Preparation and surface‐active properties of telomer‐type anionic surfactants from maleic anhydride

Abstract

AbstractMaleic acid alkyl ester and N‐alkyl maleamic acid monomers (RnMa and RnMaAm; n is alkyl chain length; n=6, 8, 10, 12, 14) were synthesized by the reaction of maleic anhydride with alkyl alcohol or alkylamine. The telomerization of RnMa or RnMaAm in the presence of alkanethiol as a chain transfer agent gave telomer‐type anionic surfactants (xRnMa, xRnMaAm; x is total average number of alkyl chains; x=2.8–3.3) having multialkyl chains and multicarboxylate groups. Their surface‐active properties were investigated by several techniques such as surface tension, foaming property, and emulsification power measurements. Critical micelle concentrations (CMC) of xRnMa were 1/110–1/14 of those of RnMa with the same alkyl chain length. xRnMa and xRnMaAm gave higher efficiencies in lowering the surface tension than RnMa and RnMaAm in aqueous solutions. In particular, the surface tension of 3.2R12MaAm was 24.4 mN m−1 at the CMC. Foaming abilities and foam stabilities of xRnMa and xRnMaAm were higher than those of RnMa and RnMaAm. The addition of 300 ppm of Ca2+ to the aqueous solutions rendered the telomers less surface active. Shaking the aqueous solutions of telomers with toluene emulsified them. The highly stable oil‐in‐water type emulsion was formed by using 3.0R10MaAm and 3.2R12MaAm, and the degree of emulsification was kept at a level of about 80% after 60 min of standing. Thus, telomer‐type surfactants showed excellent surface activities that were superior to the corresponding monomers as well as to conventional surfactants. The relationship between alkyl chain length of the telomers and the properties of surface tension, foaming, and emulsification was unclear.