Structure–Stability Relationship in Aqueous Colloids of Latex Particles and Gemini Surfactants

Abstract

The influence of gemini surfactants (GSs) on the charging and aggregation features of anionic sulfate modified latex (SL) particles was investigated by light scattering techniques in aqueous dispersions. The GSs of short alkyl chains (2-4-2 and 4-4-4) resembled simple inert salts and aggregated the particles by charge screening. The adsorption of GSs of longer alkyl chains (8-4-8, 12-4-12, and 12-6-12) on SL led to charge neutralization and overcharging of the particles, giving rise to destabilization and restabilization of the dispersions, respectively. The comparison of the interfacial behavior of dimeric and the corresponding monomeric surfactants revealed that the former shows a more profound influence on the colloidal stability due to the presence of double positively charged head groups and hydrophobic tails, which is favorable to enhancing both electrostatic and hydrophobic particle–GS and GS–GS interactions at the interface. The different extent of the particle–GS interactions was responsible for the variation of the GS destabilization power, following the 2-4-2 < 4-4-4 < 8-4-8 < 12-4-12 order, while the length of the GS spacer did not affect the adsorption and aggregation processes. The valence of the background salts strongly influenced the stability of the SL-GS dispersions through altering the electrostatic interactions, which was more pronounced for multivalent counterions. These findings indicate that both electrostatic and hydrophobic effects play crucial roles in the adsorption of GSs on oppositely charged particles and in the corresponding aggregation mechanism. The major interparticle forces can be adjusted by changing the structure and concentration of the GSs and inorganic electrolytes present in the systems.

Properties and Applications of Quaternary Ammonium Gemini Surfactant 12-6-12: An Overview

“…Regardless of the synthetic pathway, the quaternisation reaction always follows the S N 2 nucleophilic substitution mechanism. The rate of the reaction depends on the concentrations of both reagents, although there are reports of the use of excess amine [22][23][24][25] or bromide [26][27][28]. Typically, polar solvents such as alcohols (methanol [27,29], ethanol [30,31], isopropanol [32]), acetone [19,23,33], or acetonitrile [22,24,34] are used in the synthesis of 12-6-12.…”

“…12-6-12 is a white water-soluble solid [26]. It melts with decomposition at 225-226 • C [28,30]. The structure of a compound is usually confirmed using proton and carbon nuclear magnetic resonance ( 1 H and 13 C NMR).…”

“…As a compound that can be obtained economically and ecologically, it is an ideal product that has many industrial applications, including bioapplications (Table 9). Moreover, 12-6-12 can be used in chemical synthesis for the preparation of supramolecular gels [101] and as a nanoparticle stabiliser [28,41,102], an interfacial transfer catalyst [30,31,[103][104][105], and a molecular self-assembly agent [106].…”

“…In conclusion, quaternary ammonium gemini surfactants are known for their multifunctional utility properties such as antimicrobial, surfactant, and anticorrosion properties. 12-6-12 has all the above mentioned properties of gemini surfactants and can be obtained in a one-step reaction, which is an indisputable and economically justified ad- Moreover, 12-6-12 can be used in chemical synthesis for the preparation of supramolecular gels [101] and as a nanoparticle stabiliser [28,41,102], an interfacial transfer catalyst [30,31,[103][104][105], and a molecular self-assembly agent [106].…”