Heats of mixing of poly(styrenesulphonic acid) and its tetramethylammonium salt with alkali-metal poly(styrenesulphonates) in dioxan + water mixtures

The heats of mixing of poly(styrenesulphonic acid) and its tetramethylammonium salt with alkali-metal poly(styrenesulphonates) have been measured at 25 °C in 25 and 50 wt% dioxan + water mixtures. The solutions to be mixed were of the same concentration (0.06 mol dm–3). The heat effects were similar to those observed in aqueous solutions, i.e. either endothermic or exothermic. The experimental results are qualitatively interpreted in terms of the solute–solvent structural properties.