甲胺/二甲胺共取代合成氮化硼先驱体聚硼氮烷

Synthesis of Polymeric Precursor for Boron Nitride through Substitution Reaction of Methylamine/Dimethylamine

将三氯环硼氮烷(TCB)与甲胺/二甲胺进行共胺解取代反应,首先制得了不同胺基的取代单体,经过进一步热聚合反应合成了聚硼氮烷先驱体.通过对不同单体的聚合产物组成与结构分析,探讨了不同取代基对热聚合反应及产物结构的影响.研究表明,当控制甲胺/二甲胺摩尔比为1∶2,聚合温度180℃,获得的聚硼氮烷数均分子量为7603,分子量分散系数为1.80,熔点为83℃,组成为BC0.76N1.39H2.5,该聚合物具有近似线性分子结构,表现出优良的可纺性,可制得平均直径10～15μm的先驱体纤维,为制备氮化硼纤维奠定了基础.

Based on B-trichloroborazine （TCB） with boron-nitrogen ring structure, the monomer was synthesized by substitution reaction with different ratio of methylamine/dimethylamine, then the corresponding polyborazine was obtained through thermal polymerization. The chemical component and structure of polyborazine were analyzed, and the influence of different methylamine/dimethylamine molar ratio on the polyborazine properties and spinnability were examined. The results indicated when the molar ratio of methylamine/dimethylamine was 1∶2, the polyborazine with chemistry stability was prepared through thermal polymerization at 180 ℃. The melting point, number average molecular weight and polydispersity index of polyborazine precursor was 83 ℃, 7603 and 1.80, respectively. The polyborazine precursor could possess nearly linear molecule skeleton and show good processability. The precursor fibers were prepared with average diameter 10～15 μm and BC0.76N1.39H2.5 structure, which suggested that the as-achieved polymer could be used as a precursor for BN ceramic fibers.