In this study, we discovered that washing hair with surfactants causes a decrease in the internal density of hair, and we propose a cuticle-sealing strategy to inhibit this phenomenon. This phenomenon was revealed based on optical analyses such as optical microscopy, scanning electron microscopy (SEM), drop shape analysis, atomic force microscopy (AFM), and single hair analysis. Repeated treatment with surfactants creates areas of low density within the hair. Additionally, treatment with low-molecular-weight materials resulted in replenishment of the internal density of the hair. It has been shown that the more severe the degree of cuticle lifting, the more the internal density of the hair is reduced by surfactants. In addition, the study confirmed that a decrease in internal density could be prevented by sealing the cell membrane complex (CMC), and it was suggested that this reduced internal density may reflect the pore structure of hair. This study investigates the mass transfer phenomenon that occurs in hair and proposes a strategy to maintain hair homeostasis.

In order to reduce chronic hair flyaways/frizz, both reducing and oxidizing agents have to be used, leaving aside the hair damage issues. This study presents changes in hair morphology caused by treatment with a shampoo containing only reducing agents, excluding oxidizing agents that affect critical hair damages. As a result of flyaway/frizz improvement rates calculated through monitoring of the area of light transmittance in the hair tresses, reducing agents, such as ammonium thioglycolate (ATG), L-cysteine, and sodium sulfite were found to be effective in decreasing hair flyaway/frizz. Additionally, the methods to maintain homeostasis and control damage caused by oxidation during washing were also used to see flyaway/frizz improvement rates. Measurements using electrostatic force microscopy (EFM) showed that the surface charge of hair tresses treated with shampoo containing reducing agents was lowered. Using Raman spectroscopic analysis, it has been suggested that these treatments with reducing agents induced a 3D structural transition of the hair from an α-helix to a random coil. In addition, this structural release was confirmed, identifying the reduction in the enthalpy of the α-helix using differential scanning calorimetry (DSC). Furthermore, we verified that this change causes no hair damage through a tensile strength test. Therefore, the formulation of shampoo with reducing agents can be used as an effective strategy to care for hair flyaway/frizz without hair damage issues.

This study was conducted to objectively evaluate the degree of detangling needed to develop the effectiveness of cosmetic hair ingredients to prevent hair tangles. To evaluate the degree of hair tangling, the frictional force applied when combing the hair was measured. The tooth spacing of the comb used in the evaluation was examined, and it was confirmed that the 4 mm interval comb was suitable as there was a large difference in combability between different treatments and the deviation was small. To create samples to standardize hair tangles, spinning 25 cm or more of wet hair on a spinner for 5 min was found to be best for observing differences between treatments. In the case of hair shorter than 25 cm, tangles did not occur even when spun using a tool, but a suitable sample for evaluating tangles was obtained by rubbing the hair by hand about 15 times. When testing combability, the distance the comb moves until it reaches 9.8 N is considered to be proportional to the detangling efficacy, and the degree of tangling is evaluated based on the section detangling rate, which is the distance the comb travels to reach 9.8 N divided by the total tress length. As a result of evaluating the contact angle of tangled hair using an atomic force microscope (AFM) and a scanning electron microscope (SEM), it was found that the contact angle of the cuticle surface for the tangled part was larger than that of the straight part and the cuticle was damaged. After immersing tangled hair in rice bran extract containing six OH groups, the contact angle changed from 103° to 95°, which is the level of the straight part, and an increase in the section detangling rate of the hair was observed. As a result, it was suggested that the detangling efficacy could be evaluated by applying this evaluation method using the section detangling rate.