Electroactive polymers based on novel ionomers

A majority of research on ionic polymer transducers has used Nafion™ as the base material. Varying the physical and chemical properties of Nafion is difficult, which limits the understanding and development of ionic transducers. In this study we investigate a novel class of polymers called BPSH (sulfonated poly(arylene ether sulfone)s). The polymers are synthesized by the direct polymerization of sulfonated monomers. This synthetic scheme affords precise control of the amount and the location of ionic groups along the polymer backbone. These polymers differ from Nafion™ in two major ways. First, the concentration of ionic groups on a mass basis is almost double that of standard Nafion™, 1.51 meq/g for BPSH-30 versus 0.91 meq/g for Nafion™ 1100. Also, the backbone of the BPSH copolymers is much stiffer than Nafion, which affords a higher modulus material. Both of these factors, ion content and modulus, are expected to affect the performance of polymer-based actuators. Another ionomer characterized is the PATS (poly(arylene thioether sulfone)s) which is similar to BPSH. For both polymers we are varying the ionic concentration, stiffness, and water content. Those variations are fostering the understanding of operating concepts of ionic transducers, especially the correlation between ionic concentration and performance. Experiments on BPSH-35 demonstrate improved performance as compared to Nafion™. They provide larger strain per unit volt, larger force generated, and larger bandwidth. The novel polymers are characterized as sensors and actuators.