Urethane-Functionalized Graphene Oxide for Improving Compatibility and Thermal Conductivity of Waterborne Polyurethane Composites

This study provides an effective interface modification strategy for preparing graphene-based composite. Urethane-functionalized graphene oxide (FGO) was prepared by in situ polymerization and then was incorporated into a polyurethane binder (PUB) matrix to fabricate composites. The surface chemical composition and structural properties of FGO were systematically characterized by a series of measurements. It was found that urethane chains were covalently attached onto the graphene oxide surface, and the FGO possessed a comparatively regular lamellar structure and a larger interlayer distance. Additionally, amphipathic urethane chains on the FGO sheets not only improved the compatibility and interfacial interaction between the stiff FGO and the soft PUB matrix, but also alleviated the modulus mismatch between them. The most effective improvements in mechanical and thermal transport properties were achieved when 0.5 wt % FGO was incorporated into the PUB matrix, leading to improvement of tensile strength, elongation at break, and thermal conductivity by 23.4%, 12.1%, and 61.5%, respectively, in comparison with the neat PUB matrix. We expect that this work will have potential applications in functional composite coatings.