Double Emulsion‐Templated Single‐Core PLGA Microcapsules with Narrow Size Distribution and Controllable Structure by Using Premix Membrane Emulsification

Abstract A scalable and versatile strategy was developed for fabrication of double emulsion‐templated single‐core PLGA microcapsules with narrow size distribution and controllable structure. A single‐core water‐in‐oil‐in‐water (W 1 /O/W 2 ) double emulsion was generated from two‐step premix membrane emulsification, which guaranteed the narrow size distribution and size controllability of emulsion. During a secondary emulsification process, coalescence of W 1 droplets within oil droplet allowed multi‐core W 1 /O/W 2 double emulsion to spontaneously transform to a single‐core one. The osmotic pressure and solvent diffusion rate were used to control the shell‐thickness and surface morphology of single‐core PLGA microcapsules, respectively. The method proposed in this study could be extended for the fabrication of uniform single‐core polymeric microcapsules with controllable structures and size.