Gemini surfactants conclusion

DNA). Finally, conclusions and future prospects for IL-based gemini surfactants, in... 

The adsorption of gemini cationic surfactants [A], 12-5-12, 2Br on solid surfaces has been investigated. The surfactant 12-2-12, 2Br was less adsorbed than its corresponding monomer, DTAB, on silica [84] and titanium dioxide [85], when the adsorption was expressed in moles of adsorbed dodecyl chain per gram of solid. A similar conclusion was reached for the adsorption of DTAB and 12-2-12, 2Br" on laponite clay [86]. No explanation was provided for these results. The maximum amount of 12-5-12, 2Br gemini surfactant adsorbed on silica was shown to decrease very much as the spacer carbon number was increased from 2 to 10 [87]. 

The very large number of chemical relaxation studies of micellar solutions of conventional surfactants reported since 1976, including some studies of surfactants in nonaqueous solvents, all confirmed the conclusions reached in Reference 25. The most recent studies of micellar d5mamics concern aqueous solutions and two new t3rpes of surfactants the dimeric (gemini) surfactants (see Sections III.B.7 and III.C) and the amphiphilic block copol3miers (see Chapter 4). These surfactants deviate from the general behavior reported for conventional surfactants. 

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resulting rheological behavior of micellar solutions is discussed in this section based in some actual published and unpublished results, but conclusions can qualitatively be extended to aU the systems studied by Kunieda s group. 

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