METAL-ION IMPLANTATION EFFECTS ON SURFACE-PROPERTIES OF POLYMERS

Polyethylene (PE), polycarbonate (PC) and polyetherimide (PEI) have be en implanted with a variety of metallic ions from a metal vapor arc so urce at low energies yielding shallow depth implants. PC and PEI have been implanted with Cr, Ti, Si and Pt, while PE was implanted with Cr and Ti. Nanoindentation hardness and surface resistivity changes were measured for the implanted polymers. Results showed that the Ti and Si implantations caused similar hardness increases for PC and PEI while Cr implantation resulted in the largest hardness improvement for the t wo polymers. These effects were attributed to energy and dose effects. Pt implantation, on the contrary, had very little effect on hardness. This was attributed to a greater extent of chain scission caused by n uclear collisions by the heavy Pt ions than cross-linking caused by el ectronic excitation. In the case of PE, Ti and Cr yielded similar hard ness increases although the measured hardness values were smaller than those for PC and PEI. The implantations also decreased electrical res istivities of the polymers. Ti, Si and Cr implantations exhibited tren ds for a decrease in resistivity similar to those for the increase in hardness suggesting similar underlying causes, namely cross-linking. I t appears that irradiation-induced cross-links provide paths for incre ased mobility of carriers contributing towards decreased resistivity. Pt implantation yielded the largest increase in conductivity as a resu lt of the high dose used as well as the deposition of microdroplets of Pt which form at the metal ion source causing Pt to accumulate at the polymer surface leading to metallic conduction. This study represents the first use of a mixed energy spectrum of ion implantation to modif y surface properties of polymers.