(353f) Microfluidic Synthesis of Non-Spherical Polymeric Microparticles

The ability to synthesize large quantities of highly uniform nano- or micro-sized particles with diverse customizable morphologies and physicochemical properties is an asset to many advanced applications. However, the synthesis of such highly monodispersed particles with tunable functionalities has been a great challenge to the scientific community. Several reports have documented the synthesis protocols for various morphologies of inorganic nano- and micro-sized particles. Various heterophase polymerization methods including microemulsion and suspension polymerization have been developed and implemented to synthesize both polymeric particles and their composites. This polymerization approach does not offer control over the size and morphology and has been primarily used to synthesize spherical particles. However, non-spherical particles are attractive for their properties such as anisotropic responses to external fields, large surface area, and effective packing. Microfluidics technology presents an alternative approach to synthesizing non-spherical particles/composites with tunable functionalities. Using this approach, it is possible to synthesize colloidal based microparticles and their composites with predetermined shapes. The method is dependent on the use of UV-curable prepolymer, with an appropriate photo-initiator.

In this study, the prepolymer solution flows through a microfluidic channel fabricated by bonding poly-dimethylsiloxane (PDMS) molds to a glass slide. The microfluidic channel is placed under the objective of a microscope. A photo mask, patterned with pores defining the shape of the particles, is placed in the shutter of the microscope and allows the selective passage of light. The light that passes through the photomask and exits the objective cross links the liquid prepolymer in the microfluidic channel to synthesize micron sized organic particles of varying cross sectional shape. The particles are highly monodispersed, and the height of the particles is determined by the depth of the microchannel used for synthesis. The results of this study will be discussed.