title: Aromatic ionene topology and counterion-tuned gelation of acidic aqueous solutions.
abstract: Unusual gelation of acidic solutions was achieved using polycations bearing quaternary ammonium moieties. These ionene polymers are based on a disubstituted phenylene dibenzamide core, which allows the construction of different topomers (i.e. ortho-1, meta-2 and para-3). The topology of the polymers was found to play a key role on their aggregation behaviour both in pure water and in a variety of aqueous acidic solutions leading to the formation of stable acidic gels. Specifically, ortho-1 showed superior gelation ability than the analogues meta-2 and para-3 in numerous solutions of different pH and ionic strengths. Lower critical gelation concentrations, higher gel-to-sol transition temperatures and faster gelation were usually observed for ortho-1 regardless the solvent system. Detailed computational molecular dynamic simulations revealed a major role of the counterion (Cl-) and specific polymerpolymer interactions. In particular, hydrogen bonds, N-Hπ interactions and intramolecular π-π stacking networks are distinctive in ortho-1. In addition, counterions located at internal hydration regions also affect to such polymerpolymer interactions, acting as binders and, therefore, providing additional stability.
authors.affiliation: Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany. David.Diaz@chemie.uni-regensburg.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bachl
authors.forename: Oscar
authors.initials: O
authors.lastname: Bertran
authors.forename: Judith
authors.initials: J
authors.lastname: Mayr
authors.forename: Carlos
authors.initials: C
authors.lastname: Alemán
authors.forename: David
authors.initials: D
authors.lastname: Díaz Díaz