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Two new cationic surfactants containing a disulfide bond were synthesized, and the physical chemical characteristics and the fundamental surface‐active properties were determined. These new surfactants have potential applications in the textile and cosmetic field. These compounds have been prepared by condensation of a commercial Nα,Nα‐dimethyl amino betaine with cystine dimethyl ester or cystamine by means of the mixed anhydride method. The study of their properties revealed that these molecules are soluble in water (stable at pH≤8) and show surface activity with similar low critical micelle concentration values. Microscopic examination of water/surfactant systems containing these compounds shows that they form liquid crystals with patterns corresponding to typical hexagonal and lamellar structures.

A new, effective, specific quaternary ammonium compound, N-dodecyl-amino-betaine-2-mercaptoethylamine hydrochloride (dabm), is synthesized to confer permanent characteristics (antimicrobial properties, improved dyeing and softening) on keratin material (wool, human hair). We have studied the reaction between bisulphite-treated wool and dabm as a function of time in a buffered medium, and monitor it with ftir/atr spectroscopy, which allows us to follow the changes in cysteine-S-sulphonate groups (at 1023 cm–1) located in the cuticula of keratin fibers. We believe dabm links permanently to keratin fibers, given the disappearance of the cysteine-S-sulphonate band during treatment. Trend approximation and corresponding functions are obtained for experimental data.

In this paper, the antibacterial activity against Bacillus pumilus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa of the wool fabrics treated with new antimicrobial bis-quaternary surfactants, DABK and DABB, is studied. The activity was established on the basis of the agar diffusion and protective antibacterial test results and on the basis of scanning electron microscopy (SEM) observation. The results were compared with the HTAB, a monoquaternary surfactant of conventional use. The results from the agar diffusion and protective antibacterial tests do not enable us to confirm whether these compounds are potentially useful antimicrobial agents for the protection of textiles. However, SEM observations show clearly the efficacy of these compounds to protect the wool fabrics against the micro-organisms. SEM has been a useful technique for the assessment of antibacterial activity in textiles.