Highly entangled elastomer with ultra-fast self-healing capability and high mechanical strength

Abstract

Self-healing polymeric material, which can heal the cracks repeatedly and thus definitely prolong their lifetime in practical applications, has attracted intensive interesting in recent years. However, it is still a great challenge to both achieve fast self-healing ability and high mechanical strength. Considering the mechanism of fast self-healing is the re-bonding of dynamic bonds in the fracture surfaces, the dense physical cross-linking might be a good option for fast self-healing polymer to solve the trade-off between self-healing ability and mechanical strength. To this end, the highly entangled polymer chains are thereby introduced to improve the mechanical strength of the elastomer by simply increasing the monomer concentration. As expected, the mechanical strength of the resultant elastomers increases with monomer concentration, accompanied by a slight decline in self-healing ability. In addition, further increment of the mechanical strength to 18.4 Mpa is achieved by introducing anisotropic structure into the highly entangled polymers by pre-stretching. Most importantly, the resultant polymer exhibits high recovery and fast self-healing ability with a healing efficiency of 86.2 % after only 30 s healing at room temperature. Moreover, the highly entangled polymer chains also improve the actuation performance of the elastomer with anisotropic structure, which can lift up about 1000 times of its own weight reversibly upon heating–cooling cycles with a maximum tensile stroke of ca. 28 %.