Novel thermoplastic elastomeric gels as high-performance actuators with no mechanical pre-strain

Abstract

Nanostructured organic materials derived from block copolymers solvated by block-selective solvents have shown considerable potential as versatile dielectric elastomers. These materials can easily be tuned to achieve the mechanical and electrical properties required for actuator applications. They are lightweight and attractive due to their facile processing, robust properties and reliable performance. Their superb actuation behavior is realized when they are used as dielectric materials under actuation conditions promoting Maxwell compression, which produces large mechanical displacements, coupling efficiencies, and energy densities. These properties generally improve when the material is subjected to mechanical pre-strain. In most cases, mechanical pre-strain is needed to safely achieve application of a desired electrical field. Requisite pre-strain generally necessitates additional overhead in terms of weight and space for the device, and promotes changes in mechanical properties. In this study a new electroactive nanostructured polymer (ENP) is prepared from a triblock copolymer and a nonvolatile block-selective solvent, and evaluated as an actuator candidate. The copolymer exhibits reasonably high actuation strains (up to 70 area%) at relatively low electric fields and energy densities up to 50 kJ/m 3 without pre-strain. These performance metrics exceed those reported for conventional dielectric materials such as the VHB acrylic elastomer, as well as those of ENPs derived from styrenic triblock copolymers under no pre-strain.