Thermal Annealing Effects on the Physical Properties of Styrenic Pentablock Ionomers and Their Electromechanical Responses

Abstract

Thermal annealing effect on the physical properties of two ionic (poly((t-butyl-styrene)-b-(ethylene-r-propylene)-b-(styrene-r-styrene sulfonate)-b-(ethylene-r-propylene)-b-(t-butyl-styrene))) (SSPB) pentablock copolymers with different ion exchange capacities (IEC; 1.5 and 2.0 meq/g) and their electromechanical responses in ionic polymer-metal composite (IPMC) devices have been investigated. The ionic SSPB formed the microphase-separated morphology on the several tens nanometer scale and the selectively sulfonated styrene middle blocks formed the ionic channels through which ions can pass in the membrane. The thermal annealing at a high temperature led to the well developed interconnectivity between adjacent ionic channels, and thus enhanced the ion conductivity and mechanical strength of membranes, resulting in an actuation enhancement of the SSPB-based ionic actuator.