Surface modification microwave plasma

This chapter aims to discuss and summarize theoretical and practical aspects of such plasma interfaces, presenting the existing examples from our own recent work on plasma electrochemical reactions between typical ionic liquids and plasmas. First, we address the plasma state and essential properties with respect to its application in electrochemistry. Today, low temperature plasmas - mostly in the form of radiofrequency or microwave plasmas - play an important role in the treatment or modification of solid surfaces. However, as plasma chemistry is usually not an element of chemistry curricula, we include a very brief introduction but refer the reader to the literature for more detailed information. 

These surface modifications were performed in "pure" micro-wave (2.45 GHz, "single-mode") or in combined microwave/ radio frequency (2.45 GHz/13.56 MHz, "dual-frequency") plasma. Important systematic changes of the surface composition, wettability, and adhesion of thin metal films were observed for different substrate bias values, and for the different gases. The modified surface-chemical structure is correlated with contact angle hysteresis of water drops this helps to identify which surface characteristics are connected with the wettability heterogeneity and with adhesive bonding properties, and how they are influenced by plasma-surface interactions. 

Physical methods include plasma treatments, UV irradiation, corona discharge, and flame treatment. Among these, plasma treatment is widely used for the surface modification of synthetic polymers. Plasma can be obtained by exciting gases into an energetic state by radio frequency, microwave, or electrons from a hot filament discharge. Generation of plasma requires a vacuum, which normally poses several... 

It is concluded that surface modification of mica, produced by exposing the material to microwave plasmas, can create large positive or negative effects in the mechanical properties of filled polymers and polymer blends. Property enhancement is associated with the production of surface layers on the filler which... 

Operation (partly) in vacuum. Reactive gases (oxygen, hydrogen, fluorine), which are transferred into an energy-rich state (plasma)by microwave stimulation with the possibility of chemical surface modification, are fed into the plasma chamber with the adherends to be pretreated. 

Microwave irradiation has been successfully applied in polymer chemistry (Ref [10] and Chapter 14 of this book) - for the synthesis and processing of polymers, e.g. for modification of the surface and cross-linking, and also in the degradation of polymers. Microwave plasmas also have been used in the polymerization and surface modification of materials. The enhanced reaction rates have been attributed to thermal effects - although for some reactions it seems the advantages arise from the selective excitation of one of the educts involved. Shifts in selectivity have also been observed. 

Microwave Plasma System for Surface Modification of Gas-Separating Polymer Membranes... 

Microwave plasma modification of the surfaces of siloxane membranes (particularly lestosil and polycaibosil membranes) and acetate cellulose membranes is an example of plasma fabrication of asymmetric highly selective gas-separating polymer membranes (Arbatsky etal., 1988,1990). A schematic ofthe microwave plasma installation is showninFig. 9-34. 

Chemical and Stmctural Modification of Surface Layers of Gas-Separating Polymer Membranes by Microwave Plasma Treatment... 

The importance of surface modification to adhesion has been recognized by many authors. A microwave plasma treatment (16) has been used to modify the acid-base balance... 

Egitto, F.D. and Matienzo, L.J., Modification of Polytetrafluoroethylene and Polyethylene Surfaces Downstream fi om Helium Microwave Plasma , Polym. Degrad. Stab., 30,293-297 (1991)... 

SURFACE MODIFICATION OF AROMATIC POLYAMIDES BY MICROWAVE PLASMA TREATMENT... 

The use of high frequency plasmas for the surface modification of substrates, for etching processes and similar ends, is increasing rapidly. The wide ranging interest in plasma processes is reflected in our case by work involving a large volume microwave plasma apparatus,... 

The common strategies to disperse CNTs fall into two general categories chemical functionalization and noncovalent surface modification [101], In order to achieve homogeneous dispersion of carbon nanomateriais in water and various polymers, different chemical methods have been used to date. The methods are use of solvents, surfactants, functionalization with acids, amines and the fluorines, plasma, microwave, and matrix moieties. Some researchers used noncovalent functionalization, block polymers, wrapping conjugated polymers, and other methods. Some of these methods will be discussed in this section. 

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