Chain structure of isotactic polyvinyl cyclohexane

Abstract

Many types of helical chains present in the crystals of different isotactic polymers have been described in the past few years. They all correspond to successions of more or less distorted trans and gauche bonds. The chains of the polymers, which have an identity period along the fiber axis comprised between 6·4 and 6·7 A, generally correspond to successions of undistorted trans (σ 1 = 180°) and gauche (σ 2 ∼ 60°) bonds, repetition being achieved along a three-fold helix 2 [(AB) 3 or (AC) 3 ]. This chapter presents an evaluation of the structure and mode of packing of the isotactic polyvinyl cyclohexane. The isotactic structure of polyvinyl cyclohexane is confirmed by the fact that through hydrogenation of isotactic polystyrene, and hydrogenation and dehalogenation of isotactic amorphous polychloro-styrenes, the products obtained exhibit the same X-ray diffraction lines as crystalline polyvinyl cyclohexane. All X-ray reflections given by a fiber of this polymer may be indexed on the basis of a tetragonal unit cell, with a = 21·9 A.