MICELLAR MORPHOLOGY IN BULK STYRENE-CORE IONIC DIBLOCK COPOLYMERS

Diblock ionomers consisting of a short polystyrene block and a long ionic segment of poly-(4-vinylpyridinium methyl iodide) or poly(cesium methacrylate) have been investigated by small-angle X-ray scattering in the solid state. The size of the spherical microdomains formed by the polystyrene blocks in the continuous ionic matrix has been measured and compared to that of the mirror system consisting of an ionic core in a nonionic matrix, previously investigated. Similar chain stretching of the core-forming block is observed for both systems, and it is concluded that the chain extension in the microdomains is due to the high surface energy between the ionic and the nonionic phases rather than to specific ionic interactions. In addition, the core radii of the two mirror systems were fitted to the predictions of the star model for block copolymers, R proportional to aN(B)(3/5), where N-B is the length of the core-forming block.