Doctoral students seminar (September 10, 2019)

Lucas Löser on “Squid-based protein films: native material vs. molecular-engineered material”
and Robert Kahl on “Oriented Crystallization of Semiconducting Polymers in thin Films”

Martin-Luther-Universität Halle-Wittenberg 
Von-Danckelmann-Platz 3, SR 1.04 06120 Halle (Saale) 
Time: 3.20pm - 5.00pm 

Link to OpenStreetMap


Squid-based protein films: native material vs. molecular-engineered material

by Lucas Löser

In the last centuries, more and more research is focused on sustainable and environmentally-friendly plastic production and therefore also alternatives to conventional petrochemistry. One possibility is the usage of proteins as a polymer building block that are produced by E.Coli bacteria. Advantages of those protein-based polymers are e.g. their very low polydispersity, precise tuning possibilities and simply the fact that they do not rely on petrochemistry. Research has shown that materials with desired properties, that are found in nature, have repetitive elements in their genetic code, whose influence on the emerging structures are only partially understood yet. In this talk, basic NMR-investigations (1H static time-domain NMR) on a material based on squid-ring teeth proteins, are presented. First results show precise correlations of crystallinity and structural elements found in the protein network, as well as the confirmation of an elastic plateau over a certain temperature range and interesting observations that still need to be linked to structural elements in order to better understand spatial arrangement of the structural elements and their dynamics, as well as the influence of those properties on the macroscopic material properties.

Oriented Crystallization of Semiconducting Polymers in thin Films

by Robert Kahl

Driven by the growing demand for renewable energy sources, organic photovoltaics have become a field of significant scientific interest, promising to be a cost efficient alternative to silicon based solar cells. Typically, organic photovoltaics are based on thin films of semiconducting polymers. As the conductivity in semiconducting polymers is anisotropic, the orientation of the crystals in these thin films has a significant influence on the device performance. Therefore, in this project we want to study and control the mechanisms that dictate the orientation of crystals of the semiconducting polymer Poly(3-hexylthiophene) (P3HT) within thin films. As was shown in previous studies [1], the interface to vacuum gives rise to an undesired orientation of P3HT crystals, which seems to be promoted by the hexyl side-chain of P3HT [2]. Therefore, we aim to influence the orientation at this interface by modifying the side-chain of P3HT. Thin films of these P3HT derivatives will be studied with the help of GIWAXS, XRR and AFM.

[1] J. Balko et al. „Surface induced orientation and vertically layered morphology in thin films of poly(3-hexylthiophene) crystallized from the melt “, J. Mat. Res., Vol. 32, Nr. 10 (2017), pp. 1957–1968.
[2] B.M. Ocko et al. „Surface freezing in chain molecules: Normal alkanes”, Phys. Rev. E,  Vol. 55, Nr. 3 (1997), pp. 3164–3182

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