Miscibility enhancement in polymers via ionic interactions: Dynamic mechanical and NMR studies

Abstract

AbstractThe presence of ionic interactions can be used to control the degree of miscibility of otherwise immiscible polymer systems. This control, in turn, allows one to prepare blends with a very wide range of “tailor‐made” properties. Several examples are cited. In some of these, the interactions are based on proton transfer from a donor site on one polymer to an aceptor site on another leading to ion‐ion interactions. In others, the transfer of a metal cation from an ionomer to a polar polymer, as a result of ion‐dipole interactions, is involved. Systems studied to date include, among others, mixtures of polystyrene with poly(ethyl acrylate), polyisoprene, segmented poly urethanes, poly(ethyleneimine), and poly(ethylene oxide). The polyurethane blends with polystyrene are discussed in some detail, focussing especially on the mechanism of miscibility enhancement as determined by NMR. This technique has also been utilised to study the dynamics of the coil overlap process in solution as well as the proximity of the polymer coils to each other. Two particularly noteworthy applications involve mixtures of poly (tetrafluoroethylene) (PTFE) or of phenylated poly(phenylene oxide) with poly (ethyl acrylate), which are also discussed in some detail. Blends of this type may be of special interest in membrane applications.