Kinetic study of acrylamide radical polymerization initiated by the horseradish peroxidase–mediated system

Abstract

The polymerization kinetics of acrylamide (AAM) in water initiated by a ternary enzymatic system of horseradish peroxidase (HRP)/H2O2/acetylacetone (ACAC) was investigated. Conversion–time plots were obtained by dilatometry under different conditions of reaction temperatures and initial concentrations of HRP, ACAC, H2O2, and AAM. The results showed that the effect of the initial concentration of ACAC on the inhibition period was significant. The inhibition period decreases with increasing the initial concentration of ACAC. The inhibition period can be even eliminated by the use of a comparatively large amount of ACAC. From the conversion–time plots, the polymerization rate equation was obtained. Some kinetic features were explained on the basis of analysis of the reaction mechanism. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 475–481, 2012

Oxygen-mediated enzymatic polymerization of thiol–ene hydrogels

“…39 The utility of HRP for the initiation of polymerization reactions is well-documented and has been used to synthesize polymers through the oxidative polymerization of phenols 40 and the free-radical, chain-growth polymerization of acrylamides 41 and (meth)acrylates. 42 For example, poly(methyl methacrylate) (PMMA) was synthesized from a formulation of methyl methacrylate, HRP, hydrogen peroxide, and acetylacetone as a substrate for HRP-mediated oxidation.…”

Radical-Mediated Enzymatic Polymerizations

“…An in-depth exploration of the polymerization of acrylamide by HRP, hydrogen peroxide, and acetylacetone was performed by Wen and coworkers to provide insight into some of the questions raised by earlier work [ 34 ]. Regarding the lengthy inhibition periods observed by Lalot [ 31 ], Wen found that the inhibition period prior to polymerization was caused by oxygen inhibition.…”

“…This inhibition time could be reduced or eliminated by increasing the concentration of acetylacetone, to as high as 0.13 M, as this led to an increase in the radical generation rate; as these radicals reacted with and consumed oxygen, propagation reactions successfully competed with the inhibition reactions allowing the polymerization to proceed once the oxygen concentration was sufficiently low. Owing to the reduced inhibitory period, reactions times were significantly shorter than those observed by Lalot; however, the synthesized poly(acrylamide) batches were similar to those described by Lalot, having M n s of 200 to 630 kg/mol and dispersities ( Đ ), a measure of the molecular weight distribution width, of 2.0 to 3.0, with yields of 72% to 97% [ 34 ].…”

Preparation and Properties of Copolymer of Degraded Starch and CA-HPA Initiated by HRP/H₂O₂/ACAC

“…The initiation is thus totally dependent on the enzymatic activity. Indeed, hydrogen peroxide appears to have three contributions in the initiating system: (i) it is one of the two substrates of HRP (the other being ACAC) and leads to the formation of compound I; (ii) it is an inhibitor of HRP since compound III is formed in the presence of an excess of H 2 O 2 , and leads to an irreversible inactivation of HRP; this can be inter pretend as a loss of a part of the HRP initially introduced; (iii) it consumes a part of the ACAC initially added by the formation of P-IV (cyclic peroxide decomposition) [9][10][11]. The reaction for graft polymerization of degraded starch with CA-HPA is showed in Fig.…”