Deposition of Water Stable Plasma Polymerized Acrylic Acid/MBA Organic Coatings by Atmospheric Pressure Air Plasma Jet

Water stable plasma polymerized acrylic acid/methylene-bis-acrylamide (ppAA/MBA) thin films have been deposited with an atmospheric pressure air plasma jet, a fast technique to grow organic thin films. To increase the stability of the coatings, a cross-linking agent (MBA) was added to the precursor (AA), which was introduced with a home-made spraying system. The jet speed and pulse frequency of the discharge were investigated regarding the properties of the coatings. Two types of materials were obtained: in low energy conditions (high jet speed and low frequency) the films presented a water-soluble part with a certain organized structure. When more energy is supplied to the growing films, a more polymerized material with a more amorphous structure is obtained. Increasing the energy further leads to the deposition of a more cross-linked film with a better stability to water. In optimized conditions, no weight loss and no significant chemical change were noticed after soaking in water.