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The interplay between bi-modal molecular weight distribution in polystyrene and humidity induces self-assembly of biomimetic micropillars/honeycomb morphology in the thin polymer film

revised on 25.03.2021, 08:41 and posted on 26.03.2021, 07:27 by Maciej Łojkowski, Adrian Chlanda, Emilia Choińska, Wojciech Swieszkowski

Segregation of polymer chains of different molecular weights is a well-known process. A traditional experimental approach of studying phase segregation in thin films composed of polymer blends with identical chemical compositions but different molecular weights was focused on functionalisation of chemical group or modification of end-group. In this study, however, a different approach was proposed. Polystyrene with bimodal molecular weight distribution, but no additional chemical modification was used. The films were prepared by spin-coating and the segregation between polystyrene phases was investigated by force spectroscopy. The solubility of bimodal polystyrene was explored. At the right molecular weight distribution and soluted in Methyl Ethyl Ketone, the phase segregation occurred. Introduction of moist airflow induced the separation of the lower molecular weight into micropillars and the heavier fraction self-organized into a honeycomb. As a result, an easy, fast, and effective method of obtaining micropillar/honeycomb morphologies was demonstrated. The mechanism of formation of such structures was explained.



This work was supported by The Ministry of Education and Science of Poland (the subsidy funds)


Email Address of Submitting Author


Warsaw University of Technology, Materials Science and Engineering



ORCID For Submitting Author


Declaration of Conflict of Interest

The authors declare no competing financial interest.

Version Notes

March 2021