Redefining interfacial adhesion of linear ionic polyurethanes through supramolecular combinatorial strategy for the restoration of cultural heritage materials

Abstract

Redefining interfacial adhesion under harsh environmental conditions is crucial for the restoration of cultural heritage materials. In this work, we designed and synthesised a novel class of linear ionic polyurethanes (LIPUs) by incorporating ionic liquid segments into the polyurethane backbone. This approach enhances their wetting properties on various materials while maintaining cohesive strength through urethane bonds. Using a supramolecular combinatorial strategy that integrates multiple components, we precisely modulate intermolecular interactions—such as hydrogen bonding, π-π stacking, cation-π and electrostatic forces—between the LIPUs and functional additives, effectively addressing key challenges in interfacial adhesion. This combination significantly increases adhesion strength from 12.00 MPa for pure LIPUs to 26.00 MPa for the composites exhibiting exceptional stability in environments such as water, organic solvents and liquid nitrogen (adhesion maintained between 11.43 and 23.46 MPa). These advancements outperform pure LIPUs (0–4.97 MPa) and previously reported supramolecular adhesives. Furthermore, this adhesive system demonstrates remarkable potential for repairing cultural heritage artifacts, including paper, mud maid sculptures, ceramics and jade stones, providing a robust and versatile foundation for the next generation of adhesive designs in cultural heritage conservation.