Block ionomer complexes with polystyrene core-forming block in selective solvents of various polarities. 2. Solution behavior and self-assembly in nonpolar solvents

The self-assembly behavior and structural characteristics of the block ionomer complexes from poly(styrene)-block-poly(N-ethyl-4-vinylpyridinium) (PS-b-PE4VP) cations and bis(2-ethylhexyl) sulfosuccinate (AOT) anions in nonpolar solvents were examined by turbidity, viscometry, sedimentation velocity, isothermal diffusion, and dynamic light scattering techniques. The complexes were synthesized by reacting PS-b-PE4VP with ACT in aqueous media. The resulting water-insoluble materials contained PS block and PE4VP/AOT complex block. The length of PS block was constant and equal to 100 units, while the length of PE4VP/AOT block was varied (100-500 units). These complexes dissolved in hexane upon addition of small amounts (0.5-10 vol %) of aliphatic alcohols and formed stable dispersions with the size of the particles varying from 50 to 95 nm. The particles represented micelle-like aggregates of PS-b-PE4VP/AOT complexes with the core formed by PS chains and the shell formed by PE4VP chains electrostatically bound to ACT ions. The behavior and molecular characteristics of these previously unknown structures (shape, dimensions, chain stretching, and aggregation numbers) resemble those of the micelles formed by nonpolar block copolymers in selective organic solvents. Such systems are unprecedented for the block copolymer aggregates in organic solvents and may have considerable theoretical and practical significance.