Dynamic birefringence of cyclic olefin copolymers

Dynamic birefringence and viscoelasticity of amorphous polymers containing cyclic olefins were simultaneously measured over a wide frequency region from the rubbery to the glassy zone. The obtained results are discussed in terms of optical anisotropy and main chain flexibility. For copolymers of ethyelene and cyclododecene, the stress optical coefficient in the rubbery region, CR, decreased with increasing of cyclododecene contents. This could be attributed to the reduction in the nematic interaction and flexible main chain structure of cyclic olefin unit. On the other hand,in copolymers of ethylene and norbornene, systematic trend of composition dependence of CR was unclear, suggesting differences in the sequence distribution of monomers in the main chain, probably due to usage of different catalyses. Main chain flexibility decreased with increasing of cyclic olefin units when its content exceeds the 50 mol%. On the other hand, polymers produced by ring-opening polymerization of cyclic olefin showed larger CR values among the studied polymers, which can be attributed to large optical anisotropy of resulting cyclic olefin units and less-flexible main chain structure.