Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte Films

Abstract

The frequency and energy dissipation change of a quartz crystal microbalance during moisture absorption was measured for films with thickness ranging from 3 to 205 nm. Evidence of the viscoelastic nature of the films was observed for films thicker than 90 nm through the frequency and energy dissipation changes. For sufficiently thin films (t < 40 nm), the frequency change could be effectively modeled as a simple increase in mass, as predicted by the Sauerbrey equation. The viscosity of the swollen films was independent of initial polymer film thickness (93-205 nm). The equilibrium swelling ratio was independent of film thickness for all films examined (3-205 nm). The transition between the observation of a rigid film and a film showing viscoelastic character was found to be at β 1 D ) 0.26 ( 0.10, where β 1 ) 2π/λ s , λ s is the shear wavelength, and D is the film thickness. This transition agrees with the predictions of White and Schrag (J. Chem. Phys. 1999, 111, 11192).

A quartz crystal microbalance study of the kinetics of interaction of benzotriazole with copper

“…Benzotriazole (C 6 H 5 N 3 , BTAH) has been extensively studied as an inhibitor for the corrosion of copper and many of its alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], for dezincification of brass [17,18] and as additive in the etching [19], electrodeposition [20][21][22] and in the chemical mechanical polishing of copper [23][24][25]. It has also been reported to inhibit the corrosion of iron [26][27][28], cobalt [29], zinc [30], and nickel [28] and to enhance the resistance of tin bronze to oxidation in air [31].…”

QCM‐D sensitivity to protein adsorption reversibility

“…In the case of proteins, changes in dissipation upon adsorption have been predominantly attributed to intra-layer processes such as those related to changes in layer density (Vörös, 2004), with minimal contributions from changes in surface roughness and slip at the surface (Höök et al, 1998;Rodahl et al, 1997). The dissipation for the system is related to the crystal's electrical equivalent parameters (Rodahl et al, 1997) and the ratio of dissipated and stored energy (Vogt et al, 2004) according to…”

Kinetics of corrosion inhibition of benzotriazole to copper in 3.5% NaCl

“…Benzotriazole (C 6 H 5 N 3 , BTAH) has been extensively studied as an inhibitor for the corrosion of copper and many of its alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], for dezincification of brass [17,18], and as an additive in the etching [19], electrodeposition [20][21][22], and in the chemical mechanical polishing of copper [23][24][25]. It has also been reported to inhibit the corrosion of iron [26][27][28], cobalt [29], zinc [30], and nickel [28] and to enhance the resistance of tin bronze to oxidation in air up to 500 8C [31].…”

“…A quartz crystal has a well-defined natural frequency, f (caused by its shape and size) at which it prefers to oscillate. Loss or gain of mass from the surface of the crystal changes the frequency f. The change in mass (Dm) and in the oscillation frequency (Df) are related by the following equation [40,41]:…”

“…Equation (4) is valid for small evenly distributed elastic masses added to or taken from the crystal surface and when the mass change is within 2% of the mass of the quartz crystal [39,40]. Many factors affect the accuracy of measurements of the EQMB such as surface roughness, density, and viscosity of the liquid in contact with the crystal [41]. The EQMB has been used in studies of corrosion and protection of metals [13][14][15][42][43][44][45][46][47][48][49].…”