Nitrogen Plasma Modification and Chemical Derivatization of Polyethylene Surfaces - An In Situ Study Using FTIR-ATR Spectroscopy

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. In situ FTIR‐ATR spectroscopy of polyethylene surfaces modified in afterglows of barrier discharges in nitrogen–hydrogen mixtures confirms that aromatic aldehydes may not be considered as chemical derivatization reagents with selectivity for primary amino groups on the surface. Applying H/D exchange and TFBA derivatization, respectively, to the plasma‐modified surfaces two arguments are derived to support this statement.