Metal-polymer interfacial chemistry

The Influence of Polymer Surface Functional Groups in Metal/Polymer Interfacial Chemistry... 

Another S-containing polymer, PPS, represents a unique system for the smdy of metal bonding since it not only exhibits a delocalized n system, but also contains a sulphur moiety for site-specific interaction with metals. The interfacial chemistry between evaporated Ag and PPS has been investigated by XPS... 

Interestingly, protein adsorption is also a field of biological interfacial chemistry which parallels that of synthetic materials at the solid - liquid interface. A number of spectroscopic advances have been made which allow FT-IR to be used in kinetic monitoring of protein adsorption on metals and "biocompatible" polymers. In addition to providing in - situ measurements of total adsorbed protein, FT-IR can also yield information about perturbation of protein secondary structure in adsorbed layers. 

The purpose of performing calculations of physical properties parallel to experimental studies is twofold. First, since calculations by necessity involve approximations, the results have to be compared with experimental data in order to test the validity of these approximations. If the comparison turns out to be favourable, the second step in the evaluation of the theoretical data is to make predictions of physical properties that are inaccessible to experimental investigations. This second step can result in new understanding of material properties and make it possible to tune these properties for specific purposes. In the context of this book, theoretical calculations are aimed at understanding of the basic interfacial chemistry of metal-conjugated polymer interfaces. This understanding should be related to structural properties such as stability of the interface and adhesion of the metallic overlayer to the polymer surface. Problems related to the electronic properties of the interface are also addressed. Such properties include, for instance, the formation of localized interfacial states, charge transfer between the metal and the polymer, and electron mobility across the interface. 

Most of the illustrative examples will come from polyimide-metal interface studies directed at investigating the role of interfacial chemistry in adhesion at these interfaces and the non-equivalence of polymer-on-metal and metal-on-polymer interfaces. 

Photoelectron spectroscopy (PES) has become an important and widely used tool in material science (1-3). It has been a particularly fruitful technique for the investigation of polymers (4-9). In this review, we will focus on the application of photoelectron spectroscopy to the investigation of the interfaces between metals and polymers. These studies are directed primarily to understand the role of Interfacial chemistry in the adhesion between metals and polymers. Two aspects, which will be emphasized here, are the experimental approaches in PES studies of polymer/metal interfaces and the types of information accessible from the PES experiments. The experimental emphasis will be on preparation of appropriate samples for polymer/metal interface studies, practical problems... 

The properties of the polyimide-metal interface are different depending on whether the polymer is applied to a metallic substrate or whether the metal is deposited on the polymer. That a different interfacial chemistry occurs in these two situations is clearly demonstrated by a greater adhesion strength for polyimide on a metal than for the metal on polyimide (8-91. It is extremely difficult, however, to prepare for study an ideal interface consisting of one or two monolayers of polyimide on a clean metal substrate. Therefore, most of the studies of the polyimide-metal interface are restricted those involving vapor-deposited metals on polyimide. 

In the present paper. Static Secondary Ion Mass Spectrometry (SSIMS) is used to investigate the interfacial chemistry between vacuum-deposited Al and Cu on PET by following the initial stages of metallization in the submonolayer and monolayer regimes. From the SIMS intensity variations with the deposited metal flux, information on the initial growth mechanisms of the metal layer Is expected. Two metals, copper and aluminum, have been chosen In order to investigate the influence of the metal reactivity on the metal-polymer interface formation. Aluminum with its electropositive sp band is known to react strongly with the carbonyl functionalities of the whereas copper is an inert metal and its Interaction is believed to be much weaker. ... 

In order to investigate the interfacial chemistry and the possible formation of metal-polymer complex, molecular ions containing metal atom and PET fragments are researched. However these peaks may interfere with PET peaks already present and, as shown in Table 1, the isotopic mass resolution of the gwadrupole spectrometer does not allow to resolve the mass interferences for... 

These results illustrate the contribution of the ion beam techniques to study a metal-polymer interface. Moreover, they emphasize the new possibilities of TOF-SIMS to study the interfacial chemistry by identifying the exact nature of the molecular lacondary Ions containing both the metal atom and polymer fragments. 

Another class of materials, alkanethiol-stabilised metal nanoparticles, display electronic, optical and structural features that are tunable via particle size [67]. The theme of this section is to demonstrate the effects of interfacial chemistry and material heterogeneity on electronic and optical properties of luminescent conjugated polymers at metal interfaces. 

Another modeling approach involves the deposition of an ultrathin film onto a solid substrate. If the film is thin enough, XPS can then be used to look through the film to observe interfacial chemistry directly. Such an approach was first tried in a study of the process of polymer metallization for Cr, Fe, Ni [83,84], Ti [85] and A1 [86] and has recently been extended to the use of thin polymer films on metallic substrates [87], The best results have been achieved using very dilute polymer solutions (0.01-0.025 w/w/ 7f). polished substrates and very high resolution (monochromatic A1 Kq) XPS [88]. The information that can be gleaned from such studies is impressive but relies on careful peal-fitting of the Cls. spectra, as will be discussed in the. section on acid-ba.se interactions. 

Abstract This chapter explores the manner in which the surface analysis methods of X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) can be used to extract information regarding the interfacial chemistry of adhesion from polymer/metal systems such as adhesive joints. It will be shown that the analysis of a failure interface is an uncertain method to extracting interface chemistry but in certain situations, where a very thin layer of polymer remains on the metal oxide surface, this provides spectra characteristic of the interphase. In most situations, some form of chemical or mechanical sectioning is necessary, and microtomy and dissolution methods are described as ways in which chemical information at high depth resolution can be extracted from the interphase zone. 

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. 

Through a comprehensive review of the recent conductive polymer literature, it has been demonstrated that photoelectron spectroscopy provides a very unique and powerful tool for analyzing the intrinsic structure, the charge transfer interaction, and the stability and degradation behaviour of electroactive polymers. It is further demonstrated that photoelectron spectroscopy is also ideal for investigating the chemistry and electronic structure of the electroactive polymer interface with other polymers, semi-conductors, and metals. The surface and interfacial analytical capability of photoelectron spectroscopy can be further extended to include molecular specificity when coupled with the SIMS technique. Finally, the imaging XPS technique is fast becoming widely available [368]. 

The first chapter of the book deals with enzyme-like eatalysis by synthetic polymers - catalysis by polymeric acids and bases, amphoteric polyelectrolytes and nonionic polymers. Because coordination compounds of metal ions with macromolecular ligands are interesting with regard to bioinorganic chemistry, this book elucidates some problems involving the catalysis by water-soluble polymer-metal complexes. Ester hydrolysis, hydrogen peroxide decomposition, oxidation of disubstituted phenols, hydroquinones, mercaptoalcohols and other types of reaction are chosen as model processes. A section devoted to interfacial catalysis is also included. 

The first subdiscipline of chemistry in which the QCM was widely applied was electrochemistry. In 1992 Buttry and Ward published a review entitled Measurement of interfacial processes at electrode surfaces with the electrochemical quartz crystal microbalance , with 133 references [8]. This is the most widely cited paper on quartz crystal microbalances. After presenting the basic principles of AT-cut quartz resonators, the authors discuss the experimental aspects and relation of electrochemical parameters to QCM frequency changes. In their review of the investigation of thin films, they discuss electrodeposition of metals, dissolution of metal films, electrovalency measurements of anion adsorption, hydrogen absorption in metal films, bubble formation, and self-assembled monolayers. The review concludes with a brief section on redox and conducting polymer films. 

The deposition of Cr on two fluorinated poly(aryl ether) (rPAE) polymers has been investigated with x-ray photoelectron spectroscopy. Fluorine moieties were observed to be highly reactive towards the deposited Cr. Differences in polymeric fluorine chemistry (aliphatic vs. aromatic) did not affect the reaction pathway or the final reaction products. Interfacial deposition products form in a step-wise fashion dependent upon sietal coverage. A model ie proposed whereby the formation of reaction products is initiated by electron transfer from the metal to tha polymer followed by the formation of Cr-fluorldes and finally Cr-carbldes prior to the formation of a continuous unreacted metal overlayer. 

J. Campbell, R.P. Davies, D.C. Braddock, A.G. Livingston, Improving the permeance of hybrid polymer/metal-organic framework (MOF) membranes for organic solvent nanofiltration (OSN) - development of MOF thin films via interfacial synthesis, Journal of Materials Chemistry A 3 (2015) 9668-9674. 

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