No abstract

Lightly sulfonated polystyrene (7 mol %) (PS−SSA) that is ionically complexed with monodisperse tertiary amine-terminated oligomers of styrene, both mono- and bifunctional, were investigated by dynamic mechanical thermal analysis (DMA). The chain lengths of the oligomers are significantly greater than the average segmental length between the functional groups in PS−SSA. The monofunctional oligomer plasticizes PS−SSA as expected but considerably less than do alkyl chains, attributed to the greater bulkiness and stiffness of the styrene segments. The bifunctional oligomer, twice as long as the monofunctional oligomer, has very little plasticizing action and, at high concentrations, phase separates from the PS−SSA, despite extensive intercomponent interactions. This is related to a copolymer effect, suggested to be all the more pronounced because no cluster phase is apparent.

No abstract

Monodisperse tert-butyl acrylate (tBA) oligomers of several lengths, functionalized at one end by a tertiary amine, were ionically grafted to lightly sulfonated polystyrene. Despite the oligomers being immiscible with the polystyrene matrix, dynamic mechanical analysis of the blends indicates only a weak phase separation effect, and the polymer is plasticized moderately. However, the blends (studied up to 30 wt %) are translucent, suggesting phase separation on a larger scale. A possible explanation is given in terms of nonspherical tBA domains subject to a hard-wall effect coupled with interfacial ionic interactions as well as ester−acid interactions. Evidence for the latter was noted in the infrared spectra.