(651a) Design of Polymer-Based Actuators That Swell By Diffusion and Electroosmotically Induced Migration

Electrically controlled polymeric fibers have the potential to be used to actuate machinery and perform advanced mechanical work under isothermal conditions with a power to weight ratio greater than internal combustion engines. This study is motivated by the possibility of significant actuation from twisted and coiled polymer (TCP) fibers that rely on radial swelling to produce reversible work. An analytical thermodynamic expression based on Flory-Rehner Theory was combined with a numerical transport model in order to simulate transient swelling of a polymeric network driven by diffusion and migration. Radial swelling of polymer fibers was modeled, including parametric studies and comparison to experimental data. By increasing the transport distance, swelling is shown to increase the time to equilibrium, but this can be more than compensated for by applying voltage to take advantage of ion migration and electroosmotic drag. Fibers fabricated using a set of solvents of varied dipole moments are used to evaluate the contribution of migration and the effect of electroosmotic drag in the swelling of the TCP. A faster swelling rate is generated by the applied voltage which is used to move ions in a polyethylene glycol (PEG) network than from equilibrium swelling.