Aqueous Free-Radical Polymerization of Non-Ionized and Fully Ionized Methacrylic Acid
File(s)
Author(s)
Fischer, Eric Jean
Storti, Giuseppe
Cuccato, Danilo
Type
Journal Article
Abstract
Water-soluble, carboxylic acid monomers are known to exhibit peculiar kinetics when polymerized in aqueous solution. Namely, their free-radical polymerization rate is affected by several parameters such as monomer concentration, ionic strength, and pH. Focusing on methacrylic acid (MAA), even though this monomer has been largely addressed, a systematic investigation of the effects of the above-mentioned parameters on its polymerization rate is missing, in particular in the fully ionized case. In this work, the kinetics of non-ionized and fully ionized MAA are characterized by in-situ nuclear magnetic resonance (NMR). Such accurate monitoring of the reaction rate enables the identification of relevant but substantially different effects of the monomer and electrolyte concentration on polymerization rate in the two ionization cases. For non-ionized MAA, the development of a kinetic model based on literature rate coefficients allows us to nicely simulate the experimental data of conversion versus time at a high monomer concentration. For fully ionized MAA, a novel propagation rate law accounting for the electrostatic interactions is proposed: the corresponding model is capable of predicting reasonably well the electrolyte concentration effect on polymerization rate. Nevertheless, further kinetic information in a wider range of monomer concentrations would be welcome to increase the reliability of the model predictions.
Date Issued
2017-06-01
Date Acceptance
2017-04-24
Citation
Processes, 2017, 5 (2)
ISSN
2227-9717
Publisher
MDPI AG
Journal / Book Title
Processes
Volume
5
Issue
2
Copyright Statement
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Subjects
Science & Technology
Technology
Engineering, Chemical
Engineering
methacrylic acid
free radical polymerization
modeling
propagation
termination
electrostatic interactions
electrostatic screening
kinetics
NMR
PROPAGATION RATE
KINETICS
TERMINATION
POLYELECTROLYTES
COPOLYMERIZATION
ACRYLAMIDE
MECHANISM
MONOMER
Publication Status
Published
Article Number
23