Gemini-type Surfactant

Gemini (dimeric) surfactants are made up of two surfactants like moieties connected at the level of the head groups or on the alkyl 

The Gemini surfactants such as those commercialized by Sasol GmbH (Marl, Germany) have been found in the market. 

Compared to the conventional single-tail surfactants, the Gemini surfactants are related with the following merits [34-35] 

The CMC values of Gemini surfactants are at least one order of magnitude lower than that of the corresponding conventional single-tail surfactants with a similar head group. The CMC values of commonly reported Gemini surfactants and some classic conventional surfactants are listed in Table 11.7. 

It is observed that the Gemini surfactants are 10-100 times more efficient in decreasing the surface tension 

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Direct hydrothermal synthesis. Prepared using titanium isopropoxide (triethanolaminato) and TEOS as the sources of Ti and Si, respectively, and the Gemini-type surfactant 18-12-18 or cetyl-benzyl dimethylammonium chloride (CBDAC) as a template. In the grafting method, silicious MCM-48 first prepared and then the dry surface grafted with titanium isopropoxide... 

Kunieda, H., Kaneko, M., Feng,)., and Tsubone, K. (2002) Formation of microemulsions with Gemini-type surfactant./. Oleo Sci., 51, 761-769. 

Acharya, D.P., Kunieda, H., Shiba, Y., and Aratani, K. (2004) Phase and rheological behavior of novel Gemini-type surfactant systems. /. Phys. Chem. B., 108,1790-1797. 

Aramaki, K., Aratani, K., and Kunieda, H. (2005) Interfadal properties and foam stability effect of novel gemini-type surfactant in aqueous solutions./. Colloid Interface Sci., 291, 236-243. 

Sugihara, G. Miyazono, A. Nagadome, S. Oida, T. Hayashi, Y. Ko, J-S. Adsorption and Micelle Formation of Mixed Surfactant Systems in Water. II A Combination of Cationic Gemini-type Surfactant with MEGA-10. /, Oleo Sci. 2003,52,449-461. 

The present paper provides an overview of the physical properties of silica mesostructures with representative wormhole and lamellar framework structures assembled through S°P pathways. The wormhole framework silica, denoted HMS silica, was assembled using an alkylamine surfactant as the structure director and a silicon alkoxide as the inorganic precursor. The lamellar framework silica with a vesicular hierarchical structure, denoted MSU-G silica, was obtained from tetraethylorthosilicate (TEOS) as the silica precursor and a bi-functional gemini amine surfactant of the type RNH(CH2)2NH2. We then provide examples of the catalytic activity of these disordered mesostructures in comparison to more ordered framework mesostructures such as hexagonal MCM-41. 

LiuYH YuL, Zhang SH et al (2010) Dispersion of multiwaUed carbon nanotubes by ionic liquid-type Gemini imidazolium surfactants in aqueous solution. CoUoids Surf A 359 66-70... 

The transmission of chirality in membranes and other types of aggregates formed by surfactants was widely studied. The superstructures of bilayers formed by gemini dicationic surfactants based on quaternary ammonium centers can be modulated through the employ of enantiomeric tartrate salts. The twisted ribbons (Fig. 4) are formed when an enantiomeric excess of one of the tartrates is present, with the period (helical pitch) shorten-... 

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. 

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. 

The chapter is organized as follows. Section II briefly recalls the theoretical aspects of micellar dynamics and the expressions of the relaxation times characterizing the main relaxation processes (surfactant exchange, micelle formation/breakdown). Section III reviews studies of micellar kinetics of various types of surfactants conventional surfactants with a hydrocarbon chain, surfactants with a fluorinated chain, and gemini (dimeric) surfactants. Section IV deals with mixed micellar solutions. Section V considers the d5mamics of solubilized systems. Section VI reviews the dynamics of sur-... 

Banno T, Kawada K Matsumura S. 2010. Creation of novel green and sustainable Gemini-type cationics containing carbonate linkages. Journal of Surfactants and Detergents 13(4) 387-398. 

Ao, M. Q. Huang, P. P. Xu, G. Y. Yang, X. D. Wang, Y. J. (2009). Aggregation and thermodynamic properties of ionic liquid-type gemini imidazolium surfactants with different spacer length. Colloid Polym. Set, 287, 395-402. 

Furthermore, Oda et al. pointed out that there are two topologically distinct types of chiral bilayers, as shown in Figure 5.46.165 Helical ribbons (helix A) have cylindrical curvature with an inner face and an outer face and are the precursors of tubules. These are, for example, the same structures that are observed in the diacetylenic lipid systems discussed in Section 4.1. By contrast, twisted ribbons (helix B) have Gaussian saddlelike curvature, with two equally curved faces and a C2 symmetry axis. They are similar to the aldonamide and peptide ribbons discussed in Sections 2 and 3, respectively. The twisted ribbons in the tartrate-gemini surfactant system were found to be stable in water for alkyl chains with 14-16 carbons. Only micelles form... 

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. 

The most frequently used ionic SDAs are again CTAB/CTAC, OTAB/OTAC as well as hexadecylpyridinium bromide/chloride (CPB/CPC), whereby the syntheses are carried out under basic conditions, and most commonly surfactants of the Pluronic and Brij type 86 are used as nonionic SDAs under acidic conditions. In rare cases also Gemini surfactants or long alkyl chained ionic liquids were applied as SDAs, whereby an ethane-bridged PMO with a Fm-3m symmetry was successfully prepared for the first time.88... 

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