Crystal Structure of the Stereoregular Ethylene-alt-styrene Copolymer Synthesized with a Zirconocene-Based Catalyst

A stereoregular alternating ethylene−styrene copolymer, also stretchable in fiber form, has been obtained with rac -isopropylidenebis(1-indenyl)zirconium dimethyldiamide activated by the methylalumoxane catalytic system. From X-ray diffraction fiber spectra, an isotactic structure has been assigned to this copolymer as well as the previously described stereoregular ethylene−styrene copolymers. The polymer has zigzag planar chain conformation with phenyl groups oriented perpendicularly to the chain axis. The crystallographic symmetry in B 2/ m . Lattice constants (monoclinic, unique axis c ): a = 10.23, b = 15.53, c = 5.12 Å; γ = 98.6°. The disagreement index for measured reflections is R 1 = 0.10.