Structural characterization of syndiotactic 1,2‐poly(4‐methyl‐1,3‐pentadiene)

Abstract 4‐Methyl‐1,3‐pentadiene was polymerized with the MAO/CpTiCl 3 (MAO: methyl‐aluminoxane, Cp: Cyclopentadienyl) system to yield a highly stereoregular syndiotactic 1,2‐polymer. Fiber diffraction patterns indicate two crystalline modifications: a major one with a repeat of 11.73 Å and minor amounts of a zig‐zag planar polymorph (axial repeat 5.05 Å). Energy calculations account for three nearly isoenergetic conformations: the more stable one, with repeat of 11.65Å, is (T 6 G 2 T 2 G 2 ) analogous to the one recently reported for syndiotactic poly(propylene) (Chatani et al., 1991).