Research Progress on the Synthesis of Different Types of Gemini Surfactants with a Functionalized Hydrophobic Moiety and Spacer

Gemini surfactants are advantageous over conventional surfactants as they find applications as antimicrobial agents, corrosion inhibitors, enhanced oil recovery, capping agents for nanoparticle synthesis, drug delivery agents, etc. This article provides a detailed overview of synthetic procedures for various types of geminis and the fundamental physicochemical parameters of these systems. This includes a discussion on the cationic geminis based on various groups such as biphenyl, amide (with/without alkane tail), binol, quaternary ammonium (with/without hydroxyl group as a spacer), morpholinium, pyridinium, amide (with/without alkane tail), ester quaternary ammonium, and imidazolium (spacer with/without hydroxyl group and thioether/ester) types. Further, it is focused on anionic geminis with carboxylate, borate, and sulfonate head groups. Zwitterionic geminis such as betaine surfactants, cocogem surfactants based on dodecylisopropylol amine and dicarboxylic acid, diester type, sulphobetaine gemini based on S-triazine, zwitterionic hetero gemini containing ammonium and carboxylate head groups, zwitterionic gemini containing quaternary ammonium and a sulfate group, gemini containing phosphodiester anion and quaternary ammonium salt are also reviewed. Lastly, synthesis of nonionic geminis from sunflower oil, amide-based nonionic, sulfonamide nonionic, N,N'-diethylaminedialkyldiamide nonionic gemini, sugar-based gemini, and nonionic gemini with sulfonate spacer have been discussed.