A Novel Synthesis of SO₃H Type Gemini Surfactant Having Semifluoroalkyl Group as Hydrophobic Group

Abstract

In this work, novel SO₃H type Gemini surfactants having semifluoroalkyl group (RfCH₂CH-: Rf = C₄F₉, C₆F₁₃, C₈F₁₇) as hydrophobic group were successively synthesized by the radical addition of fluoroalkyl to 1,4-pentadiene using fluoroalkyl iodide and AIBN as initiator, and the following thiocyanization (-SCN), conversion to –SH, and oxidation to SO₃H as hydrophilic group. Similarly, the common 1+1 type semifluoroalkyl surfactants having SO₃H were synthesized.
Surfactant properties of their sodium salts (cmc, γ_cmc, pC₂₀, Γ_cmc, and A) were investigated by measuring surface tension. As expected, the cmc value of Gemini surfactant whose fluoroalkyl is C₄F₉ was more than one order of magnitude smaller than that of the corresponding 1+1 type. Other properties also showed the excellent efficiency of Gemini structure to reduce the surface tension.