Plasma Polymerisation

R. Förch

One way to functionalize polymer surfaces with specific reactive groups is by means of gas plasma treatment. This technique is of particular interest when materials with certain bulk properties needed for a specific application are to be modified, the surface of which, however, contain no or only a few reactive sites. The functionalization of a surface in a plasma process can be achieved either with a non-polymerizable gas such as nitrogen or oxygen, or with polymerizable gases. A polymerizable gas can, in principle, include any substance that can be brought into the gas phase at reduced pressure. Using an rf-discharge the molecules are then excited to form a range of reactive species. These react with one another and any surface groups to form a polymer film, the chemical structure of which is dependant on the process conditions employed.

For example, it has been found that pulsing the plasma in the millisecond regime is a very simple and unique method to control the film chemistry. Unlike the more conventional continuous wave plasma processes, pulsed plasma deposition allows the polymerization of monomers containing labile groups such as amines, ethers and anhydrides, to name but a few. The obtained overcoats can be used to further attach specific molecules by conventional wet chemistry techniques.

References

H. Schönherr, M.T. Van Os, R. Förch, R. B. Timmons, W. Knoll, G.J. Vancso: “Distribution of functional groups in plasma polymerised allylamine films by scanning force microscopy using functionalised probe tips”, Chem. Mater. 12, 3689-3694 (2002)
S. Schiller, J. Hu, A.T.A. Jenkins, R.B. Timmons, F.S. Sanchez-Estrada, W. Knoll, R. Förch: “Plasma polymerisation of maleic anhydride: film chemical structure and properties”, Chem. Mater. 14, 235-242 (2002)
A.T.A. Jenkins, J. Hu, Y.Z. Wang, S. Schiller, R. Förch, W. Knoll “Pulsed plasma deposited maleic anhydride thin films as supports for lipid bilayers”, Langmuir 16 (16), 6381-6384 (2000)