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Soluble and Meltable Hyperbranched Polyborosilazanes toward High-Temperature Stable SiBCN Ceramics

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journal contribution
posted on 01.04.2015, 00:00 by Jie Kong, Minjun Wang, Jianhua Zou, Linan An
High-temperature stable siliconborocarbonitride (SiBCN) ceramics produced from single-source preceramic polymers have received increased attention in the last two decades. In this contribution, soluble and meltable polyborosilazanes with hyperbranched topology (hb-PBSZ) were synthesized via a convenient solvent-free, catalyst-free and one-pot A2 + B6 strategy, an aminolysis reaction of the A2 monomer of dichloromethylsilane and the B6 monomer of tris­(dichloromethylsilylethyl)­borane in the presence of hexamethyldisilazane. The amine transition reaction between the intermediates of dichlorotetramethyldisilazane and tri­(trimethylsilylmethylchlorosilylethyl)­borane led to the formation of dendritic units of aminedialkylborons rather than trialkylborons. The cross-linked hb-PBSZ precursors exhibited a ceramic yield higher 80%. The resultant SiBCN ceramics with a boron atomic composition of 6.0–8.5% and a representative formula of Si1B0.19C1.21N0.39O0.08 showed high-temperature stability and retained their amorphous structure up to 1600 °C. These hyperbranched polyborosilazanes with soluble and meltable characteristics provide a new perspective for the design of preceramic polymers possessing advantages for high-temperature stable polymer-derived ceramics with complex structures/shapes.