ИСТИНА

One of the trends in contemporary colloid and polymer chemistry is the design of multifunctional and stimuli responsive polymeric micelles and nanostructures for purposes of stabilization of metal nanoparticles, catalysis, gene and drug delivery. To fit the requirements of multi-functionality the micelles must be composite (chemically heterogenic), i.e. contain various types of polymeric units in their core and/or corona. One of the simplest methods for preparation of such micelles is hybridization, i.e. joint micellization of several chemically different diblock-copolymers with common block in selective solvents. The presented study focuses on problems of self-assembly of hybrid spherical micelles with hydrophobic polystyrene (PS) core and mixed amphiphilic (poly[4-vinylpyridine]/poly[N-ethyl-4-vinylpyridinium bromide], P4VP/PEVP) or cationic-anionic (poly[acrylic acid]/poly[N-ethyl-4-vinylpyridinium bromide], PAA/PEVP) corona in aqueous alkaline media. Such micelles were obtained from nonselective organic solvent (dimethylformamide/methanol, 80/20 v/v) via stepwise dialysis against water. The composition of such micelles is close to the composition of mixing polymers, while chemically different blocks are supposed to be evenly distributed within the corona. In general such micelles have the “onion”-type organization. Hybrid PS-PEVP/PS-P4VP micelles consist from hydrophobic PS-core, intermediate layer from contracted P4VP blocks and lyophilizing corona from PEVP blocks (Figure A). Hybrid PS-PEVP/PS-PAA micelles consist from hydrophobic PS-core, intermediate layer from interpolyelectrolyte PEVP/PAA complexes and charged lyophilizing corona from excessive PEVP or PAA units (Figures B, C). Three main characteristic features of such micelles have been isolated. These features are: (1) essentially nonlinear dependence of micelle dispersion stability, molecular-mass and hydrodynamic characteristics vs. micelle composition; (2) the possibility of strong segregation of chemically different blocks in corona; (3) the ability of binding polymeric and amphiphilic species into corona without loss of dispersion stability of the micelles. These features are unique for hybrid polymeric micelles with cationic-anionic or amphiphilic corona