Synthesis of Branched Surfactant via Ethoxylation of Oleic Acid Derivative and Its Surface Properties

A novel series of biobased branched nonionic surfactants (ethoxylated dihydroxy stearic acid methyl ester, DMOEn) was synthesized and characterized. DMOEn was based on a hydroxyoctadecanoic acid methyl ester, which was obtained from renewable oleic acid in waste cooking oil. These new polyoxyethylene surfactants contained double hydrophilic and hydrophobic chains, which shows the surface properties of the branched surfactant. The synthesis rules and reaction kinetic were studied in detail. The physicochemical properties and surface properties of the DMOEn with different degrees of ethoxylation at various concentrations were investigated. The surface tension results indicate that DMOEn reduced the surface tension reduction and increased the diffusion rate in aqueous solution. The dynamic contact angle, foaming ability and emulsifying capacity tests showed that the DMOEn exhibited good wetting performance, low foaming, rapid defoaming and an excellent emulsifying ability, which shows that the surfactant has potential application in industrial cleaning.