Influence of Tacticity on the Crystal Structures of Hydrogenated Ring-Opened Poly(norbornene)s

The crystal structures of highly crystalline isotactic and syndiotactic hydrogenated poly(norbornene)s [H-poly(NB)s], synthesized by the stereospecific ring-opening metathesis polymerizations norbornene followed complete hydrogenation, have been determined for first time on basis X-ray diffraction data analyses. similarity difference chain conformation packing mode in lattice clarified among three kinds H-poly(NB) samples (syndiotactic, isotactic, atactic species). molecular chains were found to take essentially planar zigzag at room temperature with slight torsional angle fluctuations around skeletal C–C bonds. cyclopentylene rings protrude from plane polymer various different ways depending tacticity, resulting whole shape then structure. melting point was be tacticity: 178, 148, 134 °C atactic, H-poly(NB)s, respectively. thermal behavior has discussed qualitatively these structural pieces information.