Polymer metal system

USSR Pat. 1,479,475 (May 15, 1989), S. S. Pesetskii and co-workers (to Institute of the Mechanics of Metal-Polymer Systems, Academy of Sciences, Belomssian S.S.R. Institute of CoUoidal and Water Chemistry, Academy of Sciences, Ukrainian S.S.R.). 

Upon exposure to oxygen, all metals form surface metal oxide layers which vary in thickness and structure, depending on the identity of the base metal and the oxide formation conditions. Mercury and noble metals generally form very thin oxide films. On the other hand, most metals of primary commercial importance (i.e. aluminum, iron, zinc, etc.), tend to form oxide layers which are thick enough (40-80 A or more), so that the underlying metal atoms do not contribute in an appreciable way to the adhesion forces in metal/polymer systems U). 

There are numerous metal pretreatment techniques that can be used in addition to solvent degreasing. To obtain metal/polymer systems which exhibit strong initial adhesion it is usually sufficient to wash the metal with a solvent followed by an acid etch or sandblasting technique to remove any weak oxide layers and roughen the surface simultaneously. 

The purpose of this paper is to introduce the technique of NEXAFS spectroscopy to scientists and engineers interested in the analysis of polymers and metal-polymer interfaces. NEXAFS is just coming into its own as a powerful tool for studying bonding interactions and molecular orientation of fairly complicated systems. By presenting background material and examples of applications to metal-polymer systems, it is hoped that the reader will be left with a basic understanding and an impression of the potential of this technique. 

Metallized polymers are used nowadays in numerous industrial applications (food packaging, capacitors, magnetic tapes etc...). The adhesion and the durability of metal/polymer systems represent the most important concepts that concern many research groups (1-3). Obviously, any aggressive medium which corrodes the metal film will be directly related to some loss of adhesion and durability. The aim of this work is to investigate the influence of corrosive environments on aluminum layers evaporated onto PET film and especially on both the A1 surface and interface. 

Surface modification of a polymer prior to metallization is widely used to improve adhesion. The most common surface modifications employed are electric discharge (corona and plasma) and, more recently, ion-beam treatments QJ- Several mechanisms have been proposed for the improved adhesion after such surface modifications (2). These include mechanical interlocking, the elimination of weak boundary layers, electrostatic attractions, and chemical bonding. All of these can play a role in adhesion depending on the surface modification used, metal/polymer system, type of metal deposition, and the extent of polymer preparation employed. However, for low power, short exposure modifications, the formation of new chemical species which can provide nucleation and chemical bonding sites for subsequent overlayers is considered to be of prime importance (3-51. 

Because multilayer interconnecting networks are an important element of advanced chips and parallel processors, it is essential that an understanding of the corrosion processes that affect their reliability be developed. Needed are methods to quantify metal corrosion and ion transport in polymers and means to identify electrochemically reliable metal-polymer systems. 

Composite film coatings comprising nanodisperse silver are under intensive investigation nowadays being of interest as promising electroconductive metal-polymer systems, nonlinear optical materials, selective and active catalysts. 

Institute of Mechanics of Metal-Polymer Systems, Byelorussian S.S.R. Academy of Sciences, Gomel, U.S.S.R. 

In the Institute of Mechanics of Metal—Polymer Systems, Byelorussian SSR Academy of Sciences, USSR a method MR 74—82 (20) for evaluating the tribotechnical properties of polymer-based materials had been developed based on the generalization of techniques and talcing into consideration the friction behavior of polymers and polymer—based composites... 

The adhesion of metal layers deposited onto polymer surfaces is determined by the concentration and the bond strength of the chemical and physical interactions between the metal atoms and the functional (polar) groups at the polymer surfaces. Each type of functional group produces individual metal-polymer interactions, and makes a specific contribution depending on its concentration to the interfacial adhesion and consequently to the related shear or peel strength of metal-polymer systems (see Fig. 18.1). Thus for each type x of metal-functional group interaction a, the work of adhesion is calculated with Eq. (1), with A=area, I = Loschmidfs constant, and C = concentration. 

The most widespread corrosion types are point corrosion or pitting, filiform, crevice, contact and intercrystalline corrosion. The highest danger for the metal-polymer system is presented by the crevice type of corrosion. 

V. A. Goldade. Investigation of some physico-chemical phenomena at developing and operation of metal-polymer systems. Ph.D. Thesis, Riga, 1980. 

V.A. Goldade, V.A. Struk and S.S. Pesetsky. Wear Inhibitors of Metal-Polymer Systems. Moscow, Khimiya, 1993. 

V.A. Belyi and Yn.M. Pleskachevsky. Metal-Polymer Systems. Moscow, Znanie, 1982. 

V.G. Savkin, V.M. Ken ko and V.A. Struk. Some physico-chemical aspects of frictional interaction of metal-polymer systems. Proc. Intern. Conf. Intertribo-81, Vysoki Tatry, 1981, Vol. 1, pp. 172-179. 

In this coimection, a cryochemical solid-phase synthesis of metal-polymer systems is of special importance. As a result of such a synthesis, metal clusters and organometallic assemblies formed at low temperatures are buried in a polymer environment, which offers possibilities to stabilize and study these products over a large temperature range. This method was first offered and described in reference 10. The thermal rearrangement of the initial low-temperature system is governed by relaxation processes in polymer matrix. In particular, the aggregation of metal atom clusters to form metal nanocrystals in cryochemically produced metal-polymer systems yields new nanocomposite materials with valuable properties. The study of the mechanism of cluster aggregation, which depends on the characteristics of the polymer matrix, will allow the nanocomposite structure to proceed in the needed direction. Thus, it becomes possible to determine the methods of cryochemical synthesis of metal-polymer materials with predetermined properties. 

Metal-polymer systems obtained as a result of vapor deposition cryochemical synthesis contain stabilized small nonmetallic clusters of metal atoms and metal nanocrystals, but only metal nanocrystals participate in conductivity processes. The data on Ag-containing PPX composites [44] testify to the fact that the relative part of metal stabilized in cluster form at ambient temperature sharply decreases with increasing total metal content even in the range 0-2 vol. %. Therefore, at measurements of conductivity, which were carried out at considerably higher metal concentrations, it was accepted that as a first approximation, all metal is as nanocrystals. 

The above-mentioned factors essentially influence the thermodynamic parameters of MMC formation. One of the neigbor effects apparent in metal-polymer systems is that thermodynamic parameters do not depend on the length of the chain (i.e. the molecular weight of the macroligand). Using the temperature dependence of the constant of formation K, the changes in the free... 

Another illustration of the displacement of the electrochemical interface can be found in a recent study reported by Michalik and Rohwerder [42], They were able to locate the oxygen reduction process on a metal-polymer system using an isotopic marker ( 02). The reduction of heavy oxygen will create anions which can be recognized by mass... 

In situ generation of metal, metal salt and metal oxide produces materials with distributions of particles that would be difficult to achieve via heterogeneous doping. Surface metal or metal oxide coatings can also be obtained that would not result from conventional heterogeneously modified polymers. The chemistry and response of these microcomposite polymers to process conditions need to be explored further. As the structure and properties of the systems that have been herein described are better understood and new metal/polymer systems are explored, their application in electronic, adhesive and composite systems should emerge. 

Plasma Surface Treatment in Metal-Polymer Systems Interface Properties and Adhesion... 

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