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

Abstract

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 °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 β-phase configuration (9–10%) in their respective nanoparticles. Absolute photoluminescence quantum yields (Φ) of 21–25% were recorded for these emulsions.