Res. Chem. Intermed.
, Vol. 30, No. 7–8, pp. 807–827 (2004)
Also available online - www.vsppub.com
Investigation of radical intermediates in polymer
GARETH J. PRICE
, LEANNE GARLAND, JENNY COMINA,
MATTHEW DAVIS, DAVID J. SNELL and PETER J. WEST
Department of Chemistry, University of Bath, Bath BA2 7AY, UK
Received 22 March 2004; accepted 22 April 2004
Abstract—There is current interest in using high-intensity ultrasound to perform a range of chemical
transformations, including polymerisation reactions. In this work, the technique of radical trapping,
primarily using DPPH, has been used to measure radical production rates in a range of monomer and
related systems when exposed to high intensity ultrasound. It has been shown that realistic rates of
production can be obtained around room temperature equivalent to thermal decomposition rates >
C, making sonication a viable method for initiating polymerisation. Rates of initiation in a two-
phase organic in water system have also been measured. Some of the initiating species have been
identiﬁed recording the ESR spectra of adducts with spin traps, although further analysis is needed
before the complete range of radicals produced can be identiﬁed.
Keywords: Sonochemistry; radical production; ESR spectroscopy.
Sonication causes a range of chemical and physical effects in systems . Applica-
tions in polymer science have been a rich area of exploitation of these effects both
in synthesis and in the modiﬁcation of existing polymers [2, 3]. A range of polymer
synthesis methods have been shown to beneﬁt from sonication [4, 5].
It is widely accepted that most sonochemical effects can be attributed to cavitation
, the growth and explosive collapse of microscopic bubbles as a high-energy
sound wave propagates through the ﬂuid. This can result in extreme conditions of
temperature (>2000 K) and pressure (>500 bar) on a microsecond timescale ,
leading to the formation by ‘sonolysis’ of reactive intermediates, such as radicals,
from breakdown of the solvent. A parallel reaction pathway exists for volatile
To whom correspondence should be addressed. E-mail: G.J.Price@bath.ac.uk