A computational study on the reactivity enhancement in the free radical polymerization of alkyl α‐hydroxymethacrylate and acrylate derivatives

Abstract

The free radical polimerizability behavior of alkyl α‐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…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…HC, CO…H‐ϕ as well as π–π 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. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Relationship Between the Free Radical Polymerization Rates of Methacrylates and the Chemical Properties of their Monomeric Radicals

“…The presence of the pendant phenyl group seems to averagely increase the predicted rate of polymerization by a value of 0.0165 s −1 . In literature, this enhanced reactivity has been attributed to the possibility of π–π stacking, which is not accounted for by our two reactivity descriptors. Finally, Figure shows the high correlation between the predicted rates of polymerization, using the three separate equations, and the experimental rates of polymerization.…”

A Quantum Mechanical Study on the Propagation Kinetics ofN-methylacrylamide: Comparison WithN,N-Dimethylacrylamide in Free Radical Polymerization

“…In the model, methyl radical (CH 3 .) is attached to the monomer in order to represent the monomeric radical and the chain growth reaction is achieved by the attack of this model monomeric radical to the monomer as in similiar studies so far . Using dimeric chain in modelling free radical homopolymerization is a reasonable assumption since the penultimate unit is relatively far away from the reaction center compared to the terminal unit.…”

“…Refining energetics obtained with B3LYP geometries via single point energy calculations with other functionals is a very frequently employed method in radical polymerization in the literature . In this study, optimization of the geometries with the B3LYP functional is followed by benchmark calculations with the following functionals: BMK, MPWB1K, M05–2X, M06–2X followed by BMK is reported to have good performance in radical reactions in general; MPWB1K is known to describe hydrogen bondings accurately and yield reliable thermochemical results; M06–2X gives satisfactory results in thermochemistry; M05–2X is reported to perform well in describing radical species . 6–311 + G(3df,2p) basis set is used in all single‐point calculations in order to describe the dispersion interactions more adequately.…”

“…[17,19,[39][40][41][42] In this study, optimization of the geometries with the B3LYP functional is followed by benchmark calculations with the following functionals: BMK, [43] MPWB1K, [44] M05-2x, [45] M06-2x [46] followed by. BMK is reported to have good performance in radical reactions in general [15,[47][48][49] ; MPWB1K is known to describe hydrogen bondings accurately and yield reliable thermochemical results [15,44,50] ; M06-2X gives satisfactory results in thermochemistry [20] ; M05-2X is reported to perform well in describing radical species. [45,51,52] 6-311 þ G(3df,2p) basis set is used in all single-point calculations in order to describe the dispersion interactions more adequately.…”

“…Solvent and substituent effects on the propagation kinetics of water‐soluble monomers, acrylic acid and methacrylic acid,, acrylamide and methacrylamide, acrylonitrile and vinylchloride in their free radical polymerization were studied with quantum mechanical calculations. Propagation mechanisms and kinetic parameters of propagation of acrylates and methacrylates and polyvinylchloride were evaluated with quantum mechanical calculations. Free‐radical copolymerization of styrene and 2‐hydroxyethyl methacrylate was also studied recently with Density Functional Theory calculations and the importance of hydrogen bonding interactions and the effect of solvent polarity were demonstrated…”