Nanostructured Triblock Copolymer Network With Tailorable Electroactive Response

In recent years, the use of electroactive polymers (EAPs), which are polymeric materials that respond to an external electrical stimulus by changing shape or size, has been the focus of considerable research effort. While most studies have considered chemically cross-linked homopolymers, only a few reports have addressed the use of physically cross-linked triblock copolymer systems. We have previously demonstrated that triblock copolymer networks swollen by a midblock-selective, nonvolatile solvent constitute excellent candidates as dielectric elastomers, one class of EAP materials. Due to the presence of a molecularly self-organized nanostructure in such materials, this EAP genre is generally referred to as electro-active nanostructured polymers (ENPs). These systems not only exhibit high actuation strains (>200%), but are also amenable to facile processing and recycling. In this study, we examine the electromechanical response of symmetric triblock copolymers possessing styrenic endblocks and a rubbery midblock selectively solvated with an aliphatic mineral oil. Our findings show that the specimen thickness has a significant effect on the electroactive response of the system. Moreover, we are able to correlate the electromechanical properties of ENPs with their mechanical properties.