Fabrication of native silica, cross-linked, and hybrid aerogel monoliths with customized geometries

Abstract

In this work, a previously developed (White et al 2015 J. Mater. Chem. A 3 762) rapid synthesis approach is used to fabricate native and cross-linked aerogel monoliths with customized geometries. This technique does not require solvent exchange, therefore fabrication times do not depend on part size. To prove this, parts with a smallest dimension of approximately 3.6 cm were fabricated within the same time scale as that of small cylinders with a diameter of 7 mm. In addition, monoliths with customized geometries exhibiting physical detail on the order of 1 mm were produced to demonstrate the versatility of this technique. Furthermore, hybrid materials consisting of native silica aerogel integrated with selected regions of polymer cross-linking were produced. The cross-linked regions allow for adhesion to other surfaces or labeling while the majority of the material retains the physical characteristics of a native silica aerogel. The physical and thermal properties of all aerogel components were examined. All aerogel materials produced in this work exhibited characteristics that were within the range of aerogel materials produced using more conventional methods. For native silica materials, this includes densities in the range of 0.03–0.116 g cm−3, surface areas between 342–799 m2 g−1, mode pore sizes in the range of 30–39 nm, and thermal conductivities in the range of 0.020–0.026 W m−1 K−1. For cross-linked aerogel materials, densities ranged between 0.154–0.340 g cm−3, surface areas were between 291–388 m2 g−1, mode pore sizes were in the range of 29–41 nm, and thermal conductivities were in range of 0.038–0.066 W m−1 K−1.