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Plasma polymer films were deposited from hexamethyldisiloxane (HMDSO) in a low-pressure discharge. The influence of the energetic conditions in the gas phase as well as at the surface on the densification/cross-linking of the hydrophobic films was studied. The fragmentation of the monomer in the plasma seems to be of similar importance for film densification as the energetic particle interactions at the surface. A map of fragmentation chemical pathways can thus be proposed for HMDSO. The aging and hydration of the HMDSO films were studied and hydration history effects related to the energetic conditions applied in the plasma process were observed. Effective water penetration was possible as evidenced by silver release studies.

Activation reactions of molecules in plasma are investigated using plasma polymerization of hexamethyldisiloxane as a model system for plasma‐state polymerization. Underlying reaction pathways and film‐forming mechanisms are revisited based on a simplified macroscopic approach, considering the average energy available per monomer particle, Epl, in relation to the threshold energy, Eth, which represents an activation barrier for plasma polymerization. Basic principles are discussed involving averaged values for collision frequency, cross‐section, and reaction rate to produce film‐forming species combining macroscopic and microscopic quantities. Considering the energy uptake from the electric field by the electrons, the energy transfer from electrons to monomer molecules, and the conversion into film‐forming species, it is demonstrated that Epl/Eth is equally relevant as the electron energy distribution function for plasma‐chemical activation reactions.

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Materials for biomedical applications typically involve surface engineering. Scaffolds used for tissue engineering, for example, require a surface functionalization in order to support cell growth. The deposition of functional plasma polymer coatings seems to be an attractive approach to modify substrates for biomedical applications. Possible degradation of highly functional plasma polymers and the effect of its degradation products on cell growth, however, are not yet investigated in detail. Plasma polymer formation is governed by gas phase (mainly determining the chemical composition) and surface processes (inducing cross-linking) which both influence the incorporation of amino groups in a-C:H:N coatings deposited by NH 3 /C 2 H 4 discharges. Aging is studied in air and in aqueous conditions revealing the degradation of such plasma polymers (loss in thickness and loss of amino groups). Degradation products seem to influence viability and proliferation of mouse skeletal muscle cells on electrospun poly(ε-caprolactone) scaffolds. Thus, possible chemical changes as a function of time or exposure to different media must be taken into account in the design of functional plasma polymer coatings for biomedical applications in order to avoid possible adverse effects on cell growth.

Plasma technology offers many interesting possibilities for the production of highvalue-added textiles. Nevertheless, textiles can have a considerable structural and chemical complexity, and their properties must be taken into account for the implementation of plasma processes. The influences of some of these properties are highlighted through several examples of recent interesting applications, such as the metallization of polyester yarns, the enhancement of fabric moisture wicking and the surface functionalization with plasma polymerization.

The initial stage of film growth during plasma deposition on polymers determines many film properties such as morphology and structure, interphase formation and adhesion. Therefore, the plasma‐substrate interaction is investigated regarding the energy density during film growth, which is defined by the energy flux per depositing atom. The flux of film‐forming species and the flux of energetic particles were determined for metal sputtering (silver films) and plasma polymer deposition (amino‐functional hydrocarbon films). It is shown that enhanced energy densities can be obtained during the initial film growth due to reduced deposition rates and mixing with the polymer substrate (interphase formation). Thus, good adhesion on polymers such as polyethylene terephthalate (PET) has been achieved. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Oxygen-functional plasma polymers are of high interest in diverse fields such as, e.g., biomedical applications where stable surfaces are required, i.e., avoiding strong aging, leaching, and dissolution effects. Plasma polymer deposition from water vapor/acetylene mixtures is thus examined by varying energy input and gas ratio. Mainly, the latter was found to influence oxygen incorporation. Increasing the overall oxygen content in the plasma polymer films, however, results in film loss when immersed in water. Highly stable a-C:H:O films could be obtained for H 2 O/C 2 H 2 gas flow ratio around 5 at moderate energy input. Such films mainly comprise C-O-R groups as indicated by XPS and FTIR measurements.