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

Abstract

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‐NMe2Ph)3, the resulting polymers are obtained in excellent yields and exhibit a good number‐average molecular weight (Mn of 33 and 16 kDa, respectively). Detailed 1H 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 cm2 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