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5268710 
Journal Article 
Syndiotactic polystyrene containing ortho-dichlorobenzene: Crystal structure of the clathrate form 
Tarallo, O; Petraccone, V 
2005 
1 
Macromolecular Chemistry and Physics
ISSN: 1022-1352 
WILEY-V C H VERLAG GMBH 
WEINHEIM 
206 
6 
672-679 
English 
WOS:000228230000008 
The crystal structure of the clathrate form of syndiotactic polystyrene containing ortho-dichlorobenzene has been determined, and compared with those of the other crystalline clathrate structures of s-PS already known. This guest molecule, characterized by a quite different shape and volume from the others already described, gives rise to the only example of clathrate form of s-PS presenting a statistical orthorhombic symmetry (cell constants a = 17.5 angstrom, b 22.9 angstrom, c = 7.8 angstrom and space group Ccmb). This symmetry is generated by the random coexistence in the crystals of domains, with the same monoclinic P2(1)/a symmetry found for the other clathrate forms, that can be realized by two different but energetically equivalent packings of the chains. The unit cell constants are a = 17.5 angstrom, b = 14.4 angstrom, c = 7.8 angstrom and gamma = 127.4 degrees. The shape of the guest molecule produces a significant modification of the cavities (if compared to delta form) realized mainly through a shift of the ac layers of chains delimiting the cavities along the a axis direction that turns out in the highest gamma value found for these kinds of structures. 
Polymer Science; clathrate, crystal structures, ortho-dichlorobenzene, polystyrene,; syndiotactic; molecular-mechanics, delta form, field, polymorphism, simulations,; compound, iodine