Macromolecular Phase-Transition-Driven Motility of Hollow Hydrogel Tubes

The research emphasis and novelty of this work focus on the phase-transition effects on the structural deformation of hollow hydrogel tubes in an aqueous system, where the cross-linking poly­(N-isopropylacrylamide) (PNIPAM) plays a critical role. Upon heating/cooling to 31 °C, the hydrogel tube proceeds with a homogeneous-to-heterogeneous phase transition that enables asymmetric expansion or contraction and induces shape-programmed deformation. The phase-transition regions can be patterned to bring the tube into a shape-programmed motility. The salt effect triggers the tube for controlled shape deformation at 17 °C, which endows the hollow hydrogel tubes with more promising potential in biomedical areas.