Physicochemical Properties of α,ω-Type Surfactant in Aqueous Solution. Bis(triethylammonium) 1,20-Eicosanediyl Disulfate

Abstract

The physicochemical properties of the α,ω-type (bolaform) surfactant, bis(triethylammonium) 1,20-eicosanediyl disulfate (α,ω C20N2Et6), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization and time-resolved fluorescence quenching. The critical micelle concentration of α,ω C20N2Et6 was 1–1.3×10−3 mol dm−3. The micelle ionization degree of the surfactant was larger than a conventional surfactant having the same head group. From surface tension measurements, the molecular area of α,ω C20N2Et6 at the air–water interface was found to be about twice as large as that of a normal type surfactant, such as sodium dodecyl sulfate (SDS). This reveals that α,ω C20N2Et6 probably forms vertical looping (“wicket-like” conformation) at the air–water interface. By time-resolved fluorescence quenching measurements, the aggregation number of α,ω C20N2Et6 micelle was found to be strongly dependent on the concentration, but only slightly dependent on the temperature. At low concentrations the aggregation number is close to half that corresponding to a normal type surfactant having a chain length that is that of the bolaform. The solubilizing power of a micellar solution of α,ω C20N2Et6 toward Orange OT was 7.6×10−3 mol of dye per mol of surfactant, that is, a value smaller than that of SDS.

Physicochemical properties of ?, ?-type bolaform surfactant in aqueous solution. Eicosane-1,20-bis(triethylammonium bromide)

“…It is seen that N is independent of the surfactant concentration up to 0.2 mol din-3, i. e., well above CMC. Thus, as far as the dependence of N on concentration the behavior of C20Et 6 is rather different from that of two other bolaforms: the docosane-l,22-bis(trimethylammonium bromide) [14] and the bis(triethylammonium)-l,20-eicosane disulfate [24] where N increases significantly with C. The packing parameter [25] of C20Et6 is smaller than that of the other two bolaforms, mostly because of difference in surface areas per head group. Recall that the 1H NMR signals of the normal surfactant, cetyltrimethylammonium bromide, is dramatically broadened upon formation of rod-like micelles [23].…”

Molecular concepts, self-organisation and properties of polysoaps

“…But, strikingly, CMC values of both bola-surfactants and of gemini-surfactants are lowered by one order of magnitude or more in Examples of "oligomeric" surfactants: a "bola" dimer [426][427][428]; b "gemini" dimer [435,445,448]; c cyclic hexamer of "tail end" type [419]; d star-shaped trimer of "tail end" type [420] comparison to the corresponding "monomers" [239, 424,[428][429][430][431][432][433][434]. The reduction of the surface tension appears slightly lower than for the monomers, but the surface activities are still substantial [330,405,413,424,427,[429][430][431][432][433][434][435]. Interestingly, above the CMC a number of dimeric surfactants do not show the standard plateau of surface tension but exhibit a small but continuous decrease with increasing concentration.…”

“…From surface tension studies of bola-surfactants, it is concluded that they exhibit wicket-like conformations at the gas-water interface [239, 428,430,431]. In micelles and liquid crystals however, a stretched conformation is preferred [436,437]; this implies that surface tension data and interfacial tension data do no more describe the "micellar" interface with all the implications for solubilization (compare Sect.…”

“…In fact, some reports stress the extremely low solubilization capacity of bola-surfactants [431,432,437,438], although others obtain capacities comparable to the ones of the "monomers" [430]. Also noteworthy, solubilized fluorescence probes indicate a more polar environment for the solubilizates than in micelles of the "monomers" [430][431][432], but micellar aggregation numbers of the bola-surfactants are comparable or only slightly lower [429,432,438,439]. In exceptional cases, very high aggregation numbers and the existence of an additional pre-CMC are observed [440].…”

The Use of Surface Active Agents for Effective Removal of Dyes/Pigments: A Perspective Review on Solubilization and Foam Fractionation

“… Dye 3 OrangeOT/C.I Orange 2 11.5(Ikeda et al, 1989) Dye 4 C.I Red 19 2.7(Choi et al, 2000) Dye 5 Sudan 4/Red 25 2.2 and 2.8(Imae et al, 1986;Abe et al, 1987) …”