Paul C. Ewbank

The first synthesis and new properties of regioregular, head-to-tail coupled polythiophenes

Abstract The preparation of polythiophene derivatives with essentially 100% head-to tail (HT) couplings leads to new defect free polythiophenes. These new HT polythiophenes formed self-oriented three dimensional structure with greatly enhanced two dimensional conductivity. Presented are the synthetic method developed in our lab, the new HT-polythiophenes prepared by our method, and the preliminary physical properties of these conducting polymers. Our results show that the structure and properties of HT-substituted polythiophenes are quite sensitive to the side chains attached to the polymers backbone.

Amine functionalized polythiophenes: synthesis and formation of chiral, ordered structures on DNA substrates

Abstract Highly regioregular, head-to-tail coupled, 3-(amino functionalized)-polythiophenes can be synthesized by CuO co-catalyzed Stille coupling. Salts of one example are water soluble, and become helically ordered upon addition of DNA.

Synthesis and physical properties of regiochemically well-defined, head-to-tail coupled poly(3-alkylthiophenes)

Abstract We have recently developed a regiospecific synthetic method that produces poly(3-alkylthiophenes) (PATs) that, for the first time, contain almost exclusively head-to-tail (HT) couplings [1]. Details on the synthesis, NMR characterization of structural regularity, UV-VIS data on solutions and thin films, and preliminary X-ray, electrical conductivity, and thermal data are presented herein. NMR spectral characterization reveals >93% head-to-tail-head-to-tail (HT-HT) couplings in poly(3-butylthiophene) (PBT), poly(3-hexylthiophene) (PHT), poly(3-octylthiophene) (POT), and poly(3-dodecylthiophene) (PDDT). In the UV-VIS, these PATs show lower energy absorption maximum shifts of up to 14 nm in solution, 46 nm in the solid state, and other intense lower energy peaks with shifts of up to 129 nm (609 nm) from PATs prepared by the usual methods. X-ray analysis of unoriented (as cast) thin films of PHT on glass indicate a much more ordered structure than PHT made from FeCl 3 . It also appears that our unoriented PHT is at least as ordered as stretch oriented PHT. Preliminary maximum room temperature electrical conductivity values for PATs (doped with I 2 ) are 1000 S cm −1 for PDDT, 200 S cm −1 for POT, and 60 S cm −1 for PHT. Thermal analysis of POT prepared by this method is also presented and these samples are found to be highly crystalline.

Self-assembly and chemical response of conducting polymer superstructures

Abstract It has been found that water soluble salts of 2,5-poly(thiophene-3-propionic acid) exhibit a counter-cation dependent chromism with variations in λ max of up to 130 nm [1], Herein we report an improved synthesis and further observations on this unusual system.