Balance of mechanical and electrical performance in polyimide/nano titanium dioxide prepared by an in‐sol method

Hybrid polyimide (PI)/titanium dioxide (TiO₂) films were prepared by in situ polymerization and sol–gel and in‐sol methods (where in‐sol method indicates that in situ polymerization and the sol–gel method were used in the same samples). The mechanical and electrical properties were found to be sensitive to the processing methods and the dispersion of nano titanium dioxide (nano‐TiO₂) in the PI matrix. For the PI/TiO₂ films prepared by the in situ polymerization method, their tensile strength increased with increasing TiO_{2‐in situ} (“TiO_{2‐in situ}” is “the TiO₂ nano‐particles prepared by in situ polymerization method”) concentration. However, the optimal corona lifetime of the PI/TiO₂ films was 15 min at 20 kHz and 2 kV because of poor dispersion. For the PI/TiO₂ films prepared by the sol–gel method, the corona lifetime reached 113 min because of superior dispersion and a tensile strength of about 19.63 MPa. A balance of mechanical and electrical performances was achieved with the in‐sol method. The corona‐resistant life of the PI/TiO₂ films was 43 min, which was about six times longer than that of the neat PI. Their tensile strength was 83.5 MPa; these films showed no decrease in this value compared with the pure PI films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44666.