Preparation and Surface Activity of Complexane-type Surfactants Having Two and Three Alkyl Chains

Abstract

Complexane-type surfactants possessing two and three alkyl chains (2Rnida, 2Rnedda, 2Rndtda and 3Rndtda; n means alkyl chain length) were prepared by the corresponding amine and the appropriate alkyl bromide and examined for surface activity. Critical micelle concentration (cmc) was found to shift to lower concentration with increase in alkyl chain length, number of alkyl chains and decrease in spacer length. Cmcs of 3R8dtda and 3R12dtda having three alkyl chains were 2-3 smaller than that of the corresponding surfactant having one alkyl chain. Surface tension of complexanes was significantly affected by alkyl chain and spacer length and the number of alkyl chains. Surface tension of 3R8dtda attained to 24.0mN m-1 at cmc. Cross-sectional molecular areas of 3Rndtda with n=6-12 were extremely small in comparison with three times of that of R12NAc and those of 2Rnida, 2Rnedda and 2Rndtda. Complexane solution was emulsified by shaking with toluene. 2R12ida showed a stable water-in-oil type emulsion and 2Rnedda and 2Rndtda with n=10-12 and 3R8dtda each showed a high oil-in-water type emulsion. Interfacial tension between toluene and complexane solution was 1-2mN m-1 for complexanes with n=12. Multi-alkylated complexanes with HLB of about 22 showed the greatest surface activity. 3R8dtda was a more efficient surfactant at air/water and toluene/water interfaces.