Modification of the Wettability of Plexiglas and Carbon by Means of Ion Beam Implantation: Application to Fluid Management and Materials Processing in Microgravity.

Abstract

In the absence of gravity, the behaviour of a liquid within a container will depend on its ability to wet the container. For instance, we evidenced that wetting property is involved in the propagation of perturbation, at the liquid-air interface. Because of perturbation in space, there is a strong interest in the modification of wetting properties for fluid management and materials processing in microgravity. The use of low energy (-500 eV) ion beams is attractive. Combining their low mean range (a few nm) and erosion rate, they are well suited for the modification at will of surface composition. Nitrogen, oxygen and neon ions of low energy were used to bombard the surface of plexiglas (polymethylmethacrylate or PMMA) and carbon samples at different fluences. Advancing and receding contact angles were measured before and after the implantation. A decrease of the contact angle as a function of the fluence of implanted ions was measured. A partial recovery of the contact angles as a function of time after the implantation was also observed. There was evidence that the long term value of the contact angles was influenced by the composition of the gas surrounding the samples. These results are discussed in terms of the development of a new technology for the modification at will of wetting properties of materials.