NMR of cellulose nanocrystals, mesoporous media, and liquid crystal assemblies

Abstract

ABSTRACT This article gives an overview of cellulose nanocrystals (CNCs), liquid crystal templating based on suspensions of CNC rods, and their corresponding templated mesoporous materials. NMR cryoporometry was used to give pore size distributions in chiral nematic mesoporous silica (CNMS) and organosilica (CNMO) films, while NMR pulsed-field gradient technique was used to study diffusion anisotropy of water absorbed in these films. 14N-NMR was used to probe the orientation of a calamite liquid crystal (LC) confined in the pores of CNMO films. Effects due to confining hydrogen-bond assemblies (HBAs) in CNMS and CNMO films were investigated by means of 2H-NMR and 19F-NMR. These results were compared with the ordering in the corresponding neat HBA. The ability to tune/switch the film’s optical responses via orientation ordering of LCs in the pores of CNMO films was demonstrated by NMR.