ИСТИНА

Recent developments in polymerization techniques, including controlled radical polymerization, significantly extend the spectrum of macromolecular architectures available for self-assembly investigations. The more complicated is polymer architecture the more versatile is expected to be its behavior, both in solids and in solutions. Numerous publications are devoted to controlled synthesis of amphiphilic diblock- and graft-copolymers (including polymer brushes) and their hydrodynamic properties in different solvents. Recently we have reported about controlled synthesis of amphiphilic multiblock terpolymers based on polyacrylic acid (PAA), polystyrene (PS) and poly(n-butyl acrylate) (PBA) by means of reversible addition – fragmentation chain transfer polymerization. The synthesized block-copolymers differ by the sequence and molar/weight fraction of constituent blocks (Table 1). In current research we present the results of dynamic light scattering investigations of aggregative behavior of these copolymers in various organic solvents with different polarity and thermodynamic quality towards each of the blocks. Tetrahydrofuran ( = 7.6) being a good solvent for PS and PBA, while poor solvent for PAA, causes the aggregation of multiblock-copolymer macromolecules. Similar results have been observed in N,N-dimethylformamide ( = 36.7), which is a good solvent for PAA and PBA and a poor solvent for PS. The effective hydrodynamic radii of aggregates vary within the range 80 – 130 nm. The sequence of the blocks and their weight fraction has no influence on the aggregative behavior of block-copolymers. The scattering intensity increases linearly with the growth of polymer solution concentration, the aggregates average size is kept constant within the temperature interval 25 – 600C. In contrast to tetrahydrofuran and dimethylformamide no aggregation was observed in 1,4-dioxane ( = 2.2), which is a good solvent for all copolymer blocks. The regularities of aggregative behavior of multiblock-copolymers as a function of solvent selectivity are discussed.