Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

Abstract

Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.

Effect of Temperature and Alcohol on the Determination of Critical Micelle Concentration of Non- Ionic Surfactants in Magnetic Water

“…Temperature change affects the micellization of ionic and amphoteric surfactants due to the relative change in the interaction of the hydrophobic and hydrophilic groups in the surfactant. critical micelle concentration is a distinguishing characteristic property of surfactants as well as the Krafft temperature which is defined as the minimum temperature at which micellization occurs (22).The aim of this work is to find out some new properties of surfactants that is created under the influence of magnetic water and the study of the effects of some alcohols on the micellization process of Tweens surfactant.…”

Synthesis and Characterization of Surface‐Active Ionic Liquids Used in the Disruption of Escherichia Coli Cells

“…Bouchal et al. studied the micellization behavior of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail, being these compounds less soluble in water and more surface‐active than the analogous alkyltrimethylammonium bromides or chlorides.…”

“…Besides the imidazolium family, other types of SAILs have also been investigated, namely ammonium-, [35][36][37][38] phosphonium-, [23] morpholinium-, [38][39][40][41] and guanidinium-based SAILs. [42][43][44] Brown et al [35] reported a series of IL-based surfactants composed of tetraalkylammonium cations and common surfactant anions (derived from dodecyl sulfate and aerosol-OT) as alternatives to imidazolium-based systems, being claimed as cheaper and environmentally more benign. More recently, a series of mono and dicationic ammonium bromide ILs were synthetized and studied by Özdil and co-workers.…”

“…[38][39][40] Regarding the guanidinium cation, the alkylguanidinium chloride series was one of the most studied up to now. [42,44] Bouchal et al studied the micellization behavior of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail, [43] being these compounds less soluble in water and more surface-active than the analogous alkyltrimethylammonium bromides or chlorides.…”

“…Besides the imidazolium family, other types of SAILs have also been investigated, namely ammonium‐, phosphonium‐, morpholinium‐, and guanidinium‐based SAILs . Brown et al .…”