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Solvent effects on the rate of polymerization of 2‐hydroxyethyl methacrylate photoinitiated with aliphatic azo compounds
Author(s) -
Alvarez Juan,
Encinas Maria V.,
Lissi Eduardo A.
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19991001)200:10<2411::aid-macp2411>3.0.co;2-g
Subject(s) - chemistry , acetonitrile , polymerization , solvent , polymer chemistry , reaction rate constant , radical polymerization , photochemistry , aqueous solution , photopolymer , radical , methacrylate , quantum yield , reaction rate , solvent effects , bulk polymerization , kinetics , organic chemistry , polymer , catalysis , physics , quantum mechanics , fluorescence
The rate of polymerization ( R p ) of 2‐hydroxyethyl methacrylate, at low conversion, using aliphatic azo compounds as photoinitiators is considerably faster in water than in acetonitrile as a solvent. Active radical production in different solvents was analysed in detail. The quantum yield of active radicals showed only a minor dependence on the medium properties. These differences are due to changes in primary radical recombination reactions and they are unrelated to changes of R p observed in different media. By employing intermittent illumination techniques, it is shown that the increased R p in aqueous solution is due to a reduced rate of termination. Similar propagation rate constants were obtained in acetonitrile and water, whereas the termination rate constant increases by one order of magnitude when acetonitrile is employed instead of water. These results are discussed in terms of the effect of the cosolvent on the medium viscosity and the macroradical conformation.