Polymers with a Coiled Conformation Enable Healing of Wide and Deep Damages in Polymeric Films.

The development of efficient methods to trigger high mobility of polymer chains to migrate across the damaged areas is key for healing wide damages in intrinsic healable polymeric films deposited on solid substrates. Herein, we establish a facile strategy for the fabrication of polymeric films with a superhigh healing capability by controlling the conformational transition of the polymer chains in polymeric films. The alternately spin-coated poly(acrylic acid) (PAA)/polyurethane (PU) films with coiled PU can heal cuts with a width of 6 times the thickness of the PAA/PU films in the presence of ethanol. In contrast, the same PAA/PU films with stretched PU or those films with coiled PU but without conformational transition from a coiled state to a stretched state fail to heal cuts. The conformational transition of PU from a coiled state to a stretched state in PAA/PU films triggered by ethanol enables a long-distance migration of PAA and PU polymers to heal wide mechanical damages.