Surfactants with an amide group “spacer”: Synthesis of 3-(acylaminopropyl)trimethylammonium chlorides and their aggregation in aqueous solutions

Bell-shaped sol-gel-sol conversions in pH-responsive worm-based nanostructured fluid

A pH-switchable worm system was fabricated by simply mixing two non-surface-active compounds, N-(3-(dimethylamino)propyl)palmitamide (PMA) and citric acid (HCA), at a molar ratio of 3 : 1. Such a nanostructured fluid exhibits bell-shaped sol-gel-sol transitions with sequential pH variation, reflecting continuous structural transformations from sphere to worm to no aggregates.

Cost Effective Procedures for Extremely Efficient Synthesis of Environmental Friendly Surfactants

Für die Synthese von Tensiden mit bestimmten Eigenschaften werden verschiedene Vorgehensweisen der Synthese ausgearbeitet. In der gegenwärtigen Arbeit werden einige kostengünstige Vorgehensweisen mit reduzierter Anzahl an Reaktionsschritten zur äußerst effizienten Synthese biologisch abbaubarer und umweltfreundlicher Tenside diskutiert. Die in diesen Methoden verwendeten Ausgangsmaterialien stammen aus ökonomisch günstigen Quellen wie Monosacchariden, Harzsäuren, Fettsäuren etc. Kosten entstehen dann nur noch aufgrund des Einsatzes von Lösemitteln und Spezialreagenzien. Obwohl viele Naturprodukte bereits jetzt schon erhältlich sind, sind nur einige wenige für die Umsetzung zu Tensiden geeignet. Die Diskussion über die Herstellung von verschiedenen Tensiden für gängige Produkte ergibt sich aus der Tatsache, dass kein gutes Universaltensid für jede potentielle Anwendung erhältlich ist.

Synthesis and micellar properties of surface-active ionic liquids: 1-Alkyl-3-methylimidazolium chlorides

A series of surface-active ionic liquids, RMeImCl, has been synthesized by the reaction of purified 1-methylimidazole and 1-chloroalkanes, RCl, R=C(10),C(12),C(14), and C(16), respectively. Adsorption and aggregation of these surfactants in water have been studied by surface tension measurement. Additionally, solution conductivity, electromotive force, fluorescence quenching of micelle-solubilized pyrene, and static light scattering have been employed to investigate micelle formation. The following changes resulted from an increase in the length of R: an increase of micelle aggregation number; a decrease of: minimum area/surfactant molecule at solution/air interface; critical micelle concentration, and degree of counter-ion dissociation. Theoretically-calculated aggregation numbers and those based on quenching of pyrene are in good agreement. Gibbs free energies of adsorption at solution/air interface, DeltaG(ads)(0), and micelle formation in water, DeltaG(mic)(0), were calculated, and compared to those of three surfactant series, alkylpyridinium chlorides, RPyCl, alkylbenzyldimethylammonium chlorides, RBzMe(2)Cl, and benzyl(3-acylaminoethyl)dimethylammonium chlorides, R(')AEtBzMe(2)Cl, respectively. Contributions to the above-mentioned Gibbs free energies from surfactant methylene groups (in the hydrophobic tail) and the head-group were calculated. For RMeImCl, the former energy is similar to that of other cationic surfactants. The corresponding free energy contribution of the head-group to DeltaG(mic)(0) showed the following order: RPyCl approximately RBzMe(2)Cl>RMeImCl>R(')AEtBzMe(2)Cl. The head-groups of the first two surfactant series are more hydrophobic than the imidazolium ring of RMeImCl, this should favor their aggregation. Micellization of RMeImCl, however, is driven by a relatively strong hydrogen-bonding between the chloride ion and the hydrogens in the imidazolium ring, in particular the relatively acidic H2. This interaction more than compensates for the relative hydrophilic character of the diazolium ring. As indicated by the corresponding DeltaG(mic)(0), micellization of R(')AEtBzMe(2)Cl is more favorable than that of RMeImCl because the CONH group of the former surfactant series forms hydrogen bonds to both the counter-ion and the neighboring molecules in the micelle.