Facile synthesis of self-healing gel via magnetocaloric bottom-ignited frontal polymerization

A series of the self-healing gels facilely fabricated by VI (N-vinyl imidazole) and MAH-β-CD (β-cyclodextrin grafted vinyl carboxylic acid groups) via bottom-ignited frontal polymerization (BIFP) initiated by magnetocaloric effect. Once ignited the bottom phase, the heat upward propagates to generate the “front” in the upper phase. Then, no further energy is added to maintain the reaction and the whole polymerization process experiences within minutes. In this system, the dependence of frontal velocity and temperature, along with morphology, swelling capacity, mechanical property, and self-healing efficiency, on the preparation parameters is investigated. Interestingly, the gels show good swelling capacity in the organic solvent, comparatively almost no absorption in water. Moreover, the as-prepared gels exhibit excellent auto-healing properties without any external stimuli at ambient temperature. The healed sample possesses 97% recovery of its tensile strength after 8 h healing time, which relies largely on the host–guest interaction between VI and MAH-β-CD. The results demonstrate that FP can be utilized as an efficient and energy-saving method to synthesize self-healing supramolecular gels.