The homopolymerizations of bisphenol-A-bis(2-hydroxypropyl methacrylate) (BisGMA) and 2-hydroxyethyl methacrylate (HEMA) were monitored using FT-Raman spectroscopy and those of BisGMA also by FT-i.r. photoacoustic spectroscopy. Raman spectroscopy was applied to quantify the conversion of CyC double bonds of the monomers. Changes of intensity and wavenumber of the carbonyl band observed in the Raman spectra during the polymerizations were complementally studied by use of FT-i.r. photoacoustic spectroscopy. The carbonyl vibrational band at 1700 cm -¹ was identified as the vibrational mode of the carbonyl group with hydrogen bonds and those at 1717 cm -¹ (Raman) as well as 1725 cm -¹ (i.r.) as the modes of the 'free’ carbonyl group. Localization of the p-electrons of the carbonyl group and decreasing strength of the hydrogen bonds caused by the polymerization reaction result in a decrease of the Raman intensity and an increase of the i.r. intensity as well as of the wavenumber of the carbonyl i.r. vibrational mode at 1700 cm -¹.
Посилання на статтю:
Polymerization of hydroxyalkyl methacrylates characterized by combination of FT-Raman and step-scan FT-i.r. photoacoustic spectroscopy / S. Kammer, K. Albinsky, B. Sandner, S. Wartewig // Polymer. – 1999. – N 40. – P. 1131–1137.