Surface immobilization of poly(ethylene oxide): Structure and properties

We covalently immobilized poly(ethylene oxide) (PEO) chains onto a fluorina ted ethylene propylene copolymer (FEP) surface. On the FEP surface, aldehyd e groups were first deposited by plasma polymerization of acetaldehyde or a crolein. Then, amino-PEO chains were immobilized through Schiff base format ion, which was followed by reduction stabilization with sodium cyanoborohyd ride. The PEG-grafted polymer surfaces thus prepared were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, contact-an gle measurements, and protein adsorption. The dramatic increase in the C-O intensity of the high-resolution XPS C 1s spectrum, together with an overal l increase in oxygen content, indicated the successful attachment of PEO ch ains onto the acetaldehyde plasma surfaces. The amount of grafted PEO chain s depended on the superfacial density of the plasma-generated aldehyde grou ps. The grafted monoamino-PEO chains formed a brushlike structure on the po lymer surface, whereas the bisamino-PEO chains predominately adopted a loop like conformation. The PEO surface had a regular morphology with greater ro ughness than the aldehyde surface underneath. Surface hydrophilicity increa sed with the grafting of PEO. Also, the bisamino-PEO-grafted surface had sl ightly higher surface hydrophilicity than its monoamino-PEO counterpart. Th ese PEO coatings reduced fibrinogen adsorption by 43% compared with the sub strate FEP surface. (C) 2000 John Wiley & Sons, Inc.