Polystyrene dispersions as model for polystyrene microplastic particles
Yuanhu Zhang,a Tasmai Paul,a Valérie Jérôme,b Ruth Freitag,b Andreas Greiner,a
a University of Bayreuth, Macromolecular Chemistry and Bavarian Polymer Institute, 95440 Bayreuth, Germany
b University of Bayreuth, Bioprozesstechik, 95447 Bayreuth, Germany
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Polystyrene (PS) is also an important model polymer for the investigation of effects of microplastic (MP) and nanoplastic particles (NP) on cells and organisms. It can be processed to particles of various shapes and sizes with different surface characteristics. MP and NP of PS are usually available as aqueous dispersions. Due to the synthetic protocols, dispersions of PS MP or NP could be contaminated by styrene, which is the monomer of PS. To fully understand the effects of PS MP and NP on cells and organisms, precise knowledge of possible contamination by residual styrene is crucial.
Thus, we designed a fast method of a very sensitive analysis of residual styrene content in dispersions of PS MP and NP . We used this protocol for the establishment of an efficient method of purifying PS MP and NP dispersions by emulsifier-free emulsion polymerization. To verify the relevance of styrene contamination of the PS dispersions we correlated the effect of dispersions with different styrene content on cells by MTT assay and compared the results of our self-synthesized dispersions with commercial dispersions of PS MP. Control experiments clearly showed a very high toxicity of styrene in aqueous dispersions at relevant concentrations. In contrast, purified dispersions showed significantly less toxicity and will enable the study of the effects of size and shape of PS MP and NP.
The authors acknowledge financial support by DFG (Deutsche Forschungsgemeinschaft), Project Number 391977956, within SFB-1357.
 Y. Zhang, T. Paul, V. Jerome, R. Freitag, A. Greiner, in preparation.