Development of the potential alternative for synthetic exfoliating particles in the skin cosmetics based on biodegradable polymer poly(3-hydroxybutyrate)

Primary microplastics represent small particles that are intentionally added into personal care products therefore they can easily enter the aquatic life. Due to their small size and prevailingly non-biodegradation ability they pose a great threat to the environment [1].

This study deals with the preparation of abrasive exfoliating particles from biodegradable polymer poly(3-hydroxybutyrate) and their optimization for cosmetics usage as a potential alternative to synthetic non-degradable types. It explores morphology of prepared particles and its effect on their mechanical properties and abrasive ability.

Many ways for particles preparation were tested in order to find out factors which have an impact on the properties of particles. The potential methods were developed and refined in order to approach reliable analogue to commercial exfoliating particles. Prepared particles were analysed using scanning electron microscopy. Nowadays, there is not any available device for testing the abrasive ability of scrub particles. Therefore, a semi-automatic system for testing of abrasiveness of prepared particles was made up of basic parts of the 3D printing machine. This device was tested and calibrated using floral foam and sandpaper with different grades of granularity and used for comparison of abrasiveness of prepared particles.  Mechanical response of particles under pressure was also investigated. It was found out that measured mechanical properties correlate with the data from the abrasiveness test. Size and shape of particles, their morphology, mechanical properties and abrasiveness can be controlled by used preparation method. Several cosmetic bases were prepared with selected prepared and commercial exfoliating particles and they were applied for sensory evaluation.