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.

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.

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.

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.

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.

Primary structure of gum arabic and its dynamics at oil/water interface.

Gum arabic (GA), an arabinogalactan-based gum, is a well-known powerful emulsifier. However, the poor stability of emulsion has often been pointed out. In order to clarify the origin, the structure-property relationship of GA, especially the interfacial property at oil/water interface, needs to be investigated.

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.

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.

Nanocellulose Film Properties Tunable by Controlling Degree of Fibrillation of TEMPO-Oxidized Cellulose.

A fibrous 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized wood cellulose/water slurry was disintegrated with a magnetic stirrer or high-pressure homogenizer under various conditions to prepare TEMPO-oxidized cellulose (TOC)/water dispersions with different degrees of fibrillation. The turbidity value of the as-prepared dispersion was used as a measure of the degree of nanofibrillation of the fibrous TOC slurry in water. The fibrillated TOC/water dispersions with low degrees of fibrillation had cellulose nanonetwork (CNNeW) structures consisting of TOC nanofibrils (TOCNs), unfibrillated TOC fibers, and fibril bundles.

Synthesis of Chitin Nanofiber-Coated Polymer Microparticles via Pickering Emulsion.

Chitin nanofiber (ChNF) has received significant research attention owing to its potential for use in a variety of applications, such as medicine and cosmetics. Here, we synthesize a novel ChNF material, ChNF-coated polymer microparticles, using a Pickering emulsion-templated approach. Two varieties of ChNF with different crystal structures, lengths, and surface charges were used to form the microparticle shells.

Crystallinity-Independent yet Modification-Dependent True Density of Nanocellulose.

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.

Tailoring Nanocellulose-Cellulose Triacetate Interfaces by Varying the Surface Grafting Density of Poly(ethylene glycol).

Careful design of the structures of interfaces between nanofillers and polymer matrices can significantly improve the mechanical and thermal properties of the overall nanocomposites. Here, we investigate how the grafting density on the surface of nanocelluloses influences the properties of nanocellulose/cellulose triacetate (CTA) composites. The surface of nanocellulose, which was prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation, was modified with long poly(ethylene glycol) (PEG) chains at different grafting densities.

Dual Functions of TEMPO-Oxidized Cellulose Nanofibers in Oil-in-Water Emulsions: A Pickering Emulsifier and a Unique Dispersion Stabilizer.

The emulsifying and dispersing mechanisms of oil-in-water emulsions stabilized by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers (CNFs) have been investigated. The emulsifying mechanism was studied by changing the oil/water interfacial tension from 8.5 to 53.

Fabrication of ultrathin nanocellulose shells on tough microparticles via an emulsion-templated colloidal assembly: towards versatile carrier materials.

Here, we develop a robust approach to forming an ∼8 nm thick cellulose nanofiber (CNF) shell on polymer microparticles through an emulsion-templated assembly. The median diameter of the CNF-shelled microparticles was 3.0 μm.