Chemical properties, metal/polymer interfaces

With more reactive polymer surfaces such as with carboxylic acid group in PET, A1 deposited atoms can react with the polymer surface and produce thick chemical interface whatever their deposit energy. By contrast no chemical interaction is observed between deposited Au and silicone substrate for either sputtering or evaporation. These observations open a quite exciting investigation field where the chemical properties of the interface at an atomic level should be studied by controling the important parameters of the metallization such as deposition energy, reactivity of the substrate, reactivity of the metal atoms... and correlated with macroscopic properties such adhesion tests. 

Adhesive failure Is a problem In solar systems. In the past, polymers have been used to protect the mechanical Integrity of wood and metal structures In severe outdoor environments and to protect sensitive electronic components In relatively benign enclosed environments. Polymers used In solar equipment will have to protect the optical properties of reflectors, thln-fllm electrical conductors, and thln-fllm photovoltalcs from the effects of moisture and atmospheric pollutants In severe outdoor environments while simultaneously maintaining optical, mechanical, and chemical Integrity. In some systems, the prevention of mechanical failure Is Important frequently, adhesive failure at the metal/polymer Interface Is of particular concern because the ensuing corrosion causes optical failure. 

Electrochemical reactions that lead to a degradation of the metal-polymer interface are influenced by the following properties the electron transfer properties at the interface, the redox properties of the oxide between the metal and the polymer and the chemical stability of the interface with respect to those species, which are formed during the electron transfer reaction. 

The volume is divided into three parts Part I. Metallization Techniques and Properties of Metal Deposits, Part II, Investigation of Interfacial Interactions," and Part III, "Plastic Surface Modification and Adhesion Aspects of Metallized Plastics. The topics covered include various metallization techniques for a variety of plastic substrates various properties of metal deposits metal diffusion during metallization of high-temperature polymers investigation of metal/polymer inlerfacial interactions using a variety of techniques, viz., ESCA, SIMS, HREELS, UV photoemission theoretical studies of metal/polymer interfaces computer simulation of dielectric relaxation at metal/insulalor interfaces surface modification of plastics by a host of techniques including wet chemical, plasma, ion bombardment and its influence on adhesion adhesion aspects of metallized plastics including the use of blister test to study dynamic fracture mechanism of thin metallized plastics. 

This book presents coverage of the dynamics, preparation, application and physico-chemical properties of polymer solutions and colloids. It also covers the adsorption characteristics at and the adhesion properties of polymer surfaces. It is written by 23 contemporary experts within their field. Main headings include Structural ordering in polymer solutions Influence of surface Structure on polymer surface behaviour Advances in preparations and appUcations of polymeric microspheres Latex particle heterogeneity origins, detection, and consequences Electrokinetic behaviour of polymer colloids Interaction of polymer latices with other inorganic colloids Thermodynamic and kinetic aspects of bridging flocculation Metal complexation in polymer systems Adsorption of quaternary ammonium compounds art polymer surfaces Adsorption onto polytetrafluoroethylene from aqueous solutions Adsorption from polymer mixtures at the interface with solids Polymer adsorption at oxide surface Preparation of oxide-coated cellulose fibre The evaluation of acid-base properties of polymer surfaces by wettability measurements. Each chapter is well referenced. 

R.I. Burger, L.J. Gerenser, Understanding the formation and properties of metal/ polymer interfaces via spectroscopic studies of chemical bonding, in Proceedings of the 34th Annual Technical Conference, Society of Vacuum Coaters, 1991, p. 162. 

Studies in the 1990s revealed the good corrosion protection properties of silicon-based plasma polymers on steel substrates and the cmcial influence of the pretreatment process on the stability of the resulting interface [92-101]. The pretreatments for trimethylsilane-based films may consist of an oxidative step (02-plasma) to remove organic contaminations from the substrate and a second reductive step (Ar/H2-plasma) to remove the metal oxide layer. Although the successive application of both steps provides the best corrosion protection of various plasma treatments for steel in combination with a cathodic electrocoat, little is known about the chemical structure of the interface. Yasuda et al. [101] and van Ooij and Conners [97] in particular have shown that the deposition of plasma polymers on steel and galvanized steel might even substitute the chromatation process. 

Surface-modified electrodes — In order to alter the properties of an electron-conducting substrate, i.e., a metal or graphite or semiconductor used as a part of an electrode, different chemical compounds are produced/deposited/attached/immobilized on the surface. These electrodes are most frequently called surface-modified, chemically-modified, or polymer-modified electrodes, depending on the methods and materials used for the modification. The obvious purpose of these efforts is the production of electrodes with novel and useful properties for special applications, but also to help gain a better understanding of the fundamental charge transfer processes at the interfaces. Usually the enhancement of the rate of the electrode reaction... 

Chemical appHcations of Mn ssbauer spectroscopy are broad (291—293) determination of electron configurations and assignment of oxidation states in stmctural chemistry polymer properties studies of surface chemistry, corrosion, and catalysis and metal-atom bonding in biochemical systems. There are also important appHcations to materials science and metallurgy (294,295) (see Surface and interface analysis). 

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. 

Other than in polymer matrix composites, the chemical reaction between elements of constituents takes place in different ways. Reaction occurs to form a new compound(s) at the interface region in MMCs, particularly those manufactured by a molten metal infiltration process. Reaction involves transfer of atoms from one or both of the constituents to the reaction site near the interface and these transfer processes are diffusion controlled. Depending on the composite constituents, the atoms of the fiber surface diffuse through the reaction site, (for example, in the boron fiber-titanium matrix system, this causes a significant volume contraction due to void formation in the center of the fiber or at the fiber-compound interface (Blackburn et al., 1966)), or the matrix atoms diffuse through the reaction product. Continued reaction to form a new compound at the interface region is generally harmful to the mechanical properties of composites. 

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