Solvation structure and gelation ability of polyelectrolytes: predictions by quantum chemistry methods and integral equation theory of molecular liquids

Abstract Solvation structure and gelation ability of novel oligomeric electrolyte poly(pyridinium-1,4-diyliminocarbonyl-1,4-phenylenemethylene chloride) (1·Cl) as well as its derivatives 1·X obtained by counterion substitution: X − = BF 4 − , PF 6 − , TFSA − , I − , SCN − , DCA − , ClO 4 − , SO 3 CF 3 − have been studied by quantum chemistry methods and integral equation theory of molecular liquids. The interaction energy, ΔE tot , between the counterions and polymer chains has been estimated in the frame of density functional theory and COSMO model. The calculations show that ΔE tot for gel forming polyelectrolytes has rather high values. For cases when gel formation is not observed experimentally, calculated ΔE tot have generally lower values. The excess chemical potential of ions (xμ ion ) in water, methanol, dimethylsulfoxide and acetonitrile at infinite dilution has been estimated by means of the integral equation theory of molecular liquids, 1D-RISM-KH. According to the xμ ion values obtained, the higher gelation ability is observed for 1·X in which counterions X − have the higher absolute values of the solvation free energies. The three-dimensional solvation structure of 1·Cl in aqueous solution has been analyzed by means of 3D-RISM-KH approach.