Modification of Si(100) surface by plasma-enhanced graft polymerization of allylpentafluorobenzene

Hydrophobic fluoropolymer thin films were deposited on Si(100) substrates by plasma polymerization of allylpentafluorobenzene (APFB) under different glow discharge conditions, and in the presence and absence of Ar plasma pre-activation of the substrate surfaces. The FTIR and X-ray photoelectron spectroscopy (XPS) results suggested that the plasma polymerization proceeded mainly through the C=C bond of APFB, and the fluorinated aromatic structure in the deposited polymer films was preserved to different extents, depending on the radio-frequency (RF) power used for plasma polymerization. The use of a low RF power (∼5 W) readily resulted in the deposition of thin films having nearly the same fluorinated aromatic structure as that of the APFB homopolymer. For the plasma-polymerized APFB (pp-APFB) films deposited on the Ar plasma-preactivated Si(100) surfaces, solvent extraction results suggested that the pp-APFB films became covalently tethered onto the silicon substrate surfaces. Thermogravimetric (TG) analysis results indicated that the thermal stability of the pp-APFB films had been enhanced substantially after annealing at 270°C in a vacuum oven.