Crystal structure of the clathrate delta form of syndiotactic polystyrene containing 1,2-dichloroethane

The crystal structure of the clathrate d form of syndiotactic polystyrene containing 1,2-dichloroethane is presented. Polymer chains in s(2/ 1)2 helical conformation and 1,2-dichloroethane molecules are packed in the monoclinic unit cell with axes a=17.11Å, b=12.17Å, c=7.70Å and gamma=120° according to the space group P21/a. The crystalline density of the clathrate d form is 1.23 g/cm-3 with two chains (eight monomer units) and two 1,2-dichloroethane molecules inside the unit cell. Molecules of 1,2-dichloroethane occupy isolated cavities between the benzene rings of adjacent polymer chains and are essentially only in the trans conformation. The location and the conformation of the 1,2- dichloroethane molecule are such that both chlorine atoms are sandwiched between two benzene rings of the same polymer chain.