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This study synthesizes the anionic–nonionic surfactants by reacting tripropylene glycol, maleic anhydride, polyoxyethylenated stearyl ether and fumaric acid. The properties of a series of anionic–nonionic surfactants that feature hydrophilic groups with different lengths of chains are measured. The critical micelle concentration (CMC) value for these surfactants decreases as the length of the polyoxyethylene chain increases. This shows that long polyoxyethylene chains promote pre-micelle formation in the aqueous phase and adsorption at the interface surrounding the aqueous phase. The dispersion of a particle suspension of ${\mathrm{\text{TiO}}}_2$ is also determined using dynamic light scattering (DLS) and scanning electron microscopy (SEM). The results show that when anionic–nonionic surfactants are added into a ${\mathrm{\text{TiO}}}_2$ suspension, it prevents the precipitation of solid particles of ${\mathrm{\text{TiO}}}_2$ and allows greater de-aggregation of the nanoparticles. DLS data show that when the concentration of the anionic–nonionic surfactants is increased, the distribution range narrows and it becomes more uniform. The larger specific surface area of the surfactant results in greater dispersion of the suspension. The SEM results show that when anionic–nonionic surfactants feature hydrophilic groups with a shorter chain, a ${\mathrm{\text{TiO}}}_2$ suspension is more effectively dispersed.

This study investigated dye–surfactant interactions between a series of modified Gemini surfactants and commercial direct dyes in aqueous solution and their corresponding effects on cotton fabric dyeing. A surface tension meter was also used to measure surface activities of compounds containing electrolyte under conditions similar to those in dyeing processes. The surface tension measurements showed lower than normal surface tension in surfactant solutions containing electrolyte. From the UV-Vis spectra, the isosbestic point indicated that dye–surfactant complexes had formed and existed as hydrophilic interaction between direct dyes and modified Gemini surfactants. When dyeing cotton fabric with red dye and orange dye, the presence of these surfactants decreased dye uptake rate but increased for blue dye because the dye–surfactant interaction had formed a hydrophilic complex.