Preparation of uniform monomer droplets using packed column and continuous polymerization in tube reactor

Abstract

A two-step continuous emulsification and polymerization process was developed in which monomer droplets having narrow size distribution were prepared and polymerized while retaining their monodispersity. In the emulsification step, a column packed with glass beads, of diameters ranging from 70 μm to 1 mm, was used to prepare a monomer O/W emulsion. Monomer droplets were dispersed with an aqueous solution of poly(vinyl alcohol) (PVA). The droplet size and -distribution was studied with respect to the effects of diameter of glass beads, concentration of PVA in water phase, degree of polymerization of PVA, ratio of mass flow of water phase to that of oil phase, linear velocity of water phase and viscosity of water phase and oil phase. Droplet size was found to be strongly dependent on the diameter of the packed glass beads, while the droplet size distribution was affected by the viscosities of the continuous and dispersed phases. Increasing the viscosity of the dispersed phase by addition of poly(styrene) to the monomer mixture resulted in a narrow size distribution of glycidyl methacrylate–ethylene glycol dimethacrylate droplets. Furthermore, these initiator-containing monomer droplets were polymerized by heating in a tubular reactor, from which polymer particles with a narrow size distribution could be synthesized.