Applications of plasma modified surfaces

Abstract

Plasma processing of materials is a very promising technique. Basically, the modifications can be performed by three different procedures: plasma polymerization, plasma immersion ion implantation and through the exposure of the material to a plasma generated from an inert or reactive non-polymerizable gas. If the plasma is ignited from an organic compound pure or mixed to other gases, it can occur the deposition of a thin film onto the surfaces near or in contact with the plasma. This film is able to completely change the physical and chemical properties of the coated surfaces. This technique, the plasma polymerization or Plasma Enhanced Chemical Vapor Deposition (PECVD), has some peculiarities, which make it particularly interesting to the coating of materials. These advantages include, for instance, i) the possibility of producing extremely thin films onto objects with virtually any shape; ii) the modifications are produced only at the surface preserving the bulk properties; iii) the coatings are chemically stable and physically resistant. Furthermore, as the physical and chemical properties of the films are strongly dependent on the deposition conditions (such as, plasma composition, gas pressure and applied power) it is possible, by changing the plasma parameters, to tailor the coating characteristics to a given application. It is also possible to expose the object to be treated to plasmas that do not result in the deposition of films. This kind of plasma can be produced for inert (Ar, He, etc.) or reactive (such as SF6, O2 and NH3) gases. In this way, completely different results can be attained when different gases are used. For instance, argon plasmas are able to produced reactive species (such as free radicals and excited molecules) whereas oxygen plasmas can introduce new functional groups into the surface. The chemically activated surface can undergo a molecular rearrange and/or react with chemical species, such as atmospheric water vapor... (AU)