Mechanical and Thermal Properties of Porous Nanocellulose/Polymer Composites: Influence of the Polymer Chemical Structure and Porosity.

The excellent emulsifying capacity of nanocellulose allows for the preparation of porous nanocellulose/polymer composites through the emulsion templating process. However, the effects of the polymer chemical structure and porosity on the material properties have not been extensively explored. Here, we discuss the effects of these two factors on the thermal and mechanical properties of the composites.

Low solid content mouldable chitin physical hydrogel prepared by atypical rupture-free swelling.

In this study, the atypical swelling gelation of chitin physical hydrogels was investigated. Just by tuning the amount of the -acetylation reagent, the degree of acetylation varied and mouldable chitin hydrogels with a wide variety of gel concentrations (0.2-6.

Morphological Changes of Polymer-Grafted Nanocellulose during a Drying Process.

Nanocellulose is emerging as a sustainable building block in materials science. Surface modification via polymer grafting has proven to be effective in tuning diverse material properties of nanocellulose, including wettability of films and the reinforcement effect in polymer matrices. Despite its widespread use in various environments, the structure of a single polymer-grafted nanocellulose remains poorly understood.

Dispersion Function of a Protein, DP-1, Identified in Collimonas sp. D-25, for the Synthesis of Gold Nanoparticles.

Collimonas sp. (D-25), found in the soil of Akita Prefecture, is a gram-negative bacterium with the ability to synthesize gold nanoparticles (AuNPs). During the synthesis of AuNPs, one specific protein (DP-1) was found to have disappeared in the sonicated solution of the bacterium.

Molecular Dynamics of Drying-Induced Structural Transformations in a Single Nanocellulose.

Nanocellulose is attracting attention in the field of materials science as a sustainable building block. Nanocellulose-based materials, such as films, membranes, and foams, are fabricated by drying colloidal dispersions. However, little is known about how the structure of a single nanocellulose changes during the complex drying process.

Chitin nanofiber-coated biodegradable polymer microparticles via one-pot aqueous process.

Tailoring the surface of biodegradable microparticles is important for various applications in the fields of cosmetics, biotechnology, and drug delivery. Chitin nanofibers (ChNFs) are one of the promising materials for surface tailoring owing to its functionality, such as biocompatibility and antibiotic properties. Here, we show biodegradable polymer microparticles densely coated with ChNFs.

Counterion-Dependent Material Properties of Phosphorylated Nanocellulose.

The material properties of cellulose nanofibers (CNFs) are governed by the surface chemical structure of the fibers. The chemical structure-property relationships for monovalent carboxylated CNFs are well understood. Here, we report the basic sheet properties of divalent phosphorylated CNFs with different phosphorus contents and counterion types.

Evaluating the Emulsifying Capacity of Cellulose Nanofibers Using Inverse Gas Chromatography.

Cellulose nanofibers (CNFs) are attracting increasing attention as emulsifiers owing to their high emulsifying capacity, biocompatibility, and biodegradability. The emulsifying capacity has been experimentally shown to depend not only on the type of oil but also on the chemical structure of the CNF surface. However, the theoretical relationship between these two factors and emulsification remains unclear, and therefore, industrial applications are limited.

Linear Correlation between True Density and Crystallinity of Regenerated and Mercerized Celluloses.

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.

Structure of Polymer-Grafted Nanocellulose in the Colloidal Dispersion System.

Clarifying the primary structure of nanomaterials is invaluable to understand how the nanostructures lead to macroscopic material functions. Nanocellulose is attracting attention as a sustainable building block in materials science. The surface of nanocellulose is often chemically modified by polymer grafting to tune the material properties, such as the viscoelastic properties in rheology modifiers and the reinforcement effect in composites.

One-Pot Hierarchical Structuring of Nanocellulose by Electrophoretic Deposition.

The orientation control and the formation of hierarchical structures of nanoscale components, such as bionanofibers and nanosheets, have attracted considerable research interest with the aim of achieving sophisticated functional materials. Herein, we report a simple and flexible strategy for constructing sophisticated hierarchical structures through electrophoretic and electrochemical deposition. Cellulose nanofibers (CNFs), which are used as model materials, are deposited on an anode in an aqueous dispersion and seamlessly oriented from horizontal to vertical relatively to the electrode by adjusting the applied voltage between the electrodes.

Atomic-scale dents on cellulose nanofibers: the origin of diverse defects in sustainable fibrillar materials.

Atomic-scale dent structures on the surfaces of cellulose nanofibers were detected by comparing the experimentally measured and computer-simulated widths of single nanofibers. These dent parts constituted at least 30-40% of the total length of the dispersed nanofibers, and deep dents induced the kinking and fragmentation of nanofibers.

Uniaxial orientation of β-chitin nanofibres used as an organic framework in the scales of a hot vent snail.

Organisms use various forms and orientations of chitin nanofibres to make structures with a wide range of functions, from insect wings to mussel shells. Lophotrochozoan animals such as snails and annelid worms possess an ancient 'biomineralization toolkit', enabling them to flexibly and rapidly evolve unique hard parts. The scaly-foot snail is a gastropod endemic to deep-sea hydrothermal vents, unique in producing dermal sclerites used as sites of sulfur detoxification.

Distribution and Quantification of Diverse Functional Groups on Phosphorylated Nanocellulose Surfaces.

Phosphorylated cellulose nanofiber (CNF) is attracting attention as a newly emerged CNF with high functionality. However, many structural aspects of phosphorylated CNF remain unclear. In this study, we investigated the chemical structures and distribution of ionic functional groups on the phosphorylated CNF surfaces liquid-state nuclear magnetic resonance measurements of colloidal dispersion.

Nanocellulose Xerogel as Template for Transparent, Thick, Flame-Retardant Polymer Nanocomposites.

Cellulose nanofibers (CNFs) have excellent properties, such as high strength, high specific surface areas (SSA), and low coefficients of thermal expansion (CTE), making them a promising candidate for bio-based reinforcing fillers of polymers. A challenge in the field of CNF-reinforced composite research is to produce strong and transparent CNF/polymer composites that are sufficiently thick for use as load-bearing structural materials. In this study, we successfully prepared millimeter-thick, transparent CNF/polymer composites using CNF xerogels, with high porosity (~70%) and high SSA (~350 m g), as a template for monomer impregnation.

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

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 state.

Anisotropic thermal conductivity measurement of organic thin film with bidirectional 3ω method.

Organic thin film materials with molecular ordering are gaining attention as they exhibit semiconductor characteristics. When using them for electronics, the thermal management becomes important, where heat dissipation is directional owing to the anisotropic thermal conductivity arising from the molecular ordering. However, it is difficult to evaluate the anisotropy by simultaneously measuring in-plane and cross-plane thermal conductivities of the film on a substrate because the film is typically as thin as tens to hundreds of nanometers and its in-plane thermal conductivity is low.

Local Crystallinity in Twisted Cellulose Nanofibers.

Cellulose is crystallized by plants and other organisms into fibrous nanocrystals. The mechanical properties of these nanofibers and the formation of helical superstructures with energy dissipating and adaptive optical properties depend on the ordering of polysaccharide chains within these nanocrystals, which is typically measured in bulk average. Direct measurement of the local polysaccharide chain arrangement has been elusive.

Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction.

Scalability is a common challenge in the structuring of nanoscale particle dispersions, particularly in the drying of these dispersions for producing functional, porous structures such as aerogels. Aerogel production relies on supercritical drying, which exhibits poor scalability. A solution to this scalability limitation is the use of evaporative drying under ambient pressure.

Rate-Limited Reaction in TEMPO/Laccase/O Oxidation of Cellulose.

The environment-friendly oxidation of cellulose by the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)/laccase/O system is an alternative route with huge potential to prepare cellulose nanofibers. It is found that the concentration of TEMPO significantly affects the oxidation efficiency. An effective method for improving the oxidation effect is to increase the TEMPO concentration and prolong the oxidation time.

Controlling Miscibility of the Interphase in Polymer-Grafted Nanocellulose/Cellulose Triacetate Nanocomposites.

The miscibility at the interphase of polymer-grafted nanocellulose/cellulose triacetate (CTA) composite films was tailored using different casting solvents. The polymer-grafted cellulose nanofibrils were prepared by modifying surfaces of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized nanocellulose with amine-terminated poly(ethylene glycol) (PEG). The PEG-grafted nanocelluloses were individually dispersed in dichloromethane, 1,4-dioxane, and ,-dimethylacetamide.

Magnetically Collectable Nanocellulose-Coated Polymer Microparticles by Emulsion Templating.

Magnetic nano/microparticles offer potential benefits for environmental applications such as water purification. However, achieving functional and stable surfaces remains a critical challenge for magnetic particle design. Nanocellulose, a naturally occurring nanofiber, is a promising surface material candidate, owing to its ease of functionalization and chemical stability.

Best Practice for Reporting Wet Mechanical Properties of Nanocellulose-Based Materials.

Nanocellulose-based materials and nanocomposites show extraordinary mechanical properties with high stiffness, strength, and toughness. Although the last decade has witnessed great progress in understanding the mechanical properties of these materials, a crucial challenge is to identify pathways to introduce high wet strength, which is a critical parameter for commercial applications. Because of the waterborne fabrication methods, nanocellulose-based materials are prone to swelling by both adsorption of moist air or liquid water.

Anisotropic Thermal Expansion of Transparent Cellulose Nanopapers.

We report the anisotropic thermal expansion of a transparent nanopaper structure comprising cellulose nanofibers (CNFs). The coefficient of thermal expansion (CTE) of the nanopaper in the out-of-plane direction was 44.6 ppm/°C in the temperature range of 25-100°C, which is approximately five times larger than its CTE in the in-plane direction in the same temperature range (8.