Covalent Adaptable Liquid Crystal Networks Enabled by Reversible Ring-Opening Cascades of Cyclic Disulfides.

The development of covalent adaptable liquid crystal networks (LCNs) enabled by introducing dynamic covalent bonds has endowed liquid crystal actuators with self-healing properties and reversible shape programmability, broadening their applications in diverse soft robotic devices. However, the finite molecular design strategy limits the recyclability and the architectural diversity of these materials. Here, a strategy is first reported for fabricating photoresponsive polydisulfide-based covalent adaptable LCNs by ring-opening polymerization of cyclic dithiolane groups. Based on the disulfide metathesis, the resulting materials are self-healable, reshapable, and reprogrammable. Importantly, the equilibrium between the polymer backbones and the dithiolane-functionalized monomers enables catalytic depolymerization to recycle monomers, which could significantly weaken the disadvantage of subtractive manufacturing of photomechanical devices. This work rooted in chemistry would provide an economical and environmentally friendly strategy for the fabrication of functional soft robotics with excellent programmability and renewability and beyond.