INORGANIC-ORGANIC HYBRID AEROGELS

Abstract

Aerogels can be imagined as a huge amount of air dispersed in a nanostructured solid network and hence they possess very low density and high porosity. These materials with fascinating properties like low thermal conductivity, low dielectric strength, high surface area etc. have attracted researchers ever since their discovery by Kistler [1]. The incorporation of an organic part into an inorganic one is already known to be resulting in materials for special applications [2]. It is also reported that an organic part gives strength to the aerogel network which can withstand the capillary pressure while ambient drying [4]. In our work, we have prepared aerogels with various compositions of MTMS-GPTMS. To make a comparison study we prepared gels under supercritical and also under ambient conditions. The density of the supercritically dried hybrid aerogels lies between 0.16 to 0.31 g/cm3, while the density of the ambient dried one ranges between 0.41 to 0.35 g/cm3. The surface area of MTMS-0.25 GPTMS was found to be 464 m2/g with a pore volume and pore diameter of 1.26 cm3/g and 11.78 nm resp. It is interesting to note that GPTMS-0.25 GPTMS composition dried under ambient conditions has surface area and pore volume almost similar to the supercritically dried ones. By tuning the composition of GPTMS and also playing with the sol-gel chemistry we were able to produce flexible aerogels. The hybrid gels were also pyrolysed in inert atmosphere to yield porous oxycarbide aerogels, where they may also find possible applications in catalyst support, molecular sieves, gas adsorbants, sensors and ceramics.