With the increasing awareness of environmental protection, waterborne polyurethane (WPU) coatings have attracted extensive research and industrial attention owing to their low volatile organic compound (VOC) emissions and eco-friendly characteristics. Nevertheless, conventional WPU coatings suffer from inherent performance limitations such as insufficient mechanical strength, poor chemical resistance and single functionality, which make it difficult to satisfy the increasingly diverse application requirements in modern industries. In this context, the research on multifunctionally modified WPU coatings has become a research hotspot, which is dedicated to optimizing the comprehensive performance of WPU coatings and expanding their application scope through rational design of modification methods and functional components. This paper systematically reviews the latest research progress of five typical modification techniques for WPU coatings, including organic functional monomer modification, nanomaterial modification, bio-based modification, self-healing modification, and integrated antimicrobial/flame-retardant modification. The modification mechanisms, performance regulation effects and application characteristics of each method are elaborated, and the results show that these modification strategies can not only significantly improve the core mechanical properties and chemical resistance of WPU coatings, but also endow them with multi-functional integration, green sustainability and intelligent responsiveness. Furthermore, the practical applications of modified WPU coatings in construction, automotive manufacturing, aerospace and other key fields are summarized, which fully demonstrates their broad market application prospects and industrial development potential. Finally, the key research directions and development trends of WPU coatings are prospected: the development of multifunctional synergistic modification technology, the construction of intelligent responsive systems and the realization of green and sustainable preparation processes will become the core driving forces for the high-quality development of this field. It is expected that multifunctionally modified WPU coatings will occupy an important position in the global high-performance eco-friendly coatings market in the near future and provide technical support for the green transformation of the coating industry.
Gong et al. (Tue,) studied this question.