However, reports on combining the advantages of surface-initiate polymerization with electrochemically controlled polymerization are rare. Byers, Wang, and coworkers presented impressive work on electrochemically controlled surface-initiated polymerization catalyzed by iron complexes anchored on an electrode surface (Figure ). A bis(imino)pyridine iron(II) complex was anchored onto titanium oxide nanoparticles through protonolysis of an iron alkyl precursor surface with alcohol groups. The surface-supported redox-active iron complex was achieved by depositing the functionalized titanium oxide nanoparticles onto a fluorine-doped tin oxide surface, serving as the electrically addressable surface for electrochemical polymerization. The reactivity of the molecular iron complex toward ring opening polymerization of lactide (LA) and cyclohexene oxide (CHO) was maintained after surface functionalization. Both homogenous and heterogenized iron(II) complexes react with lactide in the reduced state. Oxidizing the iron(II) center to iron(III) by using a chemical oxidant resulted in no activity toward lactide but initiated the polymerization of CHO. Applying an oxidative potential to replace chemical oxidants resulted in the same switchable behavior for both homogenous and surface-anchored iron complexes.