Water wettability and zeta-potential of polystyrene surface modified by Ne or Na implantation

A study has been made of the modification of the wettability and the surface potential of polystyrene by ion bombardment and implantation. Substrates used were polystyrene (PS) dishes. Ne bombardment and Naion implantation were performed at energies of 50 and 150 keV with fluences between 1 x 10(14) to 1 x 10(17) ions/cm(2). The surface potential was examined by measurements of zeta-potential and the wettability was examined by the contact angle of water. The contact angle of water and the zeta-potential are found to change, depending on ion species and fluences. Two kinds of relationships between the contact angle of water and the zeta-potential are found, classified by region A and region B. From XPS results, region A means that PS surfaces modified by radiation effects of Ne-bombardment or Na-implantation have new functional groups and amorphous carbon. In region B, Na implanted PS surfaces with a high fluence show not only new functional groups and amorphous carbon but also Na atoms with chemical bonding states. (C) 1998 Academic Press.