Synthesis of pyridine-containing diamine and properties of its polyimides and polyimide/hexagonal boron nitride composite films

A pyridine-containing diamine, 4,4′-bis(5-amino-2-pyridinoxy)diphenyl ether, was prepared via a two-step procedure. Based on the diamine, a series of polyimides were prepared by traditional two-step method. The characteristic peaks of polyimides on their fourier transform infrared (FI-IR) spectra indicated full imidization. Thermogravimetric analysis (TGA), dynamical mechanical analysis (DMA), differential scanning calorimetry (DSC) and ultraviolet-visible (UV-vis) spectra data showed that the polyimides displayed good properties. Polyimide/hexagonal boron nitride (PI/hBN) composite films were prepared, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride based polyimide (PI-2) was used as the matrix. In addition, the effects of hBN content on the thermal conductivity (TC) of PI/hBN composites films were investigated. The TC of pure PI-2 was 0.148 W m−1 K−1, when the hBN content increased to 40 wt %, the TC increased to 0.686 W m−1 K−1. The enhancement in this TC value was as high as 460% compared to pure PI-2. Meanwhile, the PI/hBN composites films retained excellent thermal and dynamic mechanical properties.