Self-assembly of latex particles at droplet interface to prepare monodisperse emulsion droplets

Monodispersed Pickering emulsion droplets were prepared by self-assembling of sulfonated polystyrene (SPS) latex particles at droplet interface. The stability of emulsion was obviously improved by pre-dispersing the latex particles in oil–water two phase and then mixing them into emulsion. For oil-in-water emulsion, the optimal stability was obtained by pre-dispersing 0.33 weight fraction of the latex particles in oil phase initially. Several parameters were considered during the preparation, including sulfonation time of the SPS latex particles, the dispersed percent of the latex particles in oil–water two phases, the pre-dispersion time of water phase dispersate and oil–water volume ratio. When sulfonation time of the latex particles was close to 60 h, the stability of the particles stabilized emulsion droplets was the best. The increase of pre-dispersion time of water phase dispersate and oil–water volume ratio could obviously decrease the dispersity of emulsion droplets. Finally, monodisperse emulsion droplets were obtained with average droplet diameter 7.4 μm and standard deviation 0.37. The emulsion droplets could re-assemble into ordered array.