Interfacial healing driven by wetting of nanoparticle films

During the drying of colloidal coatings, stress release can induce mechanical instabilities that often unfold in successive stages. In particular, crack-limited fragments may partially delaminate from the substrate, forming distinct adhesion zones. This delamination process results from a complex interplay between capillary forces, internal stresses, and interfacial adhesion. While often seen as irreversible, recent findings reveal that delamination can, under certain conditions, exhibit partial reversibility. This discovery opens promising avenues for developing self-healing coatings. In this study, we investigate the reversible delamination of transparent silica nanoparticle films subjected to cyclic drying and rewetting. The transparency of the films allows for accurate mapping of delaminated and adhered regions before and after imbibition. Upon rewetting, swelling induces fragment flattening and re-adhesion to the substrate. As drying resumes, new delamination patterns emerge, comparable in size but located differently, indicating interfacial healing during the wetting phase. These results provide key insights into reversible adhesion mechanisms and contribute to the design of more resilient and adaptive coatings under fluctuating environmental conditions.