Studies On Radical Polymerization Of Vinyl Monomers Mediated By Horseradish Peoxidase Redox System

Horseradish peroxidase (HRP) is an oxido-reductase acting on hydrogen peroxide as oxidant. With the presence of H2O2 and acetylacetone (Acac), free radical polymerization of vinyl monomers, including acrylamide (AAM), methyl metha- acrylate (MMA), acrylonitrile (AN), butyl acrylate (BA), etc, have been carried out with the initiation of HRP. The enzyme-mediated products have also been measured and characterized by IR spectra. The polymerizations of acrylamide (AAM) in water initiated by a HRP/ H2O2/Acac ternary system have been investigated. It was carried out by dilatometry to obtain the different conversion curves under different conditions. The experimental rate equation was also fitted and the further reaction mechanism.wasexplained by analysis. And what is more, Microcapsules with an alginate gel core and a polyanion-polycation membrane have been investigated to immobilize HRP enzyme for their well mechanistic property and penetratable selectivity to different molecules and AAM polymerization initiated by immobilized enzyme system has been conducted successfully.From experiments and comparisons with various vinyl monomers mediated by HRP system, it can be learned that HRP/Acac/H2O2 ternary system is effective and potent to initiate the polymerizations of vinyl monomers. However, the conversions of different monomers are dissimilar. The water-soluble monomer has a higher conversion, while the oil-soluble substrate has a lower one, for an instance, about 40% for MMA.AAM radical polymerizations initiated by an HRP-mediated redox system in lower HRP initial concentration (about 0.1 mg/mL) were performed with high yields in wild ways. The molecular weight of several PAAM products were measured and characterized as with Mn and DP ranging from 2.0-6.3 X 105 DA and 2.0-3.0, respectively . In the condition of fixed other concentrations, the inhibition period was dependant on [ACAC]o. The reason was qualitative interpreted caused by residual oxygen gas, but the quantitative correlations were needed to further investigate to obtain the rate constants. From the conversion curves, it was derived of polymerization rate (RP) and gained the apparent activation energy (Ea=7.65 KJ/mol). At last, we fitted the experimental rate equation and explained by analysis withreaction mechanism.In order to use the enzyme effectively, Alginate-Chitosan-Alginate (ACA) microcapsules were used to immobilize HRP. The immobilized efficiency of this method and the ralative special ratio of immobilized to free enzyme were tested as 51.33% and about 60%, respectively. AAM polymerization initiated by immobilized enzyme system has been conducted successfully.The study of our work provides the necessary experimental basis for further investigatation.