A photo-driven metallo-supramolecular stress-free reversible shape memory polymer

Soft machines can offer remote-powering mechanisms and mechanical flexibility unmatched by conventional rigid machines. However, the molecular integration of powering and actuation functions in a simple yet versatile format has remained challenging. We achieve this with a semi-crystalline supramolecular metallo-network. The dynamic metallo-bonds offer a flexible mechanism for programming the network anisotropy, which gives rise to stress-free reversible actuation using the crystalline transition as the actuation phase. In addition, the proper choice of metallo-bonds provides suitable photo-thermal capabilities for remote powering without endangering the cyclic actuation stability, despite the supramolecular nature. Based on these principles, we illustrate that the supramolecular network can be programmed into a reptile-style device remotely powered by light. The molecularly integrated dual functionality based on supramolecular metallo-bonds provides an attractive option for the future design of soft machines with sophisticated morphing behaviors yet simple powering mechanisms.