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

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.