Deposition of 18-MEA onto alkaline-color-treated weathered hair to form a persistent hydrophobicity

The Secrets of Beautiful Hair: Why is it Flexible and Elastic?

Beautiful hair, so called “SHINAYAKA” hair in Japanese, has a good appearance not only when stationary but also when in motion, and it is a highly desirable hair condition for Japanese consumers. We investigated such SHINAYAKA hair, which was selected by sensory evaluation, for the relationship between physical properties, such as flexibility and elasticity, and hair structure. It has already been reported that human hair cortical cells have two types, similar to wool: the ortho-like cortex and the para-like cortex. Microscopic observation revealed that the ortho-like cortex is distributed in the outer layer of the hair (near the hair surface) and the para-like cortex exists in the inner layer (near the center of the fiber). This cell distribution, a concentric double-layered structure, was deemed to be a characteristic of SHINAYAKA hair. Furthermore, analysis of physical properties showed the difference between the elasticity of the outer layer and inner layer, and that this difference was bigger in SHINAYAKA hair compared to other hair. This phenomenon was observed not only in Japanese hair, but also in Caucasian hair. In addition, we have developed a new technology for creating “SHINAYAKA” hair by treatment with succinic acid. Inflexible and inelastic hair can be changed by this treatment, and its flexibility and elasticity improve by selective reduction of stiffness of the outer layer.

Degradation of Hair Surface: Importance of 18-MEA and Epicuticle

In this paper, surface degradation of hair is reviewed. Surface properties such as hydrophobicity and surface friction change as surface structures of hair fiber, that is, 18-methyleicosanoic acid (18-MEA) and epicuticle, degrade. Comparison of contact angle and amount of 18-MEA from root to tip of the sampled hair fibers clarified the contribution of not only 18-MEA but also epicuticle to surface properties. It was found that chemical treatment by itself, such as bleaching, is not enough to cause complete loss of hydrophobic nature even after 18-MEA is removed. Additional weathering processes, such as repeatedly shampooing, are required. A technology for the deposition of a persistent hydrophobicity to bleached and weathered hair surfaces using 18-MEA is presented. Combination of 18-MEA with specific cationic surfactants (Stearoxypropyldimethylamine: SPDA) made the bleached and weathered hair surface hydrophobic, and its hydrophobicity was maintained even after shampooing. Characterization of adsorbed layers of 18-MEA/SPDA on a mica surface, as a possible hydrophilic surface model, was performed using atomic force microscopy (AFM) and angle-resolved X-ray photoelectron spectroscopy (AR-XPS). The effects of the anteiso-branch moiety of 18-MEA to create a persistent hydrophobicity with 18-MEA/SPDA were investigated using controlled AFM. It was revealed that the anteiso-branch moiety of 18-MEA in the 18-MEA/SPDA system produces a persistent hydrophobicity by providing higher fluidity to the upper region of the 18-MEA/SPDA layer. The contribution to hair beauty and sensory feeling as one of the practical functions of the hair surface is described in this paper. The hydrophobic nature of the hair surface reduces surface friction in a wet state, which reduces hair disorder alignment. It is also revealed that the moisturized or dried out feeling strongly depends on the hair shape (meandering and diameter) which depends on hair surface properties in a wet environment.

Alkyl(C16, C18, C22)trimethylammonium-Based Herbicidal Ionic Liquids

In the framework of this study a synthesis methodology and characterization of long alkyl herbicidal ionic liquids (HILs) based on four commonly used herbicides (2,4-D, MCPA, MCPP, and dicamba) are presented. New HILs were obtained with high efficiency (>95%) using an acid-base reaction between herbicidal acids and hexadecyltrimethylammonium, octadecyltrimethylammonium, and behenyltrimethylammonium hydroxides in alcoholic medium. Among all synthesized salts, only three compounds comprising the MCPP anion were liquids at room temperature. Subsequently, the influence of both the alkyl chain length and the anion structure on their physicochemical properties (thermal decomposition profiles, solubility in 10 representative solvents, surface activity, density, viscosity, and refractive index) was determined. All HILs exhibited high thermal stability as well as surface activity; however, their solubility notably depended on both the length of the carbon chain and the structure of the anion. The herbicidal efficacy of the obtained salts was tested in greenhouse and field experiments. Greenhouse testing performed on common lambsquarters (Chenopodium album L.) and flixweed (Descurainia sophia L.) as test plants indicated that HILs were characterized by similar or higher efficacy compared to commercial herbicides. The results of field trials confirmed the high activity of HILs, particularly those containing phenoxyacids as anions (MCPA, 2,4-D, and MCPP).

The influence of hair bleach on the ultrastructure of human hair with special reference to hair damage

The influence of human hair bleaching agents with different bleaching strength on the ultrastructure of human hair was studied using a transmission electron microscope (TEM) and an energy dispersive X-ray spectrometer equipped with TEM (EDS-TEM). Two kinds of bleaching agents were used: a lightener agent with a weak bleaching effect and a powder-bleach with a stronger bleaching effect. From the comparison of the bleaching properties obtained by the electronic staining of black and white hair samples, it was suggested that the permeability of hair was increased by bleaching, and there was an increase of the stainability of hair subjected to electronic staining. The bleaching action provoked the decomposition of melanin granules and the flow out of granular contents into the intermacrofibrillar matrix. Some metal elements were detected in the melanin granular matrix by EDS-TEM. As a result, the diffusion of metal elements into the intermacrofibrillar matrix promoted further damage to the hair by catalytic action with the hydrogen peroxide in the bleaching agents outside the melanin granules. Further study will lead us to the edge of the development of a new bleaching agent, which reacts only with melanin granules and causes the minimum of damage to outside the melanin granules.