Ionic gelators: oligomeric and polymeric electrolytes as novel gel forming materials

In this article, novel gel-forming materials based on oligomeric and polymeric electrolytes for not only water but also organic solvents, including ionic liquids, are highlighted especially the synthesis, derivatization, and physical property. The oligoelectrolytes with cationic pyridinium backbone can be very easily prepared by the intermolecular quaternization of the ampholytic monomer. The ionene polymers with N,N'-(p-phenylene)dibenzamide linkages as polyelectrolyte were also straightforwardly synthesized in high yields by the copolymerization of 1,4-bis[4-(chloromethyl)benzamide]benzene and commercially available alpha,omega-ditertiary amines. The oligo- and polyelectrolytes provided physical hydrogels under ca. 1-5 wt% of the concentrations after heating and cooling at room temperature without any other additives. These cationic gelators have characteristic properties, such as acid resistance, a self-healing nature after mechanical collapse, and a dispersant ability for single-walled carbon nanotubes, which have been rarely attainable for conventional physical gelators.