A facile route of polythiophene nanoparticles via Fe3+-catalyzed oxidative polymerization in aqueous medium

We have demonstrated that unsubstituted thiophene can be polymerized by Fe3+‐catalyzed oxidative polymerization inside nanosized thiophene monomer droplets, that is, nanoreactors, dispersed in aqueous medium, which can be performed under acidic solution conditions with anionic surfactant. Besides, we proposed a synthetic mechanism for the formation of the unsubstituted polythiophene nanoparticles in aqueous medium. This facile method includes a FeCl3/H2O2 (catalyst/oxidant) combination system, which guarantees a high conversion (ca. 99%) of thiophene monomers with only a trace of FeCl3. The average particle size was about 30 nm, within a narrow particle‐size distribution (PDI = 1.15), which resulted in a good dispersion state of the unsubstituted polythiophene nanoparticles. Hansen solubility parameters were introduced to interpret the dispersion state of the polythiophene nanoparticles with various organic solvents. The UV–Visible absorption and photoluminescence (PL) spectrum were measured to investigate the light emitting properties of the prepared unsubstituted polythiophene nanoparticle emulsions. According to non‐normalized PL analysis, the reduced total PL intensity of the polythiophene nanoparticle emulsions can be rationalized by self‐absorption in a wavelength range less than 500 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2097–2107, 2008 This facile method is concerned with unsubstituted polythiophene nanoparticles with 30‐nm diameter and a narrow particle size distribution (PDI = 1.15), which were prepared using a Fe3+‐catalyzed oxidative polymerization inside nanosized droplets of the thiophene monomer, i.e., nanoreactors, dispersed in aqueous phase. This method includes a FeCl3/H2O2 (catalyst/oxidant) combination system, which guarantees a high conversion (ca. 99%) of thiophene monomers with only a trace of FeCl3. This practical phenomenon originated in the regeneration of Fe3+ (original state of oxidant (FeCl3)) from the useless by‐product form (Fe2+ ion) by a reaction with H2O2. The UV‐visible absorption and photoluminescence (PL) spectrum were measured to investigate the light emitting properties of the prepared unsubstituted polythiophene nanoparticle emulsions. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]