Advances in synthetic methods for the preparation of poly(3-hexylthiophene) (P3HT)

Synthetic methods for the poly(3-hexylthiophene) polymers (P3HT) preparation were reviewed. Different protocols were reported such as electropolymerization, oxidative method (mainly by FeCl3), Ni-catalyzed methods (McCullough, Rieke, GRIM), Pd- catalyzed methods such as Suzuki and Stille coupling and, the more recent, Direct Arylation Polymerization (DArP). The present review focuses on the synthetic protocols and their relationship to the final key-structural polymer characteristics like regioregularity and molecular weight control which are of importance in the final properties and application of P3HT. An extended literature review was performed covering also very recent advancements. The use of NHC palladium or nickel catalysts, disclosed the door to the preparation of “quasi” living polymers for most of the Ni and Pd catalyzed reactions, enabling a fine tuning of both regioregularity and molecular weight.