A quantum chemistry study of the free‐radical copolymerization propagation kinetics of styrene and 2‐hydroxyethyl acrylate

Abstract

Several difficulties are reported in literature about the experimental analysis of polymerizations involving 2‐hydroxyethyl acrylate (HEA), mainly due to transfer reactions that characterize the system. In particular, major problems are emerged in the study of free radical copolymerization kinetics of HEA. In this work, free‐radical copolymerization propagation kinetics of HEA and styrene (ST) are investigated through a computational approach based on density functional theory. Monomer reactivity ratios for HEA/ST copolymerization are calculated at 50°C and 125°C, obtaining values that exhibit a weak dependence on temperature. In particular, HEA reactivity ratio, rHEA, equal to 0.14 and ST reactivity ratio, rST, equal to 0.31 at 50°C, whereas rHEA = 0.17 and rST = 0.29 at 125°C. Moreover, the reliability of such parameters has been tested by analyzing copolymer composition data as a function of monomer feed composition, at the same temperatures indicated above. Experimental values proposed in literature are well predicted by the terminal copolymerization model using the kinetic parameters computationally determined. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

A QM Approach to the Calculation of Reactivity Ratios in Free‐Radical Copolymerization

“…Only data at 50 °C are reported because no remarkable differences were found between the temperatures. For this system, the prediction of the copolymer composition using the computational monomer reactivity ratios in the TM is in agreement with the experimental data 67…”

“…The promising results obtained for the ST/ x MA and VAc/MMA copolymers were recently confirmed, even for the HEA/ST copolymer system 67. The aim of this work was to support the experimental study of HEA reactivity.…”

“…In fact, the rapid and continuing increase in computer power has made it feasible to use ab initio QM to determine different properties, such as molecular geometries (i.e., bond lengths, bond angles, and torsional angles), energetic profiles of reactions, vibrational frequencies of molecular species, transition state structures, and reaction frequency factors, with good accuracy. Only a few pioneering works that use this technique to study free radical copolymerization reactions have been proposed in the literature 56, 62–67…”

A Combined Computational and Experimental Study on the Free‐Radical Copolymerization of Styrene and Hydroxyethyl Acrylate

“…The reported literature values of the TM monomer reactivity ratios for bulk ST/HEA show some scatter, as summarized previously 15. The most comprehensive study, by McManus et al,12 presents a statistical evaluation and reports monomer reactivity ratios with relatively small confidence intervals.…”

“…More recently, a computational approach based on density function theory (DFT) was applied to study the free‐radical copolymerization of HEA and ST15 to support and enrich the experimental efforts. The values of monomer reactivity ratios were estimated assuming the terminal model (TM) of copolymerization kinetics and were found to be in good agreement with experimental values from literature.…”