Influence of interface chemistry and network density on interfacial ion transport kinetics for styrene/acrylate copolymer coated zinc and iron substrates

Posner, R.; Marazita, M.; Amthor, Sebastian; Roschmann, Konrad J.; Grundmeier, Guido

doi:10.1016/j.corsci.2009.10.036

Cited by 11 publications

(16 citation statements)

References 37 publications

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“…The situation encountered in this work is significantly different from the situation in a previous work, where a larger cross-linker amount was found to lead to higher delamination rates in latex polymers because of the increase in interfacial free volume . Interfacial free volume can form in a significant amount in coatings, which form by coalescence of latex particles, but is less likely to occur in a significant amount in coatings prepared directly by free radical polymerization, as is used here.…”

Section: Resultscontrasting

confidence: 69%

Synthesis of Ultrathin Poly(methyl methacrylate) Model Coatings Bound via Organosilanes to Zinc and Investigation of Their Delamination Kinetics

Iqbal

Rechmann

Sarfraz

et al. 2014

ACS Appl. Mater. Interfaces

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Polymer coatings are widely used to protect metals from corrosion. Coating adhesion to the base material is critical for good protection, but coatings may fail because of cathodic delamination. Most of the experimental studies on cathodic delamination use polymers to study the corrosion behavior under conditions where the interfacial chemistry at the metal(oxide)/polymer interface is not well-defined. Here, ultrathin linear and cross-linked poly(methyl methacrylate) [PMMA] coatings that are covalently bound to oxide-covered zinc via a silane linker have been prepared. For preparation, zinc was functionalized with vinyltrimethoxysilane (VTS), yielding a vinyl monomer-covered surface. These samples were subjected to thermally initiated free radical polymerization in the presence of methyl methacrylate (MMA) to yield surface-bound ultrathin PMMA films of 10-20 nm thickness, bound to the surface via Zn-O-Si bonds. A similar preparation was also carried out in the presence of different amounts of the cross-linkers ethylene glycol diacrylate and hexanediol diacrylate. Functionalized and polymer-coated zinc samples were characterized by infrared (IR) spectroscopy, secondary ion mass spectrometry (SIMS), ellipsometry, and X-ray photoelectron spectroscopy (XPS). Coating stability toward cathodic delamination has been evaluated by scanning Kelvin probe (SKP) experiments. In all cases, the covalently linked coatings show lower delamination rates of 0.02-0.2 mm h(-1) than coatings attached to the surface without covalent bonds (rates ∼10 mm h(-1)). Samples with a higher fraction of cross-linker delaminate slower, with rates down to 0.03-0.04 mm h(-1), compared to ∼0.3 mm h(-1) without cross-linker. Samples with longer hydrophobic alkyl chains also delaminate slower, with the lowest observed delamination rate of 0.028 mm h(-1) using hexanediol diacrylate. For the coatings studied here, delamination kinetics is not diffusion limited, but the rate is controlled by a chemical reaction. Several possibilities for the nature of this reaction are discussed; radical side reactions of the oxygen reduction are the most likely path of deadhesion.

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Section: Resultscontrasting

confidence: 69%

Synthesis of Ultrathin Poly(methyl methacrylate) Model Coatings Bound via Organosilanes to Zinc and Investigation of Their Delamination Kinetics

Iqbal

Rechmann

Sarfraz

et al. 2014

ACS Appl. Mater. Interfaces

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show abstract

“…31 At a constant T g , the cathodic delamination velocity was found to decrease with a decreasing degree of macromolecular cross-linking and with a reduction of the average macromolecular weight. 32 In most cases, these tendencies of the polymer/substrate interface stability were not predictable based on an EIS analysis of the polymer barrier properties. 31,32 However, such a forecast will be very helpful to complement or partly replace complex SKP experiments in the future, because in contrast to Kelvin Probes, EIS expertise and equipment are comparatively widely spread and easily accessible.…”

mentioning

confidence: 99%

UV-Curable Polyester Acrylate Coatings: Barrier Properties and Ion Transport Kinetics Along Polymer/Metal Interfaces

Posner

Sundell

Bergman

et al. 2011

J. Electrochem. Soc.

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Zinc and iron substrates were coated with polyester acrylate films. The samples were cured by an exposure to different doses of ultraviolet (UV) radiation energy at different radiant fluxes of the UV light source. Infrared spectroscopy was used to estimate the resulting degree of macromolecular cross-linking. Its effect on the barrier properties of the coating was investigated by Electrochemical Impedance Spectroscopy (EIS). A reduced water uptake and a reduced swelling of the coating as well as a decelerated diffusion of water through the polymer bulk were detected on polyester acrylate coated zinc samples that were exposed to increasing UV energy doses at low UV light intensity. With the Scanning Kelvin Probe (SKP), a similar tendency was detected for the resistance of polyester acrylate/iron oxide/iron interfaces against cathodic delamination. In contrast, curing with large energy doses at high UV intensity led to decelerated ion transport kinetics along the interface, but did not further improve the barrier properties of the coating. This indicated that SKP data gained on Fe substrates and EIS data recorded on Zn substrates can be correlated if UV curing does not result in strong tension within the polyester acrylate films.

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“…The phase decreased to nearly 0°at lower frequencies due to coating pores that developed in the polymer layer. 1,[14][15][16] In general, similar Bode plots were measured during experiments performed on steel substrates coated with the unmodified epoxy. 1 Consequently, Fig.…”

Section: Resultsmentioning

confidence: 99%

Wet- and Corrosive De-Adhesion Processes of Water-Borne Epoxy Film Coated Steel

Santa¹,

Posner²,

Grundmeier³

2011

J. Electrochem. Soc.

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Low carbon steel substrates were covered with a ␥-glycidoxypropyltrimethoxysilane ͑␥-GPS͒ modified epoxy layer. Electrochemical impedance spectroscopy and attenuated total reflection infrared spectroscopy were used to investigate the barrier properties of the coating. The resistance of the samples to ion transport processes along the epoxy/steel interface was determined by in situ scanning Kelvin probe ͑SKP͒ measurements of the interface potential. X-ray photoelectron spectroscopy studies helped to analyze the resulting ion distribution on the substrate surface. The application of ␥-GPS resulted in a reduction of the interfacial water activity and temporarily stabilized the polymer/steel interface. In contrast to the experiments with the unmodified epoxy coating, interfacial ion transport processes were verifiable with the SKP. After some days of sample exposure to humid air, the stabilizing effect of ␥-GPS diminished and SKP potential profiles had to be recorded in dry atmosphere to identify the electrolyte front position, zones of cation and anion separation, and areas of local corrosion damage at the interface. This approach seems to be generally promising to analyze the degradation state of polymer/oxide/metal interfaces after long-term exposures in humid air.In Part I of this paper, the properties of a water-borne epoxy coating were analyzed. It was focused on the effect of high water activities and on the characteristics of ion transport processes at epoxy/steel interfaces. 1 Electrochemical impedance spectroscopy ͑EIS͒ indicated poor barrier properties of the polymer films. It was estimated that the H 2 O uptake level was very high and that strong wet adhesion processes occurred in humid air at the polymer/steel interface compared to substrates coated with common non-waterborne epoxy coatings. 2 Oxygen reduction induced ion transport processes along the epoxy/steel interface were not verifiable with the scanning Kelvin probe ͑SKP͒ because no characteristic sigmoid potential profiles were detected. Instead, the SKP recorded a nonspecific linear profile with a small slope. It was not possible to determine an electrolyte front position unless the humidity of the surrounding atmosphere was reduced. 1 Moreover, it was shown that both cations and anions of the defect electrolyte penetrated the epoxy/steel interface after the initialization of interfacial ion transport processes. With respect to previous studies, 3-9 it was discussed that the unexpected and uncommon anion transport was supported by the effects of fluid dynamics at the interface rather than by ion diffusion.This part of the study complements and continues the experimental approach selected in Part I. 1 It will be analyzed which effects a modification of the epoxy/steel interface with ␥-glycidoxypropyltrimethoxysilane ͑␥-GPS͒ has on the interface potentials and on the detectability of interfacial ion transport processes. Interfaces modified with adhesion promoting molecules, such as ␥-GPS, are expected to be more stable in an environment of a high ...

show abstract

Influence of interface chemistry and network density on interfacial ion transport kinetics for styrene/acrylate copolymer coated zinc and iron substrates

Cited by 11 publications

References 37 publications

Synthesis of Ultrathin Poly(methyl methacrylate) Model Coatings Bound via Organosilanes to Zinc and Investigation of Their Delamination Kinetics

Synthesis of Ultrathin Poly(methyl methacrylate) Model Coatings Bound via Organosilanes to Zinc and Investigation of Their Delamination Kinetics

UV-Curable Polyester Acrylate Coatings: Barrier Properties and Ion Transport Kinetics Along Polymer/Metal Interfaces

Wet- and Corrosive De-Adhesion Processes of Water-Borne Epoxy Film Coated Steel

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