不同金属氯化物催化制备聚甲基硅倍半氧烷气凝胶及其性能研究

Preparation of polymethylsilsesquioxane aerogels catalyzed by different metal chlorides and study of their properties

分别以甲基三甲氧基硅烷(MTMS)和甲基三乙氧基硅烷(MTES)为硅源,以氯化镁、氯化铜、氯化铝和氯化铁水溶液为酸催化剂,采用常压干燥工艺制备聚甲基硅倍半氧烷(PMSQ)气凝胶。结果表明:在MTMS溶胶中掺入氯化镁或氯化铜水溶液或在MTES溶胶中掺入氯化铝或氯化铁水溶液均可制备出轻质(69.0~96.0mg/cm^(3))、高强度(0.302~0.583MPa)、高热稳定性(≥550℃)和超疏水(145.6~151.6°)的PMSQ气凝胶。以氯化铁水溶液为酸催化剂制备的气凝胶密度最低,线性收缩率(3.2%)最小,压缩强度和最大压缩应变(87.2%±0.2%)最高。以氯化镁水溶液为酸催化剂制备的气凝胶的常温热导率[33.5mW/(m·K)]最低,可在温度低于600℃时不发生—CH_(3)的热分解反应,在800℃时的质量损失仅为7.2%,在100℃和200℃的恒温加热台上加热300s,其表面温度从30℃分别上升至42.6℃和70.6℃,体现出极好的绝热性能。

Polymethylsilsesquioxane(PMSQ)aerogels were prepared by an ambient pressure drying process using methyltrimethoxysilane(MTMS)and methyltriethoxysilane(MTES)as the silicon source,and aqueous solutions of magnesium chloride,copper chloride,aluminum chloride and ferric chloride as the acid catalysts,respectively.The results showed that lightweight(69.0~96.0mg/cm^(3)),high-strength(0.302~0.583MPa),highly thermal stability(≥550℃)and superhydrophobic(145.6~151.6°)PMSQ aerogels were prepared by the incorporation of magnesium chloride or copper chloride aqueous solutions into MTMS sols,or aluminum chloride or ferric chloride aqueous solutions into MTES sols.The aerogels prepared with ferric chloride aqueous solution as acid catalyst had the lowest density,the smallest linear shrinkage(3.2%),and the highest compression strength and maximum compressive strain(87.2%±0.2%).The aerogels prepared with magnesium chloride aqueous solution as acid catalyst had the lowest room temperature thermal conductivity[33.5mW/(m·K)].They could be used at temperatures lower than 600℃ without the thermal decomposition reaction of —CH_(3) groups,and their weight loss was only 7.2% at 800℃.Their surface temperature increased from 30℃ to 42.6℃ and 70.6℃,respectively,after being heated for 300s on a constant-temperature heating bench at 100℃ and 200℃,indicating their excellent thermal insulation properties.