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甲基三甲氧基硅烷对块状SiO_2气凝胶性能和结构的影响

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Abstract:

以正硅酸乙酯(tetraethoxysilane,TEOS)为硅源,甲基三甲氧基硅烷(methyltrimethoxysilane,MTMS)为改性剂,无水乙醇(ethanol,EtOH)为溶剂,通过溶胶–凝胶法制备了SiO2湿凝胶,并经过超临界干燥得到了SiO2气凝胶。利用N2吸脱附测试、红外光谱、热重–差热分析、扫描电镜、高分辨透射电镜、接触角测试等手段对气凝胶的基本性能、表面基团、热稳定性、微观形貌结构进行了研究。结果表明以TEOS,MTMS,EtOH,H2O的摩尔比为10.3154制得的改性气凝胶为轻质疏水块状固体材料,密度为0.1g/cm3,比表面积为1070m2/g,孔隙率为95.5%。经MTMS改性后SiO2气凝胶的比表面积、孔体积和孔隙率更大,密度更低,其疏水耐温性从250℃提高到500℃以上。

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