Photo-initiated miniemulsion polymerization as a route to the synthesis of gold nanoparticle encapsulated latexes

We report the first use of photo-initiated miniemulsion polymerization for the synthesis of well defined poly(methyl methacrylate) (PMMA) latexes. Furthermore, the application of photo-initiation is employed to the incorporation of decanethiol-capped gold nanoparticles (AuNPs). The procedure provides a low temperature polymerization for an oil-in-water miniemulsion with temperatures not exceeding 40 °C and polymerization times of only one hour. Using these mild reaction conditions allows the use of miniemulsion polymerization for the encapsulation of temperature sensitive species within the latex. Furthermore, we demonstrate the applicability of this method for the incorporation of decanethiol-capped AuNPs. Particle size distribution and morphology was studied using dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PMMA latexes ranged between 100 and 200 nm in diameter showing good particle size distribution and tendencies to form semi-ordered domains. We show that variations in surfactant, hydrophobe and initiator concentrations behave in the same manner as miniemulsions initiated through conventional thermal methods. TEM observations revealed that the latexes with encapsulated AuNPs displayed even distributions of AuNPs throughout the PMMA latex with no aggregation witnessed.