Understanding the impact of the intricate morphology and surface chemistry of ZnO nanorod arrays on their interactions with polyelectrolyte polymers is crucial for the development of nascent ZnO-based adhesion-promoting materials. AFM-based single molecule force spectroscopy was applied for the analysis of the adsorption of poly(acrylic acid) (PAA) on zinc oxide (ZnO) film covered stainless steel substrates in aqueous electrolytes at pH 7. Based on the electrodeposition process, the morphology of zinc oxide films could be varied ranging from platelet-like crystals to nanorods. This approach allowed for the morphology dependent analysis of macromolecular adsorption processes on complex ZnO nanostructures which have diverse applications in the field of adhesion-promoting thin films. The surface chemical composition, as determined by X- ray photoelectron spectroscopy, could be correlated to the AFM-based desorption studies. Only equilibrium desorption events (plateaus), centered at 42 pN, were observed on mirror polished, preconditioned stainless steel. However, for platelet-like ZnO films, the poly(acrylic acid) desorption showed a mixture of rupture events (mean rupture forces of about 350 pN) and equilibrium desorption, while ZnO nanorod structures showed solely rupture events with mean rupture forces of about 1300 pN. These results indicate that simultaneous multiple ruptures of carboxylate-zinc bonds occur due to the macromolecular coordination of poly(acrylic acid) to the ZnO nanorods. The analysis of the interfacial adhesion processes is further supported by the dwell time dependence of desorption processes.

Correction for 'Luminescent Nd2S3 thin films: a new chemical vapour deposition route towards rare-earth sulphides' by Stefan Cwik et al., Dalton Trans., 2019, 48, 2926-2938.

Monodisperse micron-sized silica particle monolayers deposited onto plasma-grown SiOx-ultra-thin films have been used as reference systems to investigate wetting, water adsorption and capillary bridge formation as a function of silica surface functionalization. 1H,1H, 2H,2H perfluorooctyltriethoxysil (FOTS) monolayers, have been deposited on the respective surfaces by means of chemical vapor deposition resulting in macroscopically low energy surfaces. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) reflection absorption spectroscopy confirmed the monolayer formation. Water adsorption isotherms were studied by a combination of in-situ FTIR reflection spectroscopy and quartz crystal microbalance (QCM) while macroscopic wetting was analysed by contact angle measurements. The comparative data evaluation indicates that the macroscopic wetting behaviour was changed as expected, however, that water nanodroplets formed both at intrinsic defects of the FOTS monolayer and at the FOTS/SiOx interface. Capillary bridges of liquid water are dominantly formed in the confined particle contact areas and between surface asperities on the particles. The comparison of wetting, adsorption and capillary bridge formation shows that the hydrophobization of porous materials by organosilane monolayers leads to the formation of morphology dependent nanoscopic defects that act as sites for preferential capillary bridge formation.

In many different hybrid materials and materials composites polymers adhere to bulk oxides or oxide covered metal. The formed polymer/oxide interfaces are of crucial importance for the functionality and durability of such complex materials. Especially, under humid and corrosive conditions such interfaces tend to degrade due to permeability of polymers for water, the high adsorption energy of water on oxide surfaces and even corrosion processes of the metal. Different experimental studies considered such interfaces ranging from spectroscopy to electrochemical analysis. However, it is still a challenge to understand the complex interaction especially under non-ideal ambient conditions. The perspective article presents an overview on the existing experimental approaches and considers most recent experimental developments with regard to their potential applications in the area of polymer/oxide interfaces in the future. (C) 2018 Published by Elsevier B.V.

Neodymium sulphide (Nd2S3) belongs to the exciting class of rare earth sulphides (RES) and is projected to have a serious potential in a wide spectrum of application either in pure form or as dopant. We demonstrate a facile and first growth of Nd2S3 thin films via metal-organic chemical vapour deposition (MOCVD) at moderate process conditions using two new Nd precursors, namely tris(N,N'-diisopropyl-2-dimethylamido-guanidinato)Nd(iii) and tris(N,N'-diisopropyl-acetamidinato)Nd(iii). The promising thermal properties and suitable reactivity of both Nd precursors towards elemental sulphur enabled the formation of high purity γ-Nd2S3. While the process temperature for film growth ranged from 400 °C to 600 °C, the films were crystalline above 500 °C. We also demonstrate that the as-deposited γ-Nd2S3 are luminescent, with the optical bandgap ranging from 2.3 eV to 2.5 eV. The process circumvents post-deposition treatments such as sulfurisation to fabricate the desired Nd2S3, which paves the way for large scale synthesis and also opens up new avenues for exploring the potential of this class of materials with properties for functional applications.

Vapor phase deposited iron oxide nanostructures are promising for fabrication of solid state chemical sensors, photoelectrodes for solar water splitting, batteries, and logic devices. The deposition of iron oxide via chemical vapor deposition (CVD) or atomic layer deposition (ALD) under mild conditions necessitates a precursor that comprises good volatility, stability, and reactivity. Here, a versatile iron precursor, namely [bis(N‐isopropylketoiminate) iron(II)], which possesses ideal characteristics both for low‐temperature CVD and water‐assisted ALD processes, is reported. The films are thoroughly investigated toward phase, composition, and morphology. As‐deposited ALD grown Fe2O3 layers are amorphous, while the CVD process in the presence of oxygen leads to polycrystalline hematite layers. The nanostructured iron oxide grown via CVD consists of nanoplatelets that are appealing for photoelectrochemical applications. Preliminary tests of the photoelectrocatalytic activity of CVD‐grown Fe2O3 layers show photocurrent densities up to 0.3 mA cm−2 at 1.2 V versus reversible hydrogen electrode (RHE) and 1.2 mA cm−2 at 1.6 V versus RHE under simulated sunlight (1 sun). Surface modification by cobalt oxyhydroxide (Co‐Pi) co‐catalyst is found to have a highly beneficial effect on photocurrent, leading to maximum monochromatic quantum efficiencies of 10% at 400 nm and 4% at 500 nm at 1.5 V versus RHE.

In situ photoelastic‐modulated Fourier transform infrared reflection absorption spectroscopy has been applied for the investigation of interfacial stability of organothiol and organosilane monolayer films on nanocrystalline zinc oxide thin films. It has been shown that for octadecyltriethoxysilane films, exposure to high water activities results in physisorption of water in the cross‐linked film. This high water activity at the interface leads to a reversible wet de‐adhesion of the interfacial silanol groups from the ZnO surface. However, the organothiol seems to form a denser monolayer and a stable by S–Zn bond that is resistant to the competition with adsorbed water. The reversible attachment for cross‐linked organosilanol films has been demonstrated for the first time by means of an in situ spectroscopic method on model ZnO surfaces. Copyright © 2016 John Wiley & Sons, Ltd.

The nucleation and film growth of SiOx plasma polymer films as a function of the substrate surface chemistry are analysed by a combination of microscopic, spectroscopic and electrochemical techniques. Self-assembled organothiol monolayers (SAMs) surfaces with different terminating groups (methyl, carboxyl-and trimethoxysilane groups) on Au(111) serve as a model system. Ultra-thin SiOx films with thickness ranging from 0.4 to 1.4 nm were deposited by microwave plasma in a mixture of HMDSO and O-2. The changes in surface, interface and thin film chemistry are characterized by PM-IRRAS. Cyclic voltammetry with ferricyanide as a redox system is used to probe the defect density of the bare SAMs and the SiOx-covered SAMs. Furthermore, the evolution of the SiOx surface morphology for increasing film thickness as function of the substrate chemical termination is investigated by AFM. A strong influence of the surface chemistry on the SiOx nucleation and film growth is observed. While the methyl and carboxyl terminated SAMs are degraded during the nucleation leading to defect rich ultrathin films, the trimethoxysilane group protects the aliphatic chain of the SAM and leads to much better barrier properties of the ultra-thin SiOx-films. A mechanistic explanation of the results is provided.

Identification and synthesis of intramolecularly donor-stabilized aluminium(III) complexes, which contain a 3-(dimethylamino)propyl (DMP) ligand, as novel atomic layer deposition (ALD) precursors has enabled the development of new and promising ALD processes for Al2 O3 thin films at low temperatures. Key for this promising outcome is the nature of the ligand combination that leads to heteroleptic Al complexes encompassing optimal volatility, thermal stability and reactivity. The first ever example of the application of this family of Al precursors for ALD is reported here. The process shows typical ALD like growth characteristics yielding homogeneous, smooth and high purity Al2 O3 thin films that are comparable to Al2 O3 layers grown by well-established, but highly pyrophoric, trimethylaluminium (TMA)-based ALD processes. This is a significant development based on the fact that these compounds are non-pyrophoric in nature and therefore should be considered as an alternative to the industrial TMA-based Al2 O3 ALD process used in many technological fields of application.

Nanostructured alpha-iron oxides are fabricated via ALD and CVD using an iron ketominate precursor by Anjana Devi and co-workers in article number 1700155. Both processes ensure deposition of iron oxide in a temperature range of 100–800 °C, enabling fine tuning of crystallinity and morphology. Iron oxide photoanodes are active in photooxidation of water with current densities of 1.2 mA cm−2 at 1.6 V versus RHE under simulated sunlight.

This study focuses on the electropolymerization of acrylic acid as a surface technology for carbon fibers. The deposition process of the polyacrylic acid is assisted by the co-deposition of Zn2+ ions. The structural properties and final characteristics in respect of adhesion and the barrier coating of the resulting deposited coatings were investigated by means of AFM, FT-IRRAS and XPS. The role of the Zn2+ and inhibitors in the electrolyte during the electropolymerization process was established.The electrodeposition mechanism of polyacrylic acid onto surfaces can be divided up into three steps. (1) A Zn(2+)AA complex is adsorbed on the surface and reduced to Zn. The electron excess in the vicinity of the interface consumes the inhibitor molecules present in the acrylic solution. (2) Once the inhibitor has been depleted, polymer activation and growth starts through the transfer of electrons from the Zn2+-AA complex. (3) The length of the PM chains increases until the supply of electrons from the surface is hindered.The chemical stability of the electropolymerized coating was proven by FT-IRRAS spectroscopy. Wet adhesion to the composite is examined by means of a peel test. The wet adhesion studies reveal a two-fold improvement in the adhesion factor when the PM is electropolymerized onto CFRP. (C) 2017 Elsevier B.V. All rights reserved.

•Single Molecular force spectroscopy as tool for investigate interaction forces.•Aluminium Oxide (11-20) surfaces serves as model oxide.•Au-cantilevers functionalized with PEG-NH2, OH and OCH3.•The lone-pair electrons are able to coordinate to the surface Al-ions.

The scanning Kelvin probe blister test (SKP‐BT) was applied to study the corrosive delamination of model epoxy films applied to ZnMgAl alloy coated steel substrates. This test allowed the superimposition of mechanical and corrosive load. Moreover, ultra‐thin 3‐aminoproptriethoxysilane ( γ ‐APS) films were studied as adhesion promoting and corrosion protecting films, which inhibit the delamination process. The surface of the ZnMgAl alloy coating with and without applied ultra‐thin organosilane thin films were analyzed by polarization modulation infrared reflection absorption spectroscopy (PM‐IRRAS) and X‐ray photoelectron spectroscopy (XPS). The spectroscopic results show films that are only few nanometer thick, and therefore cannot act as efficient barrier films. However, peel‐force studies and SKP‐BT results show an effective inhibition of the delamination process of the epoxy film for the interface which was chemically modified by γ ‐APS. The effect of the interfacial layer is mainly assigned to the higher wet‐adhesion based on the interaction of silanol groups with thin surface oxides and carbonates of the alloy. Raman spectroscopic analysis showed that the delamination on samples without organosilane thin films is based on a preceding cathode and a subsequent mixed corrosion. Only a minor cathodic delamination was observed on γ ‐APS modified samples.

Defects in SiOx, TiO2 and a-Si: H inorganic barrier films on PET are investigated. Visualization is achieved by reactive oxygen etching in capacitively coupled plasma that leads to the undercutting of the barrier films at defect sites, and defect densities are deduced by SEM imaging. Defect formation is analyzed as a function of absolutely quantified steady state atomic oxygen fluence during the deposition of silicon oxide films and the effect of an additional substrate bias is presented. Macro-defect densities as a function of film thickness are tracked. Barrier films with a barrier improvement of one order of magnitude exhibit macro-defect densities below 160 defects mm(-2).

Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous solutions.

In this work the influence of stripping/cooling atmospheres used after withdrawal of steel sheet from Zn or Zn-alloy melt on surface properties of Zn (Z) and Zn-Al-Mg (ZM) hot-dip galvanizing coatings has been studied. The aim was to understand how the atmosphere (composed by nitrogen (N-2) or air) affects adhesion strength to model adhesive and corrosive behaviour of the galvanized substrates. It was shown that the surface chemical composition and Volta potential of the galvanizing coatings prepared under the air or nitrogen atmosphere are strongly influenced by the atmosphere. The surface chemistry Z and ZM surfaces prepared under N-2 contained a higher content of metal atoms and a richer hydroxide density than the specimens prepared under air atmosphere as assessed by X-ray photoelectron spectroscopy (XPS). The induced differences on the microstructure of the galvanized coatings played a key role on the local corrosion induced defects as observed by means of in situ Atomic force microscopy (AFM). Peel force tests performed on the substrates coated by model adhesive films indicate a higher adhesive strength to the surfaces prepared under nitrogen atmosphere. The obtained results have been discussed in terms of the microstructure and surface chemical composition of the galvanizing coatings. (C) 2016 Elsevier B.V. All rights reserved.

A new Ti-precursor for low-temperature PE-ALD of titanium dioxide thin films as gas barrier layers on polymer substrates.