Preparation of double-emulsion-templated microspheres with controllable porous structures by premix membrane emulsification

A scalable and versatile strategy was developed for the fabrication of uniform polymeric microspheres with controllable interconnected porous structures. Uniform water-in-oil-in-water emulsions with linear poly(methyl methacrylate–glycidyl methacrylate) in the oil phase were generated by two-step premix membrane emulsification and used for constructing the microspheres. During the emulsion solidification process, internal water droplets were packed densely together, forming a thin oil film between the internal and external water phases. After solvent diffusion, the thin film can be ruptured and pores can be templated from the internal water droplets to form interconnected porous structures. Membranes with various pore sizes were obtained. The osmotic pressure and Laplace pressure balance were used to control the porosity and pore size precisely. The proposed method enables the fabrication of functional polymeric microspheres with uniform and controllable porous structures and particle sizes. This improves their performance and broadens the scope of their applications, especially in chromatographic separation.