Bulk free-radical copolymerization of styrene and 2-hydroxyethyl acrylate (HEA) is investigated experimentally at 50 ° C using pulsed-laser polymerization and computationally using ab initio simulations. Arrhenius parameters for HEA chain-end homopropagation are A = 1.72 × 10 7 L mol − 1 s − 1 and E a = 16.8 kJ mol − 1 , based on experiments between 20 and 60 ° C. Copoly mer composition data are well fi tted by the terminal model with reactivity ratios r ST = 0.44 ± 0.03 and r HEA = 0.18 ± 0.04, but the variation in the propagation rate coeffi cient with monomer composition is underpredicted. Results are compared with computational predictions assuming the terminal as well as the penultimate unit effect (PUE) model. Intramolecular H-bonding is shown to have a signifi cant infl uence on PUE calculations. Discrepancies between computational predictions and experiment are attributed to the infl uence of intermolecular H-bonding.

A Combined Computational and ExperimentalStudy on the Free-Radical Copolymerization ofStyrene and Hydroxyethyl Acrylate

MAVROUDAKIS, EVANGELOS;MOSCATELLI, DAVIDE;
2012

Abstract

Bulk free-radical copolymerization of styrene and 2-hydroxyethyl acrylate (HEA) is investigated experimentally at 50 ° C using pulsed-laser polymerization and computationally using ab initio simulations. Arrhenius parameters for HEA chain-end homopropagation are A = 1.72 × 10 7 L mol − 1 s − 1 and E a = 16.8 kJ mol − 1 , based on experiments between 20 and 60 ° C. Copoly mer composition data are well fi tted by the terminal model with reactivity ratios r ST = 0.44 ± 0.03 and r HEA = 0.18 ± 0.04, but the variation in the propagation rate coeffi cient with monomer composition is underpredicted. Results are compared with computational predictions assuming the terminal as well as the penultimate unit effect (PUE) model. Intramolecular H-bonding is shown to have a signifi cant infl uence on PUE calculations. Discrepancies between computational predictions and experiment are attributed to the infl uence of intermolecular H-bonding.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/674953
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