Simple and Scalable Chemical Surface Patterning via Direct Deposition from Immobilized Plasma Filaments in a Dielectric Barrier Discharge.

In this work, immobilization of the often unwanted filaments in dielectric barrier discharges (DBD) is achieved and used for one-step deposition of patterned coatings. By texturing one of the dielectric surfaces, a discharge containing stationary plasma filaments is ignited in a mix of argon and propargyl methacrylate (PMA) in a reactor operating at atmospheric pressure. From PMA, hydrophobic and hydrophilic chemical and topographical contrasts at sub-millimeter scale are obtained on silicon and glass substrates. Chemical and physical characterizations of the samples are performed by micrometer-scale X-ray photoelectron spectroscopy and infrared imaging and by water contact angle and profilometry, respectively. From the latter and additional information from high-speed imaging of the plasma phase and electrical measurements, it is suggested that filaments, denser in energetic species, lead to higher deposition rate with higher fragmentation of the precursor, while surface discharges igniting outwards the filaments are leading to smoother and slower deposition. This work opens a new route for a one-step large-area chemical and morphological patterning of surfaces at sub-millimeter scales. Moreover, the possibility to separately deposit coatings from filaments and the surrounding plasma phase can be helpful to better understand the processes occurring during plasma polymerization in filamentary DBD.