Influence of silane coupling agent on microstructure and properties of CCTO-P(VDF-CTFE) composites

Influence of the coupling agent on microstructure and dielectric properties of ceramic-polymer composites is systematically studied using CaCu₃Ti₄O12 (CCTO) as the filler, trichloro-(1H,1H,2H,2H-perfluorooctyl)-silane (Cl₃-silane) as coupling agent, and P(VDF-CTFE) 88/12mol.% copolymer as the matrix. It is demonstrated that Cl₃-silane molecules can be attached onto CCTO surface using a simple process. The experimental results show that coating CCTO with Cl₃-silane can improve the microstructure uniformity of the composites due to the good wettability between Cl₃-silane and P(VDF-CTFE), which also significantly improves the electric breakdown field of the composites. It is found that the composites using CCTO coated with 1.0wt.% Cl₃-silane exhibit a higher dielectric constant with a higher electric breakdown field. For the composites with 15vol.% CCTO that is coated with 1.0wt.% Cl₃-silane, an electric breakdown field of more than 240MV/m is obtained with an energy density of more than 4.5J/cm³. It is also experimentally found that the dielectric constant can be used to easily identify the optimized content of coupling agent.