Waterborne polyurethanes from castor oil-based polyols for next generation of environmentally-friendly hair-styling agents

Abstract

Commercial hair-styling spray is often formulated with multiple components that contribute to toxicity and environmental pollution. In this work, a series of bio-based waterborne polyurethanes (CWPU) as hair styling agent were prepared from castor oil-based polyols. The resulting polyurethane dispersions exhibit excellent storage stability for at least 24 months. The effects of the castor oil functionality and chain extender structure on the particle size of the polyurethane dispersions were systematically investigated. Hair-styling performance and skin irritation tests on animals were also carefully performed to assess styling performance and safety of these CWPUs. A series of CWPU films was successfully prepared to study the relationship between the structure and performance of the bio-based polymer films. The resulting films show low moisture uptake rate, high transmittance, hydrophilicity and good mechanical properties. When CWPU films exhibit Young’s modulus >50 MPa, elongation at break in the 15–300 % range, and moisture uptake <4 %, these samples exhibit good hair-styling performance, and even better than commercial hair spray product. The skin irritation test is also proved that there is no evidence of skin irritation for these CWPUs which hold great promise for hair styling applications.