The entry of free radicals into polystyrene latex particles

Adams, Mary E., Trau, Mathias, Gilbert, Robert G., Napper, Donald H. and Sangster, David F. (1988) The entry of free radicals into polystyrene latex particles. Australian Journal of Chemistry, 41 12: 1799-1813.

Author Adams, Mary E.
Trau, Mathias
Gilbert, Robert G.
Napper, Donald H.
Sangster, David F.
Title The entry of free radicals into polystyrene latex particles
Journal name Australian Journal of Chemistry   Check publisher's open access policy
ISSN 0004-9425
Publication date 1988
Sub-type Article (original research)
Volume 41
Issue 12
Start page 1799
End page 1813
Total pages 15
Place of publication Collingwood, VIC, Australia
Publisher C S I R O Publishing
Language eng
Formatted abstract
Mechanistic understanding of the processes governing the kinetics of emulsion polymerization has both scientific and technical interest. One component of this process that is poorly understood at present is that of free radical entry into latex particles. Measurements were made of the entry rate coefficient as a function of temperature for free radicals entering polystyrene latex particles in seeded emulsion polymerizations initiated by γ-rays. The activation energy for entry was found to be less than 24±3 kJ mol-1, consistent with entry being controlled by a physical (e.g., diffusional ) rather than a chemical process. Measurement of the entry rate coefficient as a function of the γ-ray dose rate suggested that the factors that determine the entry rate when the primary free radicals are uncharged are similar to those that determine the entry rate for charged free radicals derived from chemical initiation by peroxydisulfate. This result was consistent with measurements of the entry rate coefficient of charged free radicals derived from peroxydisulfate; these data were found to be virtually independent of both the extent of the latex surface coverage by the anionic surfactant sodium dodecyl sulfate and the ionic strength of the continuous phase. The data refute several proposals given in the literature for the rate-determining step for entry, being inconsistent with control by (1) collision of free radicals with the latex particles, (2) surfactant desorption , and (3) an electrostatic barrier arising from the colloidal nature of the entering free radical. The origin of the activation energy for entry remains obscure.

Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemistry and Molecular Biosciences
Centre for Nutrition and Food Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 35 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 07 Mar 2011, 15:36:12 EST