Azobenzene-decorated cellulose nanocrystals as photo-switchable chiral solutes in nematic liquid crystals

Abstract

In this work, we validate that cellulose nanocrystals (CNCs), surface-functionalized with pro-mesogenic azobenzene pendants, can act as photoswitchable chiral solutes in a nematic liquid crystal (N-LC). Upon UV illumination, the helical pitch and thus the helical twisting power (β_w) can be altered based on the trans–cis photoisomerization of the azobenzene pendants. This approach shows that CNCs—biorenewable chiral additives with a commensurate, rod-like shape to N-LC molecules—can be adapted just like common small molecule organic chiral solutes in LC phases based on simple surface modifications.