Influence of Monomer Structures on the High Temperature Properties of Poly((Alkylamino)Borazine))s Derived BN

Abstract

Preceramic polymers to boron nitride (BN) have been synthesized by thermal condensation of different (alkylamino)borazine monomers. Crystalline BN was obtained by pyrolysis of those polymeric precursors in NH3 and then in Ar. The influence of monomer structure on the chemical composition, microstructure, oxidation resistance and high temperature stability of BN was investigated by a combination of elemental analysis (EA), density measurement, FTIR, XPS, XRD, HRTEM and TGA. With similar chemical composition, BN derived from symmetric monomer exhibited a higher crystallinity, better oxidation resistance and higher temperature stability. This was because that the structure of the precursor polymerized from symmetric molecular was close to that of hexagonal BN (h-BN).