Shortened aerogel fabrication times using an ethanol–water azeotrope as a gelation and drying solvent

Abstract

Native and cross-linked aerogel monoliths were fabricated in a few hours using a technique that does not require solvent exchange prior to supercritical drying.

Influence of silica derivatizer and monomer functionality and concentration on the mechanical properties of rapid synthesis cross-linked aerogels

“…For these applications, a modulus of hundreds of MPa and an energy absorption of tens of J g À1 are required. In our previous work, we showed that the modulus of the composites could be increased by several times when the functionality of the cross-linking monomer was increased [4]. This result was in agreement with general trends of polymer chemistry, which show that the modulus of composites increases with the functionality of the cross-linker [5,7e9].…”

“…In these methods, aerogels are prepared using one-pot chemistry and dried using supercritical organic solvents. In previous work done by our group, native silica and crosslinked aerogels were produced in a matter of hours without requiring solvent exchange [4]. The composites fabricated with our method had Young's moduli on the order of a few tens of MPa.…”

“…The LEDs were arranged symmetrically around every sample, each with the added flexibility of a vertical adjustment of 50 mm, as described in our previous work [4]. After exposure, the samples were supercritically dried in a 2 l pressure vessel (Parr Instruments model 4602) using the ethanolewater azeotrope mixture brought to a temperature of 526 K and a pressure of 7.31 MPa by three 800 W ceramic heaters, also as described in our previous work [4]. Contrary to our previous work with HDDA cross-linked aerogels, residues were found inside the drying vessel when DPHA cross-linked aerogels were processed.…”

“…This group developed a method for cross-linking of the skeletal oxide nanoparticles with a polymer without overly compromising surface area and porosity. Processing issues have been recently addressed by the groups of Anderson and Carroll [3] and by our own group [4]. In these methods, aerogels are prepared using one-pot chemistry and dried using supercritical organic solvents.…”

Synthesis and biomedical applications of aerogels: Possibilities and challenges

“…Meador et al [128] introduced epoxy monomer in the initial sol, Wingfield et al [129] used an acrylic monomer and Duan et al [130] used a custom-synthesized, water-dispersible urethane oligomer. Recently, White [131] shortened the aerogel composite fabrication by conducting the experiment with simple one pot approach and using the more economic-friendly ethanol-water azeotrope mixture as gelation solvent.…”