Characterization of pulsed-plasma-polymerized aromatic films

Pulsed plasma polymerization is used to produce aromatic thin films from inductively coupled rf plasmas with benzene, 1,2,4-trifluorobenzene, and hexafluorobenzene as monomers. The effects of aromatic monomer fluorination and duty cycle variation on the resulting films' properties are examined. The surface and bulk properties of the films are determined using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), static contact angles, and differential scanning calorimetry (DSC). Analysis using these techniques shows a strong dependence of film chemistry and deposition rates on the plasma duty cycle. Systematic changes in film chemistry are observed with the lowest duty cycles producing films containing substituted aromatic rings. On the basis of the SIMS, XPS, and DSC data, films deposited under the optimal pulsed conditions are similar to polystyrene in structure but are more complex, somewhat cross-linked networks. These studies show pulsed plasma polymerization affords high control over film chemistry and properties.