Wenhe Jiang#, Zhongwen Sun#, Ruitong Wang#, Xiaozhu Zhao, Xianshu Zhou, Yanlin Wei, Chaowen Shen, Yongsheng Fang, Li Niu, Xinling Deng, Xinai Guo, Hongtao Bian, Hua Xu, Pujun Jin, Hui Yang, Kaiqiang Liu*, Yu Fang. Mater. Today, 2025, DOI: 10.1016/j.mattod.2025.11.011

The restoration of cultural relics demands stringent performance criteria for adhesives, which must combine excellent interfacial wettability, strong adhesion strength, and high environmental tolerance. Traditional polyurethane adhesives, despite their outstanding interfacial adhesion, have generally relied on organic solvents to improve interfacial wetting of substrates—this not only complicates restoration operations but also poses risks of environmental contamination and harm to personnel. Thus, developing polyurethane adhesives with high strength, superior wettability, and environmental friendliness has emerged as an urgent priority in cultural heritage conservation.

Figure 1 Molecular design and potential intermolecular forces before and after supramolecular combination

Figure 2 Environmental tolerance of adhered interfaces before and after supramolecular combination

To tackle this challenge, professor Liu Kaiqiang’s research group at our institute proposed a two-step supramolecular combinatorial strategy, yielding a series of high-performance, eco-friendly polyurethane adhesives. First, imidazolium ionic segments as electrostatic sites for enhanced wettability and urethane bonds providing hydrogen-bonding sites were grafted onto a linear polymer backbone via covalent modification (Figure 1). This yielded ionic polyurethanes with significantly improved interfacial wettability and initial adhesion. To address the loss of molecular cohesion and interfacial instability caused by solvation effects, the group further balanced multiple intermolecular interactions (hydrogen bonding, π-π stacking, cation-π interactions, and electrostatic forces) between ionic polyurethane and additive by tuning components. The resulting composite adhesive not only delivers exceptional interfacial strength but also exhibits robust tolerance in harsh environments—including water, organic solvents, and liquid nitrogen—outperforming most solvent-based commercial adhesives and previously reported supramolecular adhesives (Figure 2). Techniques such as NMR titration, variable-temperature NMR, and molecular dynamics simulations reveal difference of shearing energies and adhesion mechanisms before and after supramolecular combination.

Figure 3 Durability under hanging conditions, performance comparison, and bonding of broken cultural relic materials

To be summarized, such a class of functional adhesives demonstrate remarkable potential in cultural relic repair: simple intermittent preheating enables efficient bonding of diverse materials, including paper, clay sculptures, ceramics, and jade (Figure 3). It thus establishes a new paradigm for designing functional adhesives tailored to cultural heritage protection.

First Authors: Jiang Wenhe, Sun Zhongwen, and Wang Ruitong, master’s students, Shaanxi Normal University

Correspondence Author: Prof. Liu Kaiqiang, Shaanxi Normal University

Full Text Link: https://doi.org/10.1016/j.mattod.2025.11.011