Research progress on the wetting behavior of polymer melts on solid surfaces: a review from fundamental science to engineering applications

The wetting behavior of polymer melts on solid surfaces constitutes a fundamental issue in polymer materials processing science, directly affecting the interfacial quality of fiber‐reinforced composites, the demolding performance in injection molding, and the compatibility of multicomponent polymer systems. This review systematically traces the research trajectory of this field since the 1960s, elucidates the thermodynamic foundations of wetting based on surface energy components (including Fowkes theory, acid–base theory, etc.), and proceeds along three interrelated scientific themes: (1) theoretical modeling of spreading dynamics (encompassing hydrodynamic models, molecular‐kinetic theory, and combined models) together with specific analytical methodologies; (2) coupling effects of chemical reactions on wetting processes and reactive wetting mechanisms; and (3) the evolution of precision measurement and characterization methodologies for polymer melt wettability. On this basis, we discuss the prevailing assumptions, experimental constraints, and theoretical deficiencies common to existing studies, and identify key gaps that persist in the field, including theoretical voids for high‐viscosity systems, inadequacies in multiscale coupled modeling, and transferability issues from laboratory measurements to industrial processing conditions.