This paper reports the synthesis of a novel quaternary surfactant containing a hydroxyethyl group (PFPE-C) and the surface properties of its aqueous solution (investigated by comparisons with two structurally similar chemicals, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC) and PFPE-A). The minimum surface tension (${\gamma }_{CMC}$) and critical micelle concentration (CMC) of the PFPE-C aqueous solution were 17.35 mN/m and 0.024 mmol/L, respectively. This study confirms that surfactants containing hydroxyethyl groups efficiently reduce the surface tension of aqueous solutions, and fluorocarbon surfactants exhibit better surface activity than ordinary hydrocarbon surfactants with similar structures. The micellization, aggregation, air-water interfacial adsorption, and wettability of PFPE-C aqueous solutions have been systematically investigated. Highly concentrated PFPE-C aqueous solutions exhibit good wettability on PTFE and paraffin films. Moreover, the aggregates of PFPE-C in the aqueous solution were clearly seen as vesicles on Cryo-TEM micrographs. Primary biodegradation results indicate that 19% of PFPC-C can be degraded within one week.

A series of double-chain quaternary ammonium salt surfactants N-[N′[3-(gluconamide)] propyl-N′-alkyl]propyl-N,N-dimethyl-N-alkyl ammonium bromide (C_nDDGPB, where n represents a hydrocarbon chain length of 8, 10, 12, 14 and 16) were successfully synthesized from D (+)-glucose δ-lactone, N,N-dimethyldipropylenetriamine, and bromoalkane using a two-step method consisting of a proamine-ester reaction and postquaternization. Their surface activity, adsorption, and aggregation behavior in aqueous solution were investigated via measurements of dynamic/static surface tension, contact angle, dynamic light scattering, and transmission electron microscopy. An analysis of their application performance in terms of wettability, emulsifying properties, toxicity, and antibacterial properties was conducted. The results show that with increasing the carbon chain length of the C_nDDGPB surfactants, their critical micelle concentration (CMC) increased and the pC₂₀ and efficiency in the interface adsorption of the target product gradually decreased. Moreover, the influence of the hydrophobic carbon chain length on the surface of polytetrafluoroethylene (PTFE) was even greater for the wetting effect, reducing the contact angle to 32° within the length range of C8–C14. The results of the contact angle change and the wettability experiments proved that C₁₀DDGPB exhibited the best wettability. The liquid paraffin and soybean oil emulsification ability of C_nDDGPB showed an upward trend followed by a downward trend with the growth of the carbon chain, with C₁₂DDGPB exhibiting the best emulsification performance. The D_long/D_short ratio was far lower than 1, which indicates mixed-kinetic adsorption. The surfactants formed spherical micelles and showed a unique aggregation behavior in aqueous solution, which showed an increase–decrease–increase trend with the change in concentration. A cell toxicity and acute oral toxicity experiment showed that the C_nDDGPB surfactants were less toxic than the commonly used surfactant dodecyldimethylbenzyl ammonium chloride (1227). In addition, at a concentration of 150 ppm, C_nDDGPB exhibited the same bacteriostatic effect as 1227 at a concentration of 100 ppm. The results demonstrate that sugar-based amide cationic surfactants are promising as environmentally friendly disinfection products.

Amidation of lactobionic acid with N,N-dimethylaminopropyltriamine was conducted to obtain N-(3′-dimethylaminopropyl)-lactamido-3-aminopropane (DDLPD), which was quaternized with bromoalkanes of different carbon chain lengths to synthesize double-stranded lactosylamide quaternary ammonium salt N-[N′[3-(lactosylamide)]propyl-N′-alkyl] propyl-N,N-dimethyl-N-alkylammonium bromide (C_nDDLPB, n = 8, 10, 12, 14, 16). The surface activity and the adsorption and aggregation behaviors of the surfactants were investigated via equilibrium surface tension, dynamic light scattering, and cryo-electron microscopy measurements in an aqueous solution. The application properties of the products in terms of wettability, emulsification, foam properties, antistatic, salt resistance, and bacteriostatic properties were tested. C_nDDLPB exhibited a low equilibrium surface tension of 27.82 mN/m. With an increase in the carbon chain length, the critical micellar concentration of C_nDDLPBD decreased. Cryo-electron microscopy revealed that all products except C₈DDLPB formed stable monolayer, multi-layer, and multi-compartmental vesicle structures in an aqueous solution. C₁₄DDLPB has the best emulsification performance on soybean oil, with a time of 16.6 min; C₁₄DDLPB has good wetting and spreading properties on polytetrafluoroethylene (PTFE) when the length of carbon chain is from 8 to 14, and the contact angle can be lowered to 33°~40°; C_nDDLPB has low foam, which is typical of low-foaming products; C₈DDLPB and C₁₀DDLPB both show good antistatic properties. C₈DDLPB and C₁₄DDLPB have good salt resistance, and C₁₂DDLPB has the best antimicrobial property, with the inhibition rate of 99.29% and 95.28% for E. coli and Gluconococcus aureus, respectively, at a concentration of 350 ppm.

A novel tetrasiloxane-tailed surfactant bearing oligo(ethylene oxide) methyl ether and sugar moieties (TGA-2) has been evaluated. The dynamic surface tension (DST) and spreading properties imparted to water by TGA-2 have been investigated. DST parameters, namely effective diffusion coefficient, activation barrier, and contact angle have been calculated and analyzed. A general diffusion mechanism of surfactant TGA-2 has been delineated. DST analyses yielded significantly different long-term (D_L) and short-term (D_S) diffusion coefficients, implying that the adsorption process involves a mixed diffusion-kinetic mechanism. Adsorption activation energies (E_a) of the surfactant TGA-2 have been measured as 9.14 kJ/mol at 4 × 10⁻⁵ M and 19.37 kJ/mol at 4 × 10⁻⁴ M. These small E_a values suggest that the tetrasiloxane group is favorable for adsorption. A polytetrafluoroethylene (PTFE) membrane was chosen as a solid substrate to demonstrate the spreading ability imparted by TGA-2. At a TGA-2 concentration of 0.5% in water, the contact angle decreased from 57° to 7.8° in 60 s, such that the droplets became almost flat. GRAPHICAL ABSTRACT