Thermotropic phase behavior of triple-chained catanionic surfactants with varying headgroup chemistry

Catanionic surfactant films at the air–water interface

“…The catanionic surfactants were synthesized by direct mixing of cationic surfactant and anionic surfactant solutions with a slight excess anionic surfactant to form a precipitate of catanionic surfactant, according to previously reported procedures [29]. Good purity of all the catanionic surfactants was confirmed by elemental analysis, nuclear magnetic resonance, and chemical detection with Ag + .…”

“…Based on the purity of the catanionic surfactants according to elemental analysis and DSC [29], the presence of inorganic salt or excess ionic surfactant as impurities is not considered here. In general, the molecular desorption of pure surfactants may involve either the dissolution of the molecules into the subphase, the formation of a multi-layer film or, in some cases, formation of aggregates.…”

Thermotropic phase transitions of catanionic dodecylsulfates with multi-charged and multi-tailed quaternary ammonium centers

“…The existence of bilayer structures is also found for triazole-based adducts, where, unlike dimer and tetramer, the monomer bilayer-forming motifs seem to be tilted [7]. Cationic gemini surfactant arranges with sodium ndodecyl sulfate perpendicularly to the lamellar plane [15], with alternation of the cationic and anionic layers, compactly arranged due to strong electrostatic interactions, and repeating distance equal to the sum of both dodecyl chain lengths. …”

“…Compared to their parent anhydrous surfactants, they exhibit significantly different properties, as a result of specific thermal molecular motions and in correlation with their particular molecular structure, charge density and volume constraints [15], size, chemistry [15,16], number of the headgroups [15] or symmetry of alkyl chains [13]. Thermotropic behavior of various catanionic alkylsulfate salts has received huge attention.…”

Enzymatically prepared n-alkyl esters of glucuronic acid: The effect of freeze-drying conditions and hydrophobic chain length on thermal behavior

“…The increase in transition or melting temperature with the molecular mass is a well-known phenomenon in homologous series of lipids or surfactants [14,15], and is due to the decrease of chain ends (and therefore defects) inside a crystal domain as the molar mass is increased [17], in our case as the number of carbon atoms of the alkyl chain is increased. The transition enthalpy increase with increasing chain length (C8 < C10 < C12 < C14) is expected because the van der Waals (London) interactions are stronger when the number of aliphatic carbons increases [18].…”