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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Crystallization, Nucleation and Self-Assembly I

CPP 4.6: Vortrag

Montag, 17. März 2025, 12:45–13:00, H34

Crystallization and Pseudo-Isodimorphism in Statistical Co-Polythiophenes — •Alexander Johannes Much¹, Jakob Boris Günther Danziger¹, Qian Wang², Michael Sommer², and Oleksandr Dolynchuk¹ — ¹Martin-Luther-Universität Halle-Wittenberg — ²Technische Universität Chemnitz

Statistical copolymerization is a powerful and widely used way to tailor material properties like solubility or mechanical properties. The copolymer properties depend largely on their co-crystallization and the crystal structure formed, which has been studied for polyesters, polyamides, and polycarbonates. The results suggest three co-crystallization scenarios: (1) total exclusion of comonomers, (2) total inclusion of comonomers (isomorphism), and (3) partial inclusion of comonomers into two crystal lattices (isodimorphism).

Here we study the co-crystallization and crystal structure of poly-(3-hexylthiophene)-stat-poly-[3-(6-cyanohexyl)thiophene] statistical copolymers using differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS). The composition-dependent melting temperatures and enthalpies obtained from DSC show minima, which is typical of isodimorphic co-crystallization. However, WAXS clearly indicates single crystal lattices in all copolymers, with a monotonic dependence of lattice constants on composition. This finding is inconsistent with isodimorphism, making the co-crystallization of these statistical copolythiophenes only pseudo-isodimorphic. Hence, our results suggest that the current classification of statistical copolymer crystallization is incomplete and needs to be extended.

Keywords: Polythiophenes; Co-crystallization; Statistical Copolymers; Isodimorphism; P3HT