Mechanochemistry offers sustainable synthesis of the functionalized cellulose nanofiber (CNF). In this study, changes in the microstructure of the CNF aqueous sol by planetary ball milling were investigated in terms of its rheological behavior, crystallinity, and diameter distribution. The surface activity of the CNF was additionally characterized by a pulsed nuclear magnetic resonance (NMR). A decreased thixotropy hysteresis loop observed in the 100 min⁻¹-treated CNFs indicated a weaker interaction among the fibers, but still having a three-dimensional structure. 300 min⁻¹ could collapse them. A decreased x-ray diffraction peak intensity observed in the 500-min⁻¹-treated CNF could indicate a split in the fiber’s bundle as well as shredding. An increase in the wet surface area (S_NMR) could indicate surface activity in the 500-min⁻¹ milled CNF sol. Such newly formed hydroxyl groups can serve as effective reaction sites with, for example, the TiO₂ precursor and perhaps favorably works to improve the photocatalytic performance.

The shear thickening mechanism of concentrated suspensions of monodispersed silica particles is analyzed for the objective of identifying rheological control guidelines for concentrated colloidal suspensions. Monodispersed silica particles exhibit shear thickening when suspended in high-viscosity water-soluble dispersion mediums such as ethylene glycol and polyethylene glycol. The on-set shear stress at which this shear thickening occurs (i.e., the critical shear stress), decreases as the size of the particles increases, in a proportional relationship with the negative second power of the particle size. This relationship supports the hypothesis put forward by Seto and Mari et al. that the predominant factor behind shear thickening is friction caused by contact between particles.

This research examined the effects of the particle size ratio and mixture ratio on shear thickening behavior of the binary suspensions where monodispersed particles of difference sizes are mixed together. The results found that shear thickening behavior occurred at any large/small particle size ratio of 2.5 or lower, and that the critical shear stress changed in accordance with the particle size ratio. In contrast, mixture ratio ranges that suppress shear thickening were present at particle size ratios of 5 and higher, and these mixture ratio ranges expanded as the particle size ratio increased.

The understanding and optimization of the production process of secondary battery electrodes has been strongly required in the decade. The internal structure of the slurry for electrodes is one of the unknown factors in the process. The current situation about the utilization of rheological analysis for electrode slurries are firstly reviewed. The effect of particle concentration on the viscosity of dense slurries, the concept expressing the viscosity of bimodal slurries, and the significance of viscoelasticity of slurry related to the internal structure are explained. Finally, the rheological analysis of electrode slurries of LiB anode and cathode are demonstrated.

The theory is reviewed of the electrokinetics of spherical solid colloidal particles with a slip surface in an aqueous electrolyte solution. The effect of the hydrodynamic slip is characterized by the slipping length. The limiting case of zero slipping length corresponds to a hydrophilic surface. The slipping length increases as the hydrophobicity of the particle surface increases. General formulas together with approximate expressions are presented for the electrophoretic mobility, the electrical conductivity, the sedimentation velocity and potential, and the diffusion constant of particles with a slip surface. The magnitudes of the electrophoretic mobility and the sedimentation potential, in particular, are found to increase with increasing slipping length. A spherical solid colloidal particle with a slip surface is shown to be hydrodynamically similar to a liquid drop.

Submicron-sized colloidal particles having a narrow size distribution self-assemble into ordered “crystal” structures in their liquid dispersion, under appropriate conditions. Hard sphere colloids crystallize at the particle concentration of approximately 50 vol%. For charged particles, the crystallization occurs at much lower particle concentrations because of long-ranged electrostatic interparticle repulsion. In the coexistence of linear polymers, depletion attraction acting between the particles results in opal type crystals. Here we briefly review formation of 3D colloidal crystals due to electrostatic repulsion and depletion attraction. We also report our recent studies on fabrications of two-dimensional (2D) colloidal crystals by using electrostatic adsorption of three-dimensional (3D) charged colloidal crystals.