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Hydrophilic Block (hydrophilic + block)

Distribution by Scientific Domains
Polymers and Materials Science100%

Terms modified by Hydrophilic Block

  • hydrophilic block copolymer
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    Selected Abstracts

    Surfactant characteristics of polystyrene/poly(ethylene oxide) macromonomers in aqueous solution and on polystyrene latex particles: Two-step emulsion polymerizations

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2001
    Sebastien Gibanel
    Abstract Macromonomers were synthesized by anionic "living" polymerization. They comprised a poly(ethylene oxide) hydrophilic block and a hydrophobic block or sequence terminated with an unsaturation. The surface activity properties of these materials (critical micelle concentration and parking area) were determined, and the values were compared and discussed in terms of the molecular structure of these new surfactants. Some of the macromonomers were employed as emulsifiers in two-step emulsion polymerizations. The data obtained were discussed while taking into account the different chemical structures of the macromonomers and the efficiency of these species as emulsifiers in the polymerization recipes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2767,2776, 2001 [source]

    Efficient Encapsulation of Plasmid DNA in pH-Sensitive PMPC,PDPA Polymersomes: Study of the Effect of PDPA Block Length on Copolymer,DNA Binding Affinity

    MACROMOLECULAR BIOSCIENCE, Issue 5 2010
    Hannah Lomas
    Abstract We report the self-assembly of a series of amphiphilic diblock copolymers comprising a biocompatible, hydrophilic block, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and a pH-sensitive block, poly(2-(diisopropylamino)ethyl methacrylate) (PDPA), into a dispersion of colloidally stable, nanometer-sized polymersomes at physiological pH and salt concentration. The pH-sensitivity of the PDPA block affords the electrostatic interaction of these block copolymers with nucleic acids at endocytic pH, as a result of the protonation of its tertiary amine groups at pH values below its pKa. Herein we investigate the effect of PDPA block length on the binding affinity of the block copolymer to plasmid DNA. [source]

    The Influence of Pendant Hydroxyl Groups on Enzymatic Degradation and Drug Delivery of Amphiphilic Poly[glycidol- block -(, -caprolactone)] Copolymers

    MACROMOLECULAR BIOSCIENCE, Issue 11 2009
    Jing Mao
    Abstract An amphiphilic diblock copolymer PG- b -PCL with well-controlled structure and pendant hydroxyl groups along hydrophilic block was synthesized by sequential anionic ring-opening polymerization. The micellization and drug release of PG- b -PCL copolymers using pyrene as a fluorescence probe were investigated for determining the influences of copolymer composition and lipase concentration on drug loading capacity and controlled release behavior. The biodegradation of PG- b -PCL copolymers was studied with microspheres as research samples. It has been concluded that the polar hydroxyl groups along each repeat unit of hydrophilic PG block in PG- b -PCL copolymer have great influences on drug encapsulation, drug release, and enzymatic degradation of micelles and microspheres. [source]

    Micellar Structures of Hydrophilic/Lipophilic and Hydrophilic/Fluorophilic Poly(2-oxazoline) Diblock Copolymers in Water

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2008
    Ruzha Ivanova
    Abstract Amphiphilic poly(2-alkyl-2-oxazoline) diblock copolymers of 2-methyl-2-oxazoline (MOx) building the hydrophilic block and either 2-nonyl-2-oxazoline (NOx) for the hydrophobic or 2-(1H,1H,,2H,2H,-perfluorohexyl)-2-oxazoline (FOx) for the fluorophilic block were synthesized by sequential living cationic polymerization. The polymer amphiphiles form core/shell micelles in aqueous solution as evidenced using small-angle neutron scattering (SANS). Whereas the diblock copolymer micelles with a hydrophobic NOxn block are spherical, the micelles with the fluorophilic FOxn are slightly elongated, as observed by SANS and TEM. In water, the micelles with fluorophilic and lipophilic cores do not mix, but coexist. [source]

    Fabrication of Regularly Patterned Microporous Films by Self-Organization of an Amphiphilic Liquid-Crystalline Diblock Copolymer in a Dry Environment

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2010
    Dong Chen
    Abstract An amphiphilic LCBC PEO -b- PAz consisting of flexible PEO as a hydrophilic block and poly(methacrylic acid) containing an azobenzene moiety in side chain as a hydrophobic LC segment was synthesized and used to fabricated microporous films by spin-coating method under a dry environment. With the help of a small amount of water, well-arranged ellipsoidal micropores embedded in a LC matrix were obtained and the pore size is in the range of several tens µm of water. The influence of water content and rotational speed was studied in detail. It was found that regularly patterned microporous films can be prepared with certain water content, and the pore size can be easily tailored through changing the rotational speed. The obtained microporous structures showed good thermal and photo stability. [source]

    Novel Amphiphilic Styrene-Based Block Copolymers for Induced Surface Reconstruction

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 1 2008
    Lutz Funk
    Abstract This paper describes the synthesis of amphiphilic block copolymers by living radical polymerization (NMP) of new styrene-like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl- or amino-groups after deprotection) were polymerized in a "protected form" to adjust the solubility of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. In the bulk state hydrophobic and hydrophilic domains demix. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83° as a result of surface reconstruction. Through side chains of different length and with different functionalities, it was possible to adjust the glass transition temperatures to values between ,2,°C to 140,°C for the hydrophilic blocks and ,30,°C to 100,°C for the hydrophobic block. The wide range of the glass temperatures allowed it to find a block copolymer system with a slow kinetic concerning the surface reconstruction process, so that a mechanistic examination of the process by AFM was possible. It got, thereby, possible to detect the break-up of the hydrophobic surface lamella and the upfold of the hydrophilic lamella in contact with water. [source]