Figure 5.

(a) Plot of dissipation, ΔD_3, as a function of the frequency shift, −Δf₃/3, during the adsorption process of phosphonic acid PEG_1K, PEG_2K, and PEG_5K and carboxylic acid PEG_2K at pH 2.0. The straight line represents the Sauerbrey limit (slope 4 × 10^–7 Hz^–1) valid for homogeneous and rigid films.^54,55 (b) Schematic representation of PEGylated layers deposited on iron oxide substrates obtained for the four polymers in (a). The values of brush thicknesses estimated from the Voigt viscoelastic model are also indicated.⁵⁴