Glass Transition Temperatures in Styrene Ionomers and their Blends

Abstract

The effects of ion incorporation on the glass transition temperature of styrene ionomers and their blends are reviewed. Two types of ionic aggregates, i.e., multiplets and clusters, have been postulated for anionic ionomers based on styrene, and the materials are thus phase separated above a certain ion content. The effects of the nature of the anions and the cations on the glass transition temperature of each of the phases are briefly summarized. Styrene ionomers with pendant cations, e.g. 4-vinylpyridine-methyl iodide, are not phase separated. The influence of the presence of ions on the Tg in these materials are much more straightforward. Quaternization of styrene-vinylpyridine copolymers with long chain alkyl halides is obviously possible, and it leads to internal plasticization. These aspects also discussed, as are the effects of blockiness in quaternized ionomers. In the last section, the effects of ionic interactions on the glass transition temperature of ionomer blends are examined. The presence of ionic interactions increases the miscibility of otherwise immiscible polymer pairs to the point of homogeneity, and raises their glass transition temperatures.