Adsorption and Adsolubilization by Monomeric, Dimeric, or Trimeric Quaternary Ammonium Surfactant at Silica/Water Interface

Adsorption of Cationic Monomeric and Gemini Surfactants on Montmorillonite and Adsolubilization of Vitamin E

“…Since incorporation of solute molecules takes place not only within adsorbed surfactant layers but also into solution micelles, the adsolubilized amount is necessarily decreased above the cmc, as is generally seen in many adsolubilization studies 2) . Finally, we note that the adsolubilization efficiency calculated at the maximum adsolubilization point is reported to be increased when gemini surfactants are used as an adsorbate 3,5) , however, this is not clear in our current case because of the 'complete' adsolubilization observed at the lower surfactant concentrations.…”

“…sponding monomeric ones 3) . Since adsolubilization is strongly affected by micro-environmental polarities within adsorbed surfactant layers formed on solid surfaces, the increase in the adsolubilization efficiency observed for gemini surfactants presumably reflects the greater degree of molecular packing (association) at solid/liquid interfaces, caused by the molecularly restricted structure of gemini surfactants 3) .…”

“…Since adsolubilization is strongly affected by micro-environmental polarities within adsorbed surfactant layers formed on solid surfaces, the increase in the adsolubilization efficiency observed for gemini surfactants presumably reflects the greater degree of molecular packing (association) at solid/liquid interfaces, caused by the molecularly restricted structure of gemini surfactants 3) . Adsolubilization has been widely used in development of various applications such as paints, pharmaceuticals, preparation of polymer thin films, and waste water treatment to collect and remove organic pollutants 4) .…”

“…As mentioned earlier, the adsolubilization efficiency is expected to be increased when gemini surfactants are employed as an adsorbate instead of monomeric ones. Indeed, a critical concentration, at which a maximum amount of adsorption on solid particles is observed, is generally much lower for gemini surfactants than for corresponding monomeric ones, being reflective of the significantly lower critical micelle concentration (cmc) of gemini surfactants 3,5,6) . Since the maximum amount of adsolubilization is generally observed at around the bulk cmc 2) , it is possible to reduce surfactant consumption in chemical products when using gemini surfactants.…”

Recent Advances in Gemini Surfactants: Oleic Acid-Based Gemini Surfactants and Polymerizable Gemini Surfactants

“…The benefits of polymerizable gemini surfactants over polymerizable monomeric surfactants are summarized as follows: effective intermolecular polymerization is expected to occur because of the presence of two polymerizable groups in the molecules, it is possible to polymerize the surfactant fi lms formed at gas/liquid, liquid/liquid and solid/liquid interfaces even at low added concentrations and the surfactant films polymerized at such interfaces are expected to be homogeneous and closely packed at the molecular scale. The third benefi t presented is accrued by two main mechanisms: the first one is the greater adsorption density observed for gemini surfactants over monomeric ones particularly at the air/aqueous solution and solid/aqueous solution interfaces , when comparing their adsorption data normalized by the number of hydrocarbon chains 18 ; and the second is that gemini surfactants give less curved aggregates at the solid/aqueous solution interface when compared with the corresponding monomeric ones, as a result of their larger packing parameter it has been reported that, when compared to the surfactant aggregates formed in bulk solution, surface aggregates tend to favor lower curvature but follow the same general variation with surfactant geometry 19 .…”