Quantifying the influence of interfacial energies on interface-induced crystallization in polymers

• Applicant: Dr.-Ing. Oleksandr Dolynchuk
• Subject Area: Experimental and Theoretical Physics of Polymers
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 513509216

Crystallization of polymers usually starts at interfaces to foreign solid surfaces, such as substrates, the walls of containers, or small particles like impurities or nucleating agents. A rationally selected solid surface can lead to enhanced crystallization kinetics, oriented overgrowth of the material, and, therefore, enables control of many physical properties of polymers. Interface-induced crystallization is especially important for films of semiconducting polymers, as crystal morphology and orientation significantly impact the electronic properties of the material. According to existing theories, the interfacial energies between the solid surface, the polymer melt, and the polymer crystal play a decisive role in interface-induced crystallization and thus determine the resultant crystal morphology. Building on recent progress in studying interface-induced crystallization in films of model and functional polymers, the aim of this project is to work out a quantitative relation between the relevant parameters of interface-induced crystallization and the interfacial energies in thin polymer films on various substrates. For this purpose, we will combine surface-sensitive X-ray scattering and different microscopic techniques with contact angle measurements, respectively. The study will be performed for a series of model polymer-substrate systems and for functional semiconducting polymers – polythiophenes. The copolymerization of alkyl-substituted thiophene monomers bearing chemically different end groups on side chains will enable the gradual variation of the interfacial energies, whereby the gradual changes in interface-induced crystallization will become accessible.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Michael Sommer