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- Englisch (23) (entfernen)
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- Plasma polymerization (4)
- Electrospray deposition (3)
- Plasma (3)
- ESCA/XPS (2)
- NEXAFS (2)
- Surface functionalization (2)
- Underwater plasma (2)
- Adhesion promoting interlayers (1)
- Adhesion-promoting layers (1)
- Aggregation (1)
- Arrays (1)
- Beschichtung (1)
- C plasma (1)
- C pulsed (1)
- C radio frequency (1)
- Capillary discharge (1)
- Capillary-sample distance (1)
- Carbon fibres (1)
- Chemical characterization (1)
- Complete enwrapping of fibres (1)
- Continuous-wave plasma (1)
- Copolymers (1)
- D nitrogen (1)
- D oxygen (1)
- DX plasma deposition (1)
- Defects (1)
- Dielectric barrier discharge (1)
- Discharge (1)
- Donoracceptor compound (1)
- Electrophoretic effect (1)
- Electrospray ionization (1)
- Film (1)
- Film morphology (1)
- Functionalization of polymer (1)
- Funktionelle Gruppen (1)
- Gold nanoparticles (1)
- Gold surface (1)
- Macromolecular plasma (1)
- Metal-polymer systems (1)
- Modification surfaces (1)
- Molar mass (1)
- Molar masses (1)
- Monotype functional groups (1)
- Organische Filme (1)
- PTFE (1)
- Plasma bromination (1)
- Plasma polymers (1)
- Plasma polymers with functional groups (1)
- Plasma treatment (1)
- Polyethylene (PE) (1)
- Polymer aerosols (1)
- Polymer functionalization (1)
- Polymer surface modification (1)
- Polymer-Oberflächenfunktionalisierung (1)
- Polymeroberflächen (1)
- Polystyrene (1)
- Polytetrafluoroethylene (1)
- Pressure-pulsed plasma (1)
- Pulsed plasma (1)
- Residual solvent (1)
- Röntgenabsorptionsspektroskopie (1)
- SERS (1)
- Self-healing (1)
- Structure (1)
- Surface modification (1)
- Thermoluminescence (1)
- Thin films (1)
- Thiocarbonyl group (1)
- Ultra-thin layers (1)
- Ultra-thin polymer layers (1)
- Vacuum deposition (1)
- r.f. pulsed plasma (1)
Thin plasma polymer films were deposited using the pulsed plasma mode. These plasma polymers should possess a more regular structure than those produced by the conventional continuous-wave (cw) mode, because of lower monomer fragmentation caused by the plasma pulses and the chemical chain propagation during the plasmaless (free!) periods. The thermoluminescence method was applied to functional groups carrying plasma polymer layers which are used in medical technology. Examples are formation of biocompatible, biosensoric and bioactive coatings or in metal polymer composites such as adhesion-promoting interlayers.
In addition to the use of the conventional X-ray Photoelectron Spectroscopy for thin film characterization, the new method of thermoluminescence was applied to characterize undesired defects and structural specifics produced in the polymer films by pp or cw plasma mode. The main areas of focus were oxygen-containing groups produced by post-plasma oxygen introduction via auto-oxidation, oxidation of implemented unsaturations and trapped radical sites known as typical irregular structures in plasma polymers.
Nebulizing of polymer solutions, in a high-voltage field under atmospheric conditions by electrospray ionization (ESI), is a comfortable way to deposit ultra-thin layers of polar or ionic polymers onto any conductive substrate materials. The substrate is grounded and the polymer solution is sprayed through a powered capillary. The formed charged droplets shrink by solvent evaporation during their way to the grounded substrate, the charges close ranks and the droplets collapse consecutively by charge repulsion, thus forming finally charged single macromolecules. After their discharging at the grounded substrate, an ultrathin ‘quasi-monomolecular’ polymer layer is formed. It could be shown by imaging of scratches through the polymer layer by atomic force microscopy that the deposited polymer layers are dense at a thickness of about 10 nm. Carbon fibre bundles were coated with poly (allylamine) (PAAm) or poly(acrylic acid) (PAA) as potential adhesion-promoting layers in fibre–polymer composites. The polymer deposition is self-inhibiting after formation of a continuous coverage of about 200 nm for PAAm and 30 nm for PAA as result of surface charging. Continuous deposition onto such isolating layers or polymers without charging can be achieved by using current of alternating polarity. The film formation is self-healing because of the electrophoretic effect, i.e. the ion discharging occurs preferentially at noncoated areas. This electrophoretic effect of ESI was demonstrated by completely enwrapping all the carbon fibres of the roving within a distance of about 100 μm far from its outside and also at the backside of the fibre bundle with about 80% of the topside coverage, as measured by X-ray photoelectron spectroscopy and visualized using scanning electron microscopy.
Polytetrafluoroethylene (PTFE) films have been deposited onto polycarbonate (PC) substrates from the products of PTFE evaporation, activated by a cloud of accelerated electrons. A 40.68 MHz glow discharge was used during the deposition process. The polymer films have been characterised by XPS, FTIR and AFM. The use of the low power plasma during film growth led to the formation of PTFE films with modified structure. Films are amorphous and contain more cross-links, but in general, the structure of their macromolecules is still linear. An increase of RF-power leads to the formation of films with large amount of double bonds and enhanced internal stresses.
Deposition of PTFE on PC without plasma treatment led to the formation of PTFE clusters up to 50 nm in diameter. The RMS roughness of the films, deposited without plasma, was about 4 nm, while the films deposited with plasma treatment had a roughness of 1.5 nm. The use of plasma has an additional effect if a PTFE coating is deposited on the PC substrate with submicrometer-sized steps. Without plasma the steps retain a rectangular shape. Deposited with the RF-discharge the PTFE layers resemble plasma-polymerised films. Under certain conditions the deposited films can fill trenches in the substrate like a wetting liquid, while under other conditions they avoid trenches and grow in between them.
Introduction of irregularities into plasma polymers by radiative and auto-oxidative processes
(2005)
Thin metal-filled polyterafluoroethylene films with various metal concentration were produced by co-deposition in vacuum. Metal nanocluster size increased with metal concentration. Films were heated up to 300 degrees C, their optical spectra were recorded during heating. The changes in plasmon band shape and wavelength of the nanocluster ensemble during heating are not linearly related with metal concentration and heating temperature. This is caused by different thermal behavior of the complex processes, which are taking place in each of the two materials present in the film. The metal cluster size and optical properties of the whole ensemble can be purposefully formed by varying metal nature, its concentration and annealing temperature of the film. Nano- and micro-domains with properties different from original film were generated by focused excimer laser or electron beam. Gold-filled PTFE nano-structured films were used as substrate for surface enhanced Raman scattering measurements of ultrathin film of Rhodamine 6G dye.
The production of chemically-defined plasma polymers and the introduction of monotype functional groups onto polymer surfaces are described. One method is to lower the energetic level of low-pressure plasmas. Pressure- and plasma-pulsed plasmas were successfully tested for the production of chemically-defined plasma polymers by increasing the monomer supply during the plasma-off period. Well-defined ultra-thin polymer films with regular structure were deposited from atmospheric plasmas by electrospray techniques. Post-plasma wet-chemical processing was also applied, as were gas/liquid-based aerosols and underwater plasmas.