Synergism Enhancement Exploration between Novel Alkyl Fatty Acid Surface-Active Ionic Liquids and Deep Eutectic Solvents on Cyhalothrin Solubility

In order to improve the solubility of cyhalothrin and other shortcomings, such as volatile organic solvents, poor solubilization effect, and complex steps in conventional solubilization methods, and fill the gap in a surface-active ionic liquid (SAIL) and green solvent deep eutectic solvent (DES) to solubilize pesticides effectively, SAILs 1-hexyl-2-methyl-3-octanoate imidazole bromide [C6MOAmim][Br], 1-hexyl-2-methyl-3-decanoate imidazole bromine [C6MDAmim][Br], and DES 1TBAB:3EG were synthesized and confirmed by 1H NMR, 13C NMR, ESI mass spectra, FTIR, and TG-DSC. The surface activity of SAILs–water/DES four solution systems was verified and confirmed by the conductivity method and surface tension method, and the particle size was verified by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results of contact angle and adhesion work indicate that the SAILs–water/DES surfactant systems are quite helpful to improve wettability and adhesion performance of cyhalothrin on leaves. Moreover, the solubility of SAILs–water/DES surfactant systems for cyhalothrin was determined by a UV spectrophotometer. The results show that alkyl-fatty acid SAILs and DES are effective solubilizers and a cosolvent, respectively. Finally, the interaction relationships between cyhalothrin as a solute and four surfactant systems severally as a solvent were explored by standard partial molar volume, and the presence of hydrophobic–hydrophobic interactions between DES and ILs was verified by a 2D 1H–1H NOESY spectrum.