Abstract: Poly[tri(isopropylamino)borazine] (PTPiAB), a soluble and fusible precursor to hexagonal-BN (h-BN), was synthesized under mild conditions using isopropylamine and trichloroborazine (TCB) as starting materials. h-BN was obtained by pyrolysis of PTPiAB in NH3 and then in Ar. The composition, structure and properties of PTPiAB and pyrolytic product were investigated by using elemental analysis, FT-IR, XRD, TGA and Network Analyzer. The results indicate that N-H, C-H, C-N bonds and B3N3 units exist in the structure of PTPiAB. The melting point is 70 oC. The weight loss mainly occurs below 800 oC and ceramic yields for the precursor in NH3 and Ar are 45.9 % and 52.8 % at 1000 oC, separately. Crystallization occurs at around 1000 oC and the (002) interlayer spacing and density are 0.334 nm and 2.03 g·cm-3 at 1800 oC, respectively. Furthermore, the BN illustrates superior oxidation resistance with weight increase lower than 0.3% below 900 oC in air. The BN also displays low dielectric constants with real part of 2.45 and loss tangent of 0.03 at 10 GHz at ambient temperature, respectively.

Key words: Poly[(alkylamino)borazine], Pyrolysis, Boron nitride, Crystallization, Oxidation resistance, Dielectric properties