Apparent dipole moments and excess volumes of Oligo (oxyethylene glycol) monodecyl ethers in n-alkanes at T=298.15 K

Excess molar volumes and relative permittivities at a frequency of 30 kHz for binary mixtures of oligo(oxyethylene glycol) monodecyl ethers(C10Em) for m = 1-8 were determined in n-heptane, n-decane and n-dodecane at 298.15K and excess molar volumes V-E(m) in n-dodecane. Using Frohlich equation, the apparent dipole moments mu of C10Em were calculated, and the limiting values mu(0) determined by extrapolating to the infinite dilution. The value of mu(0) increased 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 the infinite dilution increased with increasing m. Those results were discussed from the view point of the interactions between oligo(oxyethylene glycol) monodecyl ethers and solvent molecules.