Synthesis, Characterization and Performance Study of Borosilazane as UV-Curable Borazine-Type Single Source Precursors for SiBNC Ceramic

A novel borosilazane monomer terminated with Si-Cl groups: B,B',B"-tris[(trichlorosilyl)methyl] borazine (TSMB) was synthesized through one-step route by reacting boron trichloride (BCl3), chloromethyl trichlorosilane (CH2ClSiCl3) with hexamethyldisilazane (HMDZ) as the starting materials. From functionalizing TSMB by 2-hydroxethyl acrylate and 2-hydroxyethyl vinyl ether, two UV-curable single source precursors a-TSMB and e-TSMB were obtained, respectively. Then ceramic materials C1 and C2 can be prepared with a-TSMB and e-TSMB through UV-curing and cracking under 1400 °C for 2 h. The chemical composition, structure, photo-curing performance and ceramic yield of the TSMB, a-TSMB and e-TSMB were investigated using infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), differential photocalorimetry (DPC), real time infrared spectroscopy (RT-IR) and thermo gravimetric analyzer (TGA). The content and high temperature performance of the ceramic C1 and C2 were studied by element analysis, X-ray photoelectron spectroscopy analysis (XPS) and X-ray diffraction (XRD). Results show that both the two ceramic precursors molecules, a-TSMB and e-TSMB, contain the B-N six-member 1036 化 学 学 报 Vol. 70, 2012 ring structure, and are terminated with acrylate or vinyl ether functional groups, which matches well with the theoretical design. The photo polymerization of the a-TSMB and e-TSMB can finish 82% and 67% in 25 s, the final conversion of the double bond can reach 90.0% and 74.0%, and the corresponding ceramic yield at 1300 °C is 57.9% and 48.5%, respectively. There are five elements, Si, B, C, N, and O in the C1 and C2 ceramic materials, and the contents of B are 4.4% and 4.9%, respectively, which can achieve the requirement for the high temperature ceramic material on the B element. Both the ceramic materials C1 and C2 can preserve amorphous states at 1400 °C and have excellent high-temperature resistance properties.