Self-assembly fibrillar network gels of simple surfactants in organic solvents

The self-assembled fibrillar network (SAFIN) organogels of a simple surfactant molecule, sodium laurate (C(11)H(23)COONa, SL), in organic solvents were investigated. The sol-gel transformation temperature depended on the SL concentration, the solvent, and the concentration of Na(+) was evaluated. An important finding is that Na(+) ions play an important role in forming organogels, which was regarded as the induction factor of gelation, but other cations, for instance, Li(+), K(+), Ca(2+), and Mg(2+), do not have this capability. The observations by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) proved that the organogels were network structures with fibers and ribbons by trapping a certain amount of organic solvent. High-resolution TEM (HR-TEM) images indicated that each of the fibers or ribbons was composed of cylindrical micelles. The X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectra demonstrated that SL molecules in gels behave similarly to those in SL crystals. The mechanism of organogel formation was elaborated to provide a better understanding of fibrous surfactant gels in organic solvents.