Exploring Nanoscale Viscoelastic Properties of Acrylate Copolymers as Models Systems for Future Eco-Friendly Cosmetic Materials

The cosmetic industry is actively seeking new eco-designed formulations that maintain optimal performance. Acrylic polymers and their derivatives are widely used due to their diverse physicochemical properties, serving as emulsion stabilizers, dispersants, and film-forming agents. When dried, acrylic polymers create a transparent and flexible coating on the skin, contributing to a smooth feel, water-resistance, and adhesion. These films exhibit excellent wear resistance, color stability, weathering, and prolonged usage in perspiration conditions. However, the lack of sufficient biodegradability in acrylic polymers necessitates the exploration of alternative options. Understanding the structure of these coatings and their impact on cosmetic performance is crucial for identifying suitable replacements.<br/>This study presents how environmental conditions can affect the viscoelastic properties of polymeric films used for cosmetics applications. To mimic skin, polymer coatings were deposited on ex-vivo stratum corneum, the outermost layer of the skin and by using Atomic Force Microscopy- based mechanical modes, the viscoelastic behavior of the material was elucidated. Viscoelastic parameters E', E", and tan δ of the films using nanoDynamic Mechanical Analysis Atomic Force Microscopy (nDMA-AFM) were studied under varying temperatures and humidity levels to simulate skin physiological conditions. Results revealed an enhanced miscible capacity under heated and moist conditions, accompanied by a significant decrease in stiffness.<br/>Future developments in polymer formulations will prioritize eco-design, emphasizing naturalness, bio-sourcing, and environmental impact. The proposed mechanical and structural AFM evaluation protocol presented in this study will contribute to the advancement of alternative acrylate materials. By comprehensively understanding the mechanical and nanostructural properties of acrylic films, we can lay the foundation for the development of environmentally friendly substitutes.