Structural Analysis of Poly(3‐hexylthiophene) Prepared via Direct Heteroarylation Polymerization

This study reports the synthesis and characterization of poly(3‐hexylthiophene) (P3HT) from a direct heteroarylation polymerization of two isomeric monomers, 2‐bromo‐3‐hexylthiophene (monomer 1 ) and 2‐bromo‐4‐hexylthiophene (monomer 2 ). Using the Herrmann–Beller catalyst along with P( o ‐NMe 2 Ph) 3 , the resulting polymers are obtained in excellent yields and exhibit a good number‐average molecular weight ( M n of 33 and 16 kDa, respectively). Detailed 1 H NMR analyses reveal less than 1% of homocouplings and no evidence of β‐branching. Dehalogenation is identified as the main chain termination step and preferentially occurs on monomer 2 . The melting temperature (237 °C) and hole mobility (up to 0.19 cm 2 V −1. s −1 ) of the nearly defect‐free P3HT obtained from this simple polymerization of monomer 1 are comparable, if not superior, to those obtained with commercially available GRIM and Rieke samples. image