Aqueous dispersions of organic pigments are most commonly prepared with the aid of pigment dispersants. Appropriate dispersants are selected through trial and error due to the lack of understanding in the relationship between the structure of a dispersant and the physical properties of dispersion. Here, we investigate the relationship between inter-particle interaction, aggregation structure and the rheological behavior of aqueous pigment dispersions employing rheology and small-angle X-ray scattering measurements.
Brushes are used in various make-up processes. However, there are few reports on quantitative analysis of movement and mechanical stimuli in the make-up process, and factors that control the usability of the make-up tool. In this study, we developed a system consisting of a high-speed camera and a mechanical evaluation device to evaluate motion and vertical/friction forces when a subject draws a line on a nail-tip with a brush. Here, we analyzed the relationship between movement and finish when 20 subjects drew a line using a commercially available nail enamel on a tip. The mechanical data suggest that the adjustment of the strength of the force and the angle of the brush, and the stable application process in which the vertical force gradually increases are important for drawing a straight line with uniform width. The present findings are useful to show the controlling factors of make-up cosmetics.
Nanoemulsions of a lipophilic vitamin A (VA) have a therapeutic effect on corneal damage. The nanoemulsion with a triblock-type polymer surfactant F127 (EOPO) showed superior efficacy. To understand the mechanism of the efficacy of EOPO nanoemulsions, we studied their inner structure and their interaction to corneal epithelial cell. It was found that they had a partially exposed vitamin core interface and interacted with lipid bilayer by their hydrophobicity. Accordingly, EOPO nanoemulsions induced the endocytic morphological changes on giant unilamellar vesicles (GUVs) and the plasma membrane of corneal epithelial cell, and promoted the membrane permeability and the efficacy of VA.
Nanomechanical analysis based on atomic force microscopy was reviewed together with the brief introduction of contact mechanics, especially JKR two-point method, necessary for the analysis. Thermoplastic vulcanizate (TPV) consisting of PP/EPDM was investigated as a model specimen for this analysis. The PP region was not pure PP region but the region contained EPDM to some extent and thereby the local mechanical response was softer than that of pure PP. In the latter half of this manuscript, Greenwood theory was reviewed by anticipating the future possibility to utilize it as the tool to extract viscoelastic properties from AFM force-distance curve.
Pigments such as titanium oxide in water-based paints are dispersed in emulsion resin that acts as a binder. It is assumed that not only the dispersant added to disperse the pigment but also the surfactant on the surface of emulsion resin affects the paint performance.
Few reports have however examined the pigment dispersion in actual paint systems.
In this report, we explain the impact of different surfactants used for emulsion resin synthesis on titanium oxide dispersibility and coating film performance, such as weathering resistance, and the improvement method for dispersibility.