(121a) Synthesis and Assembly of Size-Controlled Polymer Beads and Capsules in an Axisymmetric Co-Flowing Microsystem

We will present an axisymmetric microreactor for the synthesis of monodisperse polymer particles (CV<5%), either beads or capsules, in the size range of tens to several hundred of microns. The emulsification of the monomer phase is achieved in a very simple needle/tubing co-flowing microsystem without any surfactant or surface treatment. Polymer beads are obtained after UV irradiation while polymer capsules are directly generated at the needle tip through an interfacial polycondensation reaction. A preliminary study has shown that in the dripping regime the variation of particle diameter with respect to operating parameters (flow rates and viscosities of the dispersed and continuous phases) is fairly well described by an empirical relationship between two dimensionless numbers, the normalized particle diameter and the Capillary numbers ratio. This co-flowing microsystem also allows for the preparation of inorganic-organic hybrid beads as well as hollow and doped capsules. By using two co-flowing microsystems in parallel, two different types of particles can be obtained and assembled downstream to form polymer particles necklaces with different arrangement, alternate, block and random.