Functional materials from liquid crystalline cellulose derivatives: Synthetic routes, characterization and applications

Abstract

Cellulose is a linear syndiotactic homopolymer composed of d-anhydroglucopyranose units which are linked by β-(1→4)-glycosidic bonds. The primary and secondary free hydroxyl groups, which decorate the polysaccharide chains, can undergo chemical substitution given rise to a high range of cellulose derivatives. It is well known that cellulose derivatives are at the origin of films and fibers, which characteristics can be diverse if prepared from liquid crystalline phases. Cellulose derivatives can present thermotropic as well as lyotropic phases whose characteristics are strongly affected by the architecture of the polymer chains, which can be dictated by the size, number and type of the substituents attached to cellulose main chain. In this chapter we highlight the chemical versatility of cellulose to generate liquid crystalline cellulose derivatives, which can be at the origin of high-performance materials with different mechanical, optical, thermal and structural properties that have lately regained wider attention due to the recognition of their innovative properties associated with their biocompatibility. Special attention will be devoted to recent advances, including the use of cellulose liquid crystalline derivatives to produce a soft motor, light modulated wettability films, non-woven membranes consisting in micro- and nano-helices and matrices for electro-optical devices.