Abstract
Excess molar volumes and relative permittivities at a frequency of 30 kHz of oligo(oxyethylene glycol) monodecyl ethers (C10E (m) ) for m = 1-8 in n-heptane, n-decane or n-dodecane solutions were determined for the mole fraction range 0 < x < 0.04 at the temperature of 298.15 K. By using Frohlich's equation the apparent dipole moments, mu, of C10E (m) were calculated, and the limiting values, mu (0), were determined by extrapolating to infinite dilution. The values of mu (0) increase linearly with increasing number of oxyethylene units (m) of oligo(oxyethylene glycol) monodecyl ethers in the range m = 2-8, while mu (0) of C10E1 is less than its extrapolated value. By comparing the present results with our previous ones measured in n-heptane and decane, a solvent effect on mu (0) was found. The excess partial molar volumes of oligo(oxyethylene glycol) monodecyl ethers at infinite dilution increase with increasing m. Those results are discussed from the viewpoint of the interactions between oligo(oxyethylene glycol) monodecyl ethers and solvent molecules.