Kinetic studies of the photopolymerisation of acrylamide in aqueous solution: effects of bromoform as a Chain transfer agent

Kamonchanok Thananukul, Juraiporn Porkaew, Patchara Punyamoonwongsa, Robert Molloy*, Brian J. Tighe

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The effects of adding bromoform (CHBr3) as a potential chain transfer agent in the photopolymerisation of acrylamide (AM) in aqueous solution have been studied both in terms of influencing the rate of polymerisation and the molecular weight of the polyacrylamide (PAM) formed. Using 4,4′-azo-bis(4-cyanopentanoic acid) (ACPA) as photoinitiator, two different CHBr3 concentrations as chain transfer agent were compared: 0.5 and 2.0 mol % (relative to AM), the higher of which was determined by the limit of CHBr3 water solubility. The results showed that CHBr3 was an effective chain transfer agent that could regulate the molecular weight of the PAM formed without seriously affecting the polymerisation rate. It is concluded that chain transfer to CHBr3occurs by both Br and H atom transfer although Br transfer is the more favoured due to the weaker C-Br bond. Furthermore, Br transfer leads to Br-terminated chains in which the terminal C-Br bond can re-dissociate leading to re-initiation and re-propagation of the same chain, thereby maintaining the polymerisation rate. Continuing studies into how this mechanism can be exploited in order to synthesize water-soluble block copolymers of potential biomedical importance are currently in progress.

Original languageEnglish
Pages (from-to)1352-1360
Number of pages9
JournalChiang Mai Journal of Science
Volume41
Issue number5/2
Publication statusPublished - 10 Aug 2014

Bibliographical note

The Chiang Mai Journal of Science is an open access journal.

Keywords

  • acrylamide
  • bromoform
  • chain transfer
  • photopolymerisation
  • polyacrylamide

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