MICROPHASE STRUCTURE OF BLOCK IONOMERS .3. A SAXS STUDY OF THE EFFECTS OF ARCHITECTURE AND CHEMICAL-STRUCTURE

The structure of various ionic block copolymers of ABA and AB architecture was investigated by small-angle X-ray scattering (SAXS). Polystyrene formed the B-blocks of all materials, and vinylpyridinium methyl iodide or cesium methacrylate formed the ionic A blocks. The latter were kept short and spherical ionic domains were observed. The morphology was studied as a function of the lengths of both ionic and nonionic blocks and of the methods of preparation (neutralization in different solvents, solvent casting, or compression molding). A strong correlation peak was observed, often followed by features related to shape factors for the spherical microdomains. The radii calculated from these two different features are in good agreement. In was concluded that, within experimental error, the size of the ionic microdomains is independent of the length of the nonionic block, the chemical structure of the ionic block, the method of preparation, or the architecture. The ionic segments are highly extended in their microdomains.