Heat of dilution of aqueous solutions of sodium salts of partially sulphonated polystyrenes

Abstract

The sodium salts of partially sulphonated polystyrene (NaPSt) having different degrees of sulphonation (α) were obtained by reaction of polystyrene with chlorosulphonic acid in ethylene dichloride. Heats of dilution (ΔH) of aqueous solutions of NaPSt (α= 0.78 and 0.62) measured at 25°C became slightly smaller with decreasing α and did not agree with Manning's theory. The degrees of gegenion dissociation (ƒ) for NaPSt at 25°C measured by the transference and conductance method hardly changed with decreasing α. From these results, it may be concluded that the charge density of PSt ions did not change with decreasing α; PSt ions are believed not to become extended with sulphonation or ionization.