CAMPHORQUINONE AS A PHOTOINITIATOR IN THE POLYMERIZATION OF 2-HYDROXYETHYL METHACRYLATE IN AQUEOUS SOLUTION: A KINETIC STUDY
Journal Title: Baqai Journal of Health Sciences - Year 2017, Vol 20, Issue 1
Abstract
The photoinitiated polymerization of 2-hydroxyethyl methacrylate (HEMA) (1-3 M) using camphorquinone (CQ) \ triethanolamine (TEOHA) system has been studied in the pH range 6.0-9.0. The kinetics of the reaction has been evaluated during the initial stages causing about 5% HEMA conversion to avoid the effects of any variation in the volume of the solution. The change in the concentration of HEMA during polymerization has been determined by a UV spectrometric method at 208 nm with a precision of 3%. The apparent first-order rate constants (kobs) for the polymerization of HEMA by CQ in the presence of 0.01 M TEOHA, carried out up to 100 s, range from 3.35-7.78 (1 M), 2.72-6.78 (2 M) and 2.33`5.89x104 s-1(3 M). The second-order rate constants for the interaction of TEOHA radicals with HEMA (1-3 M) range from 2.33-7.78x10-2 M 1 s-1 at pH 6.0-9.0 indicating an increase in the reactivity of TEOHA radicals with an increase in the pH of the solution. There is a linear relation between kobs (1-3 M HEMA) and inverse of solution viscosity suggesting the quenching of CQ excited state with an increase in the viscosity of the medium.
Authors and Affiliations
Iqbal Ahmad, Kefi Iqbal, Syed Abid Ali, Sadia Hafeez Kazi, Zubair Anwar
Keywords
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