Chemo-enzymatic synthesis of arginine-based gemini surfactants

Solution Properties and Emulsification Properties of Amino Acid-Based Gemini Surfactants Derived from Cysteine

“…The results are shown in Table 1, along with data for the corresponding monomeric surfactant C 12 Cys and 2 types of sugar-based gemini surfactants with lactobionamide headgroups 2C 12 Lac and 2C 12 peLac , which have been reported previously 21 . The biodegradability of 2C 10 diCys and 2C 14 diCys increased with time; the biodegradability of 2C 14 diCys remained nearly constant after 14-28 days, whereas that of 2C 10 diCys continued to increase.…”

“…The slope for the linear relation between the logarithm of the CMC and alkyl chain length for 2C n diCys n 10 and 12 was 0.35, which is slightly higher than values for conventional ionic monomeric surfactants 0.3 19 . The CMC of 2C 12 diCys was also higher than that of the similar cystine gemini surfactant 2C 12 Cys. This can be explained by the difference in spacer structure between 2 gemini surfactants, i.e., the 2C 12 diCys possesses 2 amide groups in the spacer, while the 2C 12 Cys does not.…”

“…The CMC of 2C 12 diCys was also higher than that of the similar cystine gemini surfactant 2C 12 Cys. This can be explained by the difference in spacer structure between 2 gemini surfactants, i.e., the 2C 12 diCys possesses 2 amide groups in the spacer, while the 2C 12 Cys does not. The 2C n diCys with n of 10 and 12 showed lower surface tensions of 30 32 mN m 1 .…”

“…2C 14 diCys may exhibit a small area because of the formation of a film by relatively long alkyl chains at the air/water interface, resulting in less effective interfacial adsorption. 2C 12 diCys also showed a larger occupied area than 2C 12 Cys due to the bulky molecular structure of the spacer. These results are also supported by the Gibbs free energies of micellization and adsorption ∆G mic and ∆G ads , respectively , which can be obtained using eqs.…”

“…Surface tension decreased as concentration increased and reached a clear breakpoint, which was defined as the CMC. Table 2 summarizes the values for CMC, surface tension at the CMC γ CMC , surface excess concentration Γ , and area occupied per molecule A for 2C n diCys, which were obtained based on surface tension plots as well as data reported for the gemini surfactant N, N -dialkyl cystine 2C 12 Cys and the corresponding conventional monomeric surfactant N-dodecyl cysteine C 12 Cys 15 .…”