Structure of isotactic polyaldehydes

Abstract

Abstract The crystalline polymers having a polyacetalic chemical structure, as obtained by us by polymerization at low temperature of aldehydes in the presence of stereospecific catalysts formed by metalloorganic compounds, show an isotactic structure. The chain conformations of different isotactic polyaldehydes are discussed, and in particular the crystalline structures of polyacetaldehyde, of poly‐ n ‐butyraldehyde and of polypropionaldehyde are described. The polymeric chains of these polyaldehydes have a fourfold helix conformation with a repetition period of 4.8 A., and the packing of the macromolecules corresponds to that of the tetragonal I 4 1 / a space group. Around each fourfold screw axis present in the unit cell, isomorphous anticlined macromolecules can statistically vicariate.