Precursor polycarbosilane containing acetylenic and SiH group (PCAS) has been successfully prepared by the reaction of dilithioacetylene with methyl dichlorosilane, and characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, ¹H-NMR, ¹³C-NMR, and ²⁹Si-NMR. Thermogravimetric analysis curve in nitrogen showed the temperature of 5 wt % weight losses (T_d5) was 613°C, while the ceramic yield of PCAS was 88% at 1000°C. Pyrolysis behavior and structure evolution of the cured PCAS were studied by means of X-ray diffraction, Raman, scanning electron microscope-energy dispersive X-ray spectrometer, transmission electron microscope (selected area electron diffraction and high resolution transmission electron microscope), and elemental analysis. The polymer to ceramic conversion was completed at 1600°C and the results revealed that the ceramic consisted of β-SiC and α-SiC. The composition of the ceramic was near-stoichiometric with molar ratio of Si/C (1.02 : 1) except rare and localized free carbon inclusions. The SiC ceramics exhibited high thermo-oxidation resistance at elevated temperatures in air atmosphere. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41335.

Three novel kinds of linear silicon-containing hybrid polymers with Si−C≡C units were synthesized by polycondensation reactions using the Grignard reagent method. All the polymers were thermosetting, highly heat-resistant, moldable and easily soluble in common organic solvents. The structure, curing behavior, thermal and oxidative properties were characterized using Fourier transform infrared spectroscopy, ¹H NMR, ¹³C NMR, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The results obtained can provide theoretical guidance for determining the curing of the resin system. In addition, the cured polymers exhibit excellent thermal and oxidative stabilities with temperatures of 5% weight loss (T_d5) above 480 °C and 450 °C in nitrogen and air respectively; the residues at 1000 °C were above 70.0% and 45.0% respectively. The thermal and oxidative stabilities of the polymers are attributed to a crosslinking reaction between the Si−H and C≡C bonds or C≡C bonds. These polymers have the potential for use as high-temperature-resistant resins and ceramic precursors. © 2013 Society of Chemical Industry

The synthesis and characterization of a novel heat-resistant boron-silicon hybrid polymer containing acetylene (PBSA) and its conversion to a highly crosslinked thermoset were discussed. The polymer was synthesized from phenylboron dichloride using Grignard reagent method. The structure of PBSA was characterized by using Fourier transform infrared spectra, ¹H-NMR, ¹³C-NMR, and gel permeation chromatography. PBSA was thermosetting, highly heat-resistant, high-viscous, orange liquid at room temperature and good solubility in common organic solvents. Differential scanning calorimetry and thermogravimetric analysis analyses showed that the PBSA had excellent thermal and oxidative stability and the temperature of 5% weight loss (Td₅) were 650 and 638°C under nitrogen and air, respectively, and the residue at 1000°C were 93.3 and 91.3%, respectively, which indicated that the incorporation of boron and silicon into polymeric backbone was found to improve thermal and oxidative properties. X-ray diffraction and scanning electron microscope were also used to analyze the formation of pyrolytic products. The results showed that the pyrolysis of PBSA resin was made up of β-SiC and graphite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012