Synthesis and Characterization of Block Copolymer Ionomers with Coexisting DualMicrophase Separated Morphologies

摘要

Three types of block copolymers were used to prepare block copolymer ionomers:(1) a triblock copolymer of styrene and ethylene-co-butylene (SEBS) obtained commercially and diblock and triblock copolymers of styrene and ethylene-co-propylene (SEP and SEPS) that were synthesized by anionic polymerization of styrene and isoprene followed by hydrogenation of the polyisoprene block. The styrene content of the SEBS was 30% wt; the styrene content of the SEP and SEPS was varied from 10-50% to obtain spherical, cylindrical or lamellar microstructures. The styrene blocks were sulfonated to 0-18 mol% with acetyl sulfate, and the free acid derivative and the Na(+) and Zn(2+) salts were prepared. The block copolymer ionomers exhibited two different levels of microphase separation: (1) a block microstructure with a characteristic dimension of the order of 10-20 nm and an ionic microstructure of the order of 2A nm that was located within the styrene block microdomains. The effects of sulfonation, nature of the cation, temperature and sample preparation on the different microstructures and the properties of the polymers were studied by dynamic mechanical analysis, transmission electron microscopy, and small angle x-ray scattering. The effect of adding homopolymers that are miscible with the ionic phase was also studied. jg.