Polyimide aerogels crosslinked with chemically modified graphene oxide

Polyimide (PI) aerogels, which are generally crosslinked using expensive chemical crosslinking agents, are novel porous materials with high strength, high heat resistance, high porosity, and low density. Graphene oxide (GO) is a functional nanofiller that has aroused wide interest in recent years. The reported PI/ GO composites have mostly been in the form of fibers and films. In this study, PI/GO composite aerogels were obtained using chemically modified graphene oxide (m-GO) as the crosslinking agent, instead of traditional ones such as 1,3,5-triaminophenoxybenzene (TAB), by reaction with 4,4′-oxydianiline (ODA) and 3,3′,4,4′- biphenyltetracarboxylic dianhydride (BPDA). The chemical modification of GO was achieved by reacting GO with excess ODA using a hydrothermal method. The microstructures of the PI/m-GO aerogels were investigated using scanning electron microscopy (SEM). Nitrogen sorption tests, thermogravimetric analysis, and a hot-wire method were used to investigate the effects of m-GO on the pore properties, thermal stabilities, and thermal conductivities, respectively, of the resulting aerogels. The results show that the PI/m-GO aerogels are highly porous, thermally stable, and heat insulating. Compression tests showed that the PI aerogel prepared using 0.6% (mass fraction, w) m-GO instead of 1.8% (w) TAB as the crosslinking agent had a higher specific Young′s modulus [Young′s modulus/density (ρ)] and specific yield strength (yield strength/ρ), and less shrinkage.