Solid-State Synthesis of a Conducting Polythiophene via an Unprecedented Heterocyclic Coupling Reaction

Abstract

Prolonged storage ( approximately 2 years) or gentle heating (50-80 degrees C) of crystalline 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) affords a highly conducting, bromine-doped poly(3,4-ethylenedioxythiophene) (PEDOT), as confirmed by solid-state NMR, FTIR, CV, and vis-NIR spectroscopies. The novel solid-state polymerization (SSP) does not occur for 2,5-dichloro-3,4-ethylenedioxythiophene (DCEDOT), and requires a much higher temperature (>130 degrees C) for 2,5-diiodo-3,4-ethylenedioxythiophene (DIEDOT). X-ray structural analysis of the above dihalothiophenes reveals short Hal.Hal distances between adjacent molecules in DBEDOT and DIEDOT, but not in DCEDOT. The polymerization may also occur in the melt but is significantly slower and leads to poorly conductive material. Detailed studies of the reaction were performed using ESR, DSC, microscopy, and gravimetric analyses. SSP starts on crystal defect sites; it is exothermic by 14 kcal/mol and requires activation energy of approximately 26 kcal/mol (for DBEDOT). The temperature dependence of the conductivity of SSP-PEDOT (sigma(rt) = 20-80 S/cm) reveals a slight thermal activation. It can be further increased by a factor of 2 by doping with iodine. Using this approach, thin films of PEDOT with conductivity as high as 20 S/cm were fabricated on insulating flexible plastic surfaces.

Structure and photocatalytic activity of a low band gap donor–acceptor–donor (D–A–D) type conjugated polymer: poly(EDOT–pyridazine–EDOT)

“…Pd(PPh 3 ) 4 was synthesized according to a method in the literature. 29 All the other chemicals and solvents, including methylene blue, methyl violet, methyl orange, rhodamine B, phenol, methanol, and chloroform were used as received without further purication. Fig.…”

Step-by-step growth of epitaxially aligned polythiophene by surface-confined reaction

“…A single crystal (110) oriented Cu specimen was cleaned by repeated cycles of ion bombardment (Arþ at 600 eV) and annealing to ≈800 K. The DIEDOT was synthesized as described before (36). For evaporation, a sample of DIE-DOT was located outside the main UHV system in an evacuated vial and was dosed into the vacuum chamber through a drift tube.…”

Preparation and characterization of polyacrylate functionalized polythiophene films

“…There are several prevailing techniques in the group of LRP, including nitroxidemediated polymerization (NMP) [23], atom transfer radical polymerization (ATRP) [24] and reversible addition-fragmentation chain transfer (RAFT) [25][26][27] polymerization. Among them, the RAFT process reported by Rizzardo et al is one of the promising ones [28,29], which could be enforced in a broad extent of solvents (including water) and applicable to a wide scope of monomers under a wide range of experimental conditions. [28] Besides, a variety of functional polymers and macromolecules with special architectures including block [30,31], star [32,33], graft [34,35], telechelic [36], hyperbranched structures and supermolecular assemblies [37] are accessible.…”

“…[28] Besides, a variety of functional polymers and macromolecules with special architectures including block [30,31], star [32,33], graft [34,35], telechelic [36], hyperbranched structures and supermolecular assemblies [37] are accessible. More importantly, the RAFT process could also be used to study well-explicit macromolecular architectures with a wide scope of functional monomers [29]. Therefore, in this paper, RAFT method was chosen to synthesize a precursor from the functional monomer 3-ethyl acrylate-thiophene with narrow PDI.…”