Beneficial Effect of Solvent Pressure on Homogeneity of Poly(Ester‐co‐Syringyl Methacrylate)s During Radical Ring‐Opening Copolymerization

In free radical ring‐opening copolymerization of cyclic ketene acetals (CKA) with vinyl monomers, a major challenge is the often‐low reactivity of CKAs and thus insufficient ester incorporation and homogeneity. Most workarounds, like semibatch copolymerization, require a considerable change in the system. In this work, we report a method to improve ester incorporation into the backbone and homogeneity of the polymer by using a batch copolymerization in 1,4‐dioxane above solvent boiling point. The monomer system of 2‐methylene‐4‐phenyl‐1,3‐dioxolane (MPDL) and syringyl methacrylate (SM) showed improved copolymerization parameters ( r MPDL = 0.032 and r SM = 2.464) compared to the polymers obtained at 70°C in anisole. Basic hydrolysis with potassium hydroxide (KOH) in tetrahydrofuran (THF)/methanol (MeOH) was conducted to study structural homogeneity and was compared with semibatch experiments.