Ion-assisted vapor deposition of acryl polymer thin films

Polymer thin films were prepared by an ion-assisted vapor deposition polymerization method that involves physical vapor deposition of monomer combined with low-energy ion irradiation. In a high vacuum environment, zinc diacrylate monomer was evaporated at a rate of 0.8 nm/min on gold-coated glass substrates under simultaneous irradiation by nitrogen ions of 20 nA/cm2 at ion energy ranging from 500 to 2000 eV. The ion irradiation remarkably reduced the surface roughness of the deposited films. Infrared spectroscopy showed that the absorption bands of the vinyl group diminish with increasing ion energy. Formation of polymer molecules was confirmed by gel permeation chromatograph. Moreover, the film became insoluble to organic solvents when the ion energy was increased. These results indicate that polymer thin films can be prepared by vapor deposition of monomers under ion irradiation. The ion-assisted vapor deposition polymerization was also possible on insulating substrates.