High-performance polyimine xerogels: a lightweight and recyclable solution for high-temperature oil adsorption

The remediation of viscous oil spills and organic contaminants in harsh environments requires sorbents that possess not only adsorption capability but also exceptional thermal and chemical stability. Herein, we report the facile synthesis of a novel class of fluorinated copolyimine xerogels (XG-CoPI) following the solvent exchange method via the polycondensation of terephthalaldehyde (PA), 4,4'-oxydianiline (ODA), and 2,2'-bis(trifluoromethyl)benzidine (6FAPB). To enhance the mechanical properties and thermal stability, the material was cross-linked using tris(2-aminoethyl)amine (TREN). The copolyimine xerogel with 10 wt% solid content (XG-CoPI10) exhibits an optimum porous xerogel structure with a low density of 0.229 g cm^-3, and exceptional thermal stability, exhibiting a decomposition temperature exceeding 300 °C. Notably, XG-CoPI10 achieved a superior hot-oil adsorption capacity of 3.83 g g^-1 at 150 °C, which outperformed its room-temperature capacity (3.21 g g^-1). Furthermore, the xerogel demonstrated outstanding cyclic durability, maintaining a high adsorption efficiency over 10 high-temperature adsorption-desorption cycles. Additionally, it exhibited excellent chemical stability, with a mass retention exceeding 96% in organic solvents, including DMF and NMP. These quantitative results demonstrate XG-CoPI as a high-performance candidate for high-temperature oil spill remediation and industrial wastewater purification.