Synergistic Effects of Mechanical, Thermal, and Optical Properties of Polyimide Composite Films Reinforced with WO3 Nanorods

In this study, WO3 nanorods are directly blended with polyamic acid (PAA) solutions to improve the electrochromic capacity of WO3/PAA composite films. Specifically, the hexagonal WO3 nanorods are prepared as inorganic reinforcements using a hydrothermal method and modified by gamma-aminopropyl triethoxysilane. After curing at 300 degrees C, the WO3 nanorods/polyimide (PI) composite films demonstrate excellent mechanical and thermal properties. The tensile strength of the 1 wt% WO3/PI composite film is approximate to 110.27 MPa. The thermal stability of the 5 wt% WO3/PI composite film is better than that of the others, and the T-5 (5% thermal weight loss temperature) value is approximate to 560.05 degrees C. Moreover, the WO3/PAA composite films demonstrate electrochromic behaviors. The electrochromic range of the 5 wt% WO3/PAA composite film exceeds to 68%. For the WO3/PAA samples, the oxidation peak of the WO3 nanorods is evident in the cyclic voltammetry curves. The color contrast of WO3/PI nanocomposites can be enhanced owing to the significant synergistic effects of the electron donor-acceptor system.