Silicon-containing polyborazine, a novel precursor to boron nitride ceramic fibers, was synthesized via “one-pot” approach with a yield of about 87% (w%) using boron trichloride (BCl₃) and hexamethydisilazane (HMDZ) as the starting materials. The chemical composition, structure and properties of the obtained precursor were investigated using EA, FT-IR, NMR, TMA and dynamic rheological measurement. The results indicate that the backbone of the polymer is N—B linkage in the form of borazine and Si is in the form of Si—CH₃ and Si—N in the pendant or end group. The softening point of the precursor is 110 ℃. The precursor shows good processability and the precursor fibers with diameters of 20～25 μm can be obtained by melt spinning at 190 ℃ in N₂ atmosphere.

Key words: silicon-containing polyborazine, polymer derived ceramic, preceramic polymer, synthesis