Successive Redox‐Reaction‐Triggered Interface Radical Polymerization for Growing Hydrogel Coatings on Diverse Substrates

⋅ catalytically at the interface to initiate interface polymerization of monomers. As a result, hydrogel coatings with controllable thickness could be grown on surfaces of arbitrary substrates to change their surface characteristics regardless of materials size, category, geometry and transparency, implying considerable potential in surface engineering.