Adsorption Kinetics of Organophosphonic Acids on Plasma-Modified Oxide-Covered Aluminum Surfaces

Abstract

Tailoring of oxide chemistry on aluminum by means of low-pressure water and argon plasma surface modification was performed to influence the kinetics of the self-assembly process of octadecylphosphonic acid monolayers. The plasma-induced surface chemistry was studied by in situ FTIR reflection-absorption spectroscopy (IRRAS). Ex situ IRRAS and X-ray photoelectron spectroscopy were applied for the analysis of the adsorbed self-assembled monolayers. The plasma-induced variation of the hydroxide to oxide ratio led to different adsorption kinetics of the phosphonic acid from dilute ethanol solutions as measured by means of a quartz crystal microbalance. Water plasma treatment caused a significant increase in the density of surface hydroxyl groups in comparison to that of the argon-plasma-treated surface. The hydroxyl-rich surface led to significantly accelerated adsorption kinetics of the phosphonic acid with a time of monolayer formation of less than 1 min. On the contrary, decreasing the surface hydroxyl density slowed the adsorption kinetics.

New Hybrid Materials Synthesized with Different Dyes by Sol-Gel Method

“…For example, a phosphonic acid bound in tridentate form should result in just a broad band within 900-1200 cm −1 and the total disappearance of the normal P=O and P-O=H bands. The presence of either the P=O band or the P-O-H bands indicates the presence of mono-or bidentate binding, or a mixture of the two [35][36][37].…”

Improving the corrosion performance of hybrid sol–gel matrix by modification with phosphonic acid

“…The Al2p peak after 40 min of sputtering (Figure 10b) was deconvoluted into three components. The curves centered at 72.9 and 74.2 eV have been attributed to Si-O-Al linkages [40] and oxide aluminum [40,41],respectively, whereas the component at 71.2 eV has been attributed to metallic contribution [16,40,42]. Hoque et al [16] identified peaks centered at 71. also contains contributions from the P-O-Al bonds.…”

Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

“…Due to pressures from health and environmental legislation, researchers have devoted attention in the development of alternative coatings of lower toxicity than yellow chromatizing conversion coating for corrosion protection of metallic materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Consequently, there has been an upsurge of interest in the corrosion prevention of aluminum alloys using nanostructured surface pre-treatments based on selfassembled molecules (SAMs) [15][16][17][18][19][20][21][22]. In addition to the SAM, there are a large number of other alternative coatings in development for corrosion protection, as described in the literature [23].…”

“…The self-assembly (SA) method appeared as a strategic and promising alternative that, initially, is based on the chemical adsorption of organic molecules with specific functional groups on reactive metal surfaces [15][16][17][18][19][20][21][22][24][25][26][27][28][29].…”