Direct arylation polymerization (DArP) is an emerging alternative to Stille and Suzuki polymerizations. This method is attractive as it allows preparation of high-molecular-weight conjugated polymers in good yield without the need to metallate monomers. Despite this promise, for poly(3-hexylthiophene) (P3HT) and related polymers that have -protons on the thiophene ring, DArP is known to produce -defects, which make the polymer properties different from polymers produced by traditional methods. Here, we demonstrate that DArP conditions based on simple, inexpensive, and bench-stable reagents can be tuned to limit the amount of defects and produce P3HT with properties remarkably similar to Stille P3HT. Specifically, lowering the reaction temperature, lowering the amount of catalyst, and using a bulkier carboxylate ligand is critical. Optimized conditions include reacting 2-bromo-3-hexylthiophene with 0.25 mol % of Pd(OAc)2, 1.5 equivalents of K2CO3, and 0.3 equivalents of neodecanoic acid in N,N-dimethylacetamide at 70 degrees C and give DArP P3HT with approximate to 60% yield, regioregularity of 93.5%, molecular weight of 20 kDa, polydispersity of 2.8, and melting point of 217 degrees C, providing a very close match to Stille P3HT, which is obtained with 7080% yield, 9194% regioregularity, molecular weight of 1525 kDa, polydispersity of 2.52.8, and melting point of 214221 degrees C. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 26602668