Crystal structures of polymers

In crystals of polymers the macromolecules are longer than the unit cell parameters and each chain passes through many unit cells. The concept of an ideal crystal of polymers requires infinite molecular mass, completely regular constitution of the macromolecules, completely regular configuration of the macromolecules units, and completely regular conformation of the chains. The study of the crystal structure of polymers leads to models of packing that describe the order in the long range. The principles of equivalence and of minimum internal conformational energy allow establishing the conformation assumed by a stereoregular polymer chain in the crystalline state. Packing effects do not influence the conformation of the chains as long as the conformational energy of the isolated chain corresponds to a deep energy minimum. This chapter finally points out the important role played by the self‐poisoning effect, especially at high temperatures, in determining the curved habits of polymer crystals.