SiBCN聚合物前驱体聚合机理的研究

摘要

SiBCN陶瓷前驱体的合成对于制备非晶SiBCN 陶瓷有着重要的意义，本文研究了SiBCN聚合物前驱体聚合过程中不同阶段的产物的结构变化，研究表明在合成前驱体的氨解过程中，单体聚合反应的机理是首先氨气与氯硅烷单体上的氯发生反应生成伯胺，然后伯胺与其他的氯硅烷单体上的氯反应聚合生成仲胺。最终产物中伯胺和仲胺的数量由氨气流量的大小决定。氨气流量较小时，产物主要是仲胺；氨气流量大时，以伯胺为主。在此过程中并不会发生伯胺与伯胺发生反应脱掉氨气生成仲胺的化学反应。因此，氨气流量过大会降低陶瓷前驱体的聚合度。%The synthesis of SiBCN polymer precursor is of great importance for the amorphous SiBCN ceramics .In this paper ,the structure evolution of the products in each steps of polymerization was researched .Polymerization reaction occurs during ammonolysis process .The NH2 group is firstly produced by the reaction between NH3 and -Cl ,and then -NH2 reacts with -Cl ,whose reaction product is -NH - .The contents of -NH2 and -NH - are affected by the flow of ammonia gas . When the flow is low ,the main reaction product is -N H - ,and w hen the flow is high ,it is -N H2- .Therefore ,the high flow of ammonia gas would decrease the degree of polymerization .