Photoinitiated free radical polymerization of vinyl compounds in aqueous solution

Evans, M. G. ; Santappa, M. ; Uri, N. (1951) Photoinitiated free radical polymerization of vinyl compounds in aqueous solution Journal of Polymer Science, 7 (2-3). pp. 243-260. ISSN 0022-3832

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A new method for the photochemical initiation of polymerization of vinyl compounds in aqueous solution is described. The photochemically active species is an ion pair complex of the formula Fe3+X(X=OH, CI, N3, etc.). The light absorption by the ion pair leads to an electron transfer causing reduction of the cation and oxidation of the anion to an atom or free radical X. The latter leads to the initiation of polymerization in accordance with X+CH2═CHR→XCH2—CHR—. The kinetics of the reaction were studied by the measurement of: (a) ferrous ion formed (colorimetrically), (b) monomer disappearance (by titration and by weighting the polymer), (c) the chain length of the polymer (in the case of methyl methacrylate). The dependence of the quantum yield on the light intensity, light absorption fraction, and the concentration of vinyl monomer and ferrous ion added initially was investigated. A complete mechanism, both with regard to the formation of free radicals and the polymerization reaction, was put forward involving: (1) light absorption, (2) a primary dark back reaction, (3) dissociation of the primary product, (4) a secondary dark back reaction, (5) initiation of polymerization by free radicals, (6) propagation of polymerization, and (7) termination by recombination of active polymer endings. The mechanism was verified by the experimental results and some constant ratios were estimated quantitatively.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
ID Code:43350
Deposited On:11 Jun 2011 08:37
Last Modified:11 Jun 2011 08:37

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