Binding metal/polymer interfaces

In the current work, we focused on the following Ag-nitrides and oxynitrides (1) Ag-TiN/TiON (2) Ag-ZrN/ZrON, ° and (3) Ag-TaN/TaON. Acceleration of the bacterial reduction kinetics at the solid—air interface was explored stepwise in these studies as the guiding objective of this work. The objective was to design and produce films showing fast bacterial reduction concomitant with low cytotoxicity as reported in a few cases for nitrides. " Why use nitride/oxynitride layers to bind metal/oxides to textile or polymer substrates ... 

Finally, the investigation of noble metal bonding on semiconductor surfaces provides evidence that at moderate temperatures Cu diffuses easily into the Si surface whereas the penetration barrier for Ag is almost as large as its binding energy. The theoretical results help in the understanding of an important catalytic process in the synthesis of silicone polymers and shed light on the Cu/Si and Ag/Si interface formation. 

First, satellite structure on the high binding energy side of, for example, an XPS core-level line (or peak ) corresponds to so-called shake-up (referred to below as s.u. ) and shake-ofF2S-29 effects, the former of which is illustrated, by M+, in Fig. 3.1. Shake-off is just shake-up to the continuum rather than to an unoccupied molecular state. Considerations of (1) are important in comparisons with the results of model calculations while (2) is of use as an indication of the electronic transitions in the molecules under study, an example of which is found in studies of the early stages of interface formation, i.e., the interactions of reactive metal atoms with conjugated polymer surfaces. Since use will be made of these effects in subsequent chapters, they are outlined briefly below. 

The polyion domain volume can be computed by use of the acid-dissociation equilibria of weak-acid polyelectrolyte and the multivalent metal ion binding equilibria of strong-acid polyelectrolyte, both in the presence of an excess of Na salt. The volume computed is primarily related to the solvent uptake of tighdy cross-linked polyion gel. In contrast to the polyion gel systems, the boundary between the polyion domain and bulk solution is not directly accessible in the case of water-soluble linear polyelectrolyte systems. Electroneutrality is not achieved in the linear polyion systems. A fraction of the counterions trapped by the electrostatic potential formed in the vicinity of the polymer skeleton escapes at the interface due to thermal motion. The fraction of the counterion release to the bulk solution is equatable to the practical osmotic coefficient, and has been used to account for such loss in the evaluation of the Donnan phase volume in the case of linear polyion systems. 

The versatile properties and manufacturability of polymers has evoked immense interest in developing a class of biomaterials with the potential to interface with biological systems [1]. However, polymers are prone to pathogenic attack resulting in deterioration of properties, malfunction and so on. Various methods such as the ionic binding technique, incorporation of metal particles/metal oxides/nanoparticles (NP) and physico-chemical modification via, e.g., the addition of quaternary ammonium salts and blending with antimicrobial polymers, have been explored for the fabrication of bactericidal materials [2], However, these methods can result in reduced biocompatibility, cytotoxicity and eco-toxicity. 

There is evidence now from direct radiotracer measurements and other investigations that metals of low reactivity, in particular Cu, Ag. and Au, diffuse into polymers at elevated temperatures and sometimes form clusters inside the polymer. Diffusion is most pronounced at low deposition rates, where a large number of isolated atoms impinge onto an initially almost metal-free surface. The mobility in the polymer matrix appears to be controlled by the availability of free volume. For reactive metals such as Cr and Ti, which form relatively sharp interfaces, no significant diffusion seems to occur due to strong binding to the polymer. 

The use of surfactants that are also able to bind molecules of interest has long been of interest in the preparation of molecularly imprinted polymers, prepared by emulsion polymerization processes [12-21]. Surfactants containing functionality capable of binding to metal ions have been used in emulsion polymerization. The bifunctional surfactant l,12-dodecane-diol-0,0 -diphenyl phosphonic acid (Fig. 3) was used in the synthesis of polymers imprinted with zinc ions in a water in oil emulsion [22]. This a,co-functional surfactant sits at the interface between the organic and aqueous phases during polymerization. 

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