Photochemical gluing of colloidal particles by a simple interparticle polymerization route

We have developed a simple strategy to chemically cross-link polystyrene latex spheres by UV-light-induced polymerization after the particles, which themselves were internally cross-linked with divinylbenzene (DVB), have been carefully swollen in aqueous dispersion with a small amount of the monomer styrene. As a proof of concept, aggregates were preformed by salt-induced aggregation, and successful fixation of the aggregate structure was quantitatively confirmed by dynamic light scattering after the sample was diluted with distilled water and treated with ultrasound. Under this treatment, non-UV-irradiated aggregates dispersed and the single particle size was recovered. This concept was successfully applied also to commercial latex particles. For the future, arranging the colloids in a well-defined way by laser traps before photo-cross-linking opens up a facile method to prepare microscopic devices.