Embedding carbon nanotube to the surfaces of poly(ε-caprolactone) film for multi-responsive actuations

Although incorporation of carbon nanotube (CNT) may endow reversible shape-memory polymer (rSMP) with electric actuation, it degrades the rSMP's intrinsic actuation performance (thermally responsive reversible shape-memory effect). It remains a challenge to add CNT to rSMP without degrading its intrinsic thermal actuation. Herein, a simple approach was developed to prepare a rSMP-based multi-responsive soft actuator by embedding CNT to the surfaces of a photo-crosslinked poly (ε-caprolactone) (cPCL) film via hot pressing. Scanning electron microscopy result reveals the presence of thin CNT conductive layers on the surfaces of the cPCL film. The CNT-embedded cPCL shows significantly improved thermal stability and mechanical properties over bare cPCL. The incorporation of CNT to the surfaces endows the cPCL film with good electric actuation while maintaining its good thermal actuation. In addition, it also exhibits a much faster recovery rate and a higher recovery force when compared to cPCL and a cPCL film with single CNT-embedded surface. This work develops a facile strategy to prepare the multi-responsive soft actuator with good actuation capability by embedding CNT to the rSMP film surfaces and the obtained actuator holds great potential for the applications in soft robots, smart switch, and so on.