Self-healing graphene oxide-based nanocomposite hydrogels serve as near-infrared light-driven valves

Light-driven hydrogel actuators show increasing advantages in flowing control, soft robot and microreactor. Herein, we proposed one photothermal responsive and self-healing nanocomposite hydrogel containing poly(Nisopropylacrylamide) (PNIPAM) and poly(N,N-dimethylacrylamide) (PDMAA) to serve as light-driven valves by stimulating the bilayer and hinge-type hydrogel composites. With graphene oxide (GO) and clay, the hydrogels possess good mechanical property and near-infrared (NIR)-driven self-healing behavior because of the noncovalent bonding between the polymer chains and clay. Such bilayer-type hydrogels present local folding with the guide of NIR laser and can realize solid/liquid transportation and controllable trigger of the reaction. We proposed the integration of inhomogeneous structure via NIR light healing to form hinge-type hydrogel, consisting of one bilayer hydrogel as the hinge section and two PDMAA hydrogels as the blade section. The hinge-type hydrogel presents repeatable and obvious deformation with irradiation. Thus, the photothermal responsive and self-healing hydrogel may have potential applications in soft actuator, microfluidic, and microreactor.