Rapid remote actuation in shape memory hyperbranched polyurethane composites using cross-linked photothermal reduced graphene oxide networks

Abstract

We report near-infrared (NIR) laser-driven rapid shape recovery in hyperbranched polyurethane/epoxy (HBPU/EP) composites based on cross-linked graphene photothermal networks. Graphene-based photothermal reinforcements were synthesized by functionalizing graphene oxide (GO) with the epoxy bisphenol A diglycidil ether (DGEBA) to form DGEBA-f-GO, and by subsequent reduction of DGEBA-f-GO to DGEBA-f-reduced graphene oxide (DGEBA-f-rGO). Upon irradiation with an 808 nm NIR laser, the composites with 1 wt% cross-linked DGEBA-f-rGO exhibited a remarkable shape recovery time of 6.5 s (one-fourth that of the composites with 1 wt% GO). The rapid actuation in these composites results from excellent photothermal conversion by the cross-linked DGEBA-f-rGO owing to enhanced π conjugation in rGO and homogeneous dispersion of graphene networks in the polymer matrix due to covalent interactions. An increase in the epoxy groups on the GO surface also enhanced the mechanical properties of the composites by forming denser cross-linked networks. Graphene-based photothermal networks may be suitable for fabricating robust and remote-controllable rapid shape recovery composites.