Performance of PMMA-PnBA-PMMA dielectric film actuator with controllable phase morphology

Electromechanical responses were investigated for poly(methyl methacrylate)(PMMA)-b-poly(n-butyl acrylate)(PnBA)-b-poly(methyl methacrylate)(PMMA) films with cylindrical and lamellar morphologies, prepared with two casting solvents. Toluene and acetone were used as casting solvents because their solubility parameters are very similar to the solubility parameters of PnBA and PMMA, respectively. The mechanical responses of films revealed that when acetone was used as a casting solvent the film formed with PMMA as a continuous phase, and when toluene was used as a casting solvent, the film formed with PnBA continuous phase. Films were pre-strained right before actuation to increase actuation performance. The film with a PnBA continuous phase with cylindrical structure showed almost 12% strain, whereas the film forms with PMMA continuous phase showed almost 4% strain in an electric field with same magnitude. These results were consistent with the results of dielectric constant data. Moreover the film that formed a PnBA continuous phase started to actuate at a lower electric field strength, and showed rapid deformation with and without electric field, compared to film with PMMA continuous phase.