以三氯化硼、六甲基二硅氮烷为起始原料,采用一步法合成了一种新型含硅氮化硼陶瓷纤维先驱体——含硅聚硼氮烷.该法合成工艺简单,且合成收率约为87%（质量分数）.采用元素分析、傅立叶红外光谱、核磁共振波谱、热机械分析、动态流变分析等对含硅聚硼氮烷的组成、结构和性能进行了表征.结果表明,N—B为含硅聚硼氮烷先驱体的骨架结构,其中,B,N主要以硼氮六环形式存在,而Si则以Si—CH3,Si—N形式存在.该先驱体软化点为110℃,具有优良的成型性,在190℃的N2气氛中可纺丝得到20～25μm的有机纤维.%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.
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