Flow regimes of polymeric fluid droplet formation in a co-flowing microfluidic device

The generation of polymeric fluid droplets via a microfluidic device with co-flowing structure is investigated by experimental, and further the influences of outer phase flow rate as well as polystyrene (PS) mass concentration on the droplet formation are systematically clarified. The experimental results indicate that the polymeric fluid droplet formation can be quantitatively distinguished by three typical flow regimes, namely breakup with satellite droplet, breakup without satellite droplet, and breakup with liquid filament. It is also found that, as the PS mass concentration increases, the satellite droplet diameter correspondingly increases. However, specially, the influence of continuous fluid flow rate on the satellite droplet diameter exhibits various, and it always depends on the PS mass concentration. Finally, a flow pattern diagram based on the dimensionless numbers is also obtained. The results obtained above could provide a guidance to prepare highly monodisperse polymeric fluid droplet without satellite droplet formation via co-flowing stream.