Targeted synthesis of hydrophobic piperazine‐rich porous organic polymers for radioactive methyl iodide immobilization

Abstract Cost‐effective and leakage‐proof capture of volatile radioactive methyl iodide (CH 3 I) from nuclear off‐gas remains challenging. Guided by computational screening, we designed hydrophobic, nitrogen‐rich porous organic polymers (NPOPs) featuring N‐alkyl piperazine/piperidine motifs. The optimized NPOPs achieve record CH 3 I uptake of more than 4 g g −1 with rapid kinetics (>85% saturation within 60 min). Spectroscopic analyses ( 13 C SS‐NMR, XPS, FT‐IR) confirm irreversible chemisorption via N‐methylation as the dominant mechanism. NPOP‐1 exhibits a high dynamic breakthrough capacity of 3.86 g g −1 under simulated operational conditions and retains structural integrity after high‐dose γ‐irradiation. Crucially, in tests with radioactive CH 3 131 I, NPOP‐1 demonstrates a 99.999% retention rate. Kilogram‐scale synthesis yields material at an estimated cost of $1.5 USD g −1 . These attributes establish NPOPs as a viable, economically competitive platform for the safe, permanent sequestration of radioactive organic iodides in nuclear fuel cycle applications.