Effect of molar concentration and drying methodologies on monodispersed silica sol for synthesis of silica aerogels with temperature-resistant characteristics

Abstract

A variety of hierarchical nanoporous silica aerogels with diversified particle distributions were synthesized from well-dispersed silica sols by a traditional sol–gel method. Among the six particle sizes of aerogels, the silica aerogel with 0.4 M TEOS/MTMS surface modification and supercritical drying attains 11.61 ± 2.96 nm constituent part with well slender size particle dissemination, high-temperature confrontation and low thermal conductivity. In association with the outmoded two-step acid-base dilution of silica sols, the well-diffused form of silica sols with surface alteration also provides a low thermal conductivity of 0.01865 W.m−1 K−1 with greater thermal resistance. In addition, the drying shrinkage can be minimized with surface modification by properly silylation with TMCS. The concentrations of well-diffused silica sol were adjusted to achieve higher surface area, low density, large pore size and structure, and temperature resilience with the help of controlling the sol–gel reaction. The resilient skeleton structure developed from the assembly of tiny particles can efficiently restrict the glutinous heat dissipation between aerogel networks without collapsing a porous network up to a higher temperature of 900 °C. However, this network retains a similar pattern up to 1000 °C with only 32 % volume contraction after 2hr of heat treatments. At an elevated temperature of 1100–1200 °C, the viscid heat flow between nanoparticles and the porous network cannot be meritoriously suppressed and starts to collapse after a shorter duration. The enormous results of silica aerogels will help design suitable thermal insulation with higher resilience and low thermal conductivity.