Multifunctional Thermal, Acoustic, and Piezoresistive Properties of In Situ-Modified Composite Aerogels with Graphene Oxide as the Main Phase

Automotive and aerospace industries require advanced materials capable of multifunctional abilities while guaranteeing limited weight and volume and simple processing. Cellular materials such as graphene-based aerogels represent a promising solution. In this study, chemical modification approaches of graphene oxide and polyvinyl alcohol (GOP) aerogels are presented. The combination of a plasticizing agent, glycerol, and a cross-linking agent, glutaraldehyde, is exploited to obtain a mechanically balanced and robust cellular structure. Modified GOP aerogels show high elastic resilience (energy loss coefficient of 29% and compressive strength of 5 kPa at 30% strain, after the 10th compression cycle), low thermal conductivity (0.0424 W mK^-1), and high sound absorption (average coefficient of 0.72 between 500 and 1500 Hz) while maintaining a low density of 6.51 kg m^-3 with a maximum thickness of 25 mm. Moreover, chemically reduced GOP (rGOP) aerogels are also synthesized. They are characterized by the additional feature of piezoresistive behavior, with only a marginal impact on the other properties. These results show that modified GOP and rGOP aerogels are promising candidates for the fabrication of multifunctional structures to be applied in advanced engineering applications.