Cosurfactant and cosolvent effects on surfactant self-assembly in supercritical carbon dioxide

Abstract

The impact of alcohol additives on the self-assembly of surfactants in supercritical carbon dioxide is investigated using lattice Monte Carlo simulations. We observe that all studied (model) alcohols reduce the critical micelle concentration. The reduction is stronger the longer the hydrocarbon chain of the alcohol, and the higher the alcohol concentration. Short-chain alcohols are found to concentrate in the surfactant layer of the aggregates, replacing surfactant molecules and leading to a strong decrease of the aggregation number and a large increase of the number of aggregates. On the other hand, only a small number of alcohol molecules with longer chain length are found in the aggregates, leading to a slight increase in the aggregation number. However, structural properties such as size and density profiles of aggregates at the same aggregation number are not influenced markedly. Consequently, short-chain alcohols act as cosurfactants, directly influencing the properties of the aggregates, while alcohols with longer hydrocarbon chains work as cosolvents, altering the properties of the solvent. However, the transition between both extremes is gradual.

Adsorption and volumetric properties of Triton X-100 and propanol mixtures

“…In many of these processes its behavior in the presence of different kinds of additives at interfaces as well as in the bulk phase plays an important role. Among a very large number of additives, alcohols are the most frequently used and can behave as cosurfactants or cosolvents [4][5][6]. Short chain alcohols strongly influence both the surface and the volumetric properties of surfactants; however, the mechanism of this influence depends on their concentration in aqueous solution [4].…”

Micellization of amphiphilic block copolymers in binary and ternary solvent mixtures

“…Organic additives to aqueous surfactant solutions can be classified into cosolvents and cosurfactants [30,31]. Cosurfactants denote weakly amphiphilic polar organic molecules that cannot form micelles alone.…”

The adsorption properties of short chain alcohols and Triton X-100 mixtures at the water–air interface

“…Among the mixtures those of surfactants with short chain alcohols are often used. The same alcohols depending on their concentration in aqueous solution can be considered as cosurfactants and cosolvents [1][2][3][4][5][6][7][8].…”