Models and mechanism of the formation of poly(thio‐1,4‐phenylene)

TLDR: In this paper, the formation of poly(thio-1,4-phenylene) does not proceed by a normal polycondensation process, but is a one-electron transfer process with radical-cations as reactive intermediates.

Abstract: The formation of poly(thio-1,4-phenylene) does not proceed by a normal polycondensation process. The mechanism was found to be a one-electron-transfer process with radical-cations as reactive intermediates. This mechanism explains the formation of disulfides as side products. It could be shown in a model reaction that more than 20% of the disulfide can be formed in the early stage of the reaction and that the formation of disulfide is a reversible reaction, which explains the decrease of its content with the reaction time. Oligomers up to the octamer were prepared in a stepwise synthesis. The melting point and the enthalpy of melting of poly(thio-1,4-phenylene), crystallized as extended chains, were extrapolated from the melting points of the oligomers. From the UV spectra it could be deduced that the length of conjugated segments in solution is low.