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

Abstract In this study, WO 3 nanorods are directly blended with polyamic acid (PAA) solutions to improve the electrochromic capacity of WO 3 /PAA composite films. Specifically, the hexagonal WO 3 nanorods are prepared as inorganic reinforcements using a hydrothermal method and modified by γ ‐aminopropyl triethoxysilane. After curing at 300 °C, the WO 3 nanorods/polyimide (PI) composite films demonstrate excellent mechanical and thermal properties. The tensile strength of the 1 wt% WO 3 /PI composite film is ≈110.27 MPa. The thermal stability of the 5 wt% WO 3 /PI composite film is better than that of the others, and the T 5 (5% thermal weight loss temperature) value is ≈560.05 °C. Moreover, the WO 3 /PAA composite films demonstrate electrochromic behaviors. The electrochromic range of the 5 wt% WO 3 /PAA composite film exceeds to 68%. For the WO 3 /PAA samples, the oxidation peak of the WO 3 nanorods is evident in the cyclic voltammetry curves. The color contrast of WO 3 /PI nanocomposites can be enhanced owing to the significant synergistic effects of the electron donor–acceptor system.