Development of Water-soluble semiconducting polar polymers for smart applications

The development of new materials is pivotal for the exploitation of the new technologies. One important class of emerging semiconducting materials is represented by conjugated polyelectrolytes (CPEs) comprising an electronically delocalized ?-conjugated backbone with pendant groups bearing polar or ionic functionalities. Structurally, CPEs are generally composed of: (i) ?-conjugated backbones, which determine the main optical properties, such as absorption and emission spectra, light-harvesting ability, and quantum yield ; (ii) charged side-chains, such as cationic quaternary ammonium groups, anionic carboxyl groups, sulfonic groups, and phosphate groups. CPEs combine the typical properties of polymeric semiconductors, such as chemical tunability, easy processability, lightness and flexibility with the growing demand for environmentally friendly materials. In fact, the incorporation of polar/ionic side groups increases the solubility in water and alcohols, which can potentially endow a more environmentally friendly manufacturing options and increased biocompatibility for sensor applications One of the main problem to be addressed is the modification of the polymerization conditions, and purification traditionally carried out under dry conditions and non-aqueous solvents, which must be compatible with polar polymers. The materials obtained must also have a degree of purity suitable for bioelectronic applications. The commonly employed reactions for the synthesis of WSCPs are listed are palladium-catalyzed coupling reactions (Suzuki, Heck and Sonogashira), Wessling reaction and FeCl3 oxidative polymerization. Here we present a series of water/alcohol soluble biocompatible thiophene-based polymers synthesized via ligand free C-H direct arylation.