Tough and Recyclable Phase-Separated Supramolecular Gels via a Dehydration-Hydration Cycle

Hydrogels are compelling materials for emerging applications, including soft robotics and autonomous sensing. Mechanical stability over an extensive range of environmental conditions and considerations of sustainability, both environmentally benign processing and end-of-life use, are enduring challenges. To make progress on these challenges, we designed a dehydration-hydration approach to transform soft and weak hydrogels into tough and recyclable supramolecular phase-separated gels (PSGs) using water as the only solvent. The dehydration-hydration approach led to phase separation and the formation of domains consisting of strong polymer-polymer interactions critical for forming PSGs. The phase-separated segments acted as robust, physical crosslinks to strengthen PSGs, which exhibited enhanced toughness and stretchability in its fully swollen state. PSGs are not prone to over-swelling or severe shrinkage in wet condition and show environmental tolerance in harsh conditions, i.e., organic solvents with pH between 1 to 14. Finally, we demonstrate the use of PSGs as strain sensors in air and aqueous environments.