Tailoring thermal properties of ambient pressure dried MTMS/TEOS co-precursor aerogels

Methyltrimethoxysilane (MTMS) and tetraethoxysilane (TEOS) are used as precursors to synthesize MTMS/TEOS co-precursor aerogels (cp-aerogels) via ambient pressure drying (APD). The effects of NH3·H2O concentration on thermal properties of the MTMS/TEOS cp-aerogels were explored in detail. As the NH3·H2O concentration increased, the density slightly declined first and then dramatically ascended while the porosity presented an opposite trend. Meanwhile, the cluster size was minished and the pores became more abundant and uniform. These variations induced the changes of the thermal properties of the cp-aerogels. With the NH3·H2O concentration increasing, the thermal conductivity approximated linear decrease to 0.027 W m−1 K−1, the specific heat displayed a logarithmic reduction and the thermal diffusivity retained the similar tendency to the porosity. Furthermore, the thermostability was improved up to 508 °C with the increasing NH3·H2O concentration. All these results indicate that the thermal properties of the MTMS/TEOS cp-aerogels can be tailored by adjusting the NH3·H2O concentration.