Tough Particle-Based Double Network Hydrogels for Functional Solid Surface Coatings

Coating solid surfaces with tough hydrogels is necessary for the practical application of hydrogels in various fields. Here a simple yet versatile method for coating tough double network (DN) hydrogels onto a wide range of solid surfaces, including various materials and geometries is reported. Particle-based double network (P-DN) gels that combine ease-of-use and significantly strong mechanical properties are utilized. The P-DN gel coating process involves two steps. First, the solid surface (plastic, rubber, ceramic, and/or metal) is treated to form a thin, physically bound primer layer containing radical initiators. The pre-gel solution is then applied to the treated surface, followed by photo-induced polymerization. The P-DN gel coatings show high toughness, with one notable formulation reaching over 1000 J m(-2) in a 90 degrees peeling test. The coatings also show high stability against long-term water-storage, elevated temperatures, and solvent exposure. Moreover, it is demonstrated that the P-DN gel-coated surfaces exhibit low friction properties with high wear resistance, by pin-on-flat tests. The simple coating process can be used even on surfaces with complex geometries, including 3D shapes. This work will enable the use of DN gels in applications such as biocompatible lubricants, scratch resistance coatings, and anti-fouling paints.