Rigid planar and contorted polymer with Tröger's base for efficient NO2 physisorption and stable in-situ fixation at high temperature

The limited stability and insufficient reactivity of small molecules toward NO 2 limit their ability to suppress the autocatalytic degradation of nitrocellulose (NC) under harsh conditions. The integration of rigid planar with twisted Tröger's base (TB) yields a thermally stable polymer designed for dual function: inherent microporosity enables rapid NO 2 physisorption, while abundant N-sites facilitate stable in-situ chemisorption at elevated temperatures. Among them, the biphenyl-based Tröger's base (BTA-TB) exhibits excellent NO 2 uptake (BTA-TB, 909.81 m 2 g −1 , 3.06 mmol g −1 ). With 3% BTA-TB, it reduces NO 2 release by 63.4 % in titration tests and extends the methyl violet color-change time by a factor of 2.35, outperforming pyrene-based TB (PTA-TB, 1120.51 m 2 g −1 , 2.99 mmol g −1 ) and Tetrakis(4-aminophenyl)-1,4-benzenediamine TB (TABA-TB, 28.25 m 2 g −1 , 2.74 mmol g −1 ). Characterization and calculations revealed that NO 2 preferentially fixes adjacent to the aromatic ring's tertiary amine. BTA-TB's high performance is attributed to its microporous structure, large surface area, reduced π-conjugation, and lower activation energy. These findings establish a design strategy for materials that simultaneously achieve physical adsorption and stable chemical immobilization of NO 2 and other gases.