Phthalonitrile-Terminated Silicon-Containing Oligomers: Synthesis, Polymerization, and Properties

A novel silicon-containing phthalonitrile-terminated fluorene-based oligomer was synthesized by a novel method, and the structure was characterized by Fourier transfrom infrared spectroscopy, H-1 NMR, and gel permeation chromatography. The prepolymer was obtained by blending the oligomer with curing agent, and the curing behavior was systematically studied by differential scanning calorimetry, infrared, and rheology tests. The oligomer exhibited excellent solubility, even in acetone under room temperature, which greatly facilitated prepreg preparation. The quartz fiber-reinforced composites were prepared by a hot-pressing process. The cured polymers and composites possessed excellent thermal properties. Under inert atmosphere, the maximum 1000 degrees C residual weight was 88% and the 5% thermal degradation temperature was 662 degrees C More importantly, no obviously decrease in storage modulus was detected until 500 degrees C, suggesting sufficiently high heat resistance. Additionally, the composites exhibited outstanding flame retardant, ablative, and dielectric properties. Consequently, the current resin could be potentially applied in either high-temperature structural or functional composites.