Robust and Lubricating Interface Semi‐Interpenetrating Network on Inert Polymer Substrates Enabled by Subsurface‐Initiated Polymerization

Abstract Lubricating hydrogel coatings on inert rubber and plastic surfaces significantly reduce friction and wear, thus enhancing material durability and lifespan. However, achieving optimal hydration lubrication typically requires a porous polymer network, which unfortunately reduces their mechanical strength and limits their applicability where robust durability and wear‐resistance are essential. In the research, a hydrogel coating with remarkable wear resistance and surface stability is developed by forming a semi‐interpenetrating polymer network with polymer substrate at the interface. By employing a good solvent swelling method, monomers, and photoinitiators are embedded within the substrates' subsurface, followed by in situ polymerization under ultraviolet light, creating a robust semi‐interpenetrating and entangled network structure. This approach, offering a thicker energy‐dissipating layer, outperforms traditional surface modifications in wear resistance while preserving anti‐fatigue, hydrophilicity, oleophobicity, and other properties. Adaptable to various rubber and plastic substrates by using suitable solvents, this method provides an efficient solution for creating durable, lubricating surfaces, broadening the potential applications in multiple industries.