Abstract
Radical copolymerizations of 2-hydroxyethyl methacrylate (HEMA) with n-butyl methacrylate (BMA) and n-butyl acrylate (BA) were carried out in xylene, DMF, and n-butanol solutions. Solvent effects on copolymerization propagation kinetics were investigated using pulsed laser polymerization (PLP) combined with size exclusion chromatography (SEC) as well as proton NMR, while starved-feed higher temperature semibatch reactions were carried out in different solutions to simulate industrial production. Solvent choice, through its influence on hydrogen bonding of HEMA monomer, has a significant impact on the copolymer composition and propagation rate coefficient and thus influences the semibatch polymerization behavior of BMA/HEMA, as previously found for the styrene/HEMA system. The presence of HEMA leads to increased polymer molecular weight, a result attributed to branching reactions involving dimethacrylate impurity. Although H-bonding (and solvent choice) influences BA/HEMA kinetics, its relative effect is negligible on semibatch operation under the conditions studied.
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