DEPOSITION AND PROPERTIES OF HYDROPHILIC FILMS PREPARED BY PLASMA POLYMERIZATION OF AR/N-HEXANE/H2O

Plasma polymer films were prepared using a direct current (de) discharge operated in a working gas mixture Ar/n-hexane/H2O. Langmuir probe measurements were used to characterize the discharge conditions. The plasma polymer films were deposited on a plasma polymer of Ar/n-hexane that served as a model polymer surface to be modified for wettability. This was found to increase (as observed by contact angle measurement using an air bubble method) with the increase of water vapour concentration in the Ar/n-hexane/H2O working gas mixture. Deposition rate was determined using a quartz crystal microbalance. The rate became negative, i.e. etching (ablation) of model polymer surface took place at low n-hexane concentrations. Plasma polymer film structure and composition were studied by FTIR and ESCA and showed an increase of polar groups in a film when water vapour increased in a working gas mixture during deposition. SEM micrographs appear to confirm that films are predominantly structureless.