Surface oxidation inside of macroscopic porous polymeric materials

We investigated the penetration power of reactive particles generated in oxygen containing plasmas into the pores of cylinders made of sintered polyethylene powder. The advancing of the pore wall oxidation was studied by water uptake measurements, XPS at the outside of the cylinder and at the cross-section after cutting, and dye staining after poly(ethylene imine) coupling. It was found that sintered objects with a size of 10 mm and an average pore size of 80 mu m can be oxidized homogeneously in less than 60 s. Objects with a pore size of 7 mu m can be penetrated to about 1.2 mm. We found that the maximum penetration depth is influenced only very little by the concentration of oxygen atoms in the treatment chamber. The pore size seems to be more important. (c) 2005 Elsevier B.V. All rights reserved.