Free-radical copolymerization of styrene and m-isopropenyl-α,α′-dimethylbenzyl isocyanate studied by 1h NMR kinetic experiments

Leonie Barner, Christopher Barner-Kowollik, Thomas P. Davis

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33 Citations (Scopus)

Abstract

The free-radical copolymerization of m-isopropenyl-α,α′-dimethylbenzyl isocyanate (TMI) and styrene was studied with 1H NMR kinetic experiments at 70 °C. Monomer conversion vs time data were used to determine the ratio kp × kt-0.5 for various comonomer mixture compositions (where kp is the propagation rate coefficient and kt is the termination rate coefficient). The ratio kp × kt-0.5 varied from 25.9 × 10-3 L0.5 mol-0.5 s-0.5 for pure styrene to 2.03 × 10-3 L0.5 mol-0.5 s-0.5 for 73 mol % TMI, indicating a significant decrease in the rate of polymerization with increasing TMI content in the reaction mixture. Traces of the individual monomer conversion versus time were used to map out the comonomer mixture composition drift up to overall monomer conversions of 35%. Within this conversion range, a slight but significant depletion of styrene in the monomer feed was observed. This depletion became more pronounced at higher levels of TMI in the initial comonomer mixture.

Original languageEnglish
Pages (from-to)1064-1074
Number of pages11
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume40
Issue number8
DOIs
Publication statusPublished - 15 Apr 2002
Externally publishedYes

Keywords

  • H NMR
  • Kinetics
  • M-isopropenyl-α,α′-dimethylbenzyl isocyanate (TMI)/styrene copolymerization
  • Ratio of propagation rate coefficient to termination rate coefficient
  • Reactivity ratios

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