Hypercrosslinked polymers (HCPs) are a series of permanent microporous polymer materials initially reported by Davankov, and have received an increasing level of research interest. In recent years, HCPs have experienced rapid growth due to their remarkable advantages such as diverse synthetic methods, easy functionalization, high surface area, low cost reagents and mild operating conditions. Judicious selection of monomers, appropriate length crosslinkers and optimized reaction conditions yielded a well-developed polymer framework with an adjusted porous topology. Post fabrication of the as developed network facilitates the incorporation of various chemical functionalities that may lead to interesting properties and enhance the selection toward a specific application. To date, numerous HCPs have been prepared by post-crosslinking polystyrene-based precursors, one-step self-polycondensation or external crosslinking strategies. The advent of these methodologies has prompted researchers to construct well-defined porous polymer networks with customized micromorphology and functionalities. In this review, we describe not only the basic synthetic principles and strategies of HCPs, but also the advancements in the structural and morphological study as well as the frontiers of potential applications in energy and environmental fields such as gas storage, carbon capture, removal of pollutants, molecular separation, catalysis, drug delivery, sensing etc.

Covalent triazine frameworks (CTFs) represent an exciting new type of porous organic material (POP), which have some unique characteristics, i.e., aromatic CN linkage (triazine unit) and the absence of any weak bonds. In particular, the strong aromatic covalent bonds endow CTFs with high chemical stability and rich nitrogen content, which bring great value for many practical applications and the interesting heteroatom effect (HAE). The unique properties make CTFs attractive for various applications, such as separation and storage of gases, energy storage, photocatalysis and heterogeneous catalysis. Based on the current status of research, CTFs can be classified into two categories, i.e., amorphous and crystalline CTFs. Since 2008, a series of synthetic strategies have been developed, i.e., an ionothermal trimerization strategy, a phosphorus pentoxide (P₂O₅) catalyzed method, amidine based polycondensation methods, a superacid catalyzed method and a Friedel–Crafts reaction method. The advent of these methodologies has prompted researchers to construct well-defined crystalline CTFs. This critical review systematically summarizes the development and challenges in the synthesis and potential applications of CTFs.

Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large‐scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF‐HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Interestingly, these CTFs display a layered structure. The CTFs synthesized were also readily scaled up to gram quantities. The CTFs are potential candidates for separations, photocatalysis and for energy storage applications. In particular, CTF‐HUSTs are found to be promising photocatalysts for sacrificial photocatalytic hydrogen evolution with a maximum rate of 2647 μmol h⁻¹ g⁻¹ under visible light. We also applied a pyrolyzed form of CTF‐HUST‐4 as an anode material in a sodium‐ion battery achieving an excellent discharge capacity of 467 mAh g⁻¹.