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

摘要

Excess molar volumes and relative permittivities at a frequency of 30 kHz for binary mixtures of oligo(oxyethylene glycol) monodecyl ethers(C _(10)E _m) for m = 1-8 were determined in n-heptane, n-decane and n-dodecane at 298.15 K and excess molar volumes in n-dodecane. Using Frohlich equation, the apparent dipole moments μ of C _(10)E _m were calculated, and the limiting values μ _0 determined by extrapolating to the infinite dilution. The value of μ _0 increased linearly with increasing number of oxyethylene units (m) of oligo(oxyethylene glycol) monodecyl ethers in the range m = 2-8 while μ _0 of C _(10)E _1 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 μ _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.