Slide-ring shape memory polymers with movable cross-links

The development of shape memory materials to achieve recoverable high-strain capacities at high concentration of the crosslinker is still a great challenge due to their mutual exclusiveness. Here, slide-ring shape memory polymers (SMPs) with movable cross-links were prepared by varying the amount of the polyrotaxane cross-linkers. The slide-ring SMPs not only exhibit a combination of high strength and toughness, but also outstanding recoverable high-strain capacities and fast shape recovery. The elongation of the slide-ring SMPs at 1 mol% crosslinker was as high as 881%, closer to physically cross-linked SMPs. As the growing deformation strain from 100% to 800%, the slide-ring SMPs still showed excellent shape memory performance with > 90% shape fixity and shape recovery. The comparative analysis among movable cross-linking, chemical cross-linking and physical cross-linking SMPs in a different way revealed that the sliding effect of the polyrotaxane cross-linking is responsible for outstanding recoverable high-strain capacities of slide-ring SMPs. This design may provide a promising strategy for brittle shape memory materials to obtain high-strain capacities, such as epoxy resin and polylactic acid.