Synthesis, Thermal Properties and Ceramization Performance of Ethynylaniline-Terminated Polysilazane

Two kinds of polysilazane ceramic precursors (PCSN-A/PCSN-B) were synthesized by the ammonolysis reaction of dichloromethylsilane (MeSiHCl₂)/dimethyldichlorosilane(Me₂SiCl₂) and p-phenylenediamine terminated by m-amino-phenylacetylene (APA). The structure of PCSN was characterized by FT-IR. Differential scanning calorimetry (DSC) was used to study the curing behavior. The thermal resistance and ceramization performance of the cured polymer were investigated by thermal gravity analysis (TGA) and XRD. The results showed that PCSN-A could be highly crosslinked at a low temperature through hydrosilylation reaction and Diels-Alder reaction due to the existence of Si—H bond. PCSN-A exhibited better thermal resistance and ceramization performance than PCSN-B. The temperature of 5% weight loss (T_d5) of PCSN-A was 564 ℃ in nitrogen. After sintering at 1 450 ℃ in argon, PCSN-A thermoset turned into black inorganic ceramics composited of β-SiC, α-SiC and α-Si₃N₄ with a yield of 78.4%, indicating its potential to be used as high temperature resistant resin matrix and ceramic precursor.