Microreactor utilized preparation of monodispersed polymeric microcapsules by urea/formaldehyde phase separation method

A novel methodology was described for preparing monodispersed polymeric microcapsules by urea/formaldehyde phase separation method. Monodispersed crosslinked polyurea microcapsules were prepared by applying tubular microreactor for microencapsulation, which was connected in series with Y-shaped microreactor for emulsification. At first, the monodispersed O/W emulsion was successfully prepared (diameter: 100–126 μm; CV: 1.6–3.1%) in Y-shaped microreactor emulsification technique by use of an aqueous solution containing urea/resorcinol/formaldehyde and polymeric surfactant (poly(ethylene-alt-maleic anhydride) (poly(E-MA))) as the continuous phase and dodecane solution containing 1 wt.% Oil Blue N as the dispersed phase. The following microencapsulation of the prepared monodispersed emulsion, however, was unsuccessful, resulting in polydispersed or aggregated microcapsules at the initial stage of this research. As a result of improvement of the reaction conditions, monodispersed microcapsules without aggregation were successfully obtained (diameter: 96 μm; CV: 3.8%).