Abstract
Abstract Plasma enhanced chemical vapor deposition is a promising process for the generation of tailor-made polymer coatings on medical devices in order to improve their implant/ host interaction. The ultra-thin coatings can fulfil a variety of purposes, depending on the monomers used, the process conditions and the location of the coated implants in the human body. In addition, even complex geometries can be coated easily and without the application of solvents. Particularly hydrophilic and hydrophobic plasma polymer coatings can improve biocompatibility, especially in blood contact. Furthermore, the selection of the monomers used enables the generation of specific functional groups for further surface immobilization of drugs, such as proteins, by chemical crosslinking. The release of toxic residues from polymeric implants, such as monomers, additives or degraded components, can also be avoided. The aim of our investigation was the generation of plasma polymer films, their characterization and application as coatings for biodegradable metallic biomaterials in order to retard the degradation process. Metallic biomaterials, in various forms are frequently used in orthopaedics, dentistry, cardiovascular and neurosurgical equipment, because of their tensile strength, fracture toughness, fatigue strength and electrical conductivity. Plasma polymerization was performed using the monomers hexamethyldisiloxane and allylamine. The resulting plasma polymers were analysed in an accelerated degradation test. Both plasma polymers appear to be promising, while polyHMDSO appears to degrade over time and polyallylamine indicates to be stable.
Highlights
Plasma Enhanced Chemical Vapor Deposition (PECVD) is used to apply thin layers of e.g. polymers in the range of a few nanometres of 1-2 micrometers to surfaces [1]
Chemical changes by plasma polymerisation were visible by FTIR-ATR
For polyHMDSO (Fig. 2A green) coated samples, differences of the IR bands in the range of 1300 - 700 cm-1 and 3000 cm-1 can be observed compared to the IR spectra of the uncoated aluminium foils (Fig. 2A blue)
Summary
Plasma Enhanced Chemical Vapor Deposition (PECVD) is used to apply thin layers of e.g. polymers in the range of a few nanometres of 1-2 micrometers to surfaces [1]. PECVD coatings are characterized by a high degree of crosslinking, a short chain length and a random distribution of the monomers [2]. They allow to influence the permeation properties, e.g. as a top layer of spray coatings to delay the release of the pharmaceutical active ingredient or as a diffusion barrier of water to delay the degradation of degradable scaffolds. Accelerated degradation of the samples and cell colonization tests of the surfaces were performed
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