Using selective withdrawal to coat microparticles

We report a method that uses the process of selective withdrawal of one flu id through a second immiscible fluid to coat small particles with polymer f ilms. Fluid is withdrawn through a tube with its orifice slightly above a w ater-oil interface, Upon increasing the flow rate, there is a transition fr om a state where only oil is withdrawn to a state where the water, containi ng the particles to be coated and appropriate prepolymer reagents, is entra ined in a thin spout along with the oil. The entrained particles eventually cause the spout interface to break, producing a thin coat of controllable thickness around each particle, which can be subsequently polymerized using chemical reagents, Light, or heat. This method allows flexibility in the c hemical composition and thickness of the conformal coatings.