Conjugated Polymer Nanoparticles by Suzuki-Miyaura Cross-Coupling Reactions in an Emulsion at Room Temperature

A range of stable emulsions of spherical and rod-like conjugated polymer nanoparticles (CPN) were synthesized via Suzuki-Miyaura cross-coupling reactions of 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester with a number of different dibromoarene monomers in xylene, stabilized in water by the nonionic surfactant, Triton X-102. High molar mass poly(9,9-dioctylfluorene) (PF8), poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PF8BT), poly(9,9-dioctylfluorene-alt-4-sec-butylphenyldiphenylamine) (PF8TAA) and poly(9,9-dioctylfluorene-alt-bithiophene) (PF8T2) emulsions were obtained, at high overall conjugated polymer concentrations (up to 11,000 ppm), in the presence of the palladium complex, (IPr*)PdCl2(TEA) and base, tetraethylammonium hydroxide, in nitrogen atmosphere at 30 degrees C after 24-48 h. TEM analysis of the PF8 and PF8T2 emulsions revealed regular rod-like structures, up to 200 nm in length with aspect ratios of 4-5. PF8BT and PF8TAA formed spherical particles with diameters of between 20-40 nm in TEM analysis. UV-vis absorption spectra of the PF8 emulsions indicated high levels of ordered beta-phase configuration (9-10%) in their respective nanoparticles. Absolute photoluminescence quantum yields (Phi) of 21-25% were recorded for these emulsions.