Graphyne modified with polymeric deep eutectic solvent via unsaturated bond engineering for imidacloprid and diuron...

To address the demand for high-performance adsorbents in trace pesticide residue detection in complex matrices, a gradient series of deep eutectic solvents (DESs) bearing alkenyl, alkynyl and aryl unsaturated bonds was constructed, and a series of DES/polymeric DES (PDES) functionalized hydrogen-substituted graphyne (HsGY) composites were prepared for sample pretreatment. The regulatory effects of unsaturated bond types and polymerization on adsorption performance were systematically elucidated. Alkenyl DESs were polymerized into flexible saturated backbones with fully exposed active sites, leading to enhanced adsorption capacity, whereas alkynyl DESs resulted in decreased capacity due to tight chain stacking and active site entrapment. Density functional theory calculations confirmed that enhanced orbital delocalization after polymerization, together with synergistic hydrogen bonding, electrostatic interactions and charge transfer, underpinned the performance improvement in alkenyl systems. Based on the optimal PDES2-HsGY, a pipette-tip solid-phase extraction-HPLC method was established for simultaneous enrichment and trace detection of imidacloprid and diuron in honeysuckle and green tea samples. The method showed good linearity in the range of 0.05-10 μg·g^-1, with limits of detection of 0.008-0.012 μg·g^-1, spiked recoveries of 82.12%-94.72%, and RSDs ≤5.71%. The adsorbent exhibited superior performance to various commercial sorbents, providing a reference for the structural design of DES-based separation materials.