Prediction of the conformation of the chain in the crystalline state of tactic polymers

✍ Scribed by Natta, G. ;Corradini, P. ;Ganis, P.

• Publisher: John Wiley and Sons
• Year: 1962
• Weight: 463 KB
• Volume: 58
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1962.1205816675

✦ Synopsis

Abstract

The postulate of geometric equivalence of the monomeric units of a tactic chain with regard to an axis (I) and the postulate that the conformation is such that the internal energy of the chain, considered as not subjected to external forces, is the lowest (II), can be applied to the prediction of the conformation in the crystalline state of chains of unknown configuration, as demonstrated by the application of these postulates to known structures. Postulate (I) leads easily to the prediction of the possible linear chain repetition groups for a succession of monomeric units of given absolute configuration. In the case of polypropylene, for instance, it can be easily shown that isotactic polypropylene should have a helicoidal chain conformation, whereas syndiotactic polypropylene should have a glide plane or a helix (associated with two‐fold axes perpendicular to the chain axis) chain conformation. The angles of internal rotation defining the actual conformation of tactic polypropylene chains can be predicted on the basis of postulate (II) through semiquantitative methods of minimization of the internal energy content.