Facile access to versatile hydrogels via interface-directed frontal polymerization derived from the magnetocaloric effect

Stimuli-responsive hydrogels that are capable of adjusting to people's demands depending on environmental changes have attracted tremendous interest in recent years. To achieve flexibility for applications, multiresponsive smart materials are highly desirable, while it is still a great challenge to incorporate three or more responsive elements into one polymeric system. Herein, taking advantage of the magnetocaloric effect, we developed an interface-directed frontal polymerization to achieve the fabrication of versatile hydrogels within 5 min. The as-prepared hydrogels show auto-healing without the assistance of any external stimuli and the addition of graphene oxide (GO) can lead to better performance in toughness and healing efficiency. Moreover, the combination of chemical, pH, thermal and electrical responses takes place within the resultant copolymer that exhibits different swelling and bending behaviors towards various external changes. These features might provide the synthetic hydrogels great promise for a diverse range of applications.