Development of Mechanically Stable Polymer-Based Silica Aerogel

Abstract

Silica aerogels have attracted attention for many applications due to their unique properties such as low density (0.003 g/cm), mesoporosity (pore size 2–50 nm), high thermal insulation and high surface area (500–1200 m²/g). However, their fragility and environmental sensitivity restricts the use of monolithic silica aerogel. In this paper, silica aerogel that is crosslinked with diisocyanate is introduced and the effects of polymer concentration on aerogel properties, especially mechanical strength are discussed. Fracture of silica aerogel mainly occurs at the interface of secondary particles that are formed during aging. It is believed that if the surface of silica aerogel is covalently bonded to nanocast polymer coating, the interparticle necks become wider and can reinforce the structure of the aerogel. In this study, several characterizations are performed to investigate the properties of the aerogel. First, bulk density is measured to visualize the change in density with increase in crosslinker concentration. Brunauer Emmett and Teller (BET) illustrated the pore size, bulk density and surface area. The critical temperature up to which polymer crosslinked aerogel decompose was investigated by Thermogravimetric Analysis (TGA). The phase change in the aerogel was studied with Differential Scanning Calorimetry (DSC) testing. Using Scanning Electron Microscope (SEM), the nanoscale pore size and pore distribution throughout the aerogel surface were investigated. Furthermore, compression tests were performed to study the effect of crosslinking polymer on mechanical strength over non-crosslinked framework.