column tests, it is shown that surfactants with higher film elasticity will yield slower drainage rate and better foam cell stability. Copyright 1999 Academic Press. PMID:10419661

  19. Surfactant-enhanced spreading: Experimental achievements and possible mechanisms.

    PubMed

    Kovalchuk, N M; Trybala, A; Arjmandi-Tash, O; Starov, V

    2016-07-01

    Surfactants are broadly used to improve wetting properties of aqueous formulations. The improvement is achieved by essential reduction of liquid/air and solid/liquid interfacial tensions resulting in the decrease of contact angle. For moderately hydrophobic substrates, there is a range of surfactants providing complete wetting of substrate. With the decrease of substrate surface energy, this range of surfactants reduces very quickly and only trisiloxane surfactant solutions are capable to wet completely such highly hydrophobic substrates as polypropylene and parafilm. That is why these surfactants are referred to as superspreaders. The most intriguing feature of wetting surfactant solutions is their ability to spread much faster than pure liquids with spread area, S, being proportional to time, t, S~t, as compared to S~t(0.2) for pure liquids, which wet completely the solid substrate. Trisiloxane surfactant solutions spread faster than other aqueous surfactant solutions, which also provide complete wetting, being superspreaders in the sense of spreading rate as well. The mechanism of fast spreading of surfactant solutions on hydrophobic substrates and much higher spreading rates for trisiloxane solutions are to be explained. Below the available experimental data on superspreading and surfactant-enhanced spreading are analysed/summarised, and possible mechanisms governing the fast spreading are discussed. PMID:26282600

  20. SURFACTANT BASED ENHANCED OIL RECOVERY AND FOAM MOBILITY CONTROL

    SciTech Connect

    George J. Hirasaki; Clarence A. Miller; Gary A. Pope; Richard E. Jackson

    2004-07-01

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactants makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. Also, the addition of an alkali such as sodium carbonate makes possible in situ generation of surfactant and significant reduction of surfactant adsorption. In addition to reduction of interfacial tension to ultra-low values, surfactants and alkali can be designed to alter wettability to enhance oil recovery. An alkaline surfactant process is designed to enhance spontaneous imbibition in fractured, oil-wet, carbonate formations. It is able to recover oil from dolomite core samples from which there was no oil recovery when placed in formation brine. Mobility control is essential for surfactant EOR. Foam is evaluted to improve the sweep efficiency of surfactant injected into fractured reservoirs. UTCHEM is a reservoir simulator specially designed for surfactant EOR. A dual-porosity version is demonstrated as a potential scale-up tool for fractured reservoirs.

  1. The surfactant system protects both fetus and newborn.

    PubMed

    Hallman, Mikko

    2013-01-01

    Surfactant complex and its individual components decrease surface tension, silence inflammatory responses, bind and destroy air-borne microbes, facilitate phagocytosis by alveolar macrophages and bind endogenous and exogenous molecules. Surfactant components generally decrease harmful inflammatory responses. New exogenous surfactants and new indications for surfactant therapy remain to be studied. At term the pool of human surfactant from developing airways extends to the amniotic cavity and to the gastrointestinal tract. Preterm labor-inducing inflammatory ligands (interleukin-1 or lipopolysaccharide) cause a robust induction of surfactant complex and lower the risk of respiratory distress syndrome (RDS). The effect of antenatal glucocorticoid therapy is complementary. According to transgenic experiments or genetic evidence in humans, surfactant proteins A, D or C (SP-A, SP-D, SP-C), expressed in fetal tissue, influence the onset of term or preterm labor. After birth, the surface tension-reducing and the inflammation-silencing effects of exogenous and endogenous surfactant are complementary. Surfactant proteins influence the genetic predisposition of RDS, bronchopulmonary dysplasia (BPD) and airway infections in early infancy. Moderate to severe BPD has a strong genetic predisposition. Deleterious mutations of SP-B, ABCA3 or SP-C cause congenital interstitial lung disease that mimics the phenotype of established severe BPD. I propose that lung surfactant protects both the fetus and the newborn. Surfactant ameliorates inflammatory responses that are harmful to the mother, fetus and infant. In chorioamnionitis, inflammatory ligands are carried from the fetal membranes to the alveolar space via amniotic fluid and developing airways. They induce surfactant synthesis and secretion. Surfactant ameliorates severe inflammatory responses in fetal compartments and promotes spontaneous preterm birth. PMID:23736009

  2. Evaluation of mixed surfactants for improved chemical flooding

    SciTech Connect

    Llave, F.M.; French, T.R.; Lorenz, P.B.

    1993-02-01

    Phase behavior studies were conducted using combinations of a primary surfactant component and several ethoxylated surfactants. The objective of the study is to evaluate combinations of surfactants, anionic-nonionic and anionic-anionic mixtures, that would yield favorable phase behavior and solubilization capacity. The dependence of the solution behavior on the additive surfactant structure, surfactant type, oil, surfactant proportion, salinity, HLB, and temperature was observed. The results showed that the ethoxylated surfactants can improve the solution behavior of the overall system. The increase in optimum salinity range of these solutions corresponded to an increase in the degree of ethoxylation of additive surfactant, up to a certain limit. The nonionic surfactant additives yielded much higher salinities compared to the results from the ethoxylated anionics tested. The proportion of surfactant component in solution was critical in achieving a balance between the solubilization capacity and the enhancement in the system's salinity tolerance. Some combinations of these types of surfactants showed improved solution behavior with favorable solubilization capacity. The phase inversion temperature (PIT) method has been shown to be a relatively fast method for screening candidate surfactant systems. Comparisons were made using both the conventional salinity scan and the PIT method on selected chemical systems. The results showed good agreement between the salinity regions determined using both methods. A difference in the dependence of optimal salinity on HLB was observed for the different nonionics tested. The linear alkyl alcohol ethoxylates exhibited a behavior distinct from the dialkyl phenols at similar HLB levels with and without the primary sulfonate component in the solution. Other experiments performed at NIPER have shown that surfactant-enhanced alkaline flooding has good potential for the recovery of oil from Naval Petroleum Reserve Number 3 (NPR No. 3).

  3. Evaluation of mixed surfactants for improved chemical flooding

    SciTech Connect

    Llave, F.M.; French, T.R.; Lorenz, P.B.

    1993-02-01

    Phase behavior studies were conducted using combinations of a primary surfactant component and several ethoxylated surfactants. The objective of the study is to evaluate combinations of surfactants, anionic-nonionic and anionic-anionic mixtures, that would yield favorable phase behavior and solubilization capacity. The dependence of the solution behavior on the additive surfactant structure, surfactant type, oil, surfactant proportion, salinity, HLB, and temperature was observed. The results showed that the ethoxylated surfactants can improve the solution behavior of the overall system. The increase in optimum salinity range of these solutions corresponded to an increase in the degree of ethoxylation of additive surfactant, up to a certain limit. The nonionic surfactant additives yielded much higher salinities compared to the results from the ethoxylated anionics tested. The proportion of surfactant component in solution was critical in achieving a balance between the solubilization capacity and the enhancement in the system`s salinity tolerance. Some combinations of these types of surfactants showed improved solution behavior with favorable solubilization capacity. The phase inversion temperature (PIT) method has been shown to be a relatively fast method for screening candidate surfactant systems. Comparisons were made using both the conventional salinity scan and the PIT method on selected chemical systems. The results showed good agreement between the salinity regions determined using both methods. A difference in the dependence of optimal salinity on HLB was observed for the different nonionics tested. The linear alkyl alcohol ethoxylates exhibited a behavior distinct from the dialkyl phenols at similar HLB levels with and without the primary sulfonate component in the solution. Other experiments performed at NIPER have shown that surfactant-enhanced alkaline flooding has good potential for the recovery of oil from Naval Petroleum Reserve Number 3 (NPR No. 3).

  4. Next Generation Surfactants for Improved Chemical Flooding Technology

    SciTech Connect

    Laura Wesson; Prapas Lohateeraparp; Jeffrey Harwell; Bor-Jier Shiau

    2012-05-31

    The principle objective of this project was to characterize and test current and next generation high performance surfactants for improved chemical flooding technology, focused on reservoirs in the Pennsylvanian-aged (Penn) sands. In order to meet this objective the characteristic curvatures (Cc) of twenty-eight anionic surfactants selected for evaluation for use in chemical flooding formulations were determined. The Cc values ranged from -6.90 to 2.55 with the majority having negative values. Crude oil samples from nine Penn sand reservoirs were analyzed for several properties pertinent to surfactant formulation for EOR application. These properties included equivalent alkane carbon numbers, total acid numbers, and viscosity. The brine samples from these same reservoirs were analyzed for several cations and for total dissolved solids. Surfactant formulations were successfully developed for eight reservoirs by the end of the project period. These formulations were comprised of a tertiary mixture of anionic surfactants. The identities of these surfactants are considered proprietary, but suffice to say the surfactants in each mixture were comprised of varying chemical structures. In addition to the successful development of surfactant formulations for EOR, there were also two successful single-well field tests conducted. There are many aspects that must be considered in the development and implementation of effective surfactant formulations. Taking into account these other aspects, there were four additional studies conducted during this project. These studies focused on the effect of the stability of surfactant formulations in the presence of polymers with an associated examination of polymer rheology, the effect of the presence of iron complexes in the brine on surfactant stability, the potential use of sacrificial agents in order to minimize the loss of surfactant to adsorption, and the effect of electrolytes on surfactant adsorption. In these last four studies

  5. Drag Reduction by Polymeric and Nonpolymeric Additives

    NASA Astrophysics Data System (ADS)

    White, Christopher; Sreenivasan, K. R.

    1997-11-01

    To investigate the ``self-healing'' property of drag reducing surfactant micelles we have conducted a comparative study between high polymers and surfactants in six turbulent pipe flows (Reynolds numbers between 2000 and 90,000) with varying intensities o f secondary flow. Friction factor values are measured in a straight pipe of 185 diameters; three pipes, each turning through four 90 degree elbows, of lengths 1085 diameters, 875 diameters, and 600 diameters; and a twice-turned coiled pipe, radius of curv ature of 24 diameters and length of 290 diameters. All the flows are gravity driven to prevent degradation effects caused by pump impellers. The large stresses set up by the secondary flows degrade the fragile polymers, thus reducing their effectivness as a drag reducer. The ``self-healing'' of the micelles enables the surfactant to maintain its effectivness. We will present the ``self-healing'' characteristics of the surfactant micelles using the polymer data as the datum.

  6. The role of myosin 1c and myosin 1b in surfactant exocytosis.

    PubMed

    Kittelberger, Nadine; Breunig, Markus; Martin, René; Knölker, Hans-Joachim; Miklavc, Pika

    2016-04-15

    Actin and actin-associated proteins have a pivotal effect on regulated exocytosis in secretory cells and influence pre-fusion as well as post-fusion stages of exocytosis. Actin polymerization on secretory granules during the post-fusion phase (formation of an actin coat) is especially important in cells with large secretory vesicles or poorly soluble secretions. Alveolar type II (ATII) cells secrete hydrophobic lipo-protein surfactant, which does not easily diffuse from fused vesicles. Previous work showed that compression of actin coat is necessary for surfactant extrusion. Here, we investigate the role of class 1 myosins as possible linkers between actin and membranes during exocytosis. Live-cell microscopy showed translocation of fluorescently labeled myosin 1b and myosin 1c to the secretory vesicle membrane after fusion. Myosin 1c translocation was dependent on its pleckstrin homology domain. Expression of myosin 1b and myosin 1c constructs influenced vesicle compression rate, whereas only the inhibition of myosin 1c reduced exocytosis. These findings suggest that class 1 myosins participate in several stages of ATII cell exocytosis and link actin coats to the secretory vesicle membrane to influence vesicle compression. PMID:26940917

  7. Synthesis of surfactant-free hydroxypropylcellulose nanogel and its dual-responsive properties.

    PubMed

    An, Dong; Zhao, Di; Li, Xueting; Lu, Xihua; Qiu, Gao; Shea, Kenneth J

    2015-12-10

    Surfactant-free hydroxypropylcellulose (HPC) nanogels were synthesized by using thermo-sensitive HPC as a template to form HPC/PMAA nanoscale complex. The formation mechanism was owing to the interpolymer hydrogen bonding between HPC and PMAA induced phase transition of HPC in aqueous media. The average size of the resulting HPC nanogels ranges from about 98 to 241 nm. It was found that the average size of HPC nanogels changed little with increasing polymerization temperature below 26 °C, whereas it greatly increased above 26 °C. When the concentration of HPC was increased from 0.1 to 0.9 wt.%, the diameter of nanogels decreased firstly and then increased. Besides, an increasing crosslinker BIS concentration led to a reduced size of HPC nanogels, and the nanogels had the narrowest size distribution when its concentration was 0.1 wt.%. In addition to intrinsic thermo-sensitivity, HPC nanogels also display pH-induced phase transition due to pH-responsive PMAA contained in HPC nanogels. Surfactant-free, dual-responsive HPC nanogels would have promising applications in biotechnology and nanomedicine. PMID:26428138

  8. The role of myosin 1c and myosin 1b in surfactant exocytosis

    PubMed Central

    Kittelberger, Nadine; Breunig, Markus; Martin, René; Knölker, Hans-Joachim; Miklavc, Pika

    2016-01-01

    ABSTRACT Actin and actin-associated proteins have a pivotal effect on regulated exocytosis in secretory cells and influence pre-fusion as well as post-fusion stages of exocytosis. Actin polymerization on secretory granules during the post-fusion phase (formation of an actin coat) is especially important in cells with large secretory vesicles or poorly soluble secretions. Alveolar type II (ATII) cells secrete hydrophobic lipo-protein surfactant, which does not easily diffuse from fused vesicles. Previous work showed that compression of actin coat is necessary for surfactant extrusion. Here, we investigate the role of class 1 myosins as possible linkers between actin and membranes during exocytosis. Live-cell microscopy showed translocation of fluorescently labeled myosin 1b and myosin 1c to the secretory vesicle membrane after fusion. Myosin 1c translocation was dependent on its pleckstrin homology domain. Expression of myosin 1b and myosin 1c constructs influenced vesicle compression rate, whereas only the inhibition of myosin 1c reduced exocytosis. These findings suggest that class 1 myosins participate in several stages of ATII cell exocytosis and link actin coats to the secretory vesicle membrane to influence vesicle compression. PMID:26940917

  9. Interactions of cellulose-based comb polyelectrolyte with oppositely charged surfactant dodecyl-trimethylammonium bromide.

    PubMed

    Pan, Hong; Chen, Pei-Yao; Liu, Hai-Xue; Chen, Yu; Wei, Yu-Ping; Zhang, Ming-Jie; Cheng, Fa

    2012-07-01

    A comb ethyl cellulose-g-sodium polyacrylate (EC-g-SPA) was synthesized by atom transfer radical polymerization. The amphiphilic properties of the EC-g-SPA were determined by surface tension measurements. The interactions between EC-g-SPA and the cationic surfactant dodecyl-trimethylammonium bromide (C12TAB) were investigated by surface tension, turbidity, dynamic light scattering and transmission electron microscopy (TEM). The results revealed that the critical aggregate concentration (CAC) of the complexes was 0.8mM. When the C12TAB concentration was lower than the CAC, the hydrodynamic diameter (Dh) of the complexes decreased as the surfactant concentration was increased. As the C12TAB concentration was increased above the CAC, the Dh initially increased slightly, followed by a sharp decrease. The changes in the sizes and shapes of the aggregates were studied by TEM. The interactions between two species and the structure of the EC-g-SPA/C12TAB complexes were also discussed. PMID:24750878

  10. Microemulsion-based lycopene extraction: Effect of surfactants, co-surfactants and pretreatments.

    PubMed

    Amiri-Rigi, Atefeh; Abbasi, Soleiman

    2016-04-15

    Lycopene is a potent antioxidant that has received extensive attention recently. Due to the challenges encountered with current methods of lycopene extraction using hazardous solvents, industry calls for a greener, safer and more efficient process. The main purpose of present study was application of microemulsion technique to extract lycopene from tomato pomace. In this respect, the effect of eight different surfactants, four different co-surfactants, and ultrasound and enzyme pretreatments on lycopene extraction efficiency was examined. Experimental results revealed that application of combined ultrasound and enzyme pretreatments, saponin as a natural surfactant, and glycerol as a co-surfactant, in the bicontinuous region of microemulsion was the optimal experimental conditions resulting in a microemulsion containing 409.68±0.68 μg/glycopene. The high lycopene concentration achieved, indicates that microemulsion technique, using a low-cost natural surfactant could be promising for a simple and safe separation of lycopene from tomato pomace and possibly from tomato industrial wastes. PMID:26617046

  11. The effects of alkylammonium counterions on the aggregation of fluorinated surfactants and surfactant ionic liquids.

    PubMed

    Pottage, Matthew J; Greaves, Tamar L; Garvey, Christopher J; Tabor, Rico F

    2016-08-01

    The effects of organic counterions with varying carbon number on surfactant aggregation have been analysed by coupling perfluorooctanoate surfactant anions with various alkylammonium counterions. Both the degree of substitution (primary to tertiary) and alkyl chain length (0-3 carbons) of the counterions were varied to provide a comprehensive matrix of geometries and lipophilicities. Surface activity was measured using pendant drop tensiometry, while temperature-controlled small-angle neutron scattering was used to probe changes in aggregation morphology. It was found that the use of such alkylammonium counterions resulted in a strong preference for bilayer formation even at low surfactant concentration (<2wt%), when compared to simple inorganic counterions such as sodium which favour near-spherical micelles. At increased temperatures, some counterions led to unique phase behaviour wherein a transition between two structurally different lamellar phases is seen, rationalised as a transition into a microscopic phase separation wherein a surfactant-rich lamellar phase coexists with a dilute micellar phase. The results indicate that aggregation is controlled by a delicate balance of counterion size, hydrophilicity and diffuseness of charge, providing new methods for the subtle control of surfactant solutions. PMID:27156087

  12. Bioavailability enhancement by addition of surfactant and surfactant-like compounds

    SciTech Connect

    Strong-Gunderson, J.M.; Palumbo, A.V.

    1995-12-31

    The bioavailability and microbial degradation of contaminant compounds (e.g., toluene and naphthalene) were enhanced by adding synthetic surfactants, biosurfactants, and nutrients with surfactant like properties. In addition to enhanced contaminant degradation, these surfactant compounds have the potential to change the availability of natural organic matter (NOM), and thus may affect overall site bioremediation. Two bacterial bioreporter strains that are induced by toluene or naphthalene were used to directly measure contaminant bioavailability. A cell-free biosurfactant product, Tween-80, and an oleophilic fertilizer were added to aqueous suspensions and soil slurries containing toluene or naphthalene. The addition of these surfactant compounds at or below the critical micelle concentration (CMC) enhanced bioavailability as measured by increased levels of bioluminescence. Bioluminescence data were coupled with gas chromatographic analyses. The addition of Tween-80 increased not only the bioavailability of the contaminants but also, in a separate assay, the bioavailability of recalcitrant NOM. The enhanced NOM bioavailability was inferred from measurements of biomass by optical density increases and plate counts. Thus, adding surfactant compounds for enhanced contaminant degradation has the potential to introduce additional competition for nutrients and microbial metabolism, a significant area of concern for in situ site remediation.

  13. Hydrogels of sodium alginate in cationic surfactants: Surfactant dependent modulation of encapsulation/release toward Ibuprofen.

    PubMed

    Jabeen, Suraya; Chat, Oyais Ahmad; Maswal, Masrat; Ashraf, Uzma; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2015-11-20

    The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.5M K2CO3 concentration. The thermal stability of gel (5% SA+0.5M K2CO3) decreases with increase in surfactant concentration, a minimum is observed with increase in 16-4-16 concentration. The impact of surfactant addition on the alginate structure vis-à-vis its drug loading capability and release thereof was studied using Ibuprofen (IBU) as the model drug. The hydrogel with 16-4-16 exhibits higher IBU encapsulation and faster release in comparison to the one containing CTAB. This higher encapsulation-cum-faster release capability has been related to micelle mediated solubilization and greater porosity of the hydrogel with gemini surfactant. PMID:26344266

  14. Size influences the effect of hydrophobic nanoparticles on lung surfactant model systems.

    PubMed

    Dwivedi, Mridula V; Harishchandra, Rakesh Kumar; Koshkina, Olga; Maskos, Michael; Galla, Hans-Joachim

    2014-01-01

    The alveolar lung surfactant (LS) is a complex lipid protein mixture that forms an interfacial monolayer reducing the surface tension to near zero values and thus preventing the lungs from collapse. Due to the expanding field of nanotechnology and the corresponding unavoidable exposure of human beings from the air, it is crucial to study the potential effects of nanoparticles (NPs) on the structural organization of the lung surfactant system. In the present study, we investigated both, the domain structure in pure DPPC monolayers as well as in lung surfactant model systems. In the pure lipid system we found that two different sized hydrophobic polymeric nanoparticles with diameter of ~12 nm and ~136 nm have contrasting effect on the functional and structural behavior. The small nanoparticles inserted into fluid domains at the LE-LC phase transition are not visibly disturbing the phase transition but disrupting the domain morphology of the LE phase. The large nanoparticles led to an expanded isotherm and to a significant decrease in the line tension and thus to a drastic disruption of the domain structures at a much lower number of nanoparticles with respect to the lipid. The surface activity of the model LS films again showed drastic variations due to presence of different sized NPs illustrated by the film balance isotherms and the atomic force microscopy. AFM revealed laterally profuse multilayer protrusion formation on compression but only in the presence of 136 nm sized nanoparticles. Moreover we investigated the vesicle insertion process into a preformed monolayer. A severe inhibition was observed only in the presence of ~136 nm NPs compared to minor effects in the presence of ~12 nm NPs. Our study clearly shows that the size of the nanoparticles made of the same material determines the interaction with biological membranes. PMID:24411261

  15. Adsorption and viscoelastic analysis of polyelectrolyte-surfactant complexes on charged hydrophilic surfaces.

    PubMed

    Dhopatkar, Nishad; Park, Jung Hyun; Chari, Krishnan; Dhinojwala, Ali

    2015-01-27

    The aggregation of surfactants around oppositely charged polyelectrolytes brings about a peculiar bulk phase behavior of the complex, known as coacervation, and can control the extent of adsorption of the polyelectrolyte at an aqueous-solid interface. Adsorption kinetics from turbid premixed polyelectrolyte-surfactant mixtures have been difficult to measure using optical techniques such as ellipsometry and reflectometry, thus limiting the correlation between bulk phases and interfacial adsorption. Here, we investigated the adsorption from premixed solutions of a cationic polysaccharide (PQ10) and the anionic surfactant sodium dodecyl sulfate (SDS) on an amphoteric alumina surface using quartz crystal microbalance with dissipation (QCMD). The surface charge on the alumina was tuned by changing the pH of the premixed solutions, allowing us to assess the role of electrostatic interactions by studying the adsorption on both negatively and positively charged surfaces. We observed a maximum extent of adsorption on both negatively and positively charged surfaces from a solution corresponding to the maximum turbidity. Enhanced adsorption upon diluting the redissolved complexes at a high SDS concentration was seen only on the negatively charged surface, and not on the positively charged one, confirming the importance of electrostatic interactions in controlling the adsorption on a hydrophilic charged surface. Using the Voight based viscoelastic model, QCMD also provided information on the effective viscosity, effective shear modulus, and thickness of the adsorbed polymeric complex. The findings of viscoelastic analysis, corroborated by atomic force microscopy measurements, suggest that PQ10 by itself forms a flat, uniform layer, rigidly attached to the surface. The PQ10-SDS complex shows a heterogeneous surface structure, where the underlayer is relatively compact and tightly attached and the top is a loosely bound diffused overlayer, accounting for most of the adsorbate

  16. Surfactant controlled synthesis of crystalline phosphovanadate nanorods

    SciTech Connect

    Asnani, Minakshi; Thomas, Jency; Sen, Prasenjit; Ramanan, Arunachalam . E-mail: aramanan@chemistry.iitd.ac.in

    2007-04-12

    Phosphovanadate nanorods were obtained in a reaction of vanadium (V) oxide as a precursor and a cationic surfactant, dodecylpyridinium chloride, as structure directing template at pH {approx}3 at room temperature. The composition and morphology of the nanorods was established by powder X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The obtained nanorods have diameters of 40-60 nm with lengths up to 1 {mu}m. The effect of reaction parameters such as concentration of surfactant and pH of the solution on the growth of nanorods has been investigated. A plausible mechanism involving the coalescence of nanoparticle 'seeds' leading to one-dimensional nanorods is also discussed. The same reaction when performed under hydrothermal condition, keeping other reaction parameters unchanged, resulted in the formation of phosphovanadate nanospheres of diameter 10-15 nm.

  17. Surfactant chemical technology works for environmental jobs

    SciTech Connect

    Foley, J.T. )

    1991-11-01

    This paper reports on surface active agents that have been employed in mining and mineral processing operations for many years. They are beginning to find increasing use as tools to deal with pressing environmental problems in the industry. Surface active agents are attracting particular attention from mining operators as environmental regulations as well as safety and health standards continue to tighten. These surfactants comprise a variety of products that have different end uses. They promote foaming, wetting, emulsification and crystal growth modification, among other functions. And they are generally environmentally friendly and non-toxic. Among the major environmental issues facing mine operators are effluent control, dust and fume suppression, acid drainage control and soil reclamation and remediation. Surfactants have already been put to work in each of these areas.

  18. Polymer enrichment decelerates surfactant membranes near interfaces

    NASA Astrophysics Data System (ADS)

    Lipfert, F.; Frielinghaus, H.; Holderer, O.; Mattauch, S.; Monkenbusch, M.; Arend, N.; Richter, D.

    2014-04-01

    Close to a planar surface, lamellar structures are imposed upon otherwise bulk bicontinuous microemulsions. Thermally induced membrane undulations are modified by the presence of the rigid interface. While it has been shown that a pure membrane's dynamics are accelerated close to the interface, we observed nearly unchanged relaxation rates for membranes spiked with large amphiphilic diblock copolymers. An increase of the polymer concentration by a factor of 2-3 for the first and second surfactant membrane layers was observed. We interpret the reduced relaxation times as the result of an interplay between the bending rigidity and the characteristic distance of the first surfactant membrane to the rigid interface, which causes the hydrodynamic and steric interface effects described in Seifert's theory. The influence of these effects on decorated membranes yields a reduction of the frequencies and an amplification of the amplitudes of long-wavelength undulations, which are in accordance to our experimental findings.

  19. Surfactants and interfacial phenomena, 2nd Ed

    SciTech Connect

    Rosen

    1989-01-01

    The second edition of this monograph on surfactants has been updated to reflect recent advances in our knowledge of theory and practices. New applications run the gamut from microelectronics and magnetic recording, to biotechnology and nonconventional energy conversion. There is a new chapter on the interactions between surfactants. New sections have been added, and original sections expanded, on such topics as ultralow liquid-liquid interfacial tension; microemulsions, miniemulsions, and multiple emulsions; liquid crystal formation; hydrotropy; and steric forces in the stabilization of dispersions. There is also new material on lime soap dispersing agents; fabric softeners, adsorption and wetting of solid surfaces, both equilibrium and none-equilibrium; the relationship between adsorption and micellation in aqueous solutions and its effect on surface tension reduction; and factors determining micellar structure and shape.

  20. Surfactant protein D in human lung diseases.

    PubMed

    Hartl, D; Griese, M

    2006-06-01

    The lung is continuously exposed to inhaled pollutants, microbes and allergens. Therefore, the pulmonary immune system has to defend against harmful pathogens, while an inappropriate inflammatory response to harmless particles must be avoided. In the bronchoalveolar space this critical balance is maintained by innate immune proteins, termed surfactant proteins. Among these, surfactant protein D (SP-D) plays a central role in the pulmonary host defence and the modulation of allergic responses. Several human lung diseases are characterized by decreased levels of bronchoalveolar SP-D. Thus, recombinant SP-D has been proposed as a therapeutical option for cystic fibrosis, neonatal lung disease and smoking-induced emphysema. Furthermore, SP-D serum levels can be used as disease activity markers for interstitial lung diseases. This review illustrates the emerging role of SP-D translated from in vitro studies to human lung diseases. PMID:16684127

  1. The Equilibrium Spreading Tension of Pulmonary Surfactant.

    PubMed

    Dagan, Maayan P; Hall, Stephen B

    2015-12-01

    Monomolecular films at an air/water interface coexist at the equilibrium spreading tension (γ(e)) with the bulk phase from which they form. For individual phospholipids, γ(e) is single-valued, and separates conditions at which hydrated vesicles adsorb from tensions at which overcompressed monolayers collapse. With pulmonary surfactant, isotherms show that monolayers compressed on the surface of bubbles coexist with the three-dimensional collapsed phase over a range of surface tensions. γ(e) therefore represents a range rather than a single value of surface tension. Between the upper and lower ends of this range, rates of collapse for spread and adsorbed films decrease substantially. Changes during adsorption across this narrow region of coexistence between the two- and three-dimensional structures at least partially explain how alveolar films of pulmonary surfactant become resistant to collapse. PMID:26583569

  2. Liquid and surfactant delivery into pulmonary airways

    PubMed Central

    Halpern, David; Fujioka, Hideki; Takayama, Shuichi; Grotberg, James B.

    2008-01-01

    We describe the mechanisms by which liquids and surfactants can be delivered into the pulmonary airways. These are instilled and transported throughout the lung in clinical therapies such as surfactant replacement therapy, partial liquid ventilation and drug delivery. The success of these treatments is contingent on the liquid distribution and the delivery to targeted regions of the lung. The targeting of a liquid plug can be influenced by a variety of factors such as the physical properties of the liquid, the interfacial activity, the gravitational orientation, instillation method and propagation speed. We provide a review of experimental and theoretical studies that examine these effects in single tubes or channels, in tubes with single bifurcations and in the whole lung. PMID:18585985

  3. Anionic polymerization of azo substituted methacrylates

    SciTech Connect

    Dimov, D.K.; Dalton, L.R.; Hogen-Esch, T.E.

    1993-12-31

    The anionic polymerization of 4-phenylazophenyl methacrylate (PAM) and 6-(4-phenylazophenoxy)-hexyl methacrylate (PAHM) initiated by {open_quotes}living{close_quotes} PMMA with lithium counterion was studied in THF at {minus}78{degrees}C. The polymerization of PAM was prevented by a side termination reaction. The polymerization of PAHM proceeded smoothly to furnish PMMA/azopolymer block copolymers. The process showed features typical of {open_quotes}living{close_quotes} anionic polymerization. No phase transitions could be detected by DSC to prove liquid crystalline mesophase formation by the block copolymers.

  4. Ketoprofen as a photoinitiator for anionic polymerization.

    PubMed

    Wang, Yu-Hsuan; Wan, Peter

    2015-06-01

    A new photoinitiating system for anionic polymerization of acrylates based on the efficient photodecarboxylation of Ketoprofen (1) and the related derivatives 3 and 4 that generate the corresponding carbanion intermediates is presented. Carbanion intermediates are confirmed by deuterium incorporation in the trapped Michael adducts and by spectroscopic detection using laser flash photolysis (LFP). This novel anionic initiating system features excitation in the near UV and visible regions, potential characteristics of photocontrolled living polymerization, and metal-free photoinitiators generated from photoexcitation, different from typical anionic polymerization where the polymerizations are initiated by heat and strong base containing alkali metals. PMID:25917384

  5. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, Douglas B.; Shahinpoor, Mohsen; Segalman, Daniel J.; Witkowski, Walter R.

    1993-01-01

    Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

  6. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

    1993-10-05

    Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

  7. Ionene modified small polymeric beads

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1977-01-01

    Linear ionene polyquaternary cationic polymeric segments are bonded by means of the Menshutkin reaction (quaternization) to biocompatible, extremely small, porous particles containing halide or tertiary amine sites which are centers for attachment of the segments. The modified beads in the form of emulsions or suspensions offer a large, positively-charged surface area capable of irreversibly binding polyanions such as heparin, DNA, RNA or bile acids to remove them from solution or of reversibly binding monoanions such as penicillin, pesticides, sex attractants and the like for slow release from the suspension.

  8. Molecularly Regulated Reversible DNA Polymerization.

    PubMed

    Chen, Niancao; Shi, Xuechen; Wang, Yong

    2016-06-01

    Natural polymers are synthesized and decomposed under physiological conditions. However, it is challenging to develop synthetic polymers whose formation and reversibility can be both controlled under physiological conditions. Here we show that both linear and branched DNA polymers can be synthesized via molecular hybridization in aqueous solutions, on the particle surface, and in the extracellular matrix (ECM) without the involvement of any harsh conditions. More importantly, these polymers can be effectively reversed to dissociate under the control of molecular triggers. Since nucleic acids can be conjugated with various molecules or materials, we anticipate that molecularly regulated reversible DNA polymerization holds potential for broad biological and biomedical applications. PMID:27100911

  9. Polymerized nanotube structures new zeolites?

    NASA Astrophysics Data System (ADS)

    Chernozatonskii, Leonid A.

    1998-11-01

    Polymers of single-wall carbon nanotubes - possible new zeolites - are modeled by molecular mechanics (MM2 calculation method). The polymerization at issue occurs by bonding of 6 sp 3 atomic pairs in each nanotube unit cell with similar atomic pairs located on 6 neighboring tubes like 2+2 cycloaddition in a rhombic two-dimensional C 60 polymer. It is shown these bonding in armchair ( n, n) SWNT ropes ( n=6, 8, 10, 12) changes positive radial curvature of tube segments to a negative one.

  10. Computational studies of polymeric systems

    NASA Astrophysics Data System (ADS)

    Carrillo, Jan-Michael Y.

    Polymeric systems involving polyelectrolytes in surfaces and interfaces, semiflexible polyelectrolytes and biopolymers in solution, complex polymeric systems that had applications in nanotechnology were modeled using coarse grained molecular dynamics simulation. In the area of polyelectrolytes in surfaces and interfaces, the phenomena of polyelectrolyte adsorption at oppositely charge surface was investigated. Simulations found that short range van der Waals interaction was a major factor in determining morphology and thickness of the adsorbed layer. Hydrophobic polyelectrolytes adsorbed in hydrophobic surfaces tend to be the most effective in forming multi-layers because short range attraction enhances the adsorption process. Adsorbed polyelectrolytes could move freely along the surface which was in contrast to polyelectrolyte brushes. The morphologies of hydrophobic polyelectrolyte brushes were investigated and simulations found that brushes had different morphologies depending on the strength of the short range monomer-monomer attraction, electrostatic interaction and counterion condensation. Planar polyelectrolyte brushes formed: (1) vertically oriented cylindrical aggregates, (2) maze-like aggregate structures, or (3) thin polymeric layer covering a substrate. While, the spherical polyelectrolyte brushes could be in any of the previous morphologies or be in a micelle-like conformation with a dense core and charged corona. In the area of biopolymers and semiflexible polyelectrolytes in solution, simulations demonstrated that the bending rigidity of these polymers was scale-dependent. The bond-bond correlation function describing a chain's orientational memory could be approximated by a sum of two exponential functions manifesting the existence of the two characteristic length scales. The existence of the two length scales challenged the current practice of describing chain stretching experiments using a single length scale. In the field of nanotechnology

  11. Marketing NASA Langley Polymeric Materials

    NASA Technical Reports Server (NTRS)

    Flynn, Diane M.

    1995-01-01

    A marketing tool was created to expand the knowledge of LaRC developed polymeric materials, in order to facilitate the technology transfer process and increase technology commercialization awareness among a non-technical audience. The created brochure features four materials, LaRC-CP, LaRC-RP46, LaRC-SI, and LaRC-IA, and highlights their competitive strengths in potential commercial applications. Excellent opportunities exist in the $40 million per year microelectronics market and the $6 billion adhesives market. It is hoped that the created brochure will generate inquiries regarding the use of the above materials in markets such as these.

  12. Biosurfactants: a sustainable replacement for chemical surfactants?

    PubMed

    Marchant, Roger; Banat, Ibrahim M

    2012-09-01

    Glycolipid biosurfactants produced by bacteria and yeasts provide significant opportunities to replace chemical surfactants with sustainable biologically produced alternatives in bulk commercial products such as laundry detergents and surface cleaners. Sophorolipids are already available in sufficient yield to make their use feasible while rhamnolipids and mannosylerythritol lipids require further development. The ability to tailor the biosurfactant produced to the specific needs of the product formulation will be an important future step. PMID:22618240

  13. Use of micellar-enhanced ultrafiltration at low surfactant concentrations and with anionic-nonionic surfactant mixtures

    SciTech Connect

    Fillipi, B.R.; Brant, L.W.; Scamehorn, J.F.; Christian, S.D.

    1999-05-01

    Micellar-enhanced ultrafiltration is a separation technique which can be used to remove metal ions or dissolved organics from water. Metal ions bind to the surface of negatively charged micelles of an anionic surfactant while organic solutes tend to dissolve or solubilized within the micelles. The mixture is then forced through an ultrafiltration membrane with pore sizes small enough to block passage of the micelles and associated metal ions and/or dissolved organics. Monomeric or unassociated surfactant passes through the membrane and does not contribute to the separation. This paper considers advantages of addition of small concentrations of nonionic surfactant to an anionic surfactant; the resulting anionic-nonionic mixed micelles exhibit negative deviation from ideality of mixing which leads to a smaller fraction of the surfactant being present as monomer and a subsequently larger fraction present in the micellar form. The addition of nonionic surfactant improved the separation of divalent zinc substantially at total concentrations above the critical micelle concentration (cmc) of the anionic surfactant. Both zinc and tert-butylphenol (a nonionic organic solute) show unexpected rejection at surfactant concentrations moderately below the cmc, where micelles are absent. This is considered as due to a higher surfactant concentration in the gel layer adjacent to the membrane where micelles are present. Reduction of this rejection at lower transmembrane pressure drops supports this mechanism. Some rejection of zinc was observed in the absence of surfactant but not of tert-butylphenol, indicating an additional effect of membrane charge for ionic solutes.

  14. Partitioning of phenanthrene into surfactant hemi-micelles on the bacterial cell surface and implications for surfactant-enhanced biodegradation.

    PubMed

    Lanzon, Jacquelyn B; Brown, Derick G

    2013-09-01

    Recent studies have suggested that the ability of a surfactant to enhance the bioavailability of hydrophobic organic compounds (HOC) requires the formation of surfactant hemi-micelles on the bacterial cell surface and subsequent partitioning of HOC into the hemi-micelles. However, the studies did not provide direct evidence of HOC partitioning into surfactant hemi-micelles on the bacterial cell surface. In this study, direct evidence is provided to demonstrate that the nonionic surfactant Brij 30 forms hemi-micelles on the bacterial cell surface and that phenanthrene sorption at the bacterial surface is enhanced by the surfactant. These results are in agreement with the current theory describing surfactant-enhanced HOC bioavailability. This enhanced bioavailability is put into context with microbial kinetics and system partitioning processes, and it is demonstrated that the addition of surfactant can enhance, have no effect, or inhibit HOC biodegradation depending upon surfactant concentration and microbial growth rate. Understanding these non-linear relationships between surfactant-enhanced HOC bioavailability, biodegradation kinetics, and system partitioning will assist in the design and implementation of surfactant-enhanced bioremediation programs. PMID:23764610

  15. Adaptations to hibernation in lung surfactant composition of 13-lined ground squirrels influence surfactant lipid phase segregation properties.

    PubMed

    Suri, Lakshmi N M; Cruz, Antonio; Veldhuizen, Ruud A W; Staples, James F; Possmayer, Fred; Orgeig, Sandra; Perez-Gil, Jesus

    2013-08-01

    Pulmonary surfactant lines the entire alveolar surface, serving primarily to reduce the surface tension at the air-liquid interface. Surfactant films adsorb as a monolayer interspersed with multilayers with surfactant lipids segregating into different phases or domains. Temperature variation, which influences lipid physical properties, affects both the lipid phase segregation and the surface activity of surfactants. In hibernating animals, such as 13-lined ground squirrels, which vary their body temperature, surfactant must be functional over a wide range of temperatures. We hypothesised that surfactant from the 13-lined ground squirrel, Ictidomys tridecemlineatus, would undergo appropriate lipid structural re-arrangements at air-water interfaces to generate phase separation, sufficient to attain the low surface tensions required to remain stable at both low and high body temperatures. Here, we examined pressure-area isotherms at 10, 25 and 37°C and found that surfactant films from both hibernating and summer-active squirrels reached their highest surface pressure on the Wilhelmy-Langmuir balance at 10°C. Epifluorescence microscopy demonstrated that films of hibernating squirrel surfactant display different lipid micro-domain organisation characteristics than surfactant from summer-active squirrels. These differences were also reflected at the nanoscale as determined by atomic force microscopy. Such re-arrangement of lipid domains in the relatively more fluid surfactant films of hibernating squirrels may contribute to overcoming collapse pressures and support low surface tension during the normal breathing cycle at low body temperatures. PMID:23506681

  16. How surfactants influence evaporation-driven flows

    NASA Astrophysics Data System (ADS)

    Liepelt, Robert; Marin, Alvaro; Rossi, Massimiliano; Kähler, Christian J.

    2014-11-01

    Capillary flows appear spontaneously in sessile evaporating drops and give rise to particle accumulation around the contact lines, commonly known as coffee-stain effect (Deegan et al., Nature, 1997). On the other hand, out-of-equilibrium thermal effects may induce Marangoni flows in the droplet's surface that play an important role in the flow patterns and in the deposits left on the substrate. Some authors have argued that contamination or the presence of surfactants might reduce or eventually totally annul the Marangoni flow (Hu & Larson, J. Phys. Chem. B, 2006). On the contrary, others have shown an enhancement of the reverse surface flow (Sempels et al., Nat. Commun., 2012). In this work, we employ Astigmatic Particle Tracking Velocimetry (APTV) to obtain the 3D3C evaporation-driven flow in both bulk and droplet's surface, using surfactants of different ionic characters and solubility. Our conclusions lead to a complex scenario in which different surfactants and concentrations yield very different surface-flow patterns, which eventually might influence the colloidal deposition patterns.

  17. Surfactants for separation processes: Enhanced ultrafiltration

    SciTech Connect

    Sadaoui, Z.; Azoug, C.; Charbit, G.; Charbit, F.

    1998-08-01

    Pollution by toxic metal compounds is a deep concern in all industrial countries. A process based on enhanced ultrafiltration is proposed in order to separate cadmium and chromate ions from wastewater. Inorganic membranes (zirconium oxide coated on carbon) are used in the separation cell, and ionic surfactants (NaDS or CTABr) are added in the effluent. The surfactants, which entrap metal ions present in the feed, are retained by the membrane barrier and thus the permeate is clear of metal compounds. This paper is devoted to precise experimental fields in which the permeate is lower than 0.2 g{center_dot}m{sup {minus}3} for cadmium and 0.1 g{center_dot}m{sup {minus}3} for chromate, these concentrations being the standards for European countries. The paper presents only experimental results describing the influence of operating conditions on the efficiency of the separation; a theory of rejection of pure surfactant by the same membranes has recently been published. As long as the feed concentration is less than or equal to 150 g{center_dot}m{sup {minus}3} for cadmium or 20 g{center_dot}m{sup {minus}3} for hexavalent chromium (respectively, 750 or 200 times the norm), a satisfactory permeate is obtained in a single stage process at 25 and 30 C; more than 99% of metallic ions is retained.

  18. Probing Nanoscale Thermal Transport in Surfactant Solutions

    PubMed Central

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B.; Qiao, Rui; Yang, Bao

    2015-01-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient. PMID:26534840

  19. Probing Nanoscale Thermal Transport in Surfactant Solutions

    NASA Astrophysics Data System (ADS)

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B.; Qiao, Rui; Yang, Bao

    2015-11-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient.

  20. Probing Nanoscale Thermal Transport in Surfactant Solutions.

    PubMed

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B; Qiao, Rui; Yang, Bao

    2015-01-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient. PMID:26534840

  1. Therapeutic surfactant-stripped frozen micelles

    NASA Astrophysics Data System (ADS)

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-05-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like `top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and `bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated.

  2. Therapeutic surfactant-stripped frozen micelles

    PubMed Central

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-01-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like ‘top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and ‘bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2–3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated. PMID:27193558

  3. Therapeutic surfactant-stripped frozen micelles.

    PubMed

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K; Alexandridis, Paschalis; Lovell, Jonathan F

    2016-01-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like 'top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and 'bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated. PMID:27193558

  4. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Alfoterra-38 (0.05 wt%), Alfoterra-35 (0.05 wt%), SS-6656 (0.05 wt%), and DTAB (1 wt%) altered the wettability of the initially oil-wet calcite plate to an intermediate/water-wet state. Low IFT ({approx}10{sup -3} dynes/cm) is obtained with surfactants 5-166, Alfoterra-33 and Alfoterra-38. Plans for the next quarter include conducting wettability and mobilization studies.

  5. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2005-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory imbibition tests show that imbibition rate is not very sensitive to the surfactant concentration (in the range of 0.05-0.2 wt%) and small amounts of trapped gas saturation. It is however very sensitive to oil permeability and water-oil-ratio. Less than 0.5 M Na2CO3 is needed for in situ soap generation and low adsorption; NaCl can be added to reach the necessary total salinity. The simulation result matches the laboratory imbibition experimental data. Small fracture spacing and high permeability would be needed for high rate of recovery.

  6. Interactions of anionic surfactants with methemoglobin.

    PubMed

    Gebicka, Lidia; Banasiak, Ewa

    2011-03-01

    Interactions of two anionic surfactants, sodium dodecyl sulphate (SDS) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) at concentrations below and above critical micelle concentration with methemoglobin (metHb) have been investigated by conventional as well as by stopped-flow absorption and fluorescence spectroscopy. The absorption spectra of metHb in AOT reverse micelles have been also analyzed. Both surfactants in their monomeric form convert metHb to reversible hemichrome. This is connected with a diminution of peroxidase-like activity of metHb and with an increase of the susceptibility of heme for a damage by H(2)O(2). In micellar solutions of AOT and SDS as well as in AOT reverse micelles pentacoordinated ferric species seems to be the predominant form of this protein. It has been concluded, basing on a kinetic analysis, that conformational changes in the heme environment of metHb as induced by both surfactants occur independently of the alterations in the tertiary structure of this protein. PMID:21131182

  7. Evaulation of irritation potential of surfactant mixtures.

    PubMed

    Turkoglu, M; Sakr, A

    1999-12-01

    Irritation potential of sodium laureth sulfate (SLES) alone, and in combination with lauryl glucoside (LG), polysorbate 20 (PS) and cocoamidopropyl betaine (CAPB) was tested in 13 human subjects. Four main and six sub-formulations were prepared and evaluated. Formulations were applied to the forearm as a 24 h close patch study. Irritation was scored by two different methods using an in vivo clinical protocol based on visual scoring and on the stratum corneum capacitance measurement. Irritation was found to be dose dependent. At 2 mg/patch level ten subjects did not show any skin reaction. At 20 mg/patch level eleven subjects showed a broad range of skin irritation. The highest irritation was observed with the formula that contained SLES, LG, and cocamide DEA together. Among the sub-formulations, cocamide DEA showed the highest irritation grade. A statistically significant correlation was observed between visual, clinical and corneometer scores. It was concluded that the irritation potential of surfactants was related to the total surfactant concentration, application mode, and the thermodynamic activity of molecules in the solution as well as the chemical structure of the surfactant molecules. PMID:18503452

  8. Aggregation-Induced FRET via Polymer-Surfactant Complexation: A New Strategy for the Detection of Spermine.

    PubMed

    Malik, Akhtar Hussain; Hussain, Sameer; Iyer, Parameswar Krishnan

    2016-07-19

    A new water-soluble cationic conjugated polymer [9,9-bis(6'-methyl imidazolium bromide)hexyl)fluorene-co-4,7-(2,1,3-benzothiadiazole)] (PFBT-MI) was designed and synthesized via Suzuki cross-coupling polymerization in good yields without any tedious purification steps. PFBT-MI showed excellent photophysical responses toward SDS and SDBS with a detection limit of 0.12 μM/(34 ppb) and 0.13 μM/(45 ppb), respectively. Furthermore, occurrence of FRET from the donor (fluorene) to acceptor (BT units), via surfactant-induced aggregation, results in naked-eye detection of these common anionic surfactants (SDS/SDBS) as the color changes from blue to yellowish green in aqueous solution. The polymer-surfactant nanoaggregates thus formed via electrostatic as well as hydrophobic interactions have been explored for the sensitive detection of spermine (considered as an excellent biomarker for early cancer diagnosis) with a detection limit of 66 ppb (0.33 μM), which is much below the range 1-10 μM pertinent for the early diagnosis of cancer in urinary samples. This highly sensitive technique would facilitate the direct and noninvasive detection of spermine from urine rapidly and is likely to have great significance in early cancer diagnosis. PMID:27322621

  9. Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.

    SciTech Connect

    Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S.

    2011-02-01

    Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

  10. Rheological properties of ovalbumin hydrogels as affected by surfactants addition.

    PubMed

    Hassan, Natalia; Messina, Paula V; Dodero, Veronica I; Ruso, Juan M

    2011-04-01

    The gel properties of ovalbumin mixtures with three different surfactants (sodium perfluorooctanoate, sodium octanoate and sodium dodecanoate) have been studied by rheological techniques. The gel elasticities were determined as a function of surfactant concentration and surfactant type. The fractal dimension of the formed structures was evaluated from plots of storage modulus against surfactant concentration. The role of electrostatic, hydrophobic and disulfide SS interactions in these systems has been demonstrated to be the predominant. The viscosity of these structures tends to increase with surfactant concentration, except for the fluorinated one. Unfolded ovalbumin molecules tend to form fibrillar structures that tend to increase with surfactant concentration, except for the fluorinated one. This fact has been related to the particular nature of this molecule. PMID:21262258

  11. [Pulmonary surfactant homeostasis associated genetic abnormalities and lung diseases].

    PubMed

    Jiang, Xiaojing; Sun, Xiuzhu; Du, Weihua; Hao, Haisheng; Zhao, Xueming; Wang, Dong; Zhu, Huabin; Liu, Yan

    2016-08-10

    Pulmonary surfactant (PS) is synthesized and secreted by alveolar epithelial type II (AEII) cells, which is a complex compound formed by proteins and lipids. Surfactant participates in a range of physiological processes such as reducing the surface tension, keeping the balance of alveolar fluid, maintaining normal alveolar morphology and conducting host defense. Genetic disorders of the surfactant homeostasis genes may result in lack of surfactant or cytotoxicity, and lead to multiple lung diseases in neonates, children and adults, including neonatal respiratory distress syndrome, interstitial pneumonia, pulmonary alveolar proteinosis, and pulmonary fibrosis. This paper has provided a review for the functions and processes of pulmonary surfactant metabolism, as well as the connection between disorders of surfactant homeostasis genes and lung diseases. PMID:27455022

  12. Estimation hydrophilic-lipophilic balance number of surfactants

    NASA Astrophysics Data System (ADS)

    Pawignya, Harsa; Prasetyaningrum, Aji; Dyartanti, Endah R.; Kusworo, Tutuk D.; Pramudono, Bambang

    2016-02-01

    Any type of surfactant has a hydrophilic-lipophilic balance number (HLB number) of different. There are several methods for determining the HLB number, with ohysical properties of surfactant (solubility cloud point and interfacial tension), CMC methods and by thermodynamics properties (Free energy Gibbs). This paper proposes to determined HLB numbers from interfelation methods. The result of study indicated that the CMC method described by Hair and Moulik espesially for nonionic surfactant. The application of exess Gibbs free energy and by implication activity coefficient provides the ability to predict the behavior of surfactants in multi component mixtures of different concentration. Determination of HLB number by solubility and cloud point parameter is spesific for anionic and nonionic surfactant but this methods not available for cationic surfactants.

  13. Infrared imaging of a solid phase surfactant monolayer.

    PubMed

    Conover, T A; Saylor, J R

    2006-08-01

    A new method for visualizing solid phase surfactant monolayers is presented. This method utilizes infrared (IR) imaging of the surface of a warm subphase covered by the monolayer. When the subphase is deep, natural convection occurs, resulting in a complex surface temperature field that is easily visualized using an IR camera. The presence of a surfactant monolayer changes the hydrodynamic boundary condition at the interface, dramatically altering the surface temperature field, and permitting the differentiation of surfactant-covered and surfactant-free regions. In this work, solid phase monolayers are imaged using this IR method. Fractures in the monolayer are dramatically visualized because of the sudden elimination of surfactant in the region opened up by the crack. The method is demonstrated in a wind/water tunnel, where a stearic acid monolayer is deposited and a crack is created through shear on the surfactant surface, created by suddenly increasing the velocity of the air over the water. PMID:16863234

  14. Enhancement of enzymatic hydrolysis of cellulose by surfactant

    SciTech Connect

    Ooshima, H.; Sakata, M.; Harano, Y.

    1986-01-01

    Effects of surfactants on enzymatic saccharification of cellulose have been studied. Nonionic, amphoteric, and cationic surfactants enhanced the saccharification, while anionic surfactant did not. Cationic and anionic surfactants denatured cellulase in their relatively low concentrations, namely, more than 0.008 and 0.001%, respectively. Using nonionic surfactant Tween 20, which is most effective to the enhancement (e.g., the fractional conversion attained by 72 h saccharification of 5 wt % Avicel in the presence of 0.05 wt % Tween 20 is increased by 35%), actions of surfactant have been examined. As the results, it was suggested that Tween 20 plays an important role in the hydrolysis of crystalline cellulose and that Tween 20 disturbs the adsorption of endoglucanase on cellulose, i.e., varies the adsorption balance of endo- and exoglucanase, resulting in enhancing the reaction. The influence of Tween 20 to the saccharification was found to remain in simultaneous saccharification and fermentation of Avicel.

  15. Synthesis and engineering of polymeric latex particles for medical applications

    NASA Astrophysics Data System (ADS)

    Kim, Sangyup

    Latex particles with well-defined colloidal and surface characteristics have received increasing attention due to their useful applications in many areas, especially as solid phase supports in numerous biological applications such as immunoassay, DNA diagnostic, cell separation, and drug delivery carrier. Hemodialysis membrane using these particles would be another potential application for the advanced separation treatment for patients with end stage renal disease (ESRD). It is desirable to remove middle molecular weight proteins with minimal removal of other proteins such as albumin. Thus, it is necessary to understand the fundamental interactions between the particles and blood proteins to maximize the performance of these membranes. This improvement will have significant economic and health impact. The objective of this study is to synthesize polymeric latex particles of specific functionality to achieve the desired selective separation of target proteins from the human blood. Semi-continuous seed emulsion polymerization was used to prepare monodisperse polystyrene seed particles ranging from 126+/-7.5 to 216+/-5.3 nm in size, which are then enlarged by about 800nm. Surfactant amount played a key role in controlling the latex particle size. Negatively charged latex particles with a different hydrophobicity were prepared by introduction of a sodium persulfate initiator and hydrophilic acrylic acid monomer. The prepared polymeric particles include bare polystyrene (PS) particles, less hydrophobic PS core and PMMA shell particles, and more hydrophilic PS core and PMMA-co-PAA shell latex particles with a 370nm mean diameter. SEM, light scattering, and zeta potential measurements were used to characterize particle size and surface properties. Adsorption isotherms of two proteins, bovine serum albumin (BSA) and beta2-microglobulin (beta2M), on latex particles were obtained as a function of pH and ionic strength using the bicinchoninic acid (BCA) assay method. The

  16. Nanomechanical testing of polymeric nanofibers

    NASA Astrophysics Data System (ADS)

    Tan, E. P. S.; Lim, C. T.

    2005-04-01

    Biodegradable polymeric nanofibrous scaffold comprises individual nanofibers where their stiffnesses can promote or undermine the various cellular functions as well as structural integrity of the scaffold. As such, there is a need to investigate the nanomechanical properties of these individual nanofibers. However, conducting mechanical tests of individual fibers at the nanometer scale can pose great challenges and difficulties. Here, we present novel techniques to perform nanomechanical testing of individual polymeric nanofibers. For demonstration of the nano tensile tests, polycaprolactone (PCL) nanofibers were produced via electrospinning. These fibers were deposited across two parallel edges of a cardboard frame so that a single nanofiber can be isolated for tensile test using a nano tensile tester. For nanoscale three-point bend test, a Poly (L-lactic acid) (PLLA) nanofiber was suspended across a microsized groove etched on a silicon wafer. An atomic force microscope (AFM) tip was then used to apply a point load on the mid-span of the suspended fiber. Beam bending theory was then used to calculate the elastic modulus of the nanofiber. For nanoindentation test, a PLLA nanofiber was deposited on a mica substrate and an AFM tip used to indent the nanofiber. Modified Hertz theory for normal contact was then used to evaluate the elastic modulus of the nanofiber.

  17. Seeded emulsion polymerization as a powerful tool for the biofunctionalization of quantum dots

    NASA Astrophysics Data System (ADS)

    Habercorn, Lasse; Merkl, Jan-Philip; Kloust, Hauke Christian; Feld, Artur; Ostermann, Johannes; Schmidtke, Christian; Wolter, Christopher; Janschel, Marcus; Weller, Horst

    2016-05-01

    With the polymer encapsulation of quantum dots via seeded emulsion polymerization we present a powerful tool for the preparation of fluorescent nanoparticles with an extraordinary stability in aqueous solution. The method of the seeded emulsion polymerization allows a straightforward and simple in situ functionalization of the polymer shell under preserving the optical properties of the quantum dots. These requirements are inevitable for the application of semiconductor nanoparticles as markers for biomedical applications. Polymer encapsulated quantum dots have shown only a marginal loss of quantum yields when they were exposed to copper(II)-ions. Under normal conditions the quantum dots were totally quenched in presence of copper(II)-ions. Furthermore, a broad range of in situ functionalized polymer-coated quantum dots were obtained by addition of functional monomers or surfactants like fluorescent dye molecules, antibodies or specific DNA aptamers. Furthermore the emulsion polymerization can be used to prepare multifunctional hybrid systems, combining different nanoparticles within one construct without any adverse effect of the properties of the starting materials.1,2

  18. Surfactant effects on environmental behavior of pesticides.

    PubMed

    Katagi, Toshiyuki

    2008-01-01

    The potential effects of adjuvants, including surfactants used in pesticide formulation, have been extensively studied for many small organic chemicals, but similar investigation on pesticides is limited in most cases. Solubilizing effects leading to the apparently increased water solubility of a pesticide are commonly known through the preparation of formulations, but fundamental profiles, especially for a specific monodisperse surfactant, are not fully studied. Reduced volatilization of a pesticide from the formulation can be explained by analogy of a very simple organic chemical, but the actual mechanism for the pesticide is still obscure. In contrast, from the point of view of avoiding groundwater contamination with a pesticide, adsorption/desorption profiles in the presence of surfactants and adjuvants have been examined extensively as well as pesticide mobility in the soil column. The basic mechanism in micelle-catalyzed hydrolysis is well known, and theoretical approaches including the PPIE model have succeeded in explaining the observed effects of surfactants, but its application to pesticides is also limited. Photolysis, especially in an aqueous phase, is in the same situation. The dilution effect in the real environment would show these effects on hydrolysis and photolysis to be much less than expected from the laboratory basic studies, but more information is necessary to examine the practical extent of the effects in an early stage of applying a pesticide formulation to crops and soil. Many adjuvants, including surfactants, are biodegradable in the soil environment, and thus their effects on the biodegradation of a pesticide in soil and sediment may be limited, as demonstrated by field trials. Not only from the theoretical but also the practical aspect, the foliar uptake of pesticide in the presence of adjuvants has been investigated extensively and some prediction on the ease of foliar uptake can be realized in relation to the formulation technology

  19. Surfactant/polymer chemical flooding. Volumes 1-2

    SciTech Connect

    Not Available

    1988-01-01

    The two reprint volumes on surfactant/polymer flooding of necessity contain papers on the subject of chemical flooding. The subject was narrowed to include only surfactant/polymer flooding. An overview of chemical flooding is given. Some of the titles are: Surfactant/Oil/Brine phase behavior; Miscellar Flooding-compositional effects on oil displacement; relationships of trapped oil saturation to petrophysical properties of porous media; mobilization of waterflood residual oil; and microemulsion phase behavior.

  20. Surfactant and its role in the pathobiology of pulmonary infection.

    PubMed

    Glasser, Jennifer R; Mallampalli, Rama K

    2012-01-01

    Pulmonary surfactant is a complex surface-active substance comprised of key phospholipids and proteins that has many essential functions. Surfactant's unique composition is integrally related to its surface-active properties, its critical role in host defense, and emerging immunomodulatory activities ascribed to surfactant lipids. Together these effector functions provide for lung stability and protection from a barrage of potentially virulent infectious pathogens. PMID:21945366

  1. Surfactant Based Enhanced Oil Recovery and Foam Mobility Control

    SciTech Connect

    George J. Hirasaki; Clarence A. Miller; Gary A. Pope

    2005-07-01

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactant structures makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. A combination of two surfactants was found to be particularly effective for application in carbonate formations at low temperature. A formulation has been designed for a particular field application. The addition of an alkali such as sodium carbonate makes possible in situ generation of surfactant and significant reduction of surfactant adsorption. In addition to reduction of interfacial tension to ultra-low values, surfactants and alkali can be designed to alter wettability to enhance oil recovery. The design of the process to maximize the region of ultra-low IFT is more challenging since the ratio of soap to synthetic surfactant is a parameter in the conditions for optimal salinity. Compositional simulation of the displacement process demonstrates the interdependence of the various components for oil recovery. An alkaline surfactant process is designed to enhance spontaneous imbibition in fractured, oil-wet, carbonate formations. It is able to recover oil from dolomite core samples from which there was no oil recovery when placed in formation brine. Mobility control is essential for surfactant EOR. Foam is evaluated to improve the sweep efficiency of surfactant injected into fractured reservoirs. UTCHEM is a reservoir simulator specially designed for surfactant EOR. It has been modified to represent the effects of a change in wettability. Simulated case studies demonstrate the effects of wettability.

  2. Theory of Energy Level Tuning in Quantum Dots by Surfactants

    NASA Astrophysics Data System (ADS)

    Zherebetskyy, Danylo; Wang, Lin-Wang; Materials Sciences Division, Lawrence Berkeley National Laboratory Team

    2015-03-01

    Besides quantum confinement that provides control of the quantum dot (QD) band gap, surface ligands allow control of the absolute energy levels. We theoretically investigate energy level tuning in PbS QD by surfactant exchange. We perform direct calculations of real-size QD with various surfactants within the frame of the density functional theory and explicitly analyze the influence of the surfactants on the electronic properties of the QD. This work provides a hint for predictable control of the absolute energy levels and their fine tuning within 3 eV range by modification of big and small surfactants that simultaneously passivate the QD surface.

  3. The interactions between surfactants and vesicles: Dissipative particle dynamics

    NASA Astrophysics Data System (ADS)

    Huang, Kuei-Chun; Lin, Chun-Min; Tsao, Heng-Kwong; Sheng, Yu-Jane

    2009-06-01

    The interactions between surfactants and vesicles formed by double-tail amphiphiles are investigated by the dissipative particle dynamics. As the surfactant concentration is increased, vesicle solubilization can be generally described by the three-stage hypothesis including vesicular region, vesicle-micelle coexistence, and mixed micellar region. We study the partition of surfactants between the bilayer phase and the aqueous phase where a higher value of K indicates that more surfactant molecules are incorporated in the bilayer. It is found that ln(K-1) is proportional to the hydrophile-lipophile balance (HLB), which depicts the degree of hydrophilicity associated with a surfactant. As the overall hydrophilicity of surfactants increases, i.e., higher HLB, K declines and vice versa. When the amounts of surfactants reach a critical point, the solubilization begins and the coexistence of vesicles and mixed micelles is observed. Further increase in the surfactant concentration results in total collapse of the vesicle. Consistent with experimental observations, the three stages are identified through the vesicle size-surfactant concentration relation. Our simulations clearly demonstrate the process of the vesicle solubilization and confirm the validity of the three-stage hypothesis.

  4. Pulmonary surfactant: no mere paint on the alveolar wall.

    PubMed

    Nicholas, T E

    1996-12-01

    The gas-liquid interface within the alveolus is completely lined with a complex mixture of lipids and unique proteins termed pulmonary surfactant, which both reduces surface tension and permits it to vary directly with the radius of curvature. In this way it minimizes the work of breathing and permits alveoli of different sizes to exist in equilibrium. However, surfactant does far more in that it also controls fluid balance in the lung and appears to play a key role in host defence. Either a deficiency in surfactant or an aberrant surfactant results in atelectasis and oedema. The surfactant system is very dynamic: alveolar surfactant phosphatidylcholine, the principal component, having a half life of only a few hours, with as much as 85% being recycled. Although distortion of the alveolar type II cell is now accepted as the principal stimulus for release, much remains to be discovered of modulating factors and intracellular signalling in the control of surfactant homeostasis. Likewise, many questions remain concerning the control of synthesis of the surfactant phospholipids, neutral lipids and proteins and their assembly into the tubular myelin form of alveolar surfactant, the refining of the monolayer with breathing, the control of re-uptake of different components into the type II cells and the roles of the proteins. PMID:9441113

  5. Flexible polyelectrolyte conformation in the presence of oppositely charged surfactants.

    PubMed

    Kuhn, P S; Diehl, A

    2007-10-01

    Conformational behavior of flexible polyelectrolytes in the presence of monovalent cationic surfactants is examined. A simple model is presented for the formation of polyelectrolyte-surfactant complexes in salt-free solutions in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, including explicitly the hydrophobic interactions between the associated surfactant molecules on the polyelectrolyte. The distribution of complexes is calculated as a function of the surfactant concentration and a discrete conformational transition between an elongated coil and a compact globule was found, in agreement with experimental observations. PMID:17995019

  6. Pulmonary surfactant surface tension influences alveolar capillary shape and oxygenation.

    PubMed

    Ikegami, Machiko; Weaver, Timothy E; Grant, Shawn N; Whitsett, Jeffrey A

    2009-10-01

    Alveolar capillaries are located in close proximity to the alveolar epithelium and beneath the surfactant film. We hypothesized that the shape of alveolar capillaries and accompanying oxygenation are influenced by surfactant surface tension in the alveolus. To prove our hypothesis, surfactant surface tension was regulated by conditional expression of surfactant protein (SP)-B in Sftpb(-/-) mice, thereby inhibiting surface tension-lowering properties of surfactant in vivo within 24 hours after depletion of Sftpb. Minimum surface tension of isolated surfactant was increased and oxygen saturation was significantly reduced after 2 days of SP-B deficiency in association with deformation of alveolar capillaries. Intravascularly injected 3.2-mum-diameter microbeads through jugular vein were retained within narrowed pulmonary capillaries after reduction of SP-B. Ultrastructure studies demonstrated that the capillary protrusion typical of the normal alveolar-capillary unit was reduced in size, consistent with altered pulmonary blood flow. Pulmonary hypertension and intrapulmonary shunting are commonly associated with surfactant deficiency and dysfunction in neonates and adults with respiratory distress syndromes. Increased surfactant surface tension caused by reduction in SP-B induced narrowing of alveolar capillaries and oxygen desaturation, demonstrating an important role of surface tension-lowering properties of surfactant in the regulation of pulmonary vascular perfusion. PMID:19202005

  7. Partitioning of naphthalene to gemini surfactant-treated alumina.

    PubMed

    Neupane, D; Park, J W

    2000-09-01

    Partitioning of naphthalene to anionic surfactants adsorbed on alumina in the aqueous phase was studied for immobilization of the contaminant in the subsurface. Three anionic surfactants with different molecular structures were used: a conventional (sodium dodecylbenzene sulfonate, SDDBS), a gemini (dialkylated disulfonated diphenyl oxide with alkyl chain length of 12, DADS-C12), and a dianionic (monoalkylated disulfonated diphenyl oxide with alkyl chain length of 12, MADS-C12). Sorption of the surfactants onto alumina was studied in a series of batch experiments and the effectiveness of the adsorbed surfactants onto aluminum oxide as a sorptive phase for naphthalene was compared. PMID:10834382

  8. Infasurf and Curosurf: Theoretical and Practical Considerations with New Surfactants

    PubMed Central

    Nguyen, Thuy N.; Cunsolo, Stephanie M.; Gal, Peter; Ransom, J. Laurence

    2003-01-01

    Type II pneumocytes, normally responsible for surfactant production and release, are insufficiently formed and differentiated in the premature infant born before 34 weeks' gestation. Without an adequate amount of pulmonary surfactant, alveolar surface tension increases, leading to collapse and decreased lung compliance. Pulmonary surfactants are naturally occurring substances made of lipids and proteins. They lower surface tension at the interface between the air in the lungs, specifically at the alveoli, and the blood in the capillaries. This review examines the relative benefits of the two most recently marketed surfactants, calfactan (Infasurf) and poractant alfa (Curosurf). PMID:23300398

  9. Solution properties and electrospinning of phosphonium gemini surfactants.

    PubMed

    Hemp, Sean T; Hudson, Amanda G; Allen, Michael H; Pole, Sandeep S; Moore, Robert B; Long, Timothy E

    2014-06-14

    Bis(diphenylphosphino)alkanes quantitatively react with excess 1-bromododecane to prepare novel phosphonium gemini surfactants with spacer lengths ranging from 2 to 4 methylenes (12-2/3/4-12P). Dodecyltriphenylphosphonium bromide (DTPP), a monomeric surfactant analog, was readily water soluble, however, in sharp contrast, phosphonium gemini surfactants were poorly soluble in water due to two hydrophobic tails and relatively hydrophobic cationic head groups containing phenyl substituents. Isothermal titration calorimetry did not reveal a measurable critical micelle concentration for the 12-2-12P phosphonium gemini surfactant in water at 25 °C. Subsequent studies in 50/50 v/v water-methanol at 25 °C showed a CMC of 1.0 mM for 12-2-12P. All phosphonium gemini surfactants effectively complexed nucleic acids, but failed to deliver nucleic acids in vitro to HeLa cells. The solution behavior of phosphonium gemini surfactants was investigated in chloroform, which is an organic solvent where reverse micellar structures are favored. Solution rheology in chloroform explored the solution behavior of the phosphonium gemini surfactants compared to DTPP. The 12-2-12P and 12-3-12P gemini surfactants were successfully electrospun from chloroform to generate uniform fibers while 12-4-12P gemini surfactant and DTPP only electrosprayed to form droplets. PMID:24733359

  10. Washing of soils spiked with various pollutants by surfactant solutions

    SciTech Connect

    Yang, G.C.C.; Chang, J.H.

    1995-12-31

    In this study, the batch-type of washing with surfactant solutions was employed for the treatment of soils artificially contaminated with various volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. 15 industrial grade surfactants were tested. Washing was conducing by adding surfactant solution to the soils and mixing for one hour, then centrifuging it and analyzing the supernatant. Deionized water was used for soil washing for comparison. Results indicated that deionized water performed as well as Surfactant No. 1 in washing VOC-contaminated soils. Therefore, it is concluded that the VOCs tested can be easily washed from soils by rain water. In washing PAH-contaminated soils, nonionic surfactants performed better than anionic surfactants in terms of removal efficiency. The amphoteric surfactant performed worst in washing PAH-contaminated soils. Generally, surfactants are useful in removing cadmium from soils, but are not useful for the removal of lead and copper. Amphoteric, anionic, and low pH cationic surfactants were the most effective of those tested. For PAH/heavy metals-contaminated soils, removal efficiencies were lower than that of soils containing a single contaminant.

  11. Spring-loaded polymeric gel actuators

    DOEpatents

    Shahinpoor, M.

    1995-02-14

    Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications. 5 figs.

  12. Polymeric Additives For Graphite/Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Nir, Z.

    1990-01-01

    Report describes experimental studies of properties of several graphite/epoxy composites containing polymeric additives as flexibilizing or toughening agents. Emphasizes effects of brominated polymeric additives (BPA's) with or without carboxy-terminated butadiene acrylonitrile rubber. Reviews effects of individual and combined additives on fracture toughnesses, environmental stabilities, hot/wet strengths, thermomechanical behaviors, and other mechanical properties of composites.

  13. Radiation polymerization of diethyl fumarate [rapid communication

    NASA Astrophysics Data System (ADS)

    Alkassiri, Haroun

    2005-05-01

    Diethyl fumarate (DEF) has been polymerized by gamma irradiation using doses in the range 50-300 kGy, and in this dose range the polymerization yield increased almost linearly. The polymer has a glass transition temperature of about -20 °C, softening point about 15 °C, and decomposition temperature 300 °C.

  14. Spring-loaded polymeric gel actuators

    DOEpatents

    Shahinpoor, Mohsen

    1995-01-01

    Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications.

  15. TOXICITY COMPARISON OF BIOSURFACTANTS AND SYNTHETIC SURFACTANTS USED IN OIL SPILL REMEDIATION TO TWO ESTUARINE SPECIES

    EPA Science Inventory

    The relative environmental toxicities of synthetic and biogenic surfactants used in oil spill remediation efforts are not well understood. Acute and chronic toxicities of three synthetic surfactants and three microbially produced surfactants were determined and compared in this s...

  16. PROPERTIES OF FOOD GRADE (EDIBLE) SURFACTANTS AFFECTING SUBSURFACE REMEDIATION OF CHLORINATED SOLVENTS

    EPA Science Inventory

    In this research, several food grade (edible) surfactants are systematically evaluated for various loss mechanisms: precipitation, adsorption, and coacervation (for nonionic surfactants). Cloud points for the polyethoxylate sorbitan (T-MAZ) surfactants are much higher than aquife...

  17. HENRY'S LAW CONSTANTS AND MICELLAR PARTITIONING OF VOLATILE ORGANIC COMPOUNDS IN SURFACTANT SOLUTIONS

    EPA Science Inventory

    Partitioning of volatile organic compounds (VOCs) into surfactant micelles affects the apparent vapor-liquid equilibrium of VOCs in surfactant solutions. This partitioning will complicate removal of VOCs from surfactant solutions by standard separation processes. Headspace expe...

  18. Synthesis and characterization of β-CD-coated polystyrene microspheres by γ-ray radiation emulsion polymerization.

    PubMed

    Xu, Dezhi; Wang, Mozhen; Ge, Xuewu; Lam, Michael Hon-Wah

    2012-11-23

    Polystyrene (PS) microspheres coated with β-cyclodextrin (β-CD) were fabricated via γ-ray-induced emulsion polymerization in a ternary system of styrene/β-CD/water (St/β-CD/water). The solid inclusion complex of St and β-CD particles formed at the St droplets-water interface can stabilize the emulsion as the surfactant. TEM and XPS results showed that β-CD remains on the surface of PS particles. The average size of the PS particles increases from 186 to 294 nm as the weight ratio of β-CD to St rises from 5% to 12.5%. The water contact angle (CA) of PS latex film is lower than 90°, and reduces with the β-CD content even to 36°. Thus, this work provides a new and one-pot strategy to surface hydrophilic modification on hydrophobic polymer particles with cyclodextrins through radiation emulsion polymerization. PMID:22887797

  19. Entropic effects, shape, and size of mixed micelles formed by copolymers with complex architectures.

    PubMed

    Kalogirou, Andreas; Gergidis, Leonidas N; Moultos, Othonas; Vlahos, Costas

    2015-11-01

    The entropic effects in the comicellization behavior of amphiphilic AB copolymers differing in the chain size of solvophilic A parts were studied by means of molecular dynamics simulations. In particular, mixtures of miktoarm star copolymers differing in the molecular weight of solvophilic arms were investigated. We found that the critical micelle concentration values show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This can be attributed to the effective interactions between copolymers originated from the arm size asymmetry. The effective interactions induce a very small decrease in the aggregation number of preferential micelles triggering the nonrandom mixing between the solvophilic moieties in the corona. Additionally, in order to specify how the chain architecture affects the size distribution and the shape of mixed micelles we studied star-shaped, H-shaped, and homo-linked-rings-linear mixtures. In the first case the individual constituents form micelles with preferential and wide aggregation numbers and in the latter case the individual constituents form wormlike and spherical micelles. PMID:26651715

  20. Targeted polymeric nanoparticles for cancer gene therapy

    PubMed Central

    Kim, Jayoung; Wilson, David R.; Zamboni, Camila G.; Green, Jordan J.

    2015-01-01

    In this article, advances in designing polymeric nanoparticles for targeted cancer gene therapy are reviewed. Characterization and evaluation of biomaterials, targeting ligands, and transcriptional elements are each discussed. Advances in biomaterials have driven improvements to nanoparticle stability and tissue targeting, conjugation of ligands to the surface of polymeric nanoparticles enable binding to specific cancer cells, and the design of transcriptional elements has enabled selective DNA expression specific to the cancer cells. Together, these features have improved the performance of polymeric nanoparticles as targeted non-viral gene delivery vectors to treat cancer. As polymeric nanoparticles can be designed to be biodegradable, non-toxic, and to have reduced immunogenicity and tumorigenicity compared to viral platforms, they have significant potential for clinical use. Results of polymeric gene therapy in clinical trials and future directions for the engineering of nanoparticle systems for targeted cancer gene therapy are also presented. PMID:26061296

  1. DNA amplification via polymerase chain reaction inside miniemulsion droplets with subsequent poly(n-butylcyanoacrylate) shell formation and delivery of polymeric capsules into mammalian cells.

    PubMed

    Baier, Grit; Musyanovych, Anna; Landfester, Katharina; Best, Andreas; Lorenz, Steffen; Mailänder, Volker

    2011-08-11

    There is a growing interest in the development of stable nanocapsules that could deliver the bioactive compounds within the living organism, and to release them without causing any toxic effects. Here the miniemulsion droplets were first used as "nanoreactors" for the amplification of single-molecule dsDNA template (476 and 790 base pairs) through PCR. Afterwards, each droplet was surrounded with a biodegradable PBCA shell by interfacial anionic polymerization, enabling therefore to deliver the PCR products into the cells. The size of the initial miniemulsion droplets and the final polymeric capsules was in the range of 250 and 320 nm, mainly depending on the type of the continuous phase and presence of dsDNA template molecules. The formation of PCR products was resolved with gel electrophoresis and detected with fluorescence spectroscopy in the presence of DNA specific dye (SYBRGreen). TEM studies were performed to prove the formation of the polymeric shell. The shell thickness was measured to be within 5-15 nm and the average molecular weight of the formed PBCA polymer was around 75000 g · mol(-1) . For the cell uptake experiments, the obtained nanocapsules were transferred from the organic phase into aqueous medium containing a water-soluble surfactant. The effect of the surfactant type (anionic, cationic or non-ionic) on the HeLa cell viability and nanocapsule uptake behavior was studied by CLSM and FACS. Confocal analysis demonstrated that nanocapsules stabilized with cationic (CTMA-Cl) and non-ionic (Lutensol AT50) surfactants show almost the same uptake, whereas capsules redispersed in anionic (SDS) surfactant possess a 30% higher uptake. The release of the encapsulated material within the cell was studied on the example of Cy5-labeled oligonucleotides showing the colocalization with mitochondria of MSCs cells. PMID:21557476

  2. Effect of ionic surfactants on the iridescent color in lamellar liquid crystalline phase of a nonionic surfactant.

    PubMed

    Chen, Xinjiang; Mayama, Hiroyuki; Matsuo, Goh; Torimoto, Tsukasa; Ohtani, Bunsho; Tsujii, Kaoru

    2007-01-15

    A nonionic surfactant, n-dodecyl glyceryl itaconate (DGI), self-assembles into bilayer membranes in water having a spacing distance of sub-micrometer in the presence of small amounts of ionic surfactants, and shows beautiful iridescent color. Ionic surfactants have strong effects on this iridescent system. We have interestingly found that the iridescent color changes with time after mixing DGI and ionic surfactants and the color in equilibrium state changes greatly with concentration of the ionic surfactants. The time-dependent color change results from the transformation of DGI aggregate structure after being mixed with ionic surfactant. It is first found that the iridescent color of this nonionic system can be changed from red to deep blue by altering the concentration of ionic surfactants added even though the total concentration of surfactant is almost constant. Such large blue shift of the iridescent color in equilibrium state cannot be fully explained by the ordinary undulation theory applied so far for this phenomenon. The flat lamellar sheets tend to curve by increasing the concentration of ionic surfactants to form separated onion-like and/or myelin-like structures. These separated structures of lamellar system result in the decrease of spacing distance between bilayer membranes because some vacant spaces necessarily appear among these structures. PMID:17046012

  3. Adsorption of polyoxyethylenic surfactants on quartz, kaolin, and dolomite: A correlation between surfactant structure and solid surface nature

    SciTech Connect

    Nevskaia, D.M.; Guerrero-Ruiz, A.; Lopez-Gonzalez, J.deD.

    1996-08-10

    Adsorption of a surfactant at a liquid-solid interface makes up the basis of many technological processes such as detergency, flotation, water treatment, and enhanced oil recovery. The influence of variables such as adsorption temperature, polar chain length, and nature of functional groups on the adsorption, from aqueous solutions, of various surfactants (TX-114, TX-100, TX-165, TX-305, NP1P4E, NP4P1E, NP4S, NP10S, and NP25S) has been investigated. Several nonporous solids, including various samples of quartz, kaolin, and dolomite, were studied. Conformational changes of adsorbed surfactant molecules on one quartz, when the oxyethylenic length of Tritons increases, have been detected. For all the other solid samples the surface is not completely covered by Tritons. On quartz, the surfactants are adsorbed by hydrogen bonds between the surfactant`s ether groups and the silanol groups of the solid surface. These hydroxyl groups must be free and sufficiently separated from other hydroxyls of the solid surface. When the number of propoxy groups increases (from NP1P4E to NP4P1E) the adsorbed amount of surfactant on the solid studied decreases. Anionic surfactants are adsorbed on quartz in lower amounts than the corresponding nonionic surfactants. However, the adsorbed amounts of Tritons and sulfated Tritons on kaolin are similar, probably due to the positive charges on the edges of this material.

  4. The effect of polymer-surfactant interaction on the rheological properties of surfactant enhanced alkaline flooding formulations

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1993-02-01

    Surfactant-enhanced, lower pH (weak) alkaline chemicals are effective for mobilizing residual oil. Polymer is used for mobility control because if mobility control is lost, then oil recovery is reduced. The ability to maintain mobility control during surfactant-alkaline flooding can be adversely affected by chemical interaction. In this work, interaction between polymers and surfactants was shown to be affected by pH, ionic strength, crude oil, and the properties of the polymers and surfactants. Polymer-surfactant interaction (phase separation, precipitation, and viscosity loss) occurred between most of the polymers and surfactants that were tested. Polymer-surfactant interaction is difficult to eliminate, and no method was found for completely eliminating interaction. Polymer-surfactant interaction occurred at optimal salinity and below optimal salinity. Polymer-surfactant interaction had an adverse effect on polymer rheology; however, the adverse effect of interaction on polymer rheology was lessened when oil was present. Increasing the pH of chemical systems further reduced the adverse effects of interaction on polymer rheology.

  5. Low temperature synthesis of nanocrystalline magnesium aluminate with high surface area by surfactant assisted precipitation method: Effect of preparation conditions

    SciTech Connect

    Mosayebi, Zeinab; Rezaei, Mehran; Hadian, Narges; Kordshuli, Fazlollah Zareie; Meshkani, Fereshteh

    2012-09-15

    Highlights: ► MgAl{sub 2}O{sub 4} showed a high surface area and nanocrystalline structure. ► Addition of polymeric surfactant affected the structural properties of MgAl{sub 2}O{sub 4}. ► MgAl{sub 2}O{sub 4} prepared with surfactant showed a hollow cylindrical shape. -- Abstract: A surfactant assisted co-precipitation method was employed for the low temperature synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Pluronic P123 triblock copolymer and ammonia solution were used as surfactant and precipitation agent, respectively. The prepared samples were characterized by thermal gravimetric and differential thermal gravimetric analyses (TG/DTG), X-ray diffraction (XRD), N{sub 2} adsorption (BET) and transmission electron microscopy (TEM) techniques. The effects of several process parameters such as refluxing temperature, refluxing time, pH, P123 to metals mole ratio (P123/metals) and calcination temperature on the structural properties of the samples were investigated. The obtained results showed that, among the process parameters pH and refluxing temperature have a significant effect on the structural properties of samples. The results revealed that increase in pH from 9.5 to 11 and refluxing temperature from 40 °C to 80 °C increased the specific surface area of prepared samples in the range of 157–188 m{sup 2} g{sup −1} and 162–184 m{sup 2} g{sup −1}, respectively. The XRD analysis showed the single-phase MgAl{sub 2}O{sub 4} was formed at 700 °C.

  6. Modeling liquid crystal polymeric devices

    NASA Astrophysics Data System (ADS)

    Gimenez Pinto, Vianney Karina

    The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.

  7. Nucleate pool boiling heat transfer in aqueous surfactant solutions

    NASA Astrophysics Data System (ADS)

    Wasekar, Vivek Mahadeorao

    Saturated, nucleate pool boiling in aqueous surfactant solutions is investigated experimentally. Also, the role of Marangoni convection, driven both by temperature and surfactant concentration gradients at the vapor-liquid interface of a nucleating bubble is computationally explored. Experimental measurements of dynamic and equilibrium sigma using the maximum bubble pressure method indicate dynamic sigma to be higher than the corresponding equilibrium value, both at room and elevated temperatures. Also, nonionic surfactants (Triton X-100, Triton X-305) show larger sigma depression than anionic surfactants (SDS, SLES), and a normalized representation of their dynamic adsorption isotherms is shown to be helpful in generalizing the surfactant effectiveness to reduce surface tension. The dynamic sigma has a primary role in the modification of bubble dynamics and associated heat transfer, and is dictated by the adsorption kinetics of the surfactant molecules at boiling temperatures. In general, an enhancement in heat transfer is observed, which is characterized by an early incipience and an optimum boiling performance at or around the critical micelle concentration of the surfactant. The optimum performances, typically in the fully developed boiling regime ( q''w > 100 kW/m2), show a reverse trend with respect to surfactant molecular weights M, i.e., higher molecular weight additives promote lower enhancement. Normalized boiling performance using the respective solution's dynamic sigma correlates heat transfer coefficient by M-0.5 for anionics and M 0 for nonionics. This has been shown to be brought about by the surfactant concentration and its interfacial activity in a concentration sublayer around the growing vapor bubble, which governs the bubble growth behavior through the mechanism of dynamic sigma. The ionic nature of the surfactant influences the thickness and molecular makeup of the enveloping sublayer, thereby affecting the bubble dynamics and boiling heat

  8. Polymeric materials from renewable resources

    NASA Astrophysics Data System (ADS)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  9. Synthesis of mesostructured polyaniline using mixed surfactants, anionic sodium dodecylsulfate and non-ionic polymers and their applications in H2O2 and glucose sensing.

    PubMed

    Prathap, M U Anu; Thakur, Bhawana; Sawant, Shilpa N; Srivastava, Rajendra

    2012-01-01

    Mesostructured polyaniline was prepared by the self-assembly of a mixture of an anionic surfactant, sodium dodecylsulfate and a non-ionic polymeric surfactant (polyethylene glycol, and block-co-polymers such as Pluronic P123 and Brij-35). Materials were characterized by a complementary combination of X-ray diffraction, Scanning electron microscopy, Fourier-transform infrared spectrometer and UV-visible spectrophotometer. Mesostructured polyaniline was used for construction of biosensor, which displayed excellent electrocatalytic response for the detection of H(2)O(2) and glucose compared to conventional polyaniline. The electrocatalytic response observed in the case of mesostructured polyaniline can be correlated with the large surface area and nanopores which enhances the accessibility of H(2)O(2)/glucose molecule to the active site that result in high observed current. The methodology adopted in the present study provides a new platform for the fabrication of polyaniline based high-performance glucose and other biosensors. PMID:21958538

  10. Adsorption properties of the nanozirconia/anionic polyacrylamide system-Effects of surfactant presence, solution pH and polymer carboxyl groups content

    NASA Astrophysics Data System (ADS)

    Wiśniewska, Małgorzata; Chibowski, Stanisław; Urban, Teresa

    2016-05-01

    The adsorption mechanism of anionic polyacrylamide (PAM) on the nanozirconia surface was examined. The effects of solution pH, carboxyl groups content in macromolecules and anionic surfactant (sodium dodecyl sulfate-SDS) addition were determined. The more probable structure of polymer adsorption layer was characterized based on the data obtained from spectrophotometry, viscosimetry and potentiometric titration methods. The adsorbed amount of polymer, size of macromolecules in the solution and surface charge density of ZrO2 particles in the absence and presence of PAM were assessed, respectively. Analysis of these results indicated that the increase of solution pH and content of carboxyl groups in the polymeric chains lead to more expanded conformations of adsorbing macromolecules. As a result, the adsorption of anionic polyacrylamide decreased. The SDS presence caused the significant increase of PAM adsorbed amount at pH 3, whereas at pH 6 and 9 the surfactant addition resulted in reduction of polymer adsorption level.

  11. Characterization of Phase and Emulsion Behavior, Surfactant Retention, and Oil Recovery for Novel Alcohol Ethoxycarboxylate Surfactants

    SciTech Connect

    Lebone T. Moeti; Ramanathan Sampath

    1998-05-01

    This semi-annual technical progress report describes work performed at Clark Atlanta University under DOE Grant No. DE-FG26-97FT97278 during the period October 01, 1997 to April 01, 1998 which covers the first six months of the project. During this reporting period, laboratory space to set up the surfactant characterization measurement system in the Research Science Center was made available. A Ph.D. student in Chemistry was identified and is supported as a Graduate Research Assistant in this project. Her contribution towards this project will form her Ph.D. thesis. The test matrix to perform salinity and temperature scans was established. Supply requests to obtain refined hydrocarbon, surfactant, and crude were processed and supplies obtained. A temperature bath with a control unit to perform temperature scans was obtained on loan from Federal Energy Technology Center, Morgantown, WV. The setting up of the temperature control unit, and associated chiller with water circulation lines is in progress. Tests were conducted on several hybrid surfactants to identify the best surfactants for future experimental work that yield almost equal volumes of top, middle, and bottom phases when mixed with oil and water. The student reviewed the current literature in the subject area, and modeling efforts that were established in previous studies to predict electrical conductivities and inversion phenomena. These activities resulted in one published conference paper, and one student poster paper during this reporting period.

  12. Surfactant enhanced disinfection of the human norovirus surrogate, tulane virus with organic acids and surfactant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Human infection with foodborne viruses can occur following consumption of contaminated food, person-to-person body contact, or release of aerosols. Combinatorial treatments of surfactants and organic acids may have synergistic or additive mechanisms to inactivate foodborne viruses and prevent outbr...

  13. Effect of salt and surfactant concentration on the structure of polyacrylate gel/surfactant complexes.

    PubMed

    Nilsson, Peter; Unga, Johan; Hansson, Per

    2007-09-20

    Small-angle X-ray scattering was used to elucidate the structure of crosslinked polyacrylate gel/dodecyltrimethylammonium bromide complexes equilibrated in solutions of varying concentrations of surfactant and sodium bromide (NaBr). Samples were swollen with no ordering (micelle free), or they were collapsed with either several distinct peaks (cubic Pm3n) or one broad correlation peak (disordered micellar). The main factor determining the structure of the collapsed complexes was found to be the NaBr concentration, with the cubic structure existing up to approximately 150 mM NaBr and above which only the disordered micellar structure was found. Increasing the salt concentration decreases the polyion mediated attractive forces holding the micelles together causing swelling of the gel. At sufficiently high salt concentration the micelle-micelle distance in the gel becomes too large for the cubic structure to be retained, and it melts into a disordered micellar structure. As most samples were above the critical micelle concentration, the bulk of the surfactant was in the form of micelles in the solution and the surfactant concentration thereby had only a minor influence on the structure. However, in the region around 150 mM NaBr, increasing the surfactant concentration, at constant NaBr concentration, was found to change the structure from disordered micellar to ordered cubic and back to disordered again. PMID:17715959

  14. Formation of bilayer membrane and niosomes by double-tailed polyglyceryl-type nonionic surfactant.

    PubMed

    Aramaki, Kenji; Yamada, Junya; Tsukijima, Yoshitomo; Maehara, Tetsuya; Aburano, Daisuke; Sakanishi, Yuichi; Kitao, Kyuhei

    2015-10-01

    Vesicles with synthetic nonionic surfactants are called niosomes or NSVs, and these have been the focus of attention as an alternative to phospholipid liposomes as drug carriers. Especially it is demanded to discover novel niosomal systems with polyol-type nonionic surfactants from the viewpoint of environmental aspects. In this paper, a novel series of double-tailed nonionic surfactants, polyglyceryl dialkyl ethers, (C12)2Gn (n = 2.3, 5.4, 9.4, and 13.8), was synthesized, and its aqueous phase behavior and niosome formation were studied. Because of its double-tailed molecular structure, a lamellar liquid crystalline phase was dominant in the binary phase diagrams for different polyglyceryl chain lengths. The single lamellar liquid crystalline phase region was expanded as the polymerization degree in the hydrophilic moiety increased. Small-angle X-ray scattering spectra revealed the lamellar structure for the (C12)2G2.3 was extremely loose. Molecular packing in the lamellar phase was analyzed except for the (C12)2G2.3 system by using a geometrical model of the lamellar phase. The effective cross-sectional area per molecule at the interface increased extensively as dilution for the (C12)2G13.8 system but remained almost unchanged for the (C12)2G5.4 system. From the molecular parameters, water-holding ability in the lamellar phase was evaluated, and the results indicated strong hydration ability of the long polyglyceryl chain. In a dilute region, micron-sized giant niosomes and small niosomes of about 100 nm were formulated by vortex mixing and ultrasonication, respectively. The multilamellar structure of the small niosomes was confirmed by transmission electron microscopy. Cholesterol addition in the present surfactant lamellar phase induced the phase transition to the liquid ordered phase, which is the same phenomenon in a phospholipid-cholesterol mixture. The stability of niosomes with/without cholesterol was monitored by the niosome size change. In both cases

  15. Foam stabilisation using surfactant exfoliated graphene.

    PubMed

    Sham, Alison Y W; Notley, Shannon M

    2016-05-01

    Liquid-air foams have been stabilised using a suspension of graphene particles at very low particle loadings. The suspension was prepared through the liquid phase exfoliation of graphite in the presence of the non-ionic tri-block surfactant, Pluronic® F108. The graphene particles possess an extremely high aspect ratio, with lateral dimensions of between 0.1 and 1.3 μm as evidenced by TEM imaging. The particles were shown to exhibit a number of other properties known to favour stabilisation of foam structures. Particle surface activity was confirmed through surface tension measurements, suggesting the particles favour adsorption at the air-water interface. The evolution of bubble size distributions over time indicated the presence of particles yielded improvements to foam stability due to a reduction in disproportionation. Foam stability measurements showed a non-linear relationship between foam half-life and graphene concentration, indicative of the rate at which particles adsorb at bubble surfaces. The wettability of the graphene particles was altered upon addition of alkali metal chlorides, with the stability of the foams being enhanced according to the series Na(+)>Li(+)>K(+)>Cs(+). This effect is indicative of the relative hydration capacity of each salt with respect to the surfactant, which is adsorbed along the graphene plane as a result of the exfoliation process. Thus, surfactant exfoliated graphene particles exhibit a number of different features that demonstrate efficient application of high-aspect ratio particles in the customisation and enhancement of foams. PMID:26890385

  16. Interaction between DNA and cationic surfactants: effect of DNA conformation and surfactant headgroup.

    PubMed

    Dias, Rita S; Magno, Luís M; Valente, Artur J M; Das, Dibyendu; Das, Prasanta K; Maiti, Souvik; Miguel, Maria G; Lindman, Björn

    2008-11-20

    The interactions between DNA and a number of different cationic surfactants, differing in headgroup polarity, were investigated by electric conductivity measurements and fluorescence microscopy. It was observed that, the critical association concentration (cac), characterizing the onset of surfactant binding to DNA, does not vary significantly with the architecture of the headgroup. However, comparing with the critical micelle concentration (cmc) in the absence of DNA, it can be inferred that the micelles of a surfactant with a simple quaternary ammonium headgroup are much more stabilized by the presence of DNA than those of surfactants with hydroxylated head-groups. In line with previous studies of polymer-surfactant association, the cac does not vary significantly with either the DNA concentration or its chain length. On the other hand, a novel observation is that the cac is much lower when DNA is denaturated and in the single-stranded conformation, than for the double-helix DNA. This is contrary to expectation for a simple electrostatically driven association. Thus previous studies of polyelectrolyte-surfactant systems have shown that the cac decreases strongly with increasing linear charge density of the polyion. Since double-stranded DNA (dsDNA) has twice as large linear charge density as single-stranded DNA (ssDNA), the stronger binding in the latter case indicates an important role of nonelectrostatic effects. Both a higher flexibility of ssDNA and a higher hydrophobicity due to the exposed bases are found to play a role, with the hydrophobic interaction argued to be more important. The significance of hydrophobic DNA-surfactant interaction is in line with other observations. The significance of nonelectrostatic effects is also indicated in significant differences in cac between different surfactants for ssDNA but not for dsDNA. For lower concentrations of DNA, the conductivity measurements presented an "anomalous" feature, i.e., a second inflection point

  17. Size separation of analytes using monomeric surfactants

    DOEpatents

    Yeung, Edward S.; Wei, Wei

    2005-04-12

    A sieving medium for use in the separation of analytes in a sample containing at least one such analyte comprises a monomeric non-ionic surfactant of the of the general formula, B-A, wherein A is a hydrophilic moiety and B is a hydrophobic moiety, present in a solvent at a concentration forming a self-assembled micelle configuration under selected conditions and having an aggregation number providing an equivalent weight capable of effecting the size separation of the sample solution so as to resolve a target analyte(s) in a solution containing the same, the size separation taking place in a chromatography or electrophoresis separation system.

  18. Surfactant roles in modern sample preparation techniques: a review.

    PubMed

    Moradi, Morteza; Yamini, Yadollah

    2012-09-01

    The pressure to decrease organic solvent usage in laboratories is increasing. Thus miniaturization and improvement of sample handling using alternatives is a challenge that has been discussed by several researchers. From this perspective, surfactant-based sample preparations were an educated choice. Since the introduction of cloud point extraction by Watanabe, considerable studies have been focused on the chemical properties of surfactants in the extraction methods. The unique properties of surfactants make them flexible agents for different miniaturized sample preparation techniques based on solid- or liquid-phase extraction. As a result, the use of surfactants with different roles in sample-preparation methodologies (such as surfactant as an emulsifier, surfactant rich phase as an extraction medium, ion pair-based extraction, hemimicelle/admicelle extraction, surfactant-coated magnetic nanoparticle, solid-phase microextraction with micellar desorption) is an important contribution to minimizing the problems arising from preliminary operations, which are the weakest step in analytical measurement. This paper reviews the literature dealing with the application of surfactant-based sample preparations to the separation and the preconcentration of organic and inorganic species. PMID:22887709

  19. The Influence of Surfactants on the Zeta Potential of Coals

    SciTech Connect

    Marsalek, R.

    2009-07-01

    The surface of three different kinds of coal was modified by three surfactants (cationic, anionic, and non-ionic). Changes on coal surface were examined by the zeta potential technique. The influence of the dispersion of pH, concentration of surfactants, and contact time were investigated. The most significant change in zeta potential resulting from adding surfactants was observed in activated coal (hydrophobic surface, largest BET surface area). Adding the cationic surfactant led to an increase of the zeta potential, contrary to measuring done in water. The anionic surfactant decreased the value of the zeta potential; however, this change was not too remarkable. The results proved that even a very low concentration of the cationic surfactant (0.01 mmol/L) causes a remarkable change of the zeta potential. On the other hand, a similar effect was observed until the concentration of the anionic surfactant reached about 10 mmol/L. The mechanism of binding surfactants is not simple, but preferential hydrophobic interactions were discovered.

  20. Synthetic pulmonary surfactant preparations: new developments and future trends.

    PubMed

    Mingarro, Ismael; Lukovic, Dunja; Vilar, Marçal; Pérez-Gil, Jesús

    2008-01-01

    Pulmonary surfactant is a lipid-protein complex that coats the interior of the alveoli and enables the lungs to function properly. Upon its synthesis, lung surfactant adsorbs at the interface between the air and the hypophase, a capillary aqueous layer covering the alveoli. By lowering and modulating surface tension during breathing, lung surfactant reduces respiratory work of expansion, and stabilises alveoli against collapse during expiration. Pulmonary surfactant deficiency, or dysfunction, contributes to several respiratory pathologies, such as infant respiratory distress syndrome (IRDS) in premature neonates, and acute respiratory distress syndrome (ARDS) in children and adults. The main clinical exogenous surfactants currently in use to treat some of these pathologies are essentially organic extracts obtained from animal lungs. Although very efficient, natural surfactants bear serious defects: i) they could vary in composition from batch to batch; ii) their production involves relatively high costs, and sources are limited; and iii) they carry a potential risk of transmission of animal infectious agents and the possibility of immunological reaction. All these caveats justify the necessity for a highly controlled synthetic material. In the present review the efforts aimed at new surfactant development, including the modification of existing exogenous surfactants by adding molecules that can enhance their activity, and the progress achieved in the production of completely new preparations, are discussed. PMID:18288994