Raheema Mulla-Bala1; Diogo Baltazar1
1 – London College of Fashion, University of the Arts London, United Kingdom.
Water is a finite resource, whose overconsumption is a significant concern, as half of the world’s population is currently experiencing water scarcity. Therefore, reducing water consumption in the cosmetics industry is vital as the world is heading towards an acute water crisis. In the cosmetic industry, water is consumed directly within cosmetics and indirectly during production. Thus, solid cosmetic products can be a waterless alternative to traditional formulations to reduce water consumption. Oleogels are promising water-free, cosmetic formulas. An oleogel is a colloidal system resulting from oil entrapment within a three-dimensional network formed by an oleogelator. Oleogels can be classified into two types depending on the oleogelator: low molecular weight oleogelators (LMWOs) and high molecular weight oleogelators (HMWOs). Ethylcellulose (EC) is a polymeric HMWO that can be used to obtain oleogels of varying viscosity by direct dispersion in cosmetic oils and heating above its glass transition temperature of 120 – 140º C. This study focused on the formulation of solid EC oleogels with Flaxseed Oil and the incorporation of Stearic Acid (SA) and its derivatives Polysorbate 60, Glyceryl Monostearate (GMS) and Sorbitan Stearate (SS). The impact of these surfactants on the physical properties of EC oleogels was investigated through characterisation via pay-off and hardness tests. Results indicated that the hardness of the oleogels varies with the type of surfactant used, with SS producing the hardest gels. Adding SA in combination with one of its derivatives increased oleogel hardness, suggesting a strengthening of the gel structure via synergistic interactions between surfactants. Pay-off results showed that oleogels with lower hardness have higher pay-off, as expected. A balance between hardness and pay-off is important for the consumer experience, product efficacy, and reduce product waste. The differences in oleogel hardness may be due to structural variations in the self-assembly of different surfactants and their interactions with EC. The thermal decomposition of Flaxseed Oil and surfactants may have also affected the tested physical properties. In future work, chemical characterisation techniques, such as thermogravimetric analysis and ATR-FTIR spectroscopy, could elucidate the chemical interactions between EC and other oleogel components, as well as the structural differences that result from using different surfactant mixtures. This project contributed to the exploration of solid EC oleogels with varying physical properties as waterless alternatives in skincare, which could contribute to reducing the industry’s water footprint and minimise environmental impact.
