Fig. 2: Phase transition behavior of cocrystal ionogels and its regulation.

a Chemical structure of an imidazole cation with a long-chain alkyl group. b Relationship between alkyl group length and IL melting/crystallization temperature. c Effect of alkyl length on the melting/crystallization behavior of PILx measured by differential scanning calorimetry (DSC), and d the corresponding model diagram. e X-ray diffraction (XRD) pattern of PILx, tested at an ambient temperature of 25 °C. f Physical and model diagrams of PIL18/IL18 cocrystal gels. g Melting/crystallization behavior of PIL18/IL18 cocrystal gels at different IL contents and the corresponding (h) XRD patterns. i Melting/crystallization behavior of PILx/ILx cocrystal gels at different alkyl lengths and the corresponding (j) phase transition temperatures, where the ILx content was fixed at 30%.