不同侧基耐热聚硅乙炔树脂的制备及其热性能

Preparation and Thermostability of Heat-resistant Poly(silylene acetylene)Resins with Different Side Groups

利用格氏试剂法合成了5种含不同侧基的端乙炔基硅乙炔树脂(ETSA),通过核磁共振氢谱(^(1)H-NMR)和傅里叶转换红外光谱(FTIR)对其结构进行了表征,用体积排除色谱法测其分子量,利用示差扫描量热仪(DSC)研究了ETSA树脂的固化行为,通过热失重分析仪(TGA)研究了ETSA树脂固化物的热稳定性,并利用高分辨透射电镜(HRTEM)和小角X光散射(SAXS)研究了ETSA树脂固化物的微孔结构.另外,使用2种镍系催化剂对ETSA树脂的固化反应进行催化,并通过DSC、FTIR和TGA研究了催化剂对ETSA固化的催化效果.结果表明,ETSA树脂随主链中硅原子上侧基体积的增大,聚合度依次下降,固化放热峰峰值温度向高温方向移动,放热焓显著下降.ETSA固化树脂具有优异的热稳定性,氮气与空气中的5%热失重温度(T_(d5))都超450℃,800℃残留量(Y_(r800))分别超过80%和27%.ETSA固化树脂交联网络微孔随侧基体积增加而增大.镍系催化剂对ETSA树脂的固化反应具有较好的催化效果,降低起始固化温度大于50℃,催化固化树脂的Y_(r800)变化不大.ETSA树脂有望用作高耐热树脂基体和聚合物陶瓷前驱体.

Five ethynyl-terminated poly(silylene acetylene)(ETSA)resins with different side groups at Si atom were synthesized using the Grignard reagent method.The structures of ETSA resins were characterized by proton nuclear magnetic resonance(1H-NMR)and Fourier transformation infrared(FTIR).The size exclusion chromatography was used to measure the molecular weight and distribution of ETSA resins.The curing behaviors of ETSA resins were investigated using differential scanning calorimetry(DSC).The thermal stability of cured ETSA resins were studied by thermogravimetric analysis(TGA).Furthermore,the microporous structure of cured ETSA resin was investigated using high resolution transmission electron microscopy(HRTEM)and small angle X-ray scattering(SAXS).Additionally,two nickel-based catalysts were used to catalyze the curing reaction of the ETSA resins,and the catalytic effect of the catalysts on the curing reaction of ETSA resins were evaluated by DSC,FTIR and TGA.The results show that the degree of polymerization of ETSA resin decreases with increase of the volume of side group at Si atom in the backbone of ETSA.The peak exothermic temperature of the ETSA moves to a high temperature during curing,and the exothermic enthalpy and curing degree of the ETSA decrease with the increase of the volume of side group.The cured ETSA resins display excellent thermal stability.The temperature of 5%weight loss(T_(d5))of the cured ETSA resins in nitrogen and air are higher than 450℃.The residual yield at 800℃(Y_(r800))in nitrogen and air of the cured ETSA resins are larger than 80% and 27%,respectively.The microporous size in the cross-linked networks of ETSA increases with the increase of the volume of side group.The nickel-based catalysts exhibit the good catalytic effect on the curing reaction of ETSA.The inital temperature of catalyst-curing ETSA resins can drop over 50℃,but the Y_(r800 )of the catalyst-cured ETSA resins change not much.The ETSA resin is promising to be used as a highly heat-resistant resin matrix and a polymeric precursor.