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Unmodified Poly (unmodified + poly)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Enantioselectivity of alcohol-modified polymeric surfactants in micellar electrokinetic chromatography

ELECTROPHORESIS, Issue 15 2003
Jepkoech Tarus
Abstract A novel method of modifying sodium undecanoyl- L -leucinate (SUL) micelles employed in chiral separation of analytes in micellar electrokinetic chromatography (MEKC) to enhance selectivity toward specific analytes is discussed. The current study aimed at modifying the SUL micelles by introducing different alcohols into the mono-SUL micelles. The micellar solutions were then polymerized in the presence of alcohols followed by postpolymerization extraction of the alcohols to yield alcohol-free polymeric surfactants (poly- L -SUL). The effects of hexanol (C6OH) and undecylenyl alcohol (C11OH) on micellar properties of this surfactant were investigated by use of surface tensiometry, fluorescence spectroscopy, pulsed field gradient-nuclear magnetic resonance (PFG-NMR), and MEKC. The surface tension and PFG-NMR studies indicated an increase in the critical micelle concentration (cmc) and micellar size upon increasing the alcohol concentration. Fluorescence measurements suggested that alcohols induce closely packed micellar structures. Coumarinic and benzoin derivatives, as well as (±)-1, 1'-binaphthyl-2,2'-dihydrogen phosphate (BNP) were used as test analytes for MEKC experiments. Examination of MEKC data showed remarkable resolutions and capacity factors of coumarinic derivatives obtained with modified poly- L -SUL as compared to the unmodified poly- L -SUL. Evaluation of fluorescence, PFG-NMR, and MEKC data suggest a strong correlation between the polarity and hydrodynamic radii of alcohol-modified micelles and the resolution of the test analytes. [source]

Development and in vitro evaluation of a mucoadhesive vaginal delivery system for nystatin

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2009
Juliane Hombach
Abstract The purpose of the present study was to design and evaluate a novel vaginal delivery system for nystatin based on mucoadhesive polymers. L -Cysteine and cysteamine, respectively, were covalently attached to poly(acrylic acid), and the two different thiolated polymers were evaluated in vitro regarding their swelling behavior, mucoadhesive properties and release behavior. Tablets comprising these thiolated polymers and nystatin demonstrated a high stability in vaginal fluid simulant pH 4.2 and an increase in weight by swelling whereas control tablets comprising unmodified poly(acrylic acid) disintegrated and dissolved. The mucoadhesion time of tablets on freshly excised bovine vaginal mucosa on a rotating cylinder and the total work of adhesion of gels and tablets increased significantly due to the formation of disulfide bonds between the thiolated polymer and cysteine rich subdomaines of the mucus layer. The drug nystatin was released more slowly out of thiomer tablets and gels than out of PAA control tablets and gels. Therefore these thiolated polymers are promising delivery systems for nystatin providing a prolonged residence time and a sustained drug release in vitro under physiological relevant conditions. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:555,564, 2009 [source]

Synthesis of Poly(3,4-ethylenedioxythiophene) latexes using poly(N -vinylpyrrolidone)-based copolymers as reactive stabilizers

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2010
Muhammad Mumtaz
Abstract The synthesis by oxidative polymerization of well-defined poly(3,4-ethylenedioxythiophene) (PEDOT) nano-objects in the presence of modified and unmodified poly(N -vinylpyrrolidone)-based copolymers used as stabilizers in aqueous media is reported. Ammonium persulfate or a mixture of ammonium persulfate with CuCl2 or CuBr2 was used as oxidants. The effects of several parameters such as the molar mass and the concentration of the stabilizer as well as the nature of the oxidants on the size, morphology, and the conductivity of the PEDOT particles have been investigated. The distribution of the reactive moieties along the copolymer stabilizer backbone was shown to be crucial to get well-defined PEDOT nano-objects. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3841,3855, 2010 [source]

Hydrophobically modified polyelectrolytes II: synthesis and characterization of poly(acrylic acid-co-alkyl acrylate)

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2001
Dong-qing Zhuang
Abstract A series of hydrophobically modified poly(acrylic acid)(RH -PAA) were synthesized by solution copolymerization of acrylic acid with a small amount of alkyl acrylate (alkyl chain with a length of 8, 12, 14, 16, 18) and their solution properties were also systematically studied. It was found that the random distribution of alkyl acrylate along the polymeric backbone imparts these new materials pronounced associating ability in aqueous solution and the associating abilities vary with the chain length of the hydrophobic groups. In dilute solution, intramolecular association is observed from the intrinsic viscosity and the dependence of the intrinsic viscosity on chain length and ionic strength is also discussed. In semiconcentration solution, the modified polymers exhibit viscosities of several orders of magnitude higher than the unmodified poly(sodium acrylate) due to the strong intermolecular hydrophobic association. And the viscosifying effects become more significant with the increasing length of the alkyl chain. The copolymer solutions are highly pseudoplastic. Evidences for the hydrophobically associating interaction between hydrocarbon groups are provided by the dependence of the Brookfield viscosity on concentration, temperature, shear rate, ionic strength and pH. Copyright © 2001 John Wiley & Sons, Ltd. [source]