Effects of Chemical Structures of Polycarboxylic Acids on Molecular and Performance Manipulation of Hair Keratin

The study explored the use of non-toxic polycarboxylic acids in hair perming, focusing on their effects on the secondary structure of keratin and the resulting hair strength and perming efficacy. Traditional perming chemicals were noted for their harmful effects, prompting the investigation into safer alternatives. The research demonstrated that using cysteine as a reductant and polycarboxylic acids as crosslinkers could achieve effective perming with minimal hair strength loss. The study measured changes in carboxyl, amine, and sulfhydryl groups to assess crosslinking efficiency and used wide-angle X-ray diffraction and dynamic mechanical analysis to examine keratin structure changes. The findings indicated that polycarboxylic acids, with suitable structural characteristics, could disrupt the α-helix and increase random coil formations in keratin, offering a promising non-toxic alternative to conventional perming products.