Polymer-metal interfaces, role

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 metal polymer interface can be studied in a variety of ways using surface science methods. Recently, much emphasis has been placed on the understanding of the initial stages of metallization of polymers. In particular, the role of metal-organic interactions as they relate to the fundamentals of adhesion mechanisms are of interest. One experimental approach is to examine the first monolayers of metal as they are deposited on a polymer surface (1), i.e the polymer is the substrate. However, the organic polymer-metal interface may be studied in the opposite perspective, via understanding the roles of organic molecular or macromolecular structure and chemistry of the metal surface qua substrate (2). In the present paper, recent ion and electron spectroscopic studies of the... 

Alternatively, delamlnatlon may not be related directly to permeation, but may be due Instead to thermal and/or UV effects that are followed by the corrosive failure. Some studies and models Indicate that the polymer/metal Interface morphology, and the changes In the morphology with exposure to the environment, play a key role In corrosion rates. These characteristics may be even more Important In corrosion control than either the diffusion of vapors through the pol5mier or the Inherent corrosion resistance of the metal. 

Let us consider the role of electrode processes at the polymer-metal interface and their effect on current generation in M1-P-M2 systems. 

While the adsorption theory is the most accepted one, mechanical interlocking comes into play in case of substrates with a special kind of roughness such as galvannealed steel where the liquid can spread into cavities and thereby interlock with the substrate. The diffusion theory does not play an important role for polymer-metal interfaces. The contribution of the electrostatic theory is not easy to estimate. However, the electrical component of the adhesive force between the planar surfaces of solids becomes important if the charge exchange density corresponds to 10 electronic charges, meaning about 1% of the surface atoms [71]. 

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. 

An illustration of the role of the oxidation state in the distribution of the metal particles across the CP layer was presented in single-step potential deposition experiments on platinum in sulfonated PANl that were carried out at two values of the potential (-0.2 and -1-0.2 V vs. Ag/AgCl reference electrode), corresponding to the reduced and oxidized states of PANI [ 101 ]. In the first case a homogeneous distribution of Pt across the entire CP layer up to the underlying carrying substrate was observed, whereas in the second case (oxidized PANI) the Pt content decreased steeply within a narrow region close to the polymer/solution interface [101]. 

One extension of the uniform model is the inhomogeneous homogeneous model [134,209], where due to the strong interactions between the adsorbed polymer molecules and the metal substrate (the nature of the metal and its surface geometry may play an important role), the properties of this layer are different from the rest of the film. It can be described formally by introducing an adsorption pseudocapacitance and a resistance cormected with the charging/discharging process within the first layer of the film at the metal interface. 

It is now well established that in lithium batteries (including lithium-ion batteries) containing either liquid or polymer electrolytes, the anode is always covered by a passivating layer called the SEI. However, the chemical and electrochemical formation reactions and properties of this layer are as yet not well understood. In this section we discuss the electrode surface and SEI characterizations, film formation reactions (chemical and electrochemical), and other phenomena taking place at the lithium or lithium-alloy anode, and at the Li. C6 anode/electrolyte interface in both liquid and polymer-electrolyte batteries. We focus on the lithium anode but the theoretical considerations are common to all alkali-metal anodes. We address also the initial electrochemical formation steps of the SEI, the role of the solvated-electron rate constant in the selection of SEI-building materials (precursors), and the correlation between SEI properties and battery quality and performance. 

The aim of this chapter is to present a simple but general band structure picture of the metal-semiconductor interface and compare that with the characteristics of the metal-conjugated polymer interface. The discussion is focused on the polymer light emitting diode (LED) for which the metal-polymer contacts play a central role in the performance of the device. The metal-polymer interface also applies to other polymer electronic devices that have been fabricated, e.g., the thin-film field-effect transistor3, but the role of the metal-polymer interface is much less cruical in this case and... 

Additives are usually amphiphilic in nature, and thus are either ionic or neutral surfactants or even polymers. The role of surfactants in solvent extraction is ambiguous. Usually, they should be avoided as they lower the interfacial tension, which may lead to emulsion formation in an agitated extractor. However, every metal-loaded ion exchanger is amphiphilic, and can adsorb at the interface or aggregate in the bulk phase. This occurrence is well known with sodium or other metals [17], and above a critical surfactant concentration (cmc, critical micelle concentration) micellar aggregates are formed. A dimensionless geometric parameter is decisive for the structure of the associates, according to Fig. 10.6 ... 

The aim of this work is to give a better understanding of the role of the plasma on the surface modifications of the polypropylene. Different surface analysis techniques such as static SIMS and XPS have helped us to point out the chemical modifications of the plasma treated polymer. Auger depth profiles through the metallic coatings and their interfaces with the polypropylene have been performed in the case of both treated and non treated polypropylene. At last, Transmission Electron Microscopy (TEM) has been carried out and has allowed us to measure precisely the thickness of the metallic coating as well as to identify its growth process. 

Because polymer formation and ablation are competitive and opposing processes, polymer-forming plasma has the least ablative effect however, ablation in such plasmas cannot be completely ruled out. Sputtering of metals used as the internal electrodes for plasma polymerization has been recognized as a contamination of plasma polymers. Under certain conditions, the sputtering of the electrode materials becomes significant and plays an important role in the engineering of interface as described in Chapter 9. 

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