Polymer/particle/water intermolecular interaction regulated freeze-dried Pickering emulsion morphology

Abstract

Colloidal particles self-assembled at oil-water interfaces of Pickering emulsion served as a desired template for functional materials fabrication, raising broad attention from pharmaceutical engineering. Linking interfacial colloidal particles in Pickering emulsion based on strong molecular bonding, such as covalent bonding and ionic bonding have been widely investigated for colloidosomes preparation. This study demonstrated that relatively weak intermolecular interactions such as chemical coordination bond and hydrogen bond can also regulate the distribution of inorganic particles at the oil-water interface of emulsion. Pickering emulsion stabilized by boron nitride (BN) particles has been systematically studied by tuning the dissolved polymer in water phase after lyophilization (freeze-drying). The morphology of as-formed polymer-BN composite exhibited hollow microcapsules, “sphere-strip” mixture and aerogel, respectively, depending on the polymer/BN and polymer/water interaction. The mechanism of polymer regulating Pickering emulsion morphology has been proposed, which will enrich the current understanding of Pickering emulsion behavior during lyophilization and provide new strategy for the fabrication of functional materials.