Fabrication and excellent electroresponsive properties of ideal PMMA@BaTiO₃ composite particles

A series of core-shell-structured poly(methylmethacrylate)@BaTiO₃ (PMMA@BT) composite particles were constructed via the self-assembly of BT nanoparticles on the surfaces of PMMA cores through the covalent bonding of siloxane groups at room temperature. The PMMA@BT composite particles were characterized by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, video-based optical contact angle measurement, thermogravimetric analysis, and impedance analysis. The electroresponses of the obtained PMMA@BT composite particles were all stronger than that of pure BT, and the electroresponse depended on the weight percentage of the BT shell. The PMMA@BT particles with the optimal core-shell structure contained 58.14 wt% of BT shell. The surface hydrophilicity of the optimal particles was close to that of pure BT, and the dielectric constant was the greatest among the series of synthesized PMMA@BT particles. Thus, the optimized PMMA@BT particles demonstrated the strongest electroresponsive behavior in gelatin hydrogel elastomer, as demonstrated by polarized microscopy and dynamic mechanical analysis. The excellent electroresponsive property of the optimal PMMA@BT particles is reflected by the large sensitivity of the increase in storage modulus for the gelatin hydrogel elastomer containing the composite particles (21% at E = 0.8 kV mm^-1 and a particle loading of 1.0 wt%), far greater than that of pure BT particles (4.7%). Based on the sensitive electroresponsive properties, the PMMA@BT particles have potential applications as electroresponsive materials.