Abstract:

To solve the problems of low adsorption efficiency and limited repair effects of natural hydrolyzed proteins on hair, which is often caused by the electrostatic repulsion from hair surface, in this work, hydrolyzed keratin was modified by using 2, 3- epoxypropyltrimethylammonium chloride （EPTAC） and thus the hydroxypropyl-trimethylammonium hydrolyzed keratin （HPT-Ker） was successfully produced. The physicochemical properties of HPT-Ker were systematically studied when mixed with an anionic surfactant （AES） and an zwitterionic surfactant （CAB）. Its efficacy in clear shampoo formulations were also studied. The results showed that HPT-Ker exhibited significant synergistic effect with AES, reducing the surface tension and critical micelle concentration of the system, and meanwhile, the irritation of the system was also remarkably reduced. In hair care applications, HPT-Ker was confirmed to achieve the dual functions of “film formation on hair surface” and “intrinsic repair”, which were attributed to its cationic nature and structural similarity to hair keratin. It not only surpassed the traditional cationic conditioner JR-400 in hair combability, but also exhibited repair capabilities, including significantly enhancing hair tensile strength and smoothing the damaged hair cuticle. This work might provide theoretical foundation and practical reference for development of highly effective, mild, and multifunctional bio-based hair conditioning agents.

Key words: quaternized hydrolyzed keratin, hair treatment, mixed surfactant system, hair conditioner