Nanocellulose Fragmentation Mechanisms and Inversion of Chirality from the Single Particle to the Cholesteric Phase

Abstract

Understanding how nanostructure and nanomechanics influence physical material properties on the micro- and macroscale is an essential goal in soft condensed matter research. Mechanisms governing fragmentation and chirality inversion of filamentous colloids are of specific interest because of their critical role in load-bearing and self-organizing functionalities of soft nanomaterials. Here we provide a fundamental insight into the self-organization across several length scales of nanocellulose, an important biocolloid system with wide-ranging applications as structural, insulating, and functional material. Through a combined microscopic and statistical analysis of nanocellulose fibrils at the single particle level, we show how mechanically and chemically induced fragmentations proceed in this system. Moreover, by studying the bottom-up self-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric liquid crystals, we show via direct microscopic observations that the chirality is inverted from right-handed at the nanofibril level to left-handed at the level of the liquid crystal phase. These results improve our fundamental understanding of nanocellulose and provide an important rationale for its application in colloidal systems, liquid crystals, and nanomaterials.

Isolation and characterization of cellulose nanofibers from aspen wood using derivatizing and non-derivatizing pretreatments

“…Examination of the smallest nanofibers (1.7 nm) further reveal kinking which has been associated with mechanical damage (Saito et al 2007(Saito et al , pp. 2485(Saito et al -2491 something which has been corroborated further through geometrical analysis of CNFs in relation to sonication procedures (Nyström et al 2018). Others have additionally attributed the effect to artefacts related to drying rather than inherent properties of cellulose in the traditional sense of disordered and crystalline regions (Funahashi et al 2017).…”

Confinement‐Induced Ordering and Self‐Folding of Cellulose Nanofibrils

“…In short, fibrils of fixed contour length 〈L〉, with corresponding statistics extracted from the distributions of the unconstrained case, were generated and placed in a slit of width w. If the fibril fit into the slit it was taken into the statistics, if not it was discarded. Nyström et al [42] exploited these parameters to understand if the fibrils break along a segment or at a kink, or if a new kink is observed. This can be justified by the fact that we used a fixed kink angle, that the implemented statistics are exact only for 〈L〉, and that the simulations do not take the fibrils excluded volume into account.…”

Flow-induced order–order transitions in amyloid fibril liquid crystalline tactoids

“…Thus, these systems are effectively a fascinating example of water-in-water emulsions with anisotropic elastic features and vanishing small interfacial tension, which endow tactoids a very unique and peculiar set of physical properties. To date, liquid crystalline tactoids have been found in dispersions of many biological rod-like systems including tobacco mosaic viruses 13 , fd viruses 14 , f-actin 15 , carbon nanotubes 16 , cellulose 17 , and more recently amyloid fibrils 1 , 3 , 18 . Amyloid fibrils, generated from common food proteins, are an appealing system due to their high potential in designing new functional materials 19 , 20 , but also due to their very rich liquid crystalline behavior 3 , 18 .…”