Journal of Applied Research in Chemical-Polymer Engineering

Abstract Research Subject: Poly(dimethylsiloxane) (PDMS) is a silicone polymer that nowadays despite unique characteristics and high application potential of its microparticles, their preparation via bulk emulsification methods is a main challenge due to the limitations in mixing process, high viscosity and low surface energy of PDMS that make impossible accurate control of final obtained particles. In the present work, size-controlled PDMS microparticles were prepared from a high-viscosity material.
Research Approach: PDMS microparticles were obtained by using glass capillary co-flow microfluidic device. The designed microfluidic device is facile, inexpensive and reusable and facilitated preparation of the high-viscosity PDMS microdroplets. Stabilizing the oil-in-water emulsion was obtained by optimizing the bath components and curing process that resulted in monodisperse and spherical PDMS microparicles. Effect of the some important adjustable parameters such as microchannel diameter and flow rate on the flow regimes and microparticles polydispersity were investigated by means of optical microscopy and scanning electron microscopy.
Main Results: Results showed a dripping regime for producing monodisperse microparticles at low flow rates of the continuous phase and monodisperse microparticles from it. On the contrary, microparticles obtained from jetting regime are more polydisperse and smaller in comparison with dripping regime. By reducing the diameter of inner microchannel, microparticles with a diameter of 1.83 µm were obtained. Using the designed technology, uniform nanocomposite PDMS/ZnO microparticles 318 µm in diameter containing 15% ZnO were obtained from an oil phase viscosity of 7550 mPa.s. Therefore by an optimized and facile method, size-controllable uniform microparticles can be prepared that are proposed for various applications including drug delivery, bioengineering and electronic industry.