Gemini surfactants anionic

We distinguish four types of surfactant. Anionic (e.g. SDS), cationic (e.g. CTAB), nonionic (e.g. alkylethylene glycols), and zwitterionic (e.g. phosphatidyl choline). Beside conventional surfactants, Gemini, bolafarm, oligomeric and polymeric surfactants become more and more important. 

Kunieda, H., Masuda, N., and Tsubone, K. (2000) Comparison between phase behavior of anionic dimeric (Gemini-type) and monomeric surfactants in water and water-oil. Langmuir, 16, 6438-6444. 

Aqueous solutions of dimer amidopropyl betaine are highly viscous, and are typically non-flowable above a betaine actives concentration of 5 wt%. They display interesting rheological phenomena (25). To achieve higher concentrations for shipment of this Gemini betaine, mixtures with cocamidopropyl betaine can be made. On this basis, concentrations of 25 wt% active matter are achievable. Dimer amidopropyl betaine shows an increased substantivity, compared to cocamidopropyl betaine, on fibres and is a very effective irritancy miti-gant in anionic-surfactant-based systems. 

Figure 17.2. Structures of some gemini surfactants. Compounds 1-3 are cationics differing in the type of spacer unit, Compounds 4 and 5 are nonionic and anionic surfactants, respectively, based on the same backbone structure, while Compounds 6 and 7 are heterogemini surfactants, having non-equal polar head-groups...

Anionic Surfactants onto Canadian River Alluvium (CRA) and Alumina. The second study on gemini surfactants to be discussed was conducted in order to determine strategies for designing gemini surfactants in order to minimize adsorption. The adsorption studies were conducted on Canadian River alluvium (CRA) [9] and on alumina at room temperature. CRA is primarily a sand and is expected to behave similarly to sandstone cores. The anionic gemini surfaetants were supplied by DOW and used as received. The alkyl groups used in the CRA and alumina studies were linear and ineluded all l ehain lengths of C6, CIO, CI2, and C16. The DAMS components and the CI2 and C16 DADS were not studied due to their low water solubilities. 

Zana, R., Levy, H., Danino, D., Talmon, Y., Kwetkat, K. Mixed micellization of cetyltrimethylammonium bromide and an anionic dimeric (Gemini) Surfactant in aqueous solution. Langmuir 1997, ii(3), 402-408. 

Fig. 2.11.35. General structural formula of anionic gemini surfactants (R = spacer).

Fig.2.11.37. ESI-FIA-MS-MS(—)(CID) product ion mass spectrum of [M — H] gemini surfactant parent ion at mlz 639 of di-protonated (1,4-cyclohexylene-dimethylene)-bis(dodecylphosphate)) anion fragmentation behaviour in the inset [64].

There are many combinations of surfactants reported. For example, cationic CTA surfactant and cationic Gemini surfactant, CTA and long-chain pyridine quaternary ammonium surfactant,11] anionic and cationic surfactant,1126 CTA and amine (Q2H25NH2), neutral and cationic surfactant,11761 and neutral-neutral surfactants have been used to prepare silica with interesting mesostructures (e.g., Ia3d cubic) or morphologies (e.g., nanoparticles). 

The adsorption from aqueous solution of surfactants with two hydrophilic and two hydrophobic groups (gemini surfactants, Chapter 12) onto oppositely charged sites on solid particle surfaces—cationic geminis onto clay particles (Li, 2000), anionic geminis onto limestone particles (Rosen, 2001)—results in one hydrophilic group oriented toward the solid surface and the second oriented toward the aqueous phase. The solid particles are dispersed in both cases. 

Kunieda s group reported numerous viscoelastic worm-like micellar systems in the salt-free condition when a lipophilic nonionic surfactant such as short hydrophilic chain poly(oxyethylene) alkyl ether, C EOni, or N-hydroxyethyl-N-methylaUcanolamide, NMEA-n, was added to the dilute micellar solution of hydrophilic cationic (dodecyltrimethylammonium bromide, DTAB and hexade-cyltrimethylammonium bromide, CTAB) [12-14], anionic (sodium dodecyl sulfate, SDS [15, 16], sodium dodecyl trioxyethylene sulfate, SDES [17], and Gemini-type [18]) or nonionic (sucrose alkanoates, C SE [9, 19], polyoxyethylene cholesteryl ethers, ChEO [10, 20], polyoxyethylene phytosterol, PhyEO [11, 21] and polyoxyethylene sorbitan monooleate, Tween-80 [22]) surfactants. The mechanism of formation of these worm-Hke stmctures and the resulting rheological behavior of micellar solutions is discussed in this section based in some actual published and unpublished results, but conclusions can qualitatively be extended to aU the systems studied by Kunieda s group. 

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