PLASMA-ENHANCED SURFACE MODIFICATION OF LOW LINEAR-DENSITY POLYETHYLENE CATHETERS

Modification of the surface chemistry, topography, and frictional characteristics of medical-grade low linear-density polyethylene catheters with various plasma chemistries was accomplished in a radio-frequency (RF) vacuum chamber. Two different types of plasma treatments were examined. For surface texturing and chemistry modification, the catheters were treated with either He or CF4 gases for 0.5-60 min at RF power in the range of 30-1000 W and working pressure between 0.2 and 2 Torr. For grafting of a low friction film, the catheters were exposed to pure Ar plasma at 400 W for 2 min (surface cleaning) and then to CH4, CH4/CF4, or H-2/CF4 plasmas at power of 250-550 W and working pressure of 0.2-0.8 Torr for 10-60 min (surface modification). The effects of the different plasma treatments on the surface texture, chemical behavior, and friction characteristics of the catheters are discussed in light of results obtained from contact surface profilometry, scanning electron microscopy, atomic force microscopy, contact angle measurements, infrared spectroscopy, and friction experiments. The findings of this study demonstrate that surface crosslinking and grafting of desirable functional groups by RF plasma treatment is an effective low-temperature surface modification technique for polymeric medical devices.