Smart materials are increasingly used across diverse fields due to their rapid response capabilities. However, achieving fast, noncontact mechanical switching at the macroscopic scale while maintaining a balance between mechanical strength and self-healing properties presents a significant challenge. Addressing this issue requires innovative design strategies, which remain a critical scientific goal. Here, we report a novel polymeric material that exhibits dynamic mechanical switching and efficient self-healing behavior. We synthesized structurally controllable biopolymeric materials (AZ-PCLs) using caprolactone (CL) as the polymerization monomer and small-molecule azobenzene derivatives (AZ) as the initiator via intrinsic ring-opening polymerization. Subsequently, we incorporated the natural drug glycyrrhizic acid (GA) as a hydrogen bond donor, facilitating hydrogen-bonding interactions with AZ-PCL to yield a new elastomeric material (AZ-PCLGA) characterized by photoisomerization and dynamic bond-forming properties. This design enables AZ-PCLGA to exhibit noncontact mechanical switching capability as molecular weight increases. Mechanical strength gradually increases as AZ content decreases, with a maximum mechanical strength of up to 21.10 MPa. Remarkably, this exceptional mechanical switching behavior can be regulated by photoisomerization, accompanied by a reduction in healing time and an increase in healing efficiency as the polymer molecular weight increases, with the shortest repair time being 20 minutes and a healing efficiency of approximately 98.7%. In vitro biocompatibility assessments confirm that AZ-PCLGAs exhibit excellent biosafety, underscoring their potential for the development of advanced smart biomedical materials with noncontact, photoswitchable mechanical properties.
Zhang et al. (Thu,) studied this question.