Design of Polyhydroxyalkanoate (PHA) Microbeads with Tunable Functional Properties and High Biodegradability in Seawater

Chloé Volant,Guillaume Vignaud,Anthony Magueresse,Eric Balnois,Stéphane Bruzaud

doi:10.1007/s10924-021-02345-6

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) were used to prepare microbeads, with diameter ranging from 50 to 100 µm, by an emulsion-evaporation process. The emulsification-evaporation process enables the formation of spherical polyhydroxyalcanoate beads, with crystalline rates similar to the ones of the former polymer and with important surface roughness as compared to amorphous polylactic acid smooth beads. The mechanical properties of the different PHA beads are also found to be intimately linked with their crystalline content, with modulus varying between 1 and 7 GPa. The degradation behavior of these PHA microbeads was tested under marine environment and revealed a rapid degradation, similar to cellulose, and a degradation rate correlated with the crystalline content. These results emphasize the possibility and interest in developing PHA materials with tunable functions and degradation properties.

Highlights

Microplastics are defined as solid plastic objects smaller than 5 mm in size, insoluble in water and not biodegradable [1]
In order to limit their impact on the marine environment, many countries have attempt to ban the presence of these microplastics in rinse-off cosmetic products
The emulsion-evaporation method allowed the preparation of spherical micrometer PHA beads with tunable materials properties, surface morphologies and related degradation behavior

Summary

Introduction

Microplastics are defined as solid plastic objects smaller than 5 mm in size, insoluble in water and not biodegradable [1]. 2016, Canada and New Zealand in 2017) [10,11,12] These laws and decrees have led manufacturers to develop sustainable solutions with the use of particles or beads, for example in exfoliation products, such as natural organic ingredients including plant or fruits hulls, kernels seeds, microcrystalline cellulose or the use of mineral particles such as silica or pumice stone [13, 14]. The cosmetic industry is interested in developing biodegradable particles in the micrometer size range for applications such as facial cleaning or scrub [5-

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