Preparation and characterization of high dielectric calcium copper titanate/polyimide composite films
Calcium copper titanate (CaCu3Ti4O12; CCTO)/polyimide (PI) composite films were synthesized by 4,4' oxydianiline, CCTO, and 3,3',4,4' biphenyltetracarboxylic dianhydride through ultrasonic dispersion in situ polymerization. Scanning electron microscopic images clearly confirmed that 10 wt% CCTO particles dispersed uniformly in composite films. When the content was 20 80 wt% CCTO particles were coated by PI in good condition, and globular particles dispersed in the composite films. PI and CCTO/PI were found to exhibit excellent thermal stability. The addition of CCTO has influence on the thermal properties of PI. Weight loss temperatures (5% and 10% of the composite films containing 70 wt% CCTO reached 612degC and 673.9degC, respectively. The strong interfacial interaction between PI and CCTO improved the dielectric properties of the composite films. The dielectric permittivity and conductivity of the CCTO/PI composite films increase with the increase of CCTO content. In addition, the dielectric permittivity of films containing 40 70 wt% increased rapidly.