Poly(phenylethylnorbornene)s and their hydrogenated derivatives

Ring-opening metathesis polymerization (ROMP) was used to synthesize novel ring-opened poly[5-(2-phenylethylnorbornene)]. Hydrogenation can produce two different saturated derivatives, with the phenyl groups either preserved or saturated to cyclohexyl groups. These two different hydrogenated products allowed us to compare the effect of replacing the pendant phenyl groups with cyclohexyl groups on properties such as the glass transition temperature (T _g). We found that T_g decreased by only 2 °C (from 28 to 26 °C) upon replacement of the phenyl groups. This contrasts with the effect of saturating the phenyl groups in the addition polymer of 5-(2-phenylethylnorbornene), where the T_g increased by 34 °C, from 215 to 249 °C, a remarkable difference in magnitude and direction compared with the ROMP polymers.