Liquid crystallinity in linear, helical, columnar supramolecular polymers

Abstract

Liquid crystallinity is an important aspect of self-assembly processes in molecular and supramolecular structures of either synthetic or biological origin. Liquid crystallinity in supramolecular polymers (SPs) is controlled by the interplay between classical orientational parameters such as excluded volume, and growth parameters such as contact interactions between self-assembling unimers. A critical analysis of literature data supports the occurrence of the following modes in which liquid crystallinity is expressed by SPs. (1) Liquid crystallinity totally uncoupled to growth (case exhibited by closed SPs, and by discotic unimers characterized by weak binding constants, K); (2) liquid crystallinity uncoupled but hierarchically related to growth (case exhibited by open SPs characterized by strong K); (3) liquid crystallinity coupled to growth (case exhibited by rigid SPs characterized by intermediate values of K). The behaviour of linear, columnar, helical SPs in both lyotropic and thermotropic phases conforms to this description. Important implications and further theoretical analysis of the growth-coupled-to-orientation mechanism await further investigation.