In this paper some basic assumptions underlying the chemical derivatization analysis of polymer surfaces treated in nitrogen‐containing plasmas are critically examined. Imines, which are known to represent major constituents of such surfaces as well as of plasma polymers grown from amine precursors, show a very versatile chemical reactivity. For example, imines are generally able to exchange their carbonyl component with aromatic aldehydes. Therefore, surface reactivity of polymers treated in nitrogen‐containing plasmas with 4‐trifluoromethyl‐benzaldehyde (TFBA) or other benzaldehydes appears to be attributable not only to (primary) amines. Similar conclusions must be drawn for several other derivatization reagents.

Chemical derivatization reactions of nitrogen plasma‐treated surfaces with aromatic aldehydes, such as the prototypic 4‐trifluoromethyl‐benzaldehyde (TFBA), have for a long time been considered selective for primary amines. Results of an in situ study using FTIR‐ATR spectroscopy challenge the validity of this assumption: Modification of polyethylene surfaces by afterglows of dielectric barrier discharges in nitrogen–hydrogen mixtures with subsequent hydrogen/deuterium exchange or TFBA derivatization suggests that the latter does not follow the commonly assumed reaction scheme.

Various new plasma‐based surface technological processes are made feasible by localizing atmospheric‐pressure discharges to predefined volumes with sub‐millimeter linear dimensions. So‐called Plasma Printing processes use cold discharges in microcavities formed temporarily by contacting a substrate with a suitably designed kind of plasma stamp. Aside from dielectric barrier discharges driven by mid‐frequency (MF) AC voltages, cold microplasmas can also be sustained in arrangements without a dielectric barrier, if RF excitation is used. The modification or coating of internal surfaces in already sealed microfluidic systems promises the achievement of a wide range of physico‐chemical surface properties which are difficult to attain by wet‐chemical or low‐pressure plasma processes. Using a proper electrode arrangement, the coating or modification can be localized to a selected segment of a microfluidic system.magnified image

Microplasma stamps based upon the principle of dielectric barrier discharges are applied to a new type of area‐selective surface modification process at atmospheric pressure. This process integrates the surface treatment and lateral microstructuring within one process step. For this purpose, the plasma is ignited in cavities which are formed temporarily by compressing the microplasma stamp and the substrate to be treated. In this work, we investigate the influence of the cavity design and the ignition conditions on the surface treatment. Furthermore, peptide synthesis on area‐selectively treated poly(propylene) surfaces is presented as an application.

An environmentally friendly plasma amination process for the activation of polymers prior to electroless metallization using dielectric barrier discharges (DBD) at atmospheric pressure was investigated. One focus of the work was on the correlation between plasma parameters and palladium coverage on the polymer on the one hand and the palladium coverage and adhesion of a galvanic copper metallization on the other hand. Using XPS spectroscopy it was found that a DBD treatment of polyimide (PI) films with mixtures of N2 and H2 leads to considerably higher Pd surface concentrations than on untreated reference samples or foils treated in air‐DBD. The Pd coverages achieved result in peel strengths of a copper metallization of up to 1.4 N · mm−1.