Liquid-crystalline assembly of spherical cellulose nanocrystals

Rod-shaped cellulose nanocrystals (CNCs), also called cellulose nanorods (CNRs), possess anisotropic properties that allow for their self-organization into chiral nematic liquid crystals. Interestingly, spherical cellulose nanocrystals (cellulose nanospheres, CNSs) have also been shown to form a chiral liquid-crystalline phase in recent years. Herein, to understand how the similar assembly takes places as particle dimension changes, the organization features of CNSs were investigated. Results of this study demonstrate that above a critical concentration in suspension, CNSs organize into a liquid-crystal phase consisting of periodically parallel-aligned layer structures. This structure persists after suspension drying. In comparison with CNRs, the alignment of CNSs exhibits a shorter layer distance, lower order degree, and weaker long-range orientation. To explain the early stages of tactoid formation, a caterpillar-like model was proposed, which was captured by freezing the CNS suspension in an intermediate aggregation state. This structure serves as the fundamental unit for further liquid-crystal assembly.

Automated summary

In this study, the organization features of cellulose nanospheres (CNSs) were investigated. It was found that above a critical concentration, CNSs can organize into a liquid-crystal phase consisting of parallel-aligned layer structures, which persist after drying. Compared to cellulose nanorods (CNRs), CNSs exhibit shorter layer distance, lower order degree, and weaker long-range orientation. Additionally, a caterpillar-like model was proposed to explain the early stages of tactoid formation, serving as the fundamental unit for further liquid-crystal assembly.