Dr. M. Sommer "Well-defined, defect-free and end-functionalized poly(3-hexylthiophene) via externally initiated Grignard metathesis polymerization"
Melville Laboratory for Polymer Synthesis, Department of Chemistry University of Cambridge
| What |
|
|---|---|
| When |
May 16, 2011 from 04:00 PM to 04:45 PM |
| Where | “Hörsaal Makromolekulare Chemie”, Stefan-Meier-Str. 31 |
| Add event to calendar |
vCal
iCal
|
Abstract
In semi-crystalline conjugated polymers such as poly(3-hexylthiophene) P3HT, microstructure and degree of crystallinity are important factors that determine the electronic properties. One important method to prepare P3HT is the Kumada catalyst transfer polymerization (KCTP), which uses Ni(dppp)Cl2 as the catalyst. Owing to the mechanism of the KCTP method, one tail-to-tail (TT) defect per chain is formed and incorporated into the polymer. While it was until now assumed that the TT-defect is exclusively located at the beginning of the polymer chain, is it now clear that the major fraction of P3HT carries the TT-defect somewhere within the chain. Here we report the synthesis and characterization of defect-free P3HT via the external initiation using new nickel initiators. This method enables regioregularities of 100% via the elimination of the TT initiating dimer, quantitative incorporation of the 3-hexylthiophene starting group and accurate control over molecular weight and polydispersity. The external initiation with more complex initiator precursors is also used to synthesize endfunctionalized polymers, and the mechanism of initiation, propagation and termination reactions is studied by 1H-NMR endgroup analysis.