Janus Hollow Microstructures via an Interfacial Phase Hydrogen Bond Network

Abstract Janus hollow microstructures have been widely used in chemistry, medicine, biology, and materials science because of their anisotropy and hollow structure. Constructing multiple types of hollow microstructures and establishing structure–property relationships remain challenging. Here, the present authors developed a one-pot polymerization strategy for constructing Janus hollow microstructures in which deep eutectic solvents (DESs) completely replaced water as the continuous phase. A range of Janus hollow microstructures was produced with various compositions, as well as various ratios of the hydrophilic part and film thickness. Consequently, their corresponding morphologies ranged from 3D-like forms (such as spherical and bowl shape) to 2D-like forms (including pie shape, vesicle shape, and vacuum-bag-like). There were hydrogen bond interactions between the DESs and hydrophobic monomers. Hence, hydrogen bond networks formed at the DES–oil interface during the polymerization, inducing free radical stabilization and monomer activation, which was the underlying mechanism for forming the Janus hollow structure. The polymerization strategy provides a faster, more convenient, and more universal way to prepare Janus hollow microstructures compared with conventional methods.