Eco-Friendly Synthesis of Biodegradable, PLA-Based Exfoliant Microbeads via Droplet Microfluidics for Sustainable Cosmetics

The increasing prevalence of microplastic pollution from nonbiodegradable microbeads (MBs) in personal care cosmetic products (PCCPs) has raised significant environmental concerns, owing to their resistance to degradation and high adsorption capacity for persistent organic pollutants (POPs) in marine ecosystems. This study investigates the preparation of next-generation exfoliants by utilizing biodegradable alternatives (based on aliphatic polyesters, such as poly(lactic acid) (PLA) and PLA-poly(ethylene glycol) (PEG) triblock copolymers) to conventional MBs. The MBs were fabricated using droplet microfluidics, a green production process for the manufacturing of MBs, which enables the preparation of monodisperse particles with tunable physicochemical properties while minimizing energy consumption and material waste. Degradation studies in various aqueous environments demonstrated that the microfluidics-generated PLA and PLA–PEG–PLA MBs exhibited faster hydrolytic and soil degradation profiles compared with conventional MBs. POP adsorption experiments, using phenanthrene (PHEN) as a POP model compound, revealed a low adsorption capacity for the biodegradable MBs, likely due to their reduced specific surface area induced by the employed droplet microfluidics process. Finally, sensory analysis, with 13 trained and qualified assessors, highlighted the suitability of the PLA-based MBs for cosmetic applications. In summary, the presented findings suggest that the combination of droplet microfluidics with PLA-based copolymers presents a promising and more sustainable alternative to conventional MBs in personal care applications.