Evolution of interfacial adhesion modification strategies between waterborne polyurethane and low-surface-energy substrates

To meet the demands of lightweighting, functionalization and aesthetics, low-surface-energy （LSE） materials, such as polyolefins and polyesters, often need to be bonded and compounded with other materials. Waterborne polyurethane （WPU） is a commonly used bonding material, but improving its wettability and adhesion on LSE substrates remains a great challenge. This paper systematically reviews the strategies for enhancing the bonding performance of WPU with LSE substrates in recent years, including tailoring polyurethane chain structure, introducing polar functional groups, and constructing nanocomposite systems to enhance interfacial interactions. Meanwhile, surface pretreatment techniques for LSE substrates and state-of-the-art dynamic characterization methods for probing interfacial adhesion behavior are also summarized. The analysis shows that strengthening covalent or ionic bond interaction at the bonding interface is central to improving the bonding performance. The synergistic application of multi-scale modification strategies and precise characterization of interfacial adhesion behavior holds promise for broadening the application scope of WPU in bonding LSE materials.