S. Sahoo, Wei Liu, L. Samuelson
Dec 5, 2002
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0
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38
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Journal
Macromolecules
Abstract
The nature of the initial coupling mechanism in the enzymatic polymerization of p-cresol was investigated by in-situ 1H NMR spectroscopy in an aqueous−organic media. Two types of in-situ experiments were performed, in which the course of polymerization was monitored with (i) incremental additions of H2O2 to the reaction mixture in the NMR tube at a regular interval and (ii) a function of reaction time after a known amount of addition of H2O2. These experiments were used to understand the coupling mechanism at the very early stage of reaction and during the course of polymerization reaction. In the early stage of the polymerization, the reaction mixture contains monomer as a dominant fraction and a small concentration of low molecular weight oligomers such as dimer, trimers, etc. The analysis of the reaction mixture by 1D and 2D in-situ NMR methods suggests the ortho−ortho C−C coupling as the dominant coupling mechanism during the initial stage of the polymerization. The quantitative NMR analysis indicates...