Supramolecular Chemistry and Liquid Crystal Polymers

The liquid crystalline properties of a polymer are normally varied by changing the molecular structure via chemical synthesis, and knowledge-based rules relating structure to properties have been developed to guide the chemist in this endeavour. By contrast, the mesogenic properties of a new class of polymers, namely, supramolecular liquid crystal polymers, are tailored via noncovalent interactions. This review discusses supramolecular liquid crystal polymers in which either the liquid crystal behaviour of one component is strongly modified or enhanced by the addition of a second component, or liquid crystallinity is observed in mixtures of otherwise amorphous materials. The driving force responsible for the induction or enhancement of liquid crystallinity in these systems is the specific molecular interactions (for example, hydrogen bonds or charge-transfer interactions) between the unlike components in the mixtures. This tuning of mesogenic properties via noncovalent interactions is a new approach in the molecular engineering of liquid crystal polymers and a range of examples are discussed along with some possible applications for such materials.