Tailored Postsynthetic Nitration of a Hypercrosslinked Polymer for Single-Step Ethylene Purification from a Ternary C Gas Mixture.

Purifying CH from a ternary CH/CH/CH mixture poses a substantial industrial challenge due to their close physical and chemical properties. In this study, we introduce an innovative design approach to regulate and optimize the nitration degree of a hypercrosslinked polymer to achieve targeted separation performance. We synthesized a porous organic polymer (HCP) using the solvent knitting method and carried out its postsynthetic nitration, resulting in HCP-NO-1 and HCP-NO-2 with different nitration degrees. Notably, the adsorption capacity shifted from CH > CH ≈ CH for HCP to CH > CH > CH for HCP-NO-1 and to CH > CH ≈ CH for HCP-NO-2, demonstrating the controllable nature of the separation process via the polar nitro group insertion. Remarkably, HCP-NO-1 exhibited a desirable, selective separation of CH from the CH/CH/CH mixture thanks to an exquisite combination of the acidic proton-polar nitro group and nonpolar C-H⋅⋅⋅π interactions. Separation capability was further corroborated by computational simulations and breakthrough tests. This work marks a significant advancement as the first successful postsynthetic functionalization strategy for CH purification from a ternary gas mixture among porous organic polymers.