Correlation of reactivity ratios, transition-metal salts and ester hydrolysis to radical polymerization of electron-deficient comonomers with 2-(N, N-dimethylamino)ethyl methacrylate as the inimer. (March 2018) - Wang, Xiuting
Graphical abstract: Highlights: Acrylamides depress hydrolysis and ensure the preferential conversion of DMAEMA. FeCl3 -DMAEMA-DMAAm pairs underwent redox-initiated reverse self-condensing ATRP. High-MW PDMAAm (Mη > 2.0 × 10 7 g mol −1 ) was obtained via one-pot procedure. Abstract: The radical copolymerization of 2-(N, N-dimethylamino)ethyl methacrylate (DMAEMA, M1 ) as the inimer and electron-deficient monomers (M2, including methyl methacrylate (MMA), acrylamide (AAm) and N, N-dimethylacrylamide (DMAAm)) with transition-metal salts (such as copper II and iron III ) as the oxidizing agent was correlated to their reactivity ratios ( r 1 and r 2 ), counterions to transition-metal salts and ester hydrolysis of DMAEMA with an objective to obtain high-molecular weight (MW) branched polymers. As r 1 ≈ r 2 ≈ 1.0, primary chain initiation occurred even at high MMA conversion during CuSO4 -DMAEMA redox-initiated radical polymerization of MMA, and thus the polymerization failed to form high-MW branched PMMA free from linear analogues. As r 1 > 1.0 > r 2, DMAEMA was preferentially converted into -DMAEMA- units during Fe(NO3 )3 -DMAEMA redox-initiated aqueous radical polymerization of AAm/DMAAm, but N, N-dimethylaminoethanol formed via hydrolysis led to lower-MW chains. Under optimal conditions with minimum hydrolysis, FeCl3 -DMAEMA redox-initiated aqueous radical polymerization of DMAAm proceeded via redox-initiated reverse atom transfer radical polymerization (ATRP) generating DMAEMA-terminated chains with a carbon-chloride terminal. Fe II -catalyzed self-condensing ATRP led to high-MW branched PDMAAm even under aerobic conditions.