Gemini Surfactants with a Disaccharide Spacer

Abstract

A gemini surfactant is an amphiphile possessing (in sequence) the following: hydrocarbon tail/polar group/spacer/polar group/hydrocarbon tail. Widespread interest in geminis has emerged recently from both industrial and academic laboratories. In the present contribution, two related families of geminis have been synthesized, both with trehalose, a disaccharide, as a polar spacer. One family, Series-A, is nonionic and has amide groups separating the long chains from the trehalose spacer. The other family, Series-B, has quaternary ammonium ions connecting the long chains to the trehalose spacer. It was found that Series-A geminis are water insoluble despite the two amides and multiple hydroxyls. When hydrated or extruded, these geminis form microscopically visible vesicular and tubular structures above their transition temperatures (which were determined calorimetrically). Insoluble monomolecular films, constructed from these geminis, have interfacial areas that are dominated by the sugar spacer although intermolecular chain/chain interactions seem to stabilize the films. Thus, the behavior of Series-A geminis in many ways parallels that of phospholipids and simple double-chain surfactants. It is as if the trehalose is less of a spacer than a large but conventional headgroup. In contrast, cationic Series-B geminis are water soluble and form micelles with critical micelle concentrations an order of magnitude lower than that of corresponding conventional surfactants. Molecular modeling using the Amber force field explains the difference in properties between the two families of geminis. Series-A are tubular in shape and thus prefer bilayer packing as do other amphiphiles in which the headgroups are similar in width to the sum of the tail diameters. Series-B geminis are conical-shaped and pack more readily into spherical micelles. This work entails synthesis, tensiometry, conductance, microscopy, surface balance studies, calorimetry, light scattering, and molecular modeling. In colloid chemistry, a balanced perspective cannot be achieved by one methodology alone but only through the pursuit of consilience among multiple approaches.

Preparation and characterization of polysiloxane‐acrylate latexes with MPS‐PDMS oligomer as macromonomer

“…The mixture of conventional/Gemini Surfactants would exhibit the synergism in the decline of surface tension and the formation of mixed micelles. 15 At the end of the reaction, the conversion of the monomer reached to 95% (determined gravimetrically in an independent experiment), which was consistent with , which suggested that almost all the monomer had participated in the reaction and there was no C¼ ¼C bonds left in the system. The characteristic peaks of PDMS were similar with that of MPS-PDMS oligomer.…”

“…First, the critical micelle concentration (CMC) values of Gemini surfactants lower one to two orders of magnitude than that of corresponding single-chain surfactants. 15 Second, they are much more efficient than their corresponding monomeric surfactants in decreasing the surface tension of water. 16 For example, the C20 (surfactant concentration required for lowering the surface tension of water by 20 mN/m) for 12-2-12 Gemini is 0.0083 wt %, whereas that for C12TAB is 0.25 wt % 14 .…”

Synthesis, Surface-Active Properties, and Antimicrobial Activities of New Double-Chain Gemini Surfactants

“…Over the last two decades, the growing demand for highperformance surface-active agents has multiplied the interest of the academic and industrial communities for the development of new gemini surfactants [1][2][3][4][5] . Their identical amphiphilic moieties connected by a spacer group impart them unique surface-active properties and selfassembly patterns, and also play a significant role in their antimicrobial performances 6,7) .…”

Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

“…With the aid of a Langmuir film balance, surfactant monolayers were slowly compressed by a moveable barrier and the isotherms recorded. The resulting "surface pressuremolecular area isotherms" provide insight into the packing behavior of the surfactant molecules within the monolayers [16]. Fig.…”