## 1 Introduction  
Low molecular weight organogelators (LMWOGs) are gaining increased attention due to their potential applications in a variety of industrial sectors related to materials, cosmetics, health care, food and oil technology [1; 2; 3; 4; 5; 6; 7; 8; 9]. The design and elucidation of structure-property relationships of gelators is also a valuable area of research, in particular, establishing the relationship between the chemical structure of a gelator and its gelation properties in a given solvent [10; 11; 12; 13; 14; 15; 16; 17; 18]. Thermally reversible physical gels are generally formed by self-assembly of the gelator molecules in solvent, leading to the formation of a fibrous supramolecular network with the encapsulation of solvent. This complex process of self-assembly into supramolecular structures varies based on the functionalities present in the organogelator and external factors, including solvent, temperature, and pH. Various non-covalent interactions, such as hydrogen bonding, \(\pi\)-\(\pi\) stacking, hydrophobic interactions, and metal coordination, influence the formation and stabilization of the organogelator self-assemblies [1, 2, 10, 11, 12, 13, 14, 19, 20, 21]. However, the non-covalent forces influencing gelation are relatively weak compared to covalent bonds, and a combination of many of these interactions is required to form a strong intermolecular network. Each molecule of an organogelator can establish several types of physical interactions with a neighboring molecule. For example, intermolecular hydrogen bonding usually facilitates the growth of linear, elongated aggregates with solvent entrapment. Evaporation of solvent from a gel results in the formation of a dried gel (xerogel) with a fibrous or web-like morphology [21]. It is possible to alter the surface morphology of the substrate, and thus surface properties, if the gelation and subsequent evaporation of solvent are performed on a substrate. Hence, gel impregnation methodology could provide the low surface energies desired for fabricating superhydrophobic surfaces [19, 21, 22, 23, 24]. Surfaces on which the contact angle of water exceeds 150\({}^{\circ}\), and shows low contact angle hysteresis, are described as superhydrophobic or ultrahydrophobic [25, 26, 27]. These surfaces repel water like a lotus leaf and are also considered'self-cleaning', since any surface contamination is removed by water as the droplets roll across the surface [28, 29, 30]. The self-cleaning ability of these surfaces is largely due to the increased surface area created by a two-tier micro and nano roughness morphology. It is possible to incorporate nano- or microscale morphologies on any substrate via organogelator impregnation, which could be further controlled by suitable gelling solvents, as well as concentration and temperature effects. In addition, incorporation of low surface energy functionalities like fluorinated groups in the gelator framework could further lower the surface energy and provide oleophobic properties to the modified surface [31]. Urea and amide derivatives are exceptionally well-suited candidates for the design of low molecular weight gelators owing to their rigidity, strength and ability to form highly directional hydrogen bonds [32]. We recently demonstrated this concept by fabricating low surface energy surfaces via the surface modification of nonwoven substrates using partially fluorinated urea-amide gelators [33]. The general structure and examples of these urea-amide gelators reported in that study are shown Figure 1.  
The compounds depicted in Figure 1 were prepared via amidation of the \(N\)-Boc protected amino acid with fluorinated amines, followed by deprotection and reaction with an alkyl isocyanate. They showed excellent gelation behavior in organic solvents. Gelation in the presence of a nonwoven  
Figure 1: General structure and examples of partially fluorinated urea-amide gelators described in [31].