Microchannel insulating foams comprising a multifunctional epoxy/graphene‐nanoplatelet nanocomposite

Graphene nanomaterials have demonstrated simultaneous enhancement of both the thermal and mechanical properties of many base polymer systems, but for application as a reinforcement in multifunctional thermally insulating polymer foam the graphene additive must not significantly increase the macroscopic thermal conductivity. In an effort to study and decouple these mechanical and thermal properties, low loadings of reduced graphene oxide nanoplatelets have been added into epoxy formulations to comprise the matrix structure of hollow microchannel nanocomposite foams. Substantial improvements of 226% were achieved in the microchannel foam specific flexural modulus at only 0.15% graphene nanoplatelet loading without compromising the foam flexural strength and while also maintaining the low thermal conductivity of the baseline epoxy foam material. These results support the use of these nanocomposite foams as mechanically reinforced thermal insulation, with the addition of the graphene nanoplatelets potentially providing additional multifunctional improvements to the foam such as reduced UV‐radiation transmittance, improved electrical surface conductivity for diminished static charge buildup, and/or lowering of the coefficient of thermal expansion for enhanced structural stability in extreme environments. This particular combination of multifunctional properties makes these materials well suited as high‐performance structural thermal insulation materials in support of next generation space system applications. With the goal of enhancing the mechanical performance of microchannel epoxy foams using graphene nanomaterials, without reducing their thermal insulation properties, the addition of low loadings of reduced graphene oxide nanoplatelets to the epoxy formulations were explored. It was found that at a 0.15% graphene nanoplatelet loading, the specific flexural modulus of the microchannel foam could be approximately tripled without compromising the foam flexural strength, and while also maintaining the low thermal conductivity of the baseline epoxy foam material. This combination of properties makes these nanocomposite foams well suited as high‐performance structural thermal insulation materials for space system applications.