Raman spectroscopy was used to investigate the kinetics of the free-radical polymerization of methyl methacrylate in toluene, initiated with azobisisobutyronitrile at 70OC. The decrease in the intensity of the 1636 cm-' C=C stretching band compared with a solvent band as an internal standard allows an accurate determination of the rate of conversion of monomers to polymeric chains. A careful quantitative study of the evolution of the C -0 stretch band profile, interpreted in terms of intra-chain dipoldipole interactions, gives a similar dependence for the conversion. ~~~~~
Measurements of the low-frequency Raman spectra (LFRS) (below 100 cm-') of poly(methy1 methacrylates) in solution are reported. The reduced intensity exhibits a power law dependence on the frequency at any concentration and at any conversion rate of the polymerization reaction. Even monomeric liquids such as toluene and methyl methacrylate show such a power law behaviour. The results are compared with recent theories on low-frequency Raman scattering from fractal structures and suggest that a more careful interpretation of LFRS is needed.
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