Control of surface wettability for inkjet printing by combining hydrophobic coating and plasma treatment

We have obtained a wide range of surface wettabilities of PI substrate for inkjet printing by combining hydrophobic solution coating and O-2 or Ar plasma treatments. Experiments were conducted to investigate the variation in inkjet-printed dot diameters with different surface treatments. The change in chemical and physical characteristics of treated surfaces was evaluated using static contact angle measurements, field emission scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Only hydrophobic coated surface produces the smallest dot diameter and the largest contact angle. Dot diameter increases and contact angle decreases as the plasma treatment time increases. Since the removal of hydrophobic layer from the surface occurs due to the etching effect of O-2 and Ar plasma during the plasma treatments, F/C ratio decreases with increasing the plasma treatment time. Surface roughness variations are also observed after plasma treatments. The ranges of printed dot sizes for O-2 and Ar plasma treatments are 38 mu m-70 mu m and 38 mu m-92 mu m, respectively. Ar plasma treatment shows a wider range of surface wettability because of higher removal rate of the hydrophobic layer. This combination of hydrophobic coating and plasma treatment can offer an effective way to obtain a wide range of surface wettabilities for high quality inkjet-printed patterns. (C) 2013 Elsevier B.V. All rights reserved.