Hypercrosslinked polymer by an external crosslinker strategy: formation mechanism, structural regulation and applications

Abstract

Hypercrosslinked polymers (HCPs) are a type of porous organic polymer that have been rapidly developed over the past few decades. These polymers are primarily synthesized through Friedel–Crafts alkylation over Lewis acid catalysts such as ferric chloride and aluminum chloride, leading to the formation of porous materials by cross-linking. HCPs can be prepared through strategies such as post-cross-linking of polystyrene-type polymer precursors, self-cross-linking of specific aromatic monomers, and cross-linking by external agents with aromatic monomers. Among these methods, the external cross-linking approach has been utilized in fields such as gas storage, adsorption, catalysis, separation, and energy storage due to its mild synthesis conditions, good stability, high yield, broad availability of monomers, and tunable structure. In this paper, recent research progress in the preparation of HCPs by external cross-linking methods, with a focus on the formation mechanisms, structural regulation, and applications, is reviewed. Additionally, the drawbacks and challenges while projecting future developments in HCPs are highlighted.