We focused on dissociation of hypochlorous acid (HOCl) and considered the decoloring mechanism of indigo by sodium hypochlorite (NaOCl) which is used for denim bleach. In the case of indigo-dyed cotton and indigo-dispersed water, indigo particles were agglomerated and decoloring increased as the pH of NaOCl.aq. was lowered. On the other hand, in the case of the aqueous solution of indigo derivative (indigocarmine), which was dissolved at the molecular level, the higher the pH of NaOCl.aq., the higher was the decoloring. The dissociation of HOCl made it clear that the decoloring of the agglomerated indigo particle was dependent on the undissociated HOCl concentration. Since dissociated hypochlorite ions (OCl－) cannot diffuse into hydrophobic indigo aggregates, they act only at the solid-liquid interface. On the other hand, electrically neutral HOCl can penetrate into the indigo aggregates and can act also in the diffused interior of them, so it is considered that undissociated HOCl can decolor the indigo more efficiently.
Effects of alkyl substitutions on the crystal structures of some bisazomethine dyes and quinacridone dyes were systematically investigated. The molecular geometries and the low-dimensional arrangements of the molecules in their crystal structures were characterized using some geometric parameters. Lattice energy calculations were also carried out to interpret the effects of the alkyl substituents on important low-dimensional arrangements of the molecules stabilizing the total lattice energies by strong intermolecular interactions. The alkyl substituents on the terminal amino groups of the bisazomethine dyes were found to affect the slip angles between the π-π stacked molecules forming one-dimensional arrangements. In the alkoxylated-bisaomethine dyes, the methyl and ethyl substituents on the terminal amino groups were found to be a key in determining the two-dimensional arrangement of the π-π stacked molecules. The alkyl substituents on the amino groups of the quinacridone dyes played a role in determining the one-dimensional arrangements of the molecules giving the strongest energetic contribution to the total lattice energies.
Recently, noble metal nanoparticles have attracted interest for various applications such as plasmonic materials, sensing devices or high-performance catalysts. However, the cost of the materials limits their usage or requires the development of a novel recovery method which allows the redispersion and reuse of noble metal nanomaterials. In this paper, recovery of noble metal nanoparticles, including Au and Ag, is reviewed based on the characteristic properties of amphiphilic compounds. pH-responsive amphiphile C16CA acted as an adsorbent of nanoparticles, and optical and catalytic properties of nanoparticles were hardly affected during the recovery procedure, due to surface protection with the C16CA.
Fibers with their useful long and thin shapes can be processed into a wide variety of products.
Controllling the fineness of the fiber is one of the most important subjects both academically and industrially.
Nanofibers show nano-size effects not apparent in conventional fibers because of high specific surface area and the existence of nanoscale spaces between the fibers.
Product designers and manufacturers must always guarantee the life of the product.
Market surveys and outdoor exposure tests have been carried out as means to know the lifespan, and actual weather resistance deterioration is confirmed. We also conduct an accelerated weather resistance test in order to know the product lifetime earlier, and compared with results with outdoor exposure tests to predict lifespan. Following this process, measurement examples of outdoor exposure test methods with different atmospheric environmental factors using painted steel plates and outdoor exposure test results will be introduced. We also describe the characteristics of various light sources used for accelerated weathering test and the accelerated weathering resistance test results. There are differences in weather resistance depending on environment, light source, and test method.