新型SiBNC陶瓷先驱体——聚硼硅氮烷的合成与表征

Synthesis and Characterization of Polyborosilazane as Novel Precursor to SiBNC Ceramic

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15～20μm的有机纤维,1000℃时相应陶瓷产率约为63%(w%).

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.