Radiation‐Resistant Piperazine‐Tröger's‐Base Porous Organic Polymer for Efficient Chemical Immobilization of Methyl Iodide With Low Leakage

ABSTRACT

Preventing secondary release after capture remains a critical challenge in the management of radioactive methyl iodide (CH ₃ I) from nuclear off‐gas. Here, a metal‐free porous organic polymer, TBPOF‐PZ, was developed by covalently integrating piperazine‐derived tertiary amines and Tröger's‐base bridgehead nitrogen centers into a thermally stable porous architecture. TBPOF‐PZ achieves a high total CH ₃ I uptake of 4.35 g g ⁻¹ , while 1.60 g g ⁻¹ remains irreversibly retained after thermal desorption. Spectroscopic analysis, density functional theory, and pyrohydrolytic combustion‐ion chromatography collectively clarify the chemical immobilization mechanism. TBPOF‐PZ exhibits excellent CH ₃ I retention performance in multicomponent fixed‐bed breakthrough experiments using a simulated realistic gas mixture. Importantly, no obvious deterioration in performance is observed after exposure to an NO _x ‐containing atmosphere or 240 kGy γ‐irradiation. In addition, CH ₃ I‐loaded TBPOF‐PZ effectively retains iodide under both high‐temperature conditions and prolonged storage. These results establish a covalent porous‐polymer strategy for integrating efficient capture, durable chemical fixation, and leakage resistance under demanding nuclear off‐gas conditions.