Incorporation of amino moieties through atmospheric pressure plasma: Relationship between precursor structure and coating properties

Parallel plates dielectric barrier discharge (DBD) at atmospheric pressure has been used to investigate the introduction of amino groups on a polypropylene substrate. For this purpose the plasma polymerization of aminopropyl triethoxysilane, trimethoxysilylpropyl ethylenediamine, allylamine, butylamine, ethylenediamine, and nitrogen/ammonia has been systematically studied and compared. The coatings have been characterized through wettability measurements, interferometry, labeling coupled with X-ray photoelectron spectroscopy, and IR spectroscopy. Significant hydrophilicity enhancement of the polypropylene substrate has been observed for butylamine, ethylenediamine or allylamine, with a surface energy up to 76 mN.m−1. Higher reactivity in the plasma is observed for trimethoxysilylpropyl ethylenediamine which also gives rise to the maximum final amino group concentration of about 6 at.%. According to the choice of the precursor, surface properties can be tuned in terms of polarity, coating composition, and coating thickness.