Kinetics of Radical Ring Opening Polymerization of the Cyclic Ketene Acetal 2-Methylene-1,3-dioxepane with Vinyl Monomers

Radical ring opening polymerization (rROP) of cyclic ketenes such as 2-methylene-1,3-dioxepane (MDO) is a promising method for introducing (bio)degradability to the backbone of chain-growth polymers. However, the copolymerization of MDO with other vinyl monomers is challenging due to its low propagation rate and unfavorable reactivity ratios. In this work, the bulk copolymerization of MDO with vinyl acetate (VAc) is revisited and accurate reactivity ratios are calculated ( r MDO = 0.43 ± 0.06 and r VAc = 3.25 ± 0.12). Furthermore, for the first time the copolymerizations of MDO with 2-octyl acrylate (2OA) as well as lauryl methacrylate (LMA) are analyzed, and the reactivity ratios of MDO and these hydrophobic (meth)acrylate monomers are assessed. The lowest composition drift was measured for the MDO/2OA system with estimated reactivity ratios of r MDO = 0.0000 + 0.0003 and r 2OA = 1.29 ± 0.053. A higher composition drift was observed for the MDO/VAc system, for which reactivity ratios have been estimated. The MDO/LMA system presented the highest composition drift with estimated reactivity ratios of r MDO = 0.022 ± 0.002 and r LMA = 8.471 ± 0.028.