Despite the loss of directed, self-complementary hydrogen bonding through alkylation of the imidazole ring, electrostatic aggregation of imidazolium salts is a tunable, self-assembly process, which is instrumental to several applications. Imidazolium salts are used to extract metal ions from aqueous solutions and coat metal nanoparticles [15], dissolve carbohydrates [16], and create polyelectrolyte brushes on surfaces [17]. For example, atom transfer radical polymerization (ATRP) was used to graft poly(1-ethyl 3-(2-methacryloyloxy ethyl) imidazolium chloride) brushes onto gold surfaces [17]. One of the imidazolium salt’s most promising attributes is its antimicrobial action [12,18] and molecular self-assembly into liquid crystals [19,20]. 1-Alkyl-3-methylimidazolium chlorides and bromides, 1-alkyl-2-methyl-3-hydroxyethylimidazolium chlorides, and N-alkyl-N-hydroxyethylpyrrolidinonium, for example, all exhibit strong biocidal activity [18]. Hydrogels form from polymerized methylimidazolium-based ionic liquids with acryloyl groups; the polymer self-assembles into organized lamellae with unique swelling properties, leading to bioactive applications [19]. Other bioactive applications for imidazolium salts include antiarrhythmics [21], anti-metastic agents [22,23], and imidazolium-based steroids [24]. Separation applications include efficient absorption of CO2 [25]. Imidazolium salts enhance vesicle formation as imidazolium surfactants [26], and they also find application in polymeric actuators [27].
