Functional polybithiophenes: Novel syntheses approaches, characterization and application aspects

Abstract

This work is a study of an organometallic polycondensation process based on a modified Stille coupling reaction. This polymerization methodology was investigated with the use of various aryl monomeric units. This polycondensation process uses hexabutylstannane, Bu3SnSnBu3, to react with dibrominated aryl monomers in the presence of a palladium catalyst to synthesize the corresponding polymers. This polymerization process was applied to the syntheses of functionalized polybithiophenes using 3-(I?-functionalized-hexyl)-5,5a??-dibromo-2,2a??-bithiophenes, 3,3a??-dialkyl-5,5a??-dibromo-2,2a??-bithiophenes and 3-alkyl-5,5a??-dibromo-2,2a??-bithiophenes as monomers. This methodology provided a straightforward process that was also found to be tolerant to certain functional groups. Two series of copolymers comprising pi-excessive and pi-deficient monomeric units were also synthesized for possible use in single-layer polymer LEDs. The pi-excessive units used were 5,5a??-dibromo-3,3a??-dihexyl-2,2a??-bithiophene and 5,5a??-dibromo-3-dihexyl-2,2a??-bithiophene while the pi-deficient units were dibromopyridines, dichloropyridazine and 2,7-dibromofluorenone. With the use of different monomers in the syntheses of the copolymers, thermally stable materials with a range of optical properties were prepared.