Constructing Gemini‐Like Surfactants with Single‐Chain Surfactant and Dicarboxylic Acid Sodium Salts

Abstract

Construction of gemini‐like surfactants using the cationic single‐chain surfactant cetyltrimethylammonium bromide C16H33N(CH3)3Br2 (CTAB) and the anionic dicarboxylic acid sodium salt NaOOC(CH2)n‐2COONa (CnNa2, n = 4, 6, 8, 10, 12) by way of non‐covalent interactions has been investigated by surface tension measurements, hydrogen‐1 nuclear magnetic resonance (1H NMR) spectroscopy and isothermal titration microcalorimetry (ITC). The critical micelle concentrations (cmc) of the CTAB/CnNa2 mixtures are obviously lower than that of CTAB and strongly depend on the mixing ratio. Moreover, the cmc values of the CTAB/CnNa2 mixtures decrease gradually with an increasing methylene chain length of CnNa2, indicating hydrophobic interaction between the hydrocarbon chains of CTAB and CnNa2 facilitates micellization of the mixtures. In particular, the ITC curves and 1H NMR spectra indicate that the binding ratio of CTAB to CnNa2, except C4Na2, is around 2:1, i.e., (CTAB)2CnNa2. Additionally, CTAB/CnNa2 mixtures are soluble in a whole molar ratio and concentration ranges have been studied, even at the electrical neutralization point. Therefore, these results reveal that highly soluble gemini‐like surfactants are conveniently constructed with oppositely‐charged cationic single‐chain surfactants and dicarboxylic acid sodiums. In an attempt at improving the performance of surfactants this work provides guidance for choosing additives that form gemini‐like surfactants via an uncomplicated synthesis.

Aggregation Behavior of Sodium Lauryl Ether Sulfate with a Positively Bicharged Organic Salt and Effects of the Mixture on Fluorescent Properties of Conjugated Polyelectrolytes

“…A series of gemini-like surfactants were previously constructed with cationic single-chain surfactant cetyltrimethylammonium bromide C 16 H 33 N(CH 3 ) 3 Br (CTAB) and anionic dicarboxylic acid sodiums NaOOC(CH 2 ) n−2 COONa (C n Na 2 , n = 4, 6, 8, 10, 12) through electrostatic attraction synchronously assisted by hydrophobic interaction. 26 It was also shown that a geminilike surfactant was constructed by sodium dodecyl sulfate (SDS) and 1,2-bis(2-benzylammoniumethoxy)ethane dichloride (BEO) predominantly through electrostatic attraction as well as hydrophobic interaction and π−π interaction. 27 The SDS/BEO mixture forms large loose irregular aggregates, spherical vesicles, and then long thread-like micelles with the increase of SDS concentration.…”

Molecular thermodynamics of soft self-assembling structures for engineering applications

“…In this mixture, reversible switching between colorless, gel‐like state and fluorescent green color, liquid‐like state can be attained by pH adjustment. Particularly interesting additives are dicarboxylic acids that form Gemini‐like surfactants by non‐covalent bonding to CTAB …”

“…Apart from alkanols 22,23 and ILs 21 other organic additives (amines, 23 sugars, aminoacids, 24 phenolic 25 and dicarboxylic acids, 26 and organic salts 27 ) have been studied extensively, including hydrophobic organic molecules 28 (e.g. chlorophylls 29 or drugs 14 ) and various hydrotropes, 23,30,31 particularly in combination with Gemini surfactants.…”

“…Particularly interesting additives are dicarboxylic acids that form Gemini-like surfactants by non-covalent bonding to CTAB. 26 For micellar solutions with additives, experimental data on thermodynamic functions of micellization are numerous. 22 -31 Thermodynamic modeling of such systems has been traditionally performed using the regular solution theory to describe the nonideality of a mixed micelle.…”

Facile construction of gemini-like surfactants at the interface and their effects on the interfacial tension of a water/model oil system

“…The synergistic effects between the electrostatic interaction and other intermolecular or intramolecular interactions may be the most effective and facile approach to construct gemini-like surfactants. [31][32][33][34][35][36][37][38][39][40][41] Feng et al designed two pH-switchable gemini-like surfactants using a bola-type dicarboxylic acid or salt and a single-chain surfactant with opposite charge. [31][32][33] Wang's group systematically investigated the effects of single-chain structures in surfactants on the properties of obtained gemini-like surfactants.…”