Electric-Field-Induced Actuation of Poly(vinyl alcohol) Microfibers

Poly­(vinyl alcohol) (PVA) microfibers were actuated by application of a direct current (dc) electric field; there were large electrosensitivity differences between water-soluble and high-tenacity fibers. In particular, a bending actuation was observed for water-soluble PVA fibers with high sensitivity and large deformation upon applying a dc electric field. The mechanism of bending actuation was investigated through analysis of the chemical constituents, dielectric properties, bending rigidity, and morphology. It was found that the actuation behavior depends mainly on the mechanical and dielectric properties, which are related to the chemical structures of the fibers. It is clear that hydroxyl and carbon–oxygen double bonds are key factors influencing the electroactive characteristics. The content of hydroxyl groups not only determines the solubility of PVA fibers in water but also controls the antielastic bending. The content of CO groups may be related to the dielectric constant and bending rigidity. Furthermore, the CS bond in the X-ray photoelectron spectrum indicates that dimethyl sulfoxide remains even after solvent removal, and this can make it easier for the PVA fibers to become positively charged and then bend toward the cathode.