Equilibrium, dynamic surface tensions and application properties of fatty alcohol ether carboxylic ester surfactants

Abstract

A series of fatty alcohol ether carboxylic ester (AECE) surfactants were mainly synthesized from succinic anhydride and different fatty alcohol ethers (AEO) with green and atom economic process. The chemical constitutions of AECE were characterized by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (1HNMR) and matrix-assisted laser desorption/ionization time of flight mass spectra (MALDI–TOF–MS). The equilibrium and dynamic surface tensions (DST) of AECE surfactants were investigated, and Ward–Tordai equation was employed to analyze the adsorption and diffusion process of surfactants by calculating the relevant parameters (n, t*, ti , tm , R 1/2) as well as the effective diffusion coefficients (D long and D short) from DST curves. Equilibrium surface tension results showed that AECE surfactants have strong surface activities, and their equilibrium surface tension and critical micelle concentration values are less than 30 mN/m and 0.4 mmol/L, respectively. According to DST parameters, nonionic surfactant AEC5E-H is more favorable to diffuse and adsorb to the air/water interface than others. In addition, the movement of surfactant molecules is also related to the concentration of solutions, and a reasonable concentration can be selected in practical applications based on the experimental results. The outcomes of the diffusion coefficients illustrated that the adsorption mechanism is the mixed diffusion–kinetic adsorption. Moreover, the application performances results showed that the ionic surfactants (AEC3E-Na and AEC5E-Na) are superior to the nonionic surfactants (AEC3E-H and AEC5E-H) in terms of wetting, foam and detergency, while the emulsifying ability is different for various oil phases.