Using bis(pinacolato)diboron to improve the quality of regioregular conjugated co-polymersElectronic supplementary information (ESI) available: Additional syntheses and further discussion of co-polymerizations. See DOI: 10.1039/c0jm02359k

We demonstrate the use of bis(pinacolato)diboron to directly polymerize symmetric, bisbromo, thiophene-based monomers via a Suzuki homo-polymerization to form co-polymers in less steps than the corresponding co-polymerization. We compare this method to the commonly used Stille co-polymerization by preparing four thiophene-based co-polymers using both methods. We use MALDI-TOF mass spectrometry to show that this new method produces high-quality, uniform polymers with narrow distributions of end-groups. By varying the electronegativity of the monomers, we demonstrate rudimentary control over these end-groups, forming either bis-H-, mono-H-mono-Br-, or bis-Br-terminated polymers in order of increasing electronegativity. This paper shows a dramatic increase in the uniformity of polymer chains and end-groups of conjugated co-polymers prepared by homo-polymerization due to the suppression of side-reactions. The general application of this technique is expected to translate into superior device properties by increasing the overall quality of conjugated co-polymers.