Tailoring stimuli-responsive copolymers via a universal poly(glycidyl methacrylate) modification strategy

In this work, glycidyl methacrylate (GlyMA) copolymers have been synthesized together with methyl methacrylate (MMA) as a comonomer via living anionic polymerization. Under mild and precisely chosen reaction conditions in tetrahydrofuran (THF) at -78 °C, the ring-opening and crosslinking reaction of the epoxide could be prevented during the polymerization. The polymers were analyzed by size-exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, yielding a copolymer with a dispersity of 1.10 and a number-average molecular weight of 25 kDa. After confirming the presence of intact epoxide units, redox-active amines, such as 2-aminoanthraquinone (2AAQ) and 3-ferrocenyl propylamine, were used to functionalize the GlyMA-containing polymer. As an alternative, more effective route, the epoxide ring was opened with an azide as the nucleophile, thereby generating a platform for further copper-catalyzed click reactions in a quantitative manner. Ethynylferrocene and ethynylcobaltocenium hexafluorophosphate were reacted with the azide to yield the corresponding triazole system bearing a redox-active metallocene side chain. Finally, all functionalized polymers with electrochemically addressable groups were then measured by cyclic voltammetry (CV) to assess their electrochemical behavior. The demonstrated strategies show the universal use of GlyMA as a functional monomer for several post-polymerization modifications, combined with the advantages of living anionic polymerization.