Emulsion interfacial synthesis of hierarchically porous covalent organic framework microcapsules with multilayered boronic acid binding sites for specific molecular separation

Abstract

Although capsule-like materials as matrix for separation have been a hot research in recent years, creating abundant recognizing sites for enhanced adsorption performance is still a formidable challenge. Herein, we created a two-step continuous Pickering emulsion interfacial assembly to fabricate boronate affinity covalent organic framework microcapsule (BA-TAPB-BTAC-BPTA MC) for selective separation of Naringin (NRG). The COF particles were stabilized at water–oil interface during the first emulsion interfacial assembly. The other COFs species were then grown using low concentration of catalyst in the multiphase emulsion interface. As expected, the highly reactive alkynylation COFs particles and COFs species shell could effectively stabilize the pre-Pickering W/O emulsion. The azide-phenylboronic acid were introduced in confine space of alkynylation COFs MC via “click” modification. The sorbents presented promising adsorption capacity (20.36 µmol g−1) in 360 min under the phosphate buffer/methanol solution (pH = 8.0, v/v, 9/1). Additionally, sorbents possess excellent stability after 5 cycles of adsorption–desorption experiments (93.57%). Moreover, the commercially NRG could be effectively extracted to 93.07%. Our findings provided an idea for constructing affinity ligands COFs MC with fast penetrability and multilayered binding sites have great potential for separation and purification of industrial samples.