Functional plasma polymers were deposited from pure ethylene discharges and with the addition of carbon dioxide or ammonia. The incorporation of oxygen and nitrogen-containing functional groups depends on the fragmentation in the gas phase as well as on the densification during film growth. While a minimum energy per deposited carbon atom is required for cross-linking, the densification and accompanying reduction of functional group incorporation was found to scale linearly with momentum transfer through ion bombardment during film growth.
The deposition of functional plasma polymers such as a‐C:H:O films is mainly influenced by fragmentation of the parent molecules in the gas phase as well as by the energetic conditions during film growth at the surface. The influence of gas phase and surface processes on the a‐C:H:O film properties was thus investigated in order to optimize cross‐linking and functional group density. The control of both conditions enables permanent functional plasma polymer films deposited within different reactor geometries (capacitively coupled symmetric vs. asymmetric at driven electrode and at grounded electrode). Comparison and up‐scaling of such plasma polymerization processes are facilitated by knowing the internal energy input into the plasma and into the growing film surface.
Titanium nanocluster films were prepared using a gas aggregation cluster source based on a planar magnetron following a Haberland concept and using Ar as a working gas. The films were deposited in dependence on the argon pressure inside the cluster source and on the magnetron current. Prior to the analysis, deposited metal nanocluster films were allowed to oxidize in air at room temperature. Selected nanocluster films were annealed in air at 420 °C. The films were studied by TEM, SEM, and AFM in order to describe their morphology and topography. Crystal structure of the nanoclusters was estimated from electron diffraction patterns by SAD analysis. Chemical composition of the film surface was determined by XPS. Special attention was paid to describing the changes in the nanocluster films connected with ageing.
Cell behavior depends strongly on the physical and chemical properties of the material surface, for example, its chemistry and topography. The authors have therefore assessed the influence of materials of different chemical composition (i.e., glass substrates with and without TiO(2) films in anatase form) and different surface roughness (R(a) = 0, 40, 100, or 170 nm) on the adhesion, proliferation, and osteogenic differentiation of human osteoblast-like MG63 cells. On day 1 after seeding, the largest cell spreading area was found on flat TiO(2) films (R(a) = 0 nm). On TiO(2) films with R(a) = 170 nm, the cell spreading area was larger and the number of initially adhering cells was higher than the values on the corresponding uncoated glass. On day 3 after seeding, the cell number was higher on the TiO(2) films (R(a) = 0 and 40 nm) than on the corresponding glass substrates and the standard polystyrene dishes. On day 7, all TiO(2) films contained higher cell numbers than the corresponding glass substrates, and the cells on the TiO(2) films with R(a) = 40 and 100 nm also contained a higher concentration of β-actin. These results indicate that TiO(2) coating had a positive influence on the adhesion and subsequent proliferation of MG63 cells. In addition, on all investigated materials, the cell population density achieved on day 7 decreased with increasing surface roughness. The concentration of osteocalcin, measured per mg of protein, was significantly lower in the cells on rougher TiO(2) films (R(a) = 100 and 170 nm) than in the cells on the polystyrene dishes. Thus, it can be concluded that the adhesion, growth, and phenotypic maturation of MG63 cells were controlled by the interplay between the material chemistry and surface topography, and were usually better on smoother and TiO(2)-coated surfaces than on rougher and uncoated glass substrates.
Fluorocarbon plasma polymer films were prepared by RF magnetron sputtering in Argon from a balanced magnetron equipped with polytetrafluoroethylene (PTFE) target. Depending on the deposition conditions, primarily on the working gas pressure and distance between the target and the substrate, plasma polymer films were obtained with distinctly different chemical composition and/or morphology, as measured by means of XPS, FTIR and AFM. These films possessed static contact angle of water values ranging from 112° to ≈170° i.e. their behaviour ranged from hydrophobic to superhydrophobic ones.
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