Preparation and Surface-Active Properties of N-Alkyl Maleamic Acid Telomer Type Surfactants Having Several Hydrocarbon Chains.

Abstract

Telomerization of N-alkyl maleamic acid monomer (RnMaAm, n is the alkyl chain length; n=6-14), which was synthesized by reaction of maleic anhydride with alkylamine, in the presence of alkanethiol as a chain transfer agent gave the telomers (xRnMaAm, x is total number of alkyl chains; x=2.9-3.2) in 60-90% yields. The surface-active properties such as surface tension, foaming property and emulsion stability were examined in water as well as in hard water containing 300 ppm of Ca2+. The critical micelle concentrations (cmcs) of 2.9-3.2RnMaAm telomers were 1/142-1/42 of those of RnMaAm monomers with the same alkyl chain length. The surface tensions of aqueous solutions of RnMaAm monomers and 2.9-3.2RnMaAm telomers were 30-35 and 24-32 mN m-1, respectively. The addition of Ca2+ to the aqueous solutions of 2.9-3.2RnMaAm lowered the cmc, while gave a low efficiency at reducing the surface tension. Of the telomers, 3.0R12MaAm gave the highest foaming ability and the highest foam stability in water. Shaking of the mixtures of organic solvent and the aqueous solutions of xRnMaAm telomers formed oil-in-water type emulsions. The emulsion stabilities were in the orders of toluene > n-octane > n-dodecane > n-hexadecane > kerosene as an oil phase. The highly emulsions for toluene or n-dodecane were formed by using 3.0R8MaAm and 3.0R10MaAm. The aqueous solutions of RnMaAm monomers and 2.9-3.2RnMaAm telomers gave interfacial tension of 8-10 and 4-6 mN m-1, respectively, for the interface with toluene. Thus, N-alkyl maleamic acid telomer type anionic surfactants having several alkyl chains showed greater surface activities than the corresponding monomeric monomers as well as the conventional surfactants.