Synthesis of Soluble Silsesquioxane–Polythiophene Hybrid Copolymers with a Controlled Morphology

We report the synthesis of hybrid copolymers in which RAFT-synthesized poly(dimethylaminoethyl methacrylate)-b-polymethacrylate (PDMA-b-PMA) and poly(3,4-ethylenedioxythiophene) (PEDOT) were combined in a precise cluster core of deca-functionalized silsesquioxane via sequential click grafting and oxidative coupling polymerization. Controlled extension of the conjugated chains from the end functionality on the cage periphery was performed via a modified interfacial synthesis protocol, which yielded a soluble hybrid polythiophene-conjugated polymer without requiring the use of thiophene monomers that contain bulky solubilizing side chains. The obtained polymers were fully characterized via various techniques, including NMR, FTIR, UV-vis, and fluorescence spectroscopies as well as SEC and AFM measurements. The combination of the star-shaped architecture and interchain compositional heterogeneity allowed for the formation of a transparent, flexible, and electroactive polymer film. Thermal annealing induced an ordered nanostructure in the thin films, which may be related to the local interaction constraints, corresponding to the reduced pi-stacking distance that facilitates hopping of electrons. On the basis of these promising results, these hybrid polythiophene-containing copolymers could find applications in imaging and chemosensing and in the design of flexible optoelectronics.