Mechanisms of hydrophobization of polymeric composites etched in CF₄ plasma

Achieving optimal hydrophobicity of polymer materials especially polymer–matrix composites is important for many material applications. Herein the interplay of factors determining hydrophobic surface is presented during CF₄ plasma treatments which lead to functionalization as well as selective polymer–matrix etching. The continuous exposure to plasma reactive species induces functionalization and etching on the surface, which decides the surface morphology and surface chemistry. Consequently, exothermic processes during the plasma–surface interactions are another important factor which influences the surface chemistry and etching rate of the material. The results demonstrate that despite etching and increasing surface roughness, the major contribution to hydrophobic character is dependent on the number of carbon atoms populated with fluorine, whereas the temperature is a deciding factor for type of created bonds.