Figure 3.

Real-time binding curves for frequency Δf₃/3 and dissipation ΔD₃ during the adsorption of phosphonic acid PEG copolymers onto Fe₃O₄ substrates at pH 2.0. PEG pending side chains have molecular weights of 1000 g mol^–1 (a, b), 2000 g mol^–1 (c, d), and 5000 g mol^–1 (e, f). The data are those from the third overtone of the QCM-D acoustic device. In each panel, the first arrow at t = 0 denotes the time at which the polymer solution (concentration 0.1 wt %) is injected. The second arrow denotes the time at which DI water (pH 7.4) is introduced for rinsing. (g) Histogram for the steady-state frequencies upon polymer adsorption and rinsing.