Styrene based copolymers for consistent reactivity ratio evaluation

The reactivity ratio parameters or r-parameters are the most important indicators for the characterization of copolymers. Consequently, over the last decades, a variety of methods have been developed to determine and predict the r-parameters. Among these, the prediction with the Alfrey-Price Q,e-scheme is one of the oldest and most commonly used techniques. The synthesis of 21 binary methacrylate-based copolymers with lauroyl peroxide as the initiator (radical starter) shows large deviations between the experimentally determined copolymerization parameters and those calculated with the Q,e-values taken from the established literature. Assuming an error tolerance of ±0.05, only 20.6% of the r-parameters were predicted correctly. To address this problem, copolymerizations with styrene as the comonomer are performed to maintain comparable Q,e-values. It is found that structural similarities of the monomers favor correct prediction. Furthermore, the use of specific parameter sets can improve the prediction, resulting in the maximum of 42.3% correct findings.