Counter anion dependent swelling behaviour of poly(octadecyl acrylate)-based lipophilic polyelectrolyte gels as superabsorbent polymers for organic solvents

Molecular design of superabsorbent materials for organic solvents has attracted much attention due to their superior applications for the removal of hazardous leakages or spillages of volatile organic compounds (VOCs) and waste oils. One approach for preparing such soft matter is loosely crosslinked lipophilic polyelectrolytes. Here, we demonstrate the counter anion effect for superabsorbency for various organic solvents in a series of poly(octadecyl acrylate)-based lipophilic polyelectrolyte gels bearing tetraalkylammonium with relatively hydrophobic counter-anions: dodecyl sulfate (DS), tetrakis(3,5-bis(trifluoromethyl)phenyl) borate (TFPB) and (μ-(1H-imidazolato κ-N1:κ-N3) hexakis(pentafluorophenyl borate) (IM). The benefit of high-swelling abilities due to dissociation of ionpairs was observed in less- and non-polar media (3 < ε < 13), when TFPB and IM were selected as counter anions. These results indicate that molecular design of superabsorbent materials requires that the ionic groups have sufficient bulkiness and lipophilicity for ionic dissociation in nonpolar solvents.