Comparative Raman spectroscopy studies of photosensitive polymers

We present Raman studies on various substituted polyvinylcinnamates, [-CH2CH(O2CCH=CHC6H5)-](n), are well known for undergoing cycloaddition when exposed to UV radiation. Our comparative studies on these unphototransformed polymers show that the substitutions on the aryl cycle play a fundamental role in the vibrational dynamics of these molecules. We have been able to identify the characteristic modes of each type of fluoro-substitution (mono, para and ortho), and as a result, it is possible to determine whether the two isomers and two rotating conformers coexist in the samples. In order to proceed to further investigations on the phototransformation process, we have determined how the C=C and C=O double-bond stretching modes behave versus the type of substitution. (C) 1998 Elsevier Science S.A. All rights reserved.