Formulation of dyes for consumer care applications

• Main Author: Lim, Apryl Zi Xian
• Other Authors: Lam Yeng Ming
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/166680
• Institution: Nanyang Technological University

In this present work, photochromic molecules, specifically organic P-type diarylethene, were used to develop photochromic systems with defined and switchable absorption spectra. The objective was to achieve the full range of visible light colour spectrum using the photochromic systems for consumer care applications. Formulations containing cyan, magenta, and yellow (CMY) dyes were prepared in various concentrations and stored in vials. The CMY dyes were also mixed into a single formulation. These samples were analysed using ultraviolet-visible spectrophotometry (UV-Vis) to determine the energy at which the molecules absorb electromagnetic radiation and to study the effects of the concentration of dyes on the colour vibrancy. This allowed a better prediction of the amount of dyes required and leverage the different absorption spectra of each molecule in order to control each colour channel in the solution separately. This study highlights the significant effects of surface cleaning protocols and ozone treatment on surface hydrophilicity and uniformity, while also emphasising the need for careful consideration of dye concentration and UV exposure time to achieve the desired colour intensity and longevity in hair colouring systems. Additionally, the study demonstrates the potential of colour activation methods through exposure to specific wavelengths of light to adjust the colour of photochromic diarylethene dyes. The dyes were also applied onto hair using different concentrations of CMY dyes. However, it was observed that the colour change on hair was not as pronounced as that seen in vial solutions. To improve the colour-changing efficiency, the study suggests exploring more efficient substrate coating in future studies such as changing the background colour of the hair to a colour other than blonde.