Behavior of Polyethylene Glycol Molecules at an Oscillating Solid-Liquid Interface

抄録

The behavior of polyethylene glycol (PEG) molecules at an oscillating solid-liquid interface was examined using a quartz crystal microbalance (QCM). The number-average molecular weights (M_n) of PEG molecules were systematically varied. This study revealed that the shift in the energy dissipation factor, ΔD, of the QCM against square root of the density-viscosity product of the PEG solution is linear and has an intercept. Moreover, the systematical analysis revealed that the ΔD slope rapidly decreases with M_n, and the ΔD intercept becomes constant above 1.1×10⁴ g/mol. Those results indicated that the resonant length of PEG molecules moving with the oscillating plate at 9 MHz is 97.6 Å. We also found that the difference between the resonant lengths calculated from ΔD and series resonance-frequency shift, ΔF, is related to the density of the thin PEG layer formed on the gold electrode.