Defects and their relationship to molecular configurations in nematic polymers

Abstract

Some recent observations of defects in main-chain nematic and chiral polymers are reviewed in order to obtain a better understanding of the nature of molecular configurations. Important parameters are (a) the chain length, the density of free ends and the length of flexible spacers and (b) the orientational correlations between chains. The first topic, (a), is discussed with respect to observations of defects in uniaxial nematics; the second, (b), is discussed in the light of observations of biaxial nematics and of cholesteric textures of rigid polymers of biological interest. The elements of a geometrical (structural) model which includes local competitions between coiling and orientational correlations and which uses the methods developed for the representation of frustration in curved spaces are given.