Polymer modified oxide surfaces properties

Metal finishing is the name given to a range of processes carried out to modify the surface properties of a metal, for example by the deposition of a layer of another metal or a polymer, or by formation of an oxide film. The origins of the industry lay in the desire to enhance the value of metal articles by improving their appearance, but in modern times the importance of metal finishing for purely decorative reasons has decreased. The trend is now towards surface treatments which will impart corrosion resistance or particular physical or mechanical properties to the surface (e.g. conductivity, heat or wear resistance, lubrication or solderability) and hence to make possible the use of cheaper substrate metals or plastics covered to give them essential metallic surface properties. 

Particles with hydrophobic surfaces can be recognized by the mononuclear phagocyte system (MPS) and cleared from the blood stream [123]. Therefore, hydrophilic polymers including PEG [124] and poly(ethylene oxide)-b-poly(propylene oxide)-h-poly(ethylene oxide) (PEO-b-PPO-b-PEO poloxamer) [125] have often been used to modify the surface property. 

Adhesion of non-polar polymers is sometimes improved by oxidation, so essentially what is normally thought of as degradation may be used to introduce an enhancing surface property. Nevertheless, in both cases the oxidation process modifies the polymer surfaces, and the analysis tools can be rather similar, see, e.g., Ref. [101]. 

The parameters of treatment were chosen since these led to the most pronounced changes of polymer surface in our previous experiments [70-74]. It was observed elsewhere that plasma treatment of polymer macromolecules results in their cleavage, ablation, alterations of chemical structure and thus affects surface properties e g. solubility [75]. The chemical structure of modified polyethylene (PE) was characterized by FTIR and XPS spectroscopy. Exposition to discharge leads to cleavage of polymeric chains and C-H bonds followed by generation of free radicals which easily oxidize [10,76]. By FTIR spectroscopy the presence of new oxidized structures within whole specimen volume can be detected. IR spectra in the 1710-1745 cm" interval [71,77] from PE, exposed to... 

Thin-film electrode — An electrode covered with a thin film of a given substance. The purpose of placing a thin film on the electrode surface is to obtain desired electrode properties. Many different substances have been used to prepare film electrodes they include among others mercury (see - thin mercury film electrodes) gold, boron-doped diamond (see - boron-doped diamond electrode), conductive polymers (see - polymer-modified electrode), and alkanethiols. The film thickness can vary from several micrometers (mercury) to monomolecular layers (thiols). In some cases (e.g., for - spectroelectrochemistry purposes) very thin layers of either gold or tin oxide are vapor-deposited onto glass plates. Thin film electrodes are often called - surface-modified electrodes. 

Plasma vs. Corona Treatment of Polypropylene (PP1. Corona treatments of polyolefins to modify their surfaces are very common in the polymer industry. The chemistry at such surfaces has been widely studied by XPS (4). It is generally assumed that corona treatments create abundant amounts of radicals which react with oxygen to form a hydroperoxide. This reacts further to eventually form crosslinks, oxidized products (ranging from hydroxyls to esters) with and without chain scission. The latter process is believed to lead to low-molecular weight material. There is some controversy over this material. Its role in determining the surface properties of the modified polymer is not completely understood. Its formation cannot be demonstrated directly by XPS, but only by comparing spectra before and after washing. 

Many surface properties of solid, smooth polymers are strongly dependent upon the chemical constitution of the surface layer of molecules [25,26,27] therefore, to modify a given surface property it is necessary to alter the chemical composition of the surface in some way. One example of such a modification is the commercial use of controlled oxidation of the surface of polyethylene foil to ensure wetting by and adhesion of polar printing inks [2]. 

Conducting polymers, for example, polyaniline, polypyrrol, have been extensively investigated taking into account its possible technological applications. From the specific point of view of modified surfaces, it has been shown that, when adsorbed on oxide surfaces such as molybdenum [1], arsenic [2,3], and iron [3] oxides, polyaniUne exerts remarkable effects on their redox properties [4] and/or thermal stabihty of the respective oxides. This chapter presents a brief outline about the achievements on this field of investigation. 

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