Durable and hydrophobic surface modification by plasma polymers deposited from acetylene/hexafluoroacetone ethylene/hexafluoroacetone, and ethane/hexafluoroacetone mixtures

Plasma polymerization of mixtures of ethane/hexafluoroacetone (HFA), ethylene/HFA, and acetylene/HFA deposit hydrophobic and thin films. The IR and XPS measurements of the deposited films show that fluorination with HFA occur to yield hydrophobic plasma films which possess CF3, CF2, and CF moieties. The advancing contact angle of water on the surface of the deposited films increases with increasing the HFA concentration, especially plasma polymer films prepared from the acetylene/HFA mixture (87.5 mol % HFA) show an advancing contact angle of 126 degrees. Such high hydrophobicity of the plasma polymer surface is attributed to high concentration of fluorinated carbons, especially CF3 side groups. The CF3 concentration in the plasma polymers reach about 30 mol % of the total carbon units. These surfaces show no change in advancing contact angle even when stored in a moist atmosphere of 60% RH at 20°C for at least 2 weeks.