title: Direct observation by laser scanning confocal microscopy of microstructure and phase migration of PVC gels in an applied electric field.
abstract: The fluorescent probe lucigenin was incorporated in poly(vinyl chloride) (PVC) gels, and laser scanning confocal microscopy (LSCM) was used to clarify the internal structures of the gels. From the two-dimensional and three-dimensional information by LSCM, we first observed the internal structure of the PVC gel at a wet status, where the PVC gels comprised a polymer-rich phase and a polymer-poor phase uniformly with a three-dimensional network structure. After an electric field was applied, an effect of the electric field resulted in the change of internal structure in the gels. The polymer-poor phase moved from the cathode to the anode and the polymer-rich phase formed linelike arrangement between electrodes due to the attraction force. On the other hand, the freeze-dried PVC gels with/without in-situ dc voltage casting were particularly fabricated to confirm above results by the field emission scanning electron microscopy (FE-SEM). It was found that many craters remained on the surface of the gel near the anode due to sublimation in freeze-drying. This phenomenon did not appear on the surface near the cathode. The results of in-situ dc voltage casting also suggested that a substantial amount of polymer-poor phase was moved and fixed at the anode. Thus, results of both LSCM and in-situ dc voltage casting corresponded to the effect of electric field on PVC gels and provided a convincing evidence for the interpretation of the deformation mechanism of PVC gel actuators by an applied electric field.
authors.affiliation: Smart Materials Engineering, Faculty of Textile and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan.
authors.forename: Hong
authors.initials: H
authors.lastname: Xia
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Ueki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Hirai