Covalently sewing dual-sided Janus coatings via photoiniferter surface chain extension

Abstract

Janus coatings can combine strong substrate adhesion with surface hydrophobicity, but they often suffer from weak interlayer interfaces. Here we use visible-light photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization for surface chain extension to “sew” together an all-covalent Janus bilayer (dual-sided functional bilayer), thus delivering 9.0 MPa interlayer adhesion strength and ∼100-fold improved corrosion protection on AZ31B, with similar performance on Q235 and H62.