Dibromomethane Knitted Highly Porous Hyper‐Cross‐Linked Polymers for Efficient High‐Pressure Methane Storage

Abstract Hyper‐cross‐linked polymers (HCPs) with ultra‐high porosity, superior physicochemical stability, and excellent cost‐effectiveness are attractive candidates for methane storage. However, the construction of HCPs with BET surface areas exceeding 3000 m² g⁻¹ remains extremely challenging. In this work, a newly developed DBM‐knitting method with a slow‐knitting rate is employed to increase the cross‐linking degree, in which dichloromethane (DCM) is replaced by dibromomethane (DBM) as both solvent and electrophilic cross‐linker, resulting in highly porous and physicochemically stable HCPs. The BET surface areas of DBM‐knitted SHCPs‐Br are 44%–120% higher than that of DCM‐knitted SHCPs‐Cl using the same building blocks. Remarkably, SHCP‐3‐Br exhibits an unprecedentedly high porosity (S_BET = 3120 m² g⁻¹) among reported HCPs, and shows a competitive volumetric 5–100 bar working methane capacity of 191 cm³ (STP) cm⁻³ at 273 K calculated by using real packing density, which outperforms sate‐of‐art metal‐organic framework (MOFs) at comparable conditions. This facile and versatile low‐knitting‐rate strategy enables effective improvement in the porosity of HCPs for porosity‐desired applications.