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Adsorpcja dwufunkcyjnych labilnych surfaktantów kationowych na granicy faz ciecz/gaz : opis za pomocą modelu kwazi-dwuwymiarowego elektrolitu

Frąckowiak Renata, Para Grażyna, Lamch Łukasz, Szyk-Warszyńska Lilianna, Wilk Kazimiera A., Warszyński Piotr

Wiadomości Chemiczne

2021

[Z] 75, 9-10

1119--1155

There is an increasing interest in surfactants that comprise a linkage that breaks down in a controlled way. The most known examples of the cleavage mechanism include acid or alkaline hydrolysis, UV irradiation, enzymatic or heat decomposition. For practical reasons, the labile grouping can be inserted between the hydrophobic tail of the surfactant and the polar head group. Chemically and/or enzymatically induced cleavage of this labile bond would cause the separation of the polar part and the hydrophobic tail and, consequently, change of surface activity, an event usually referred to as the primary degradation of the surfactant. Dicephalic labile cationic surfactants belong to the class of surface active compounds with many potential applications often associated with their biological activity for a wide range of bacteria, viruses, fungi, or algae. Thus, they can be used in disinfecting agents or for protecting against the occurrence of these microorganisms. They adsorb well on negatively charged surfaces, which can be used in the treatment of fabrics. Due to excellent antistatic properties, they can be used for the final rinsing of fabrics, especially synthetic ones. In flotation processes, they can act as collectors, and in catalysis, they can be used as phase transfer catalysts or templates for zeolite synthesis. We present the surface quasi-two-dimensional electrolyte (STDE) model as a universal model for the description of ionic surfactants’ adsorption at fluid interfaces that explicitly considers the electric double formation upon surfactant adsorption. The model was adapted to describe phenomena occurring for adsorption of dicephalic surfactants as counterion specificity or formation of surfactant ioncounterion associates. As an example, we applied the model to explain the mechanism of adsorption at water/air interface of novel dicephalic cationic surfactants, N,N-bis[3,3′-(trimethylammonio)propyl]alkylamide dibromides and N,N-bis[3,3′-(trimethylammonio)propyl]alkylamide dimethylsulfates, both belonging to the class of chemodegradable surfactants having amide bond between two quaternary amine cationic groups and a single hydrophobic tail. Additionally, we used the same model to describe adsorption isotherms of N,N-bis[3,3- (dimethylamine)propyl]alkylamide dichlorides, having as two hydrophilic groups tertiary amines, which charge is pH-dependent. Application of the STDE model allowed an excellent description of experimental adsorption isotherm of dicephalic cationic surfactants and explained the specific features connected with the presence of multicharged headgroup.