Ultra‐Stretchable Multicolor Fluorescent Hydrogels Based on Polymer Networks Involving both Strong and Weak Crosslinks

Abstract Owing to their inherent soft wet nature and the capacity to offer tunable emission color/intensity responses, multicolor fluorescent polymeric hydrogels (MFPHs) are attracting tremendous research interests. However, most of the reported MFPHs suffer from poor stretchability, thus restricting their versatile uses in artificial muscles, soft robotics, and so on. In this study, a robust type of lanthanide coordinated MFPHs with an ultra‐stretchability of over 1200% is designed and prepared. It is found that the ultra‐stretchability originates from the unique polymer network structure, in which a small quantity of strong crosslinking interactions (polymer chain entanglement/fixation around the nano‐clay and lanthanide coordination) are utilized to ensure the polymer network integrity, and a large quantity of hierarchical (single, double, and quadruple) hydrogen‐bonding interactions are designed to efficiently dissipate energy. Furthermore, a braiding strategy is proposed to tightly twist several hydrogel stripes into mechanical strong hydrogel ropes that still keep the ultra‐stretchability (>1000%) but can lift heavy weights >350 times their own weight. This study provides new insights into the design of ultra‐stretchable fluorescent hydrogels, and is expected to inspire the future development of multifunctional artificial hydrogel muscles.