Wetting Characteristics of Plasma-Modified Porous Polyethylene

This paper examines the wetting characteristics of porous polyethylene surfaces modified by exposure to reactive oxygen glow discharge gas plasma, through the direct measurement of the wicking properties of the modified material. It is well-known that oxygen plasma can be used to chemically alter the surface of polyethylene to enhance wetting properties. Chemical and physical modification of a polymer's surface is the consequence of reactions initiated by the collision of high-energy species in the plasma with the polymer surface. The conditions of the plasma treatment, such as electric field strength (power), exposure time, and chamber pressure, govern the frequency and energy of collisions and, thus, determine the nature and degree of the chemical modification of the polyethylene surface. Comparisons of the chemical modification of sintered porous polyethylene surfaces achieved through treatments with reactive oxygen glow discharge gas plasmas generated at various powers, chamber pressures, and times of exposure were made by measuring the wicking rate of distilled and deionized water in the modified materials. A strong correlation was observed between the electric field power used to generate the plasma and the degree of chemical modification of the polyethylene surfaces. In addition, the rate of chemical modification was also found to be a function of the electric field power.