采用有机无机复合的方式,制得异氰酸酯增强的SiO2气凝胶。将硅酸甲酯(TMOS)、甲基三甲氧基硅烷(MTMS)、3-氨丙基三乙氧基硅烷(APTES)配成混合硅源,经水解缩聚后形成凝胶,老化后浸泡在含六亚甲基二异氰酸酯单体(HDI)的乙腈溶液中,最后经CO2超临界干燥,获得了具有良好机械性能的SiO2气凝胶。制备过程中引入的MTMS增加了凝胶与有机物间的浸润性,与使用有机物低聚体相比,使用单体可使有机物更易进入凝胶网络,反应更充分,形成纳米尺度更均匀的复合气凝胶。复合后的气凝胶密度为330mg/cm3、比表面积为446.3m2/g、热导率为0.068W·m^-1·K^-1,该气凝胶良好的力学性能(压缩强度为19.96MPa、压缩模量为82.37MPa)使气凝胶的机械加工成为可能。
The reinforced silica aerogels with isocyanate were prepared by the method of organic-inorganic-hybrid. The gels were produced by hydrolysis and condensation polymerization of tetramethoxysilane (TMOS), methyltrimethoxysilane (MTMS) and (3-aminopropyl) triethoxysilane (APTES) with water, aged and then immersed in acetonitrile with the monomer of hexamethylene diisocyanate (HDI), supercritically dried by CO2 to form mechanically strong silica aerogels. In this work, replacing TMOS with some MTMS improves the infiltration between silica gels and HDI. Comparing with oligomer, monomers can infiltrate into the network of gel more easily and make thereaction more amplified, ultimately, forming the nano-scale network more uniform. The good mechanical properties of the reinforced aerogels (compressive modulus 82.37 MPa and compression strength 19.96 MPa) make the machining of aerogels as possible.