A fluorocarbon (FC) surfactant is the most effective and efficient surfactant to generate a low surface energy, resulting in very low aqueous surface tensions of &lt; 25 mN/m and repellences for water and oil. However, as these compounds are typically expensive and environmentally unfriendly, a low surface energy fluorine-free surfactant comparable to a FC surfactant has been required for practical applications in chemical industries.<br/>To develop a low surface energy fluoride-free surfactant, this study synthesized double and triple hydrocarbon-tail surfactants having tail terminal trimethylsilyl (TMS) groups (AOTSiC and TCSiC, respectively), and examined interfacial properties and aggregation behavior of those surfactants in water and/or heptane. Interestingly, TMS surfactants were found to have an excellent surface tension lowering ability in water, and to achieve very low surface tensions of 23.8-23.9 mN/m at 35 °C. The excellent surface tension lowering ability of AOTSiC was further enhanced with the optimum quantity of calcium or magnesium chloride, and it succeeded the aqueous surface tension of 21.3 mN/m. This value is similar to that of a short or middle fluorocarbon surfactant and extremely lower than for a conventional hydrocarbon surfactant (i.e. 30-40 mN/m). Small-angle neutron scattering measurements for micelles in water and reverse micelles in water/heptane mixtures found the TMS surfactants to form molecular assemblies with low curvatures compared with surfactants having tail terminal t-butyl and isopropyl groups. These results will give useful information to design a low surface energy fluorine-free surfactant.

Effect of tail terminal trimethyl silyl groups on interfacial properties and aggregation behavior of surfactants

256th National Meeting (2018)

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