Search

A new kind of amine oxide surfactant – cocotriethoxylpropanediamine oxide (CTPDAO) – was synthesized by a two-step process. The molecular structure was characterized by FTIR spectra and1H NMR. The new surfactant showed high surface activity in aqueous solution in the surface tension measurement. Emulsifying capacity and wetting ability were studied in comparison to dodecyldimethylamine oxide (DDMAO). The results indicate that this new surfactant could reach the lowest surface tension of 30.4 mN m−1in aqueous solution with a critical micelle concentration (CMC) of 0.23 mmol L−1. The wetting ability of DDMAO is better than that of CTPDAO. Compared with CTPDAO, DDMAO shows a greater capacity to emulsify soybean oil, although CTPDAO is a better emulsifying agent for liquid paraffin. The foaming properties and thickening function of DDMAO and CTPDAO mixed with alcohol ether sulfate (AES) and dodecylbenzene sulfonate (LAS) were also investigated. The results show that CTPDAO is a superior foam stabilizer than DDMAO while CTPDAO and DDMAO both have excellent thickening functions. [ABSTRACT FROM PUBLISHER]

Abstract: Two series of long chain guanidine surfactants, mono-alkylguanidine and N,N,N′-dimethylalkylguanidine were synthesized and the effect of the alkyl chain length and the nature of the cationic headgroup on aggregation and antimicrobial activity were investigated. Surface tension and conductivity were applied to study the aggregation of the amphiphilic molecules in aqueous solution. The antimicrobial activity was evaluated against Gram-negative, Gram-positive bacteria and fungi. The results showed that N,N,N′-dimethylalkylguanidine had much higher surface activity than those of mono-alkylguanidine with the hydrophobicity of the amphiphilic cation. Guanidine surfactants containing 8–12 carbon atoms in the alkyl chain showed antimicrobial activity at the concentration of 25–100ppm, and their efficiency as antimicrobial agents increased with the chain length. [Copyright &y& Elsevier]

Abstract The surface activities and application properties for the mixtures of cationic surfactant didecylmethylhydroxyethylammonium acetate (DEAQ) and anionic surfactant sodium fatty alcohol ether carboxylate (AEC 9 -Na) were studied systematically. The interaction parameters and thermodynamic micellization parameters of DEAQ/AEC 9 -Na mixtures were evaluated. Results showed that the mixed systems have higher surface activity, lower contact angle and better wetting ability than either component due to the synergistic effect and there are attractive interactions between molecules for the surfactant mixtures at the mixed micelles and the air/liquid interfaces. The thermodynamic parameters indicate that the micellization of the mixtures is an entropically driven process. When the mole fraction of DEAQ (α DEAQ) is 0.608, the emulsifying capacity for liquid paraffin and soybean oil of DEAQ/AEC 9 -Na mixtures is the best among the mole ratios studied, and the emulsifying capacity of the mixtures is stronger than that of AEC 9 -Na except α DEAQ = 0.509. For the mixed systems, the foaming ability is the best when α DEAQ = 0.608, whereas the foam stability is the best when α DEAQ = 0.280. And there were greater foaming abilities and foam stabilities for mixed systems than those of DEAQ. Graphical abstract Unlabelled Image Highlights • DEAQ is a novel type quaternary ammonium surfactant. • Adding DEAQ to AEC 9 -Na with different mole proportions gets superior properties. • The interaction between DEAQ and AEC 9 -Na in the mixture is strong. [ABSTRACT FROM AUTHOR]