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2013
Book Article
Titel
Combinatorial Plasma-Based Surface Modification of Polymers by Means of Plasma Printing with Gas-Carrying Plasma Stamps at Ambient Pressure
Abstract
In this work a new method of achieving combinatorial area-selective modification of polymer surfaces is presented, utilizing atmosphericpressure plasma printing with novel gas permeable electrodes. In these "plasma stamps" a microporous gas-carrying layer provides exchange of gaseous species from the gas stream to the individual microcavity discharges. Additionally, the electrodes can be fed with two (or more) different gases from spatially separate locations, allowing the generation of spot arrays with controlled gradients of physicochemical surface properties. Plasma-printed gradient surfaces can be used for combinatorial studies, for example in biomedical or polymer electronic research. In combination with spatially resolved surface characterization methods, the investigation of plasma-surface interaction processes can be significantly simplified. In the present contribution, gradient spot arrays were applied to optimize gas composition and functionalization paramete rs to provide optimal nucleation and growth of an electroless metal coating on a polymeric substrate. Locally plasma-modified surfaces were quantitatively characterized applying chemical derivatization (CD) followed by FTIRATR or SEM-EDX analyses in order to determine the area densities and spatial distributions of functional groups which are reactive towards the derivatization reagents used. Two chemical derivatization techniques were utilized: gas-phase derivatization (i) with 4-(trifluoromethyl)benzaldehyde (TFBA), forming a stable Schiff base with primary - but not secondary - amino groups, and (ii) with 4-(trifluoromethyl)phenyl isothiocyanate (TFMPITC) which is able to react with both primary and secondary amino groups forming thioureas, but - under the conditions used - not hydroxyl groups. It was, however, recently pointed out by us that other nitrogen-bearing functional groups such as imines can be captured by these methods as well.