Synthesis and characteristics of polycarbomethylsilane via a one-pot approach

Abstract

A one-pot approach was developed to synthesize polycarbomethylsilane by using dicholorodimethylsilane, titanocene dichloride, and sodium metal as the reactants. This approach was developed because polycarbomethylsilane is a well-known polymeric precursor for fabricating silicon carbide fibers. The as-synthesized product and the derived fibers were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, 29Si nuclear magnetic resonance spectroscopy, gel permeation chromatography, simultaneous thermogravimetry-differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy coupled with energy-dispersive X-ray microscopy. The results revealed that the as-synthesized product was Ti-containing polycarbomethylsilane with a linear-chain structure and possessed an appropriate molecular weight and a narrow molecular distribution. It was found that the dicholorodimethylsilane-to-titanocene dichloride molar ratio affected the characteristics of the product, such as the product yield, molecular weight, and polydispersity. Based on the experimental results and referring to the catalytic polymerization of 1-olefin, a possible heterogeneous reaction mechanism is proposed. The as-synthesized product could be electrospun into green fibers. After curing at 180 °C for 1 h in air and calcining at 1200 °C for 2 h under a N2 atmosphere, the green fibers were transformed into ceramic fibers with a diameter less than 2 μm and an aspect ratio greater than 200. The fibers were composed of β-silicon carbide and titanium carbide.