Size-Controlled Preparation of Cellulose Microspheres and Preliminary Investigation of their Use as Additives in Cosmetic Products

Plastic microbeads (PMs) having sizes in the micrometer range (10-1000 m) are added to cosmetic products as colorants, as exfoliating agents, and as additives to improve spreadability and texture. The use of PMs in cosmetic products contributes significantly to microplastic pollution in aquatic ecosystems. Not only may PMs themselves be toxic to certain aquatic life forms, but as part of formulations of rinse-off cosmetics they may also adsorb and concentrate toxic chemicals on their way through waste water systems and into aquatic ecosystems where they may be ingested by smaller aquatic animals. This toxic effect may then be amplified going up the food chain as a result of bioaccumulation. Consequently, the use of PMs in rinse-off cosmetics has recently been banned in many countries.2,3 Cellulose microspheres (CMs) have many applications in chromatography, drug loading and release, ion exchange and water treatment, protein immobilization, and solid-phase synthesis.4 Additionally, CMs are biodegradable and could be developed to be potential alternatives to PMs as additives in rinse-off cosmetics. In this study we have, in a size-controlled manner (diameter = 40-700 m), prepared CMs by thermal regeneration of cellulose from surfactant-stabilized water-in-oil emulsions of viscose solutions. We have found that factors such as surfactant type and concentration, viscose droplet size, rotor speed and size affect the diameter of CMs formed. We have been able to dye these CMs with dermatologically benign dyes and demonstrate stability of such dyed CMs in pH 3-10 environments for extended periods of time. We have also discovered two distinct methods to modulate the density of CMs (normally dcellulose = 1.5 g/cm3) so that they could float in water and remain suspended in some cosmetic formulations (Figure 1).Acknowledgement: We gratefully acknowledge partial financial support from TÜBİTAK (Project 118Z442) for these studies.Footnotes and References:1) Undergraduate student researchers2) Amelia et al. Prog. Earth Planet. Sci. 2021, 8:12, DOI: 10.1186/s40645-020-00405-43) Sun et al. Sci. Total Environ. 2020, 742, 1402184) Gericke, M.; Trygg, J.; Fardim P. Chem. Rev. 2013, 113, 4812−4836.