A calorimetric study of binary mixtures containing some glycols and polyglycols+anisole at 308.15 K and at atmospheric pressure

Excess molar enthalpies, HmE, of binary mixtures of anisole+glycols and polyglycols were measured by a flow microcalorimeter at 308.15 K and at atmospheric pressure over the whole composition range. Binary mixtures contained anisole+diethylene glycol, anisole+triethylene glycol, anisole+tetraethylene glycol, anisole+poly(ethylene glycol)-200, anisole+poly(ethylene glycol)-300, anisole+poly(ethylene glycol)-400, anisole+poly(ethylene glycol)-600. Effects of the molecular weight distribution (MWD), of the polymer were investigated too, by preparing three additional samples of poly(ethylene glycol) (PEG) with the same number average molecular weight (Mn≈300), but different MWD. Values of HmE of the corresponding binary mixtures with anisole were measured. For all mixtures, results were fitted to the Redlich–Kister polynomial. HmE curves are asymmetrical, showing positive deviations for mixtures containing glycols and poly(ethylene glycol)-200, negative deviations for poly(ethylene glycol)-600, and an inversion of sign in the other cases. Values of HmE vary from a maximum of 440 J mol−1 (anisole+triethylene glycol) to a minimum of −390 J mol−1 (anisole+poly(ethylene glycol)-600). Effects of changes in the glycols chain length and in MWD on the molecular interactions between the mixture components are discussed.