Synthesis and polymer‐to‐ceramic conversion of tailorable copolysilazanes

Abstract

Tailorable copolysilazanes (CPSZs) with variable chemical structure and molecular weights were prepared by coammonolysis of dichloromethylsilane, dichloromethylvinylsilane, and trichloromethylsilane. The as-synthesized CPSZ was characterized by gel permeation chromatography, Fourier transformed infrared (FTIR) spectroscopy, and nuclear magnetic resonance spectroscopy. The CPSZ could be cured in an inert atmosphere at 180 C for 24 h. Pyrolysis behavior and structure evolution of the cured CPSZ were studied by means of thermal gravimetric analysis and FTIR. Hydrosilylation, transamination, dehydrogenation, and demethanation reactions were involved in the polymer-toceramic conversion of CPSZ. The ceramization process was complete at 900 C with a ceramic yield of 81-84%. Elemental analysis indicated that the compositions of final ceramics can be tailored by controlling the feed ratios of the starting chlorosilanes. Moreover, the microstructural evolution of the resultant SiACAN ceramics was further investigated by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy.

Molecular‐Level Processing of Si‐(B)‐C Materials with Tailored Nano/Microstructures

“…This confirms that the hydroboration is complete and is not regioselective. The main signal from −10 to 3 ppm can be assigned to Si− C H 3 and Si− C H 2 − environments, whereas the signal at 50 ppm is tentatively attributed to the −O C H 3 environment on the basis of the 1 D 1 H decoupled 13 C and DEPT‐135 and 90 spectra (see Figure S2 a, Supporting Information) and the 2 D spectra of AHPCS, including Heteronuclear Single Quantum Correlation (HSQC, see Figure S2 b), Heteronuclear Multiple Bond Correlation (HMBC, see Figure S2 c), and 1 H– 1 H correlation spectroscopy (COSY, see Figure S2 d). This indicates that oxygen does not come from the reaction, but from AHPCS.…”

Preparation, characterization and properties of fiber reinforced composites using silicon-containing hybrid polymers

“…While in the third stage (>300 °C), the storage modulus and viscosity of matrix resins change very little and tend to be constant again. This can be explained by the reactions between APABS and PMES, which occurred during the second stage (200–300 °C) to form crosslinking structures . The results are consistent with the obtained DSC analysis.…”

“…Figure shows the DSC curve of matrix resins. An obvious exothermic peak at 237 °C indicates crosslinking reactions due to (i) the hydrosilylation reaction between Si‐H and C≡C; (ii) Diels‐Alder reaction between C≡C groups; (iii) dehydrogenative coupling of Si‐H and N‐H units; (iv) the hydronitrilation reaction between N‐H and C≡C units, and a thermally stable structure is formed (Scheme ). No endothermic or exothermic transitions are observed for higher temperature, which imply that the matrix resins can be cured under 300 °C.…”

A new organosilicon adhesive based on polysiloxane and polysilazane

“…It is worth noting that the absorptions of Si-H at 2163 cm À1 and Si-Vi at 1594 cm À1 did not appear to change. 28 These facts suggest that the curing of the adhesive at room temperature is due to the reaction between Si-OH in PSO and Si-N in PSN, which results in the formation of Si-O-Si linkage. This is in accordance with the results obtained for other siloxane and silazane systems.…”