High dielectric performance of tactic polynorbornene derivatives synthesized by ring-opening metathesis polymerization

Functional polynorbornenes (PNBEs) containing pyrrolidine moiety and bis(trifluoromethyl)biphenyl side group were synthesized via ring-opening metathesis polymerization (ROMP), and the microstructure of polymer chain was characterized by NMR spectroscopy. Poly(N-3,5-bis(trifluoromethyl)biphenyl- norbornene-pyrrolidine) (PTNP) and poly(N-phenyl-norbornene-pyrrolidine) (PPNP) are supposed to have practically trans double bonds and adopt isotactic syn conformation, whereas poly(N-3,5-bis(trifluoromethyl)biphenyl-norbornene- dicarboximide) (PTNDI) has both trans and cis double bonds and atactic microstructure. PTNP, PTNDI, and PPNP have much different dielectric constants of 20, 7, and 3, respectively, which is attributed to both the polar 3,5-bis(trifluoromethyl)biphenyl group and the stereoregular chain structure. The existence of rigid pyrrolidine moiety has a positive contribution to form the tactic polymer chain during ROMP. Polymers are highly thermal stable up to ∼300 °C. Having good dielectric properties and thermal stability, these functional PNBEs are expected as the potential dielectric material in thin film capacitors.