A New Design Strategyfor the Synthesis of UnsubstitutedPolythiophene with Defined High Molecular Weight.

Unsubstituted polythiophene (PT) with defined and knownhigh molecularmass (up to ca. 36 000 g mol–1(Mw)) and low structural defects (ca. 3.6 mol %) as highlyattractive semiconducting material is presented. The new syntheticstrategy for this polymer is based on the combination of Stille-typepolycondensation reactions, ultrasound-assisted dispersion technique,and microwave-assisted ring-closure reactions. The use of Stille-typepolycondensation produces a diketal prepolymer with good solubilityand prescient and controllable degree of polymerization (DP) for thefinal insoluble PT. Ultrasonication preserves a high interfacial area,while microwave provides fast and effective heating for the last heterophasering-closure reaction. The characterization of the final product bysolid-state NMR, TEM, UV–vis absorption and fluorescence emissionspectroscopy, XRD, TGA, andconductivity measurements exhibits significant features for electronicand photoelectronic applications, such as broadened absorption, relativelyhigh crystallinity, high thermal stability, and typical semiconductingproperties. [ABSTRACT FROM AUTHOR]