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 unphot otransformed polymers show that the substitutions on the aryl cycle pl ay 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 po ssible to determine whether the two isomers and two rotating conformer s coexist in the samples. In order to proceed to further investigation s on the phototransformation process, we have determined how the C=C a nd C=O double-bond stretching modes behave versus the type of substitu tion. (C) 1998 Elsevier Science S.A. All rights reserved.