Gemini Surfactants

How easy it is to dismiss the humdrum surfactant! After all, its structure is unglamorous by present-day norms. And the surfactant has been entrenched in so many areas of commerce for so many decades that its chemistry might seem old and tired. The purpose of this review is to persuade the reader otherwise, all the while focusing on a remarkable new surfactant, the gemini. Geminis, the common name for “bis-surfactants”, can self-assemble at concentrations almost a hundredfold lower than for corresponding conventional surfactants. Surface activity can be improved a thousandfold. Geminis have already shown promise in skin care, antibacterial regimens, construction of high-porosity materials, analytical separations, and solubilization processes. Scores of patents dealing with geminis have appeared in the last few years. Indeed, geminis might well turn out, in the opinion of some, to be more useful to “l'homme de la rue” than crown ethers or fullerenes. This review delves into such topics as synthesis, critical micellization concentration, aggregate size and shape, gels, vesicles, and films. The information comes from scientists all over the world; one might say that gemini research is bathed in a continuous sunlight or summer. No prior knowledge of colloid chemistry is presupposed in this article.