This result is contrary to the fact that the solvent mixture containing ethanol is usually characterized by a smaller gel-forming concentration (i.e., a higher gel-forming efficiency) than toluene. In fact, ethanol (and isopropanol) is a competitor to form a hydrogen bond network because of the existence of ethanol groups. This characteristic weakens the hydrogen bond network in principle, thus reducing the driving force of gel formation. However, in polar solvents, the hydrophobic effect caused by fatty acid side chains not contacting with the medium is beneficial to aggregation. This consideration shows that different intermolecular forces play a leading role in self-assembly, and gel formation efficiency is the result of this delicate balance.

The thermal properties of the gel were studied by differential scanning calorimetry (DSC). For each gel, a large number of DSC measurements were collected under the conditions of changing the gel concentration and changing the solvent of the compound. These experiments enable us to determine the gel-sol and gel-sol transition temperatures. The obtained DSC diagram is not always easy to explain, but often shows more than one transformation. However, the "main" transition with the strongest peak characteristics can always be identified and selected as the gel-sol transition peak. The result is shown in Figure 3.

Fig. 3 shows that Tgel-sol usually depends on the concentration of gel, at least within the experimental range, especially for compound 9 and 10, as most organic gels reported in the literature. The derivative 1 1 is characterized by wide conversion, which hinders the accurate evaluation of the conversion temperature, while the compound 10 shows strange unstable behavior (data not shown). The concentration range is basically determined by the solubility limit of gel in hot solvent and the lowest concentration at which stable gel can be obtained. In order to study the reasonable concentration range, different solvents must be selected for each organic gel, and the strict comparison between different conversion temperatures cannot be carried out on this basis. However, it should be noted that the onset of gel can be changed and controlled by comprehensive selection of solvents and proper chemical functionalization around the same molecular building structure.