The crystal structure of isotactic 1,4-trans-poly(2-methylpentadiene). An application of the Rietveld method

The crystal structure of isotactic 1,4-trans-poly(2-methylpentadiene) has been determined through best fitting of the X-ray diffraction powder profile (Rietveld method). The final refinement cycles were carried out on 12 structural and 18 nonstructural parameters; three constraints were introduced in the form of Lagrange multipliers. A different half-height width for equatorial and layer reflections was adopted in connection with given crystallite dimensions. The final disagreement factor Rz = - Icl,/xInet was 0.099. The conformation of the polymer chain can be described as a sequence of TS'TS-torsions. Crystal packing is described, and no particularly short contact is detected.