COMPARISON OF MOLECULAR-ORIENTATION IN IONOMER-RELATED POLYSTYRENE-BASED COPOLYMERS AND BLENDS

The molecular orientation, measured by infrared dichroism, is compared for several polystyrene-based systems stretched uniaxially above their glass transition temperatures. These systems contain controlled amounts of interactions of various types and strengths. For ah those involving hydrogen bonding with carboxylic acid, such as poly(styrene-co-methacrylic acid) (PS-MAA) and blends of PS-MAA with poly(styrene-co-4-vinylpyridine) (PS-VP), there is no increase in the orientation measured compared to that of polystyrene. The orientation increases significantly, however, for the more strongly interacting poly(styrene-co-styrenesulfonic acid) (PS-SSA) copolymer. Greatest orientation is observed in blends of PS-SSA with PS-VP, known to be characterized by intermolecular ionic interactions. The results are discussed in terms of the strong interactions slowing down chain relaxation or acting as effective cross-links in the time scale of the experiment.