Recovery of the Irreversible Crystallinity of Nanocellulose by Crystallite Fusion: A Strategy for Achieving Efficient Energy Transfers in Sustainable Biopolymer Skeletons**

Abstract

Crystallite refers to a single crystalline grain in crystal aggregates, and multiple crystallites form a grain boundary or the inter-crystallite interface. A grain boundary is a structural defect that hinders the e cient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide brillar crystallites of wood cellulose were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals without passing through a melting or dissolving state. Accordingly, the crystallinity of wood cellulose, which has been considered irreversible once decreased, was signi cantly enhanced, and the thermal energy transfer in the aggregate was improved. Other brillar crystallites of crab shell chitin also showed a similar fusion phenomenon by enhancing the inter-crystallite interactions. These ndings imply that such crystallite fusion naturally occurs in biological structures with network skeletons of aggregated brillar crystallites.

Molecular Dynamics of Drying‐Induced Structural Transformations in a Single Nanocellulose

“…This result provides deeper insight into the crystallinity increase occurring during drying and the hydrothermal annealing processes. [18,[34][35][36] Insight into the process is key to gaining a better understanding of the dynamics of CNF assembly in water; currently, the assembly of cellulose fibrils remains a topic of debate, with some models proposing crystallite fusion, [18,[35][36][37] while others suggest that the fusion is prevented by a mismatch of the fibril twist. [38] Moreover, our results have potential to provide valuable insights into the mechanism underlying the formation of disordered regions along the cellulose microfibril that occur after drying treatments.…”