Roughness-Mediated SI-Fe⁰CRP for Polymer Brush Engineering toward Superior Drag Reduction

Surface-initiated iron(0)-mediated controlled radical polymerization (SI-Fe⁰CRP) with low toxicity and excellent biocompatibility is promising for the fabrication of biofunctional polymer coatings. However, the development of Fe(0)-based catalysts remains limited by the lower dissociation activity of the Fe(0) surface in comparison to Cu(0). Here, we found that, by simply polishing the Fe(0) plate surface with sandpaper, the poly(methacryloyloxy)ethyl trimethylammonium chloride brush growth rate has been increased significantly to 3.3 from 0.14 nm min^-1 of the pristine Fe(0) plate. The excellent controllability of roughness-mediated SI-Fe⁰CRP can be demonstrated by customizing multicompartment brushes and triblock brushes. Furthermore, we found that the resulting polymer brush coatings exhibit remarkably low water adhesion (0.097 mN) and an outstanding drag reduction rate of 52% in water. This work provides a promising strategy for regulating the grafting rate of polymer brushes via SI-Fe⁰CRP for biocompatible marine drag reduction coatings.