Synthesis of New Flexible Aerogels from MTMS/DMDMS via Ambient Pressure Drying

Although silica aerogel is expected to be the material for energy savings, the lack of the strength prevents from commercial applications such as to low-density thermal insulators and acoustic absorbents. To improve mechanical properties, methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) are used as the co-precursor of aerogels in this study because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS/DMDMS-derived condensates, phase separation occurs, which must be suppressed in aqueous sol to obtain uniform and monolithic gel networks. We also employed surfactant nhexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, various microstructures of pores are obtained. In the uniaxial compression test, the aerogel showed high flexibility and spring-back to the original shape after removing the stress.