Comparative Study on Silicone Water-Repellent for Hydrophobic Coating by Atmospheric Pressure Plasma

Abstract

The application of silicone water repellents to hydrophobic coatings by atmospheric pressure plasma (APP) generated by dielectric barrier discharge (DBD) was investigated. We compared the effects of silicone water repellent on hydrophobic coatings, the input energy density estimated from the voltage-current waveform, and the excitation temperature from the argon line of the measured optical emission spectrum. Hexamethyldisiloxane (HMDSO), KF-96 or KF-99, mixed with argon gas, was supplied as a silicone water repellent to the DBD reactor. The results showed that the irradiated samples became hydrophobic in all cases. Comparing the contact angles of these samples, the contact angle using KF-96 plasma became highly hydrophobic faster than the other conditions. The input power densities to the plasma were about 20 mW/cm² for KF-96 and KF-99, and 80-110 mW/cm² for HMDSO. The excitation temperature of argon was 0.9 eV for KF-99, 1 eV for KF-96, and 1.3-2 eV for HMDSO. It reveals that KF-96 is a better silicone water repellent on hydrophobic and input power density than HMDSO.