新型SiBNC陶瓷先驱体——聚硼硅氮烷的合成与表征

以甲基氢二氯硅烷、三氯化硼、六甲基二硅氮烷为起始原料, 采用共缩合的方法合成了一种新型的可溶可熔的SiBNC陶瓷先驱体--聚硼硅氮烷(PBSZ). 该法合成工艺简单, 且合成收率约为91% (w%). 采用元素分析、傅立叶红外光谱、核磁共振波谱、X射线光电子能谱、动态热机械分析、热重分析等对PBSZ的组成、结构和性能进行了表征. 结果表明, 先驱体的主要骨架为-Si-N-B-, 其中, B, N以硼氮六环形式存在, 而C则以Si-CH₃形式存在. 该先驱体熔点为69 ℃, 数均分子量为10802, 分子量分散系数为1.50. 此外, 所合成的先驱体具有优良的成型性, 在80 ℃的N₂气氛中可纺丝得到15～20 μm的有机纤维, 1000 ℃时相应陶瓷产率约为63% (w%).

Synthesis and Characterization of Polyborosilazane as Novel Precursor to SiBNC Ceramic

A novel soluble preceramic polymer to SiBNC ceramic, polyborosilazane (PBSZ), was synthesized via a cocondensation approach with a yield of about 91% (w%) by using dichloromethylsilane (MeHSiCl₂), boron trichloride (BCl₃) and hexamethydisilazane (HMDZ) as the starting materials. The chemical composition, structure and properties of the obtained polymer were investigated using element analysis, FT-IR, NMR, XPS, TMA and TG. The results indicate that the backbone of the polymer is —Si—N—B— linkage in the form of borazine ring and C is in the form of Si—CH₃ in the pendant or end group. The melting point, number average molecular weight and polydispersity index of PBSZ is 69 ℃, 10802 and 1.50, respectively. PBSZ shows good processability and PBSZ fibers with diameter of 15～20 μm can be obtained by melt spinning at 80 ℃ in N₂ atmosphere. The ceramic yield of the PBSZ at 1000 ℃ in nitrogen atmosphere is 63% (w%), which suggests that the as-achieved polymer can be used as a precursor to SiBNC ceramic fiber.