Graft eopolymer eontaining poly(ethylene oxide)side chains on a polystyrene backbone were acrylamided. The amide groups in the copolymers were ionized by using potassium naphthalene, and grafting was achieved by utilizing the amide anions as initiator sites for the polymerization of ethylene oxide at 70℃. The graft copolymers was characterized with respect to molecule weight and composition using NMR, IR, GPC, and DSC. GPC result from the graft copolymer sample suggested a narrow size distribution. 相似文献
Cationic amphiphilic polymers were prepared from PEI and functional ethylene carbonates bearing cationic, hydrophobic or amphiphilic groups. The polymers are designed to exhibit antimicrobial properties. In a one-step addition, different functional ethylene carbonates were added to react with the primary amine groups of PEI. The water soluble polymers were studied regarding their ability to form soluble aggregates. Their hydrodynamic radii, their inhibition potential against proliferation of E. coli and their hemolytic potential were determined. A structure-property relationship was established by analyzing the antimicrobial activity as a function of the ratio of alkyl to cationic groups, length of the alkyl chains, and molecular weight of the PEI. 相似文献
Summary: Aqueous dispersions of diblock copolymer micelles with homogeneous hydrophobic core (polystyrene) and heterogeneous amphiphilic corona from ionic N-ethyl-4-vinylpyridinium bromide (EVP) and hydrophobic 4-vinylpyridine (4VP) units have been prepared at pH 9. The structure and dispersion stability of micelles as function of the ratio and distribution pattern of ionic and hydrophobic units in corona have been systematically studied by means of transmission electron microscopy, static and dynamic light scattering, UV-spectrophotometry techniques. It was shown that gradual decrease of the quantity of EVP-units in corona had no impact on micelle structure until its fraction was above 0.7. When EVP-fraction dropped below this point noticeable changes in micelle mass and dimensions were observed. In the case of random distribution of 4VP and EVP units these changes were moderate in value and jump-like in character. In the case of mictoarm (starlike) distribution of 4VP and EVP blocks changes were large in value and monotonous in character. The presented results may be of certain use for design of polymer micelles with nanosegregated corona. 相似文献
Metal nanoparticles of various size and shape are prepared by the reduction of metal precursors in polymer micellar architectures (nanoreactors). The nanoreactors are developed from the amphiphilic invertible polyesters solved over a wide concentration range in solvents that strongly differ in polarity. In a non‐polar medium, the micelle core contains hydrophilic [poly(ethylene oxide)] fragments, which acts as a reducing agent of metal ions. Nanoparticle stabilization occurs because of the presence of hydrophobic (polymethylene) fragments outside of the micelle structure. The size and shape of the nanoreactors may be altered by the polyester composition and molecular weight as well as by the solvent polarity and concentration of the amphiphilic polyester.
We have synthesized light sensitive nano micelles for their applications as drug delivery agents. Various azo compounds having different dipole moment values have been covalently attached to an amphiphilic pegylated co‐polymer and their light sensitive behavior has been studied in both aqueous and organic media with ultra violet light to understand the light dependent supramolecular organization. 相似文献