Synergistic Effect in the Ternary System of Citral Microemulsion Based on Self-Assembled Complex Surfactants

Complex ternary supramolecular systems constituted by citral, surfactants, and cyclodextrins were constructed in this paper. The composite emulsifier formed by Tween-80 and hydroxypropyl-β-cyclodextrin showed the best synergistic encapsulation effect. The emulsion has the mean particle diameter of 12 nm, a polydispersity index of 0.120 and the maximum entrapment efficiency of 87.25%. The formation of the inclusion was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. The amorphous morphology of the inclusion was indicated by X-ray diffraction and scanning electron microscopy. Finally, the formation mechanism of the inclusion was explored by means of molecular simulation. The ternary system was the combination of the long-chain Tween-80 with cyclodextrins to form a supramolecular system followed by binding with citral through the H-bond. The main driving force was the van der Waals force. The binding free energy was ΔGbind = −19.15 ± 3.25 kcal/mol, which confirmed that the reaction was a spontaneous process.