Epoxy Reinforced Aerogels Made Using a Streamlined Process

Reinforcing silica aerogels by conformally coating the nanoskeleton with a polymer has been demonstrated to be an effective way to improve mechanical properties. In addition, the mesoporosity and low thermal conductivity is maintained, making this robust form of aerogel an enabling material for a variety of aerospace applications. However, the process for making the aerogels can be quite long, involving production of the gel, solvent exchanges, and diffusion of monomer, followed by more solvent exchanges and supercritical fluid extraction. This paper for the first time compares a synthetic scheme that shortens the process to make epoxy reinforced aerogels by eliminating monomer diffusion and half of the solvent washes to the previously described diffusion-controlled process. The ethanol-soluble epoxy monomers are included in the initial step of the sol-gel process without interfering with gelation of the starting silanes. Notably, properties of aerogels made using a low amount of amine reactive sites have properties similar to those previously reported that used the longer diffusion controlled process, whereas higher amounts of amine sites produce less desirable monoliths with much higher density and lower surface areas.