Multi-functional composite aerogels enabled by chemical integration of graphene oxide and waterborne polyurethane via a facile and green method

Practical thermal-insulating applications require aerogels to possess multi-functionality in addition to a low thermal conductivity. However, it is still a challenge to fabricate multi-functional aerogels. Here we use an environmentally friendly method to obtain multi-functional hybrid aerogels by chemical integration of waterborne polyurethane (WPU) and graphene oxide (GO). In the hybrid aerogels, covalent networks are formed in WPU itself and between WPU molecules and GO sheets through the deblocking and condensation reactions, while physical networks are formed by stacking between GO sheets and phase separation in WPU. The existence of both physical and chemical networks imparts high mechanical property and excellent shape-memory capability to the hybrid aerogels. The interfaces between different networks play a role of phonon-scattering, thus enabling a low thermal conductivity for the hybrid aerogels. Moreover, rough structures on the surface endow the hybrid aerogels with high hydrophobicity. The multi-functionality properties presented in this paper provide a potential usage of aerogels with a wide range of thermal-insulating characteristics which can improve the energy efficiency effectively.