Amphiphilic Properties of Dodecylammonium Chloride/4‐(1‐Pentylheptyl) Benzene Sodium Sulfonate Aqueous Mixtures and Study of the Catanionic Complex

Abstract

Surfactants are often used in supramolecular chemistry, due to their ability to self‐organize. Surfactant molecules aggregate spontaneously and reversibly to adopt a defined intermolecular arrangement. In this work, general phase behavior, adsorption and association in aqueous mixtures of dodecylammonium chloride, DACl and sodium 4‐(1‐pentylheptyl) benzenesulfonate, NaDBS, were studied by a combination of techniques including surface tension and conductivity measurements, light scattering and optical microscopy. The strong synergistic properties of the system were brought out with the Regular Solution Theory. Various colloidal objects are observed in wide range of composition: conventional small vesicles, large giant multilamellar or multivesicular vesicles. An excess of NaDBS provides extremely large tubular and elongated multilamellar vesicles. The new catanionic 1:1 complex, dodecylammonium‐4‐(1‐pentylheptyl) benzenesulfonate, formed in the equimolar conditions is a result of intramolecular charge neutralization. The thermal properties of this solid compound were examined by thermal polarizing microscopy, differential scanning calorimetry, and X‐ray diffraction. The most probable ion‐pair amphiphilic cluster of the crystal smectic phase, at room temperature, consists of ionic groups formed in ordered layers with dodecyl chains packed into somewhat disordered layers, tilted to the layer plane.

Mesomorphism of a new series of catanionic 4-(1-pentylheptyl)benzenesulfonates

“…Solid catanionics exhibit complex polymorphic and mesomorphic behavior during thermal treatment. 3,4,14,[17][18][19][20][21][22]26 The occurrence of mesophases depends on the geometric shape of the units, and the distribution of polar groups in the molecule. As the difference in pendant chain lengths between cation and anion increases, a poorer hydrophobic match in the bilayer is attained.…”

“…12,40 Relatively few studies on pure homologues and isomers are available. 22,40,41 An example is our previous study of 4-(1-pentylheptyl)benzenesulfonate. 22 Sulfonate based catanionic molecules or metal complexes oen have some kind of layer-like arrangement in the crystals.…”

“…22,40,41 An example is our previous study of 4-(1-pentylheptyl)benzenesulfonate. 22 Sulfonate based catanionic molecules or metal complexes oen have some kind of layer-like arrangement in the crystals. 17,18,[42][43][44] Calixarenes based on sulfonates show typical bilayer structures with calixarene molecules held together by p-p interactions forming hydrophobic layers and sulfonate groups covering the hydrophilic surfaces of the bilayer.…”

“…These were mostly examinations of micellar and vesicular self-assembly, 1,2,[5][6][7][8][9][10][11][12] or of the formation and structure of the lamellar phase comparable with mechanisms in biological membranes, 13 while at the same time studies of their bulk solid state are relatively scarce. 3,4,[14][15][16][17][18][19][20][21][22][23][24] The structure of catanionic aggregates can be ne-tuned by tailoring the nature of the components, owing to the interplay between electrostatic effects, surfactants' molecular size and geometry, and hydrogen bonding network. Design of different complexes and tailored functionalized assemblies opens opportunities for potential applications in commercial products; from transport agents in drug and gene delivery 5 and template materials, to sensors and semiconductors, 6 information storage and nanotechnology.…”

“…18 Alkylammonium benzenesulfonates, naphthalenesulfonates and related salts form SmA mesophases. [20][21][22] Most known catanionic compounds based on alkylammonium are bilayered structures, 3,4 but also some of them, such as alkylammonium-AOT complexes, form hexagonal columnar phases. 14 Hexadecyl and octadecyl derivatives of alkylammonium poly(vinylsulfonate)s, 17 like hexadecylpyridinium and hexadecyltrimethylammonium 4-octylbenzenesulfonate, 19 exhibit low temperature SmB and high temperature SmA phases, while dodecyl and tetradecyl derivatives of N,N dimethyl-N-cyanopropyl-n-alkylammonium poly(vinylsulfonate) s form cubic phases that consist of warped molecular bilayers.…”