GRAFTING OF PEO TO POLYMER SURFACES USING ELECTRON-BEAM IRRADIATION

A new method was developed for binding poly(ethylene oxide) (PEO) to p olymer surfaces that involves the use of electron beam irradiation in two steps. In the first, methacrylic acid was grafted and polymerized to a polymer surface, changing it from hydrophobic to hydrophilic. Exp osure of this surface to aqueous PEO solutions resulted in strong hydr ogen bonding of the PEO, which was covalently grafted in a second radi ation step. The PEO grafts were stable; they could not be removed with extensive washing with water, soaking in basic solution, or gentle me chanical scraping. Both monolayers and multilayers of PEO were formed. The density of the monolayers were found to have little dependence on the molecular weight or concentration of the PEO solution; multilayer s could be controlled by varying the viscosity of the PEO solution and the method of application. The PEO-grafted monolayers were tested for their ability to prevent protein adsorption of cytochrome-c, albumin, and fibronectin. Monolayers of star PEO were the most effective, at b est showing a 60% decrease in adsorption from untreated controls. One million molecular weight-linear PEO monolayers were almost as effectiv e as star monolayers, and 35,000 g/mol linear PEO was bound too closel y to the surface, owing to its small size, to have much impact in prev enting protein adsorption. The reason for the continued protein adsorp tion was believed to be due to a close grafting of the PEO to the surf ace, as well as the grafted methacrylic acid chains being long enough to extend through the PEO monolayer, thus being accessible on the surf ace. (C) 1998 John Wiley & Sons, Inc.