Regensburg 2022 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 41: Crystallization, Nucleation and Self-Assembly

CPP 41.1: Invited Talk

Thursday, September 8, 2022, 15:00–15:30, H39

Interface-induced crystallization in polymers: From model systems to applications for semiconducting polymers — Muhammad Tariq¹, Robert Kahl¹, Mukundan Thelakkat², Thomas Thurn-Albrecht¹, and •Oleksandr Dolynchuk¹ — ¹Experimental Polymer Physics, Martin Luther University Halle-Wittenberg — ²Applied Functional Polymers, University of Bayreuth

Crystallization is usually initiated at interfaces. Understanding the physical process underlying interface-induced crystallization (IIC) is of fundamental interest and is relevant for material applications. IIC of liquids can occur either by heterogeneous nucleation (HN) or by the equilibrium phenomenon of prefreezing. First, we present a combined theoretical and experimental study of the effect of the substrate-material interactions on the thermodynamics of prefreezing and on the kinetics of HN in model polymers on various substrates. Second, the acquired knowledge about IIC elucidates the role of interfaces for crystal orientation in films of conjugated polymers, which is important for device performance. Using polythiophenes as model conjugated polymers, we show that different crystal orientations can be formed at the interfaces to a substrate and vacuum as a result of two competing interfacial interactions. Our results demonstrate that increasing the polarity of polythiophene side chains influences the interactions at the interfaces, resulting in a change of crystal orientations. Thus, we disclose the crucial role of the interfacial interactions for crystallization kinetics, thin film morphology, and control of molecular orientation in films of model and semiconducting polymers.