Strain-enhanced nanocomposites of electrostrictive polymers and high-k nanofillers for micro-actuation applications

This paper reports on nanocomposites of enhanced field induced strain based on an electrostrictive polymer mixed with BaTiO3 and TiO2 nanofillers of high dielectric constants. Nanocomposite thin film bimorph actuator stacks were optimized with respect to the nanofiller homogeneous dispersion and thin film surface roughness upon film annealing. The investigations showed that the nanocomposite properties are strongly dependent on the nanofiller content, nanoparticle size and relative permittivity. By the addition of nanofillers, the electro-mechanical properties of the polymer matrix have been significantly improved. Particularly, we obtained increased permittivity to about 44 and about two-fold larger strain for a 2 wt% BaTiO3 nanocomposite and a 1.4 times larger strain for a 10 wt% TiO2 nanocomposite. FEM simulations indicate that nanocomposite based bending actuators can exhibit remarkably large deformation.