Electrochemically Mediated Atom Transfer Radical Polymerization from a Substrate Surface Manipulated by Bipolar Electrolysis: Fabrication of Gradient and Patterned Polymer Brushes

We report the first ever use of electrochemically mediated atom transfer radical polymerization (eATRP) employing a bipolar electrochemical method for the fabrication of both gradient and patterned polymer brushes. A potential gradient generated on a bipolar electrode allowed the formation of a concentration gradient of a Cu^I polymerization catalyst through the one‐electron reduction of Cu^II, resulting in the gradient growth of poly(NIPAM) brushes from an initiator‐modified substrate surface set close to a bipolar electrode. These polymer brushes could be fabricated in three‐dimensional gradient shapes with control over thickness, steepness, and modified area by varying the electrolytic conditions. Moreover, by site‐selective application of potential during bipolar electrolysis, a polymer brush with a circular pattern was successfully formed. Polymerization was achieved using both a polar monomer (NIPAM) and a nonpolar monomer (MMA) with the eATRP system.