A cross-linked silica aerogel undergoing a three-point flexural bending test. The density of the monolith is ~0.55 g/cm3. The density of the underlying silica is ~0.18 g/cm3, and the silica has been cross-linked with polyhexamethylene diisocyanate.
Polymer Cross-Linked Aerogels (X-Aerogels)
Aerogels are very low density, highly porous materials developed by NASA that have been used in a variety of applications throughout the years. Polymer cross-linked aerogels (x-aerogels) are 3 times as dense as native aerogels, but more than 300 times as strong. X-aerogels were developed to resolve the two main problems that continued to hinder the market acceptance of native aerogels: brittleness and hydrophilicity. By coating and cross-linking the aerogel nanoparticles with polymers such as epoxies, isocyanates, and polyimides, the strength was greatly increased and the affinity for water was decreased.
X-Aerogels were developed and used by NASA for a variety of space operations. Currently, the NASA Glenn Research Center is looking for industry and/or academic partners to assist in developing this material further and to help identify new applications. They also hope that one day it can be successfully commercialized.
What is Aerogel?
Aerogel is the lightest and lowest-density solid known to exist. It is typically 50-99.5% air, yet can hold (theoretically) 500 to 4,000 times its weight in applied force. Aerogel can have surface areas ranging from 250 to 3,000 square meters per gram, meaning that a cubic inch (2.5 cm x 2.5 cm x 2.5 cm) of aerogel flattened-out (again theoretically) would have more surface area than an entire football field! Aerogel's superlow density makes it useful as a lightweight structural material, and its superhigh internal surface area makes it a superinsulating solid material. Silica aerogel is transparent with a blue color and feels like styrofoam.