Homogeneous silicone network formation in aqueous sol–gel systems toward low-density porous materials

Low-density porous materials, so-called aerogels, with silicone networks have been developed through aqueous sol–gel systems. We found that the two-step acid-base process is suitable for the meso-scaled homogeneous hydrophobic network formations with the aid of surfactant. Optically transparent aerogels have been prepared from various organo-substituted alkoxysilanes [RSi(OR′)3, R and R′ are organic groups] and organo-bridged alkoxysilanes (R′O)2(CH3)Si–R–Si(CH3)(OR′)2 and (R′O)3Si–R–Si(OR′)3. Most aerogels, poly(methylsilsesquioxane) aerogels in particular, from these precursors show mechanical flexibility against compression and bending deformations, which allows spring-back during ambient pressure drying to yield xerogels with almost the same properties with supercritically dried aerogels. In addition to these scientific works on aerogels, applications of aerogels to visual arts and designs are also discussed.