Supramolecular polymers with water-triggered dense domains enabling mechanical robustness programmability and weather resistance.

Polymers play a crucial role in our daily lives; however, achieving a balance among mechanical performance, resistance to high and low temperatures, and mild shaping remains challenging. Here, we report a water-triggered supramolecular polymer composed of cellulose and polymethyl methacrylate. Following water-induced transformation of a stretchable supramolecular network into a densified cross-linked domain, the resulting polymer exhibits a remarkable increase in tensile strength from 2.7 MPa to 61.7 MPa, representing more than a 22-fold enhancement, and a flexural strength of 97 MPa, while maintaining structural integrity across a temperature range of -196 °C to 200 °C. In addition, the polymer enables scalable water-mediated shaping and reinforcement even in seawater, surfactant wastewater, and dye wastewater, while retaining high mechanical performance. Economic analysis and recycling assessment demonstrate that this polymer is amenable to scalable production and has considerable market potential. This study provides a biomimetic formulation for the fabrication of high-performance supramolecular polymers and broadens their potential applications across diverse fields.