Dresden 2026 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 59: Crystallization

CPP 59.6: Talk

Friday, March 13, 2026, 12:45–13:00, ZEU/0260

Surface-induced ordering and continuous breaking of translational symmetry in conjugated polymers — Anton Sinner, Alexander Much, and •Oleksandr Dolynchuk — Martin Luther University Halle-Wittenberg, Germany

Surface-induced liquid crystalline (LC) phase transitions elicit fundamental interest and hold potential for leveraging the accompanying anisotropic order at the surface. Board-like conjugated polymers are of particular interest due to the novel sanidic LC phases they exhibit, which have remained largely unexplored. Specifically, although preferential molecular orientation near the free surface has been observed in films of conjugated polymers, the mechanism of its formation is not yet fully understood. In this study, grazing-incidence X-ray scattering is employed to monitor the formation and breaking of positional order in situ in thin films of two conjugated polymers representative of two classes: polythiophenes and polydiketopyrrolopyrroles. Our findings demonstrate that the surface induces positional order in films of both conjugated polymers via the formation of a highly oriented, sanidic disordered LC phase. The ordering process continues upon cooling and undergoes multiple LC transitions into more ordered phases, both at the surface and in the bulk, which can compete with each other. The positional smectic-like order parameter displays continuous temperature dependence in the vicinity of the transition, signifying a continuous breaking of translational symmetry by the surface. Theoretical analysis enables accurate description of the order parameter when critical behavior is considered.

Keywords: Liquid crystals; Conjugated polymers; Surfaces; Thin films; Symmetry breaking