Synthesis of Cobaltocenium-Containing Methacrylate Monomer

Chain transfer agent 2-cyano-2-propyl benzodithioate (97%, CPB) was purchased from Sigma-Aldrich and used directly. Monomer 2-cobaltocenium amidoethyl methacrylate hexafluorophosphate (CoAEMAPF₆) was synthesized by reacting cobaltocenium monocarboxylic acid with 2-aminoethyl methacrylate hydrochloride in the presence of coupling agent N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide (EDC) according to established methods.^{47 (link)–49 (link)} 2-aminoethyl methacrylate hydrochloride (90%), N-(3-dimethylaminopropyl)-N'-ethylcarbodi imide hydrochloride (EDC-HCl, 98%), 4-(dimethylamino)pyridine and tetrabutylammonium chloride (TBACl) were purchased from Sigma-Aldrich and used as received. HPMA was purchased from Alfa-Aesar, which comprises approximately 75% 2-hydroxypropyl methacrylate and 25% 2-hydroxyisopropyl methacrylate. AIBN and 2,2'-azobis (2-(2-imidazoline-2-yl)propane) dihydrochloride were purchased from VWR. Water was purified using Thermo Scientific Nanopure with ion conductivity at 18.2 MΩ. All other chemicals were from commercial sources and used as received.