M. Jayakannan, J. V. Dongen, R. Janssen
Jun 23, 2001
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Macromolecules
Abstract
Thiophenebisboronic derivatives (acids and esters) have been successfully utilized for the first time in palladium-catalyzed Suzuki polycondensations to prepare well-defined alternating thiophene−phenylene copolymers. 2,5-Thiophenebis(boronic acid) and its corresponding 1,3-propanediol and pinacol diesters have been synthesized and polymerized with 2,5-dialkoxy-1,4-diiodobenzenes in the presence of Pd(OAc)2 or Pd(PPh3)4 catalysts. SEC analysis showed that the polymers have moderate molecular weight with a polydispersity of 1.2 to 2.4. The role of the boronic derivatives and the catalyst on the yield and molecular weight of the resulting polymers have been investigated in detail. MALDI−TOF mass spectrometry has been used to elucidate the limiting steps in the polymerization and to assess the end groups. The results suggest that hydrolytic deboronation limits the formation of high molecular weight polymers. The polymers prepared using Pd(OAc)2 possess various end groups and contain macrocycles, whereas Pd(P...