"On-the-Fly" Fabrication of Highly-Ordered Interconnected Cylindrical and Spherical Porous Microparticles via Dual...

A microfluidic platform with dual photopolymerization zones has been developed for production of novel uniform interconnected porous particles with shapes imposed either by the geometry of the external capillary or by the thermodynamic minimization of interfacial area. Double w/o/w (water/oil/water) drops with well-defined internal droplet size and number were produced and then exposed to online photopolymerization to create the porous particles. Cylindrical interconnected porous particles were produced in a segmented flow where the drops took the shape of the capillary. The microfluidic setup included an extension capillary where the drops relaxed and conformed to their thermodynamically favored morphology. Window opening of the particles occurred "on-the-fly" during UV polymerization without using any offline auxiliary methods. A distinction was made between critically and highly packed arrangements in double drops. The window opening occurred consistently for highly packed spherical drops, but only for critically packed drops containing more than six internal cores at internal phase ratios as low as 0.35. The size and number of cores and shape and structure of double drops could be precisely tuned by the flow rate and by packing structure of the inner droplets.