Quantitative Contrasts in the Copolymerization of Acrylate- and Methacrylate-Based Comonomers

Abstract

Automatic continuous online monitoring of polymerization reactions (ACOMP) was used to assess quantitatively the reactivity, average composition drift and distributions, as well as molar mass and intrinsic viscosity evolution of comonomers from the acrylate and methacrylate families during free radical copolymerization. In the latter case, N-methacryloxysuccinimide (MASI) was of chief interest because of its promise as a starting material from which highly tailored polymers can be produced by postpolymerization modifications. It was found that the reactivity ratios of MASI with an acrylate, such as butyl acrylate (BA), were widely separated and comparable to the case of methyl methacrylate (MMA) and BA. In contrast, reactivity ratios for MMA/MASI were closer together, consistent with general trends in the literature for MMA copolymerization with other methacrylates. While this is intuitively reasonable from a chemical point of view, this comprehensive online characterization confirms that at least some predictions about MASI copolymerization behavior can be made using the much wider knowledge base for MMA. The disparity between BA/MASI copolymerization compared to MMA/MASI is also seen in the unusual increase in weight-average molar mass and intrinsic viscosity as conversion increases. This work establishes the precedents and methodologies that can be used as a general tool in MASI-based developments and paves the way toward monitoring ATRP copolymerization of MASI, as well as postpolymerization modifications such as hydrolysis and derivitization.