Quick and large electrostrictive deformation of non-ionic soft polymer materials

Various type of non-ionic soft polymer materials from polymer gel to elastomers were actuated in efficient and remarkable manners by applying an electric field. The polymer gel swollen with large amount of dielectric solvent showed not only remarkable contraction and relaxation in the direction of the field, but also huge bending deformation within dozens of milliseconds. Molecular orientation of solvent did not play a critical role in the bending deformation, but a solvent drag induced by the field was the origin of an asymmetric pressure distribution which bended the gel. In the case of plasticized polymer, the solvent (or plasticizer) drag was difficult and negligibly small. However, we found a reversible creep deformation of the plasticized polymer. The deformation only occurred on the electrode surface. The strain induced could have reached over 300%. The sample was stable over 2 years. This creep deformation was successfully applied in bending of 100 degree per 30 milli-second under the current of nano-ampere range. Non-ionic polyurethane elastomers, which contained neither solvents nor plasticizers, could also be electrically bended, and the deformation was controlled systematically by changing chemical structures. The bending deformation showed memory effect, and the direction of the bending was chemically controllable. It was suggested that an asymmetric space charge distribution in the polymer film plays a critical role in the bending deformation. The concept presented through these works will be a guide to a novel type of electrically active dielectric-soft-polymer actuator or a kind of artificial muscles.