Bis‑p‑Sulfonatocalix[4]arene-Based Supramolecular Amphiphiles with an Emergent Lower Critical Solution Temperature Behavior in Aqueous Solution and Hydrogel

An unexpected lower critical solution temperature (LCST) phenomenon is observed in a bis-p-sulfonatocalix­[4]­arene-based supramolecular amphiphile system, and the mechanism of this intriguing phenomenon is studied. The unusual macroscopic thermoresponsive behavior is based on the switch of the system from water-soluble assemblies to insoluble netlike cross-linked nanoparticles under temperature stimulus, which is regulated by multiple weak interactions, including hydrophilic and hydrophobic interactions, π–π stacking, and host–guest recognition. By using the LCST solution as the dispersion medium, a hydrogel with LCST behavior can be fabricated. This work contributes toward better understanding about calixarene-induced aggregation (CIA) and thermoresponsive self-assembled systems. It will also help to enrich the designing of complexed supramolecular amphiphile systems and develop their potential applications in hydrogels.