Modification of Transparent Polyimide with High Aspect Ratio Nanowires to Simultaneously Improve the Thermal Conductivity, Haze, and Mechanical Properties.

Abstract

Currently, the high light transmittance and high haze thermally conductive polyimide film with excellent comprehensive performance exhibits great application prospects, while there are still challenges for achieving. Here, boehmite nanowires (BhNs) with an aspect ratio up to 60 for the modification of transparent polyimide (CPI) derived from the polymerization of fluorodiamine and fluorodianhydride, are prepared. Due to the unique size and orientation distribution of BhNs in CPI films, the as prepared CPI-BhN composite films show in-plane thermal conductivity up to 5.89 W m^-1 K^-1, which is almost an order of magnitude higher than that of pure CPI (0.626 W m^-1 K^-1). Meantime, optimal CPI-BhN composite films show a light transmittance of 52.9% at 550 nm and a haze of 35.3%. In addition, the BhNs form a strong hydrogen bond with the CPI polymer chains, enhancing the mechanical properties of the composite films. Studies on thermal stability, fatigue resistance, and flame retardancy indicate that the CPI-BhN composite films have excellent performances. These findings provide a new idea for the design and fabrication of high-performance composite films for new-generation optoelectronic devices.