Volumetric properties of (1-propoxypropan-2-ol + water) mixtures between (283 and 303) K: The effect of branching on alkoxyalcohols

Accurate density values are reported for aqueous binary mixtures of 1-propoxypropan-2-ol (1-PP-2-ol) over the whole composition range and temperatures between (283 and 303) K at intervals of 5 K. Excess molar volumes of the mixture, , apparent molar volumes of 1-PP-2-ol, V_φ,2, as well as excess partial molar volumes, , of both components were obtained over the entire composition and temperature ranges. Thermal expansibility effects on this (amphiphile + water) mixture are analysed in terms of excess molar isobaric expansions, , of the mixture and from the temperature dependence of limiting excess partial molar isobaric expansions, , for both chemical substances in the mixture. An analytical method based on Redlich−Kister fitting equations for as a function of the mole fraction has been used to obtain limiting excess partial molar volumes, . The excess properties are referred to a thermodynamically defined ideal liquid mixture. Interesting insights into the mixing process are gained from the visual impact of plots showing the composition and temperature dependence of different excess molar thermodynamic properties. The choice of 1-PP-2-ol was specially meant to highlight the role of branching in the alcohol versus alkoxy moieties. The present thermodynamic data are compared with that for isomeric 2-butoxyethanols, which are structural isomers of 1-PP-2-ol, and for 2-isopropoxyethanol. From this comparison an extended insight is gained into the role of branching and chain length on the mixing process and particularly in changes of local H-bond patterns of hydration water.