Local dielectric relaxation and formation of a molecular network in photosensitive comb-shaped polymers and copolymers

Relaxation of dipole polarization in the photosensitive comb-shaped poly(6- methacryloyloxyhexyl cinnamate) and in its random copolymers with MAA or oc tafluoroamyl methacrylate was studied at temperatures below room temperatur e in the frequency range from -0.1 to 100 kHz. In each of the systems studi ed, two regions of dielectric absorption related to the local motion in the side chains were found. It is established that thermal or photoinitiated c ross-linking proceeding by the double bond cleavage in the side chains of a photosensitive component leads to an increase in the relaxation times and in the activation energy for the polarization of the local processes of mol ecular mobility. This tendency is also observed in the side chains of the s econd component that is not involved in the cross-linking reaction. The ret arding effect of the molecular network formed through the side chains on th e local mobility of a polymer fragment free of cross-links is explained by the increased rigidity of its main and side chains.