A prerogative of plasma is the possibility of carrying out polymerization reactions by condensation of a chemical precursor, such as a liquid monomer, fluxed into plasma as vapor or aerosol. The application of nanometric thin films on numerous materials offers the possibility of extending the use of cold atmospheric pressure plasma to innumerable fields of application: from biomedical sensors to optoelectronic devices, with the advantage of working in an open environment without the use of expensive vacuum equipment.
The 27.12 MHz Dielectric Barrier Discharge configuration of the Nadir Plasma Jet offers many advantages compared to other atmospheric plasma devices on the market: an argon plasma rich in active species and cold (temperatures even lower than 40°C). The internal coaxial configuration guarantees an inert atmosphere around the plasma, which prevents unwanted oxidative reactions, that would risk damaging the chemical structure of the precursor. Furthermore, a central ceramic channel allows the transport of precursor vapors or aerosols directly into the plasma jet, so that condensation reactions favor the functionalization and growth of nano-coatings on the surface.
The Department of Industrial Engineering of the University of Trento, the Institute of Physics of Trento, and the Department of Physics of the University of Padua have published the results on the co-deposition of pp-n-hexane (plasma-polymerized-n- hexane) and ZnO nanoparticles in thin films on silicon substrate thanks to the Nadir Plasma Jet; thin coatings interesting for their optical properties. ZnO nanoparticles in solvent were transported in aerosol form and combined with n-hexane vapors, conveying them through the central channel to the plasma, in order to block the ZnO nanoparticles in a pp-n-hexane coating. It was thus possible to spread a thin film stable to most solvents using Plasma Jet. Another interesting result is the luminescence enhancement in the UV emission of ZnO nanoparticles caused by the passivation by encapsulation in pp-n-hexane.
