Synthesis and characterization of phenylethynyl-terminated polyimide/carboxylated multiwalled carbon nanotube composite film

Phenylethynyl-terminated polyimide (PI)/carboxylated multiwalled carbon nanotube (MWCNT) composite films were synthesized from 4,4′-oxydianiline, carboxylated MWCNTs, and 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and capped by 4-phenylethynylphthalic anhydride through in situ polymerization under sonication. The results of scanning electron microscopy indicated that the carboxylated MWCNTs were uniformly dispersed in the phenylethynyl-terminated PI matrix. Thermal gravimetric analysis indicated that the initial thermal decomposition temperatures of the films were up to 500°C, and the addition of carboxylic MWCNT have advantage of thermal properties of the phenylethynyl-terminated PI. The dynamic mechanical thermal analysis results clearly indicated that the glass transition temperature increases with increasing carboxylated MWCNT content. In addition, the mechanical properties of the composite films were improved by the carboxylated MWCNTs. The electrical properties were greatly enhanced due to the good conductivity of the carboxylated MWCNTs.