Calorimetric studies of polycarboxylic acids in aqueous solution. II. Maleic acid–butyl vinyl ether copolymer

A calorimetric investigation of the heat of dissociation of a maleic acid‐butyl vinyl ether copolymer sample in aqueous solution has been carried out. Measurements were performed using dilute copolymer solutions (ca. 10−2 equiv/liter) in water, 0.04M NaCl, and 0.20M NaCl, respectively, at 25°C. Heat of dissociation data for the copolymer in water at 45°C are also reported. The calorimetric data allow evaluation in each case, (except for the solutions in 0.2M NaCl) of the enthalpy for the conformational transition which the maleic acid‐copolymer undergoes upon ionization. With the aid of potentiometric data the associated entropy changes are finally estimated. Our data point out the notable influences of temperature and of added simple salts on the energetics of the conformational transition.