CRYSTAL-STRUCTURE OF THE EMPTIED CLATHRATE FORM (DELTA(E) FORM) OF SYNDIOTACTIC POLYSTYRENE

The crystal structure of the emptied clathrate form (delta(e) form) of syndiotactic polystyrene, obtained by removing the guest molecules fr om different clathrate delta forms, is presented. Chains in s(2/1)2 he lical conformation are packed in the monoclinic unit cell with axes a = 17.4 Angstrom, b = 11.85 Angstrom, c = 7.70 Angstrom, and gamma = 11 7 degrees according to the space group PS1/a. The crystalline density of the emptied clathrate form (0.977 g/cm(3)) is lower than that of th e amorphous phase (1.055 g/cm(3)). The differences between the structu res of the emptied clathrate form and clathrate delta forms are discus sed by the analysis of X-ray diffraction patterns and packing energy c alculations.