A Computational Study on the Reactivity Enhancement in the Free Radical Polymerization of Alkyl alpha-Hydroxymethacrylate and Acrylate Derivatives

The free radical polimerizability behavior of alkyl alpha-hydroxymethacrylate (RHMA) derivatives (M1-M3) has been modeled by considering the propagation of the dimeric units of the compounds of interest. All the transition structures in this class of monomers are stabilized by long-range C=O center dot center dot center dot H-C interactions. The RHMA monomer bearing the ester functionality (M2) polymerizes slightly faster than the one with the ether functionality (M1) because of stronger electrostatic interactions between the C=O and H-C groups. 2-(Methoxycarbonyl)allyl benzoate (M3) shows higher reactivity as compared to M1 and M2 due to stronger electrostatic interactions. The same type of study has been carried out for hexyl (M4), benzyl (M5), and phenyl (M6) acrylate derivatives whose increasing reactivity has been attributed to the presence of C=O center dot center dot center dot H-C, C=O center dot center dot center dot H-Phi as well as p-p stabilizing interactions, respectively. While B3LYP/6-31+G(d) has been used to locate the stationary points along the free radical polymerization of nonaromatic species, long-range stabilizing interactions have only been detected with M06-2X/6-31+G(d). The kinetics that we obtain with this latter methodology for the free radical polymerization reactions of M1-M6 agree well qualitatively with experiment. An implicit solvent model has reproduced the kinetics of M1-M3 in benzene the best. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 880-889