Kazuho Daicho

In trees, a-few-nanometers-wide crystalline fibrils of cellulose are tightly bundled with other biopolymers, such as lignin and hemicelluloses, to form robust cell walls. Cellulose nanofibers (CNFs) are obtained by successive treatments including the purification, modification, and disintegration of cell-wall cellulose. Herein, we report that the crystallinity of CNFs is governed by the interface between the bundled cellulose fibrils. The cellulose molecules at the interface or at the surface of

In materials science and crystallography, the true density is an important derived physical quantity of solids. Here we report the correlation of the true density of nanometer-wide fibrillar crystallites of cellulose with their purity, crystallinity, morphology, and surface functionality. In the single fibrils, all the cellulose molecules are uniaxiallly oriented. Thus, the true density indicates the molecular packing density in the single fibrils and is essential for the precise estimation of t

Crystallites form a grain boundary or the inter-crystallite interface. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of crystalline cellulose nanofibers (CNFs) were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals, without passing through a melting or dissolving

Abstract Cellulose forms crystalline fibrils, via biosynthesis, that can be just a few nanometers wide. The crystallinity is a structural factor related to material performance. Recently, many routes to isolate these fibrils as nanocellulose have been developed, and there exist various types of nanocellulose with different crystallinities. Quantitative assessment of the crystallinity of nanocellulose is thus essential to advance knowledge in the high performance and functionality of such materia

Regenerated and mercerized celluloses are widely used in our daily life and industries. Examples include clothes, medical supplies, and separation membranes. In such applications, the true density is an important derived physical quantity for refining the structural designs of regenerated and mercerized celluloses. Here, we report the true density-crystallinity correlation of regenerated and mercerized celluloses. Seven samples were prepared through either dissolution-regeneration or mercerizati

Plant cell walls are composed of skeletal cellulose and a filling matrix of hemicelluloses and lignin. Cellulose has slender crystallite units referred to as microfibrils or elementary fibrils, and these crystallites form a dense network skeleton in the cell walls. In this study, we assessed the morphology and crystallinity of individually dispersed microfibrils isolated from the cell walls of wood, cotton, and ramie celluloses. It is well known that microfibrils in higher plants exhibit structu

Abstract The crystallinity of cellulose decreases when bundled microfibrils are dispersed in water as cellulose nanofibers (CNFs) or physically separated into finer nanoscale fibrils or single microfibrils. The crystallinity of these CNFs is recovered when they become densely assembled through the dehydration of the dispersion. In this process, multiple CNFs are assumed to partially fuse, leading to the enlargement of crystallite widths. The mechanism of this CNF fusion is, however, not well und

Wood-derived cellulose nanofiber (CNF) offers excellent electrical insulation, mechanical strength, flexibility, thermal stability, and low thermal expansion, meeting the growing demand for sustainable materials in electronic devices. However, the dielectric properties of CNF-based material crucial for beyond-fifth-generation (B5G) applications at frequencies above 10 GHz remain underexplored. This study investigates dielectric behaviors of CNF films with varying surface functional groups and po

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 efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide fibrillar crystallites of wood cellulose were crystallized by enhancing their inter-crystallite interacti

Abstract Crystallites form a grain boundary or the inter‐crystallite interface. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of crystalline cellulose nanofibers (CNFs) were crystallized by enhancing their inter‐crystallite interactions; multiple crystallites were coupled into single fusion crystals, without passing through a melting or di

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 efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide fibrillar crystallites of wood cellulose were crystallized by enhancing their inter-crystallite interacti

The crystallinity of cellulose decreases as the cell wall structure of pulp fibrillates to cellulose nanofibers (CNFs) in water. The decreased crystallinity is partially recovered when the CNFs are reassembled into bulk structures through dehydration. We analyzed the molecular mechanism that underlies these changes in crystallinity via two-dimensional ¹³C-¹³C solid-state nuclear magnetic resonance (NMR) spectroscopy. A cellulose sample was extracted from a ¹³C-la