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

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.

Graphical abstract

KEYWORDS:

• NMR
• cellulose
• organosilica
• hydrogen-bond
• liquid-crystal templating

Acknowledgments

The author would like to thank all the collaborators who have contributed to the work in this report, and in particular to Professors Carl Michal and Michael Giese for their support and discussions.

Dedication

The review is dedicated to the late Zeev Luz, a friend and a colleague to whom I had great admiration.

Disclosure statement

No potential conflict of interest was reported by the author.