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Polymer surfaces were modified in low-pressure glow discharge plasmas for introduction of monotype functional groups of different type and density. For this purpose three ways are selected, (i) oxygen plasma treatment followed by wet-chemical reduction of O functional groups to OH groups, (ii) plasma bromination for introducing C-Br groups and (iii) coating by deposition of thin plasma (co-) polymerized layers of functional groups-carrying monomers with OH, NH2, COOH, epoxy etc. functionalities. Subsequently, these groups were used as anchoring points for chemical grafting of spacer molecules, oligomers, prepolymers, fluorescence labels, ionic and nucleic acid residues. This chemical grafting of organic molecules uses different simple chemical reactions. The yield in monosort functional groups at polymer surfaces ranged from 10-14 (process (i)), 20-45 (process (ii)) and 18-31 groups per 100 C atoms (process (iii)). The consumption of functional groups amounts 40-90% of all functional groups present at the surface and depending on the dimensions of grafted molecules. For infinitely variable tuning the number of functional groups process iii was executed as copolymerization of a functional group-carrying comonomer with a non-functionalized ('chain-extending') comonomer. This monosort functionalization on polymer surfaces is a helpful prerequisite for both to start graft reactions as well as to investigate metal-polymer interactions. The functional groups could be formed by a combination process (plasma oxidation + chemical reduction, process i), by bromination (process ii) and by coating with monotype functional groups carrying polymer layers (process iii). The combination process leads to moderate yield in OH groups formation (10-14 OH/100 C) and shows moderate selectivity (60% of all O-functionalities appear as OH groups). On the other hand, this process allows it to covalently bond the OH groups directly onto the polymer molecules. The OH modification was stable if stored and exposed to air over longer periods (> 1 year). An adjusting of the OH group density at polymer surface was not reproducibly possible. The bromination was very selective and high concentrations could be introduced onto the polymer surface. The functional groups were also directly bonded to polymer backbones. Nearly all Br-sites were situated at the surface and, therefore, were open for chemical graft reactions. The concentration of C-Br groups was maximum compared with the other functionalization methods. Up to 40 C-Br/100 C could by produced with only negligible amounts of side-products. The concentration of C-Br groups could be slightly tuned by variation of the bromination time. Plasmapolymers from functional groups-carrying monomers allow a broad range of variation of both the type of monosort functional groups and the concentration. The concentration could be infinitely varied by copolymerization from 0 to 31 groups per 100 C atoms. In such a way OH and COOH groups carrying layers could be easily produced. They were resistant to long-time exposure to air. In contrast to that NH2 groups containing layers show generally low yield in NH2 formation, indications for reactions at the amino groups and a pronounced tendency of post-plasma oxidation. This oxidation during exposure to air may be ascribed to the auto-oxidation with oxygen from air initiated by trapped C radical sites in the layer. Applications of these layers as targets for fluorescence sensor devices and biocompatible materials as well as for adhesion promotion have illustrated the ability of polymer surface chemistry.