Modulating Polar Heterogeneity and Spatial Effects for Ultra‐High ReO ₄ ⁻ / ⁹⁹ TcO ₄ ⁻ Capture in Extremely Acidic and Alkaline Conditions

Abstract The selective capture of ⁹⁹ TcO ₄ ⁻ in extremely acidic and alkaline conditions remains a long‐standing challenge in nuclear waste treatment. Herein, a strategy is proposed to rationally modulate polar substituents and spatial effects, resulting in the development of three ultra‐stable cationic polymers, designated as V‐P, V‐3B, and V‐YX. These polar‐heterogeneous materials consistently achieve removal efficiencies exceeding 98.6% across a broad pH range (1–11), with saturated adsorption capacities of 1115.0, 655.1, and 871.4 mg g ⁻¹ for ReO ₄ ⁻ (a nonradioactive surrogate for ⁹⁹ TcO ₄ ⁻ ), respectively. The phosphonium‐functionalized V‐P demonstrates exceptional suitability for capturing ReO ₄ ⁻ from extremely acidic solutions and achieves a record‐high capacity of 204.8 mg g ⁻¹ in long‐term dynamic column experiments. Through the adjacent steric hindrance and unique electron‐withdrawing effects in V‐3B and V‐YX, the alkaline stability of the imidazolium‐N ⁺ moiety is significantly enhanced, culminating in extraordinary ReO ₄ ⁻ removal of ≈100% in 3 M NaOH solutions. In breakthrough experiments of simulated Beishan groundwater, V‐3B and V‐YX demonstrate dynamic capacities of 64.6 and 62.0 mg g ⁻¹ , respectively. Molecular dynamics simulations and machine learning analyses further elucidate host‐guest interaction mechanisms and the critical role of polar heterogeneity. These findings offer innovative and universal strategies for designing and screening materials tailored for radionuclide decontamination.