HYBRID BIOMATERIALS PREPARED BY OZONE-INDUCED POLYMERIZATION .1. OZONATION OF MICROPOROUS POLYPROPYLENE

We employed an ozone-induced grafting process to prepare membrane-hydr ogel hybrid biomaterials. Exposure of isotactic polypropylene to ozone resulted in surface oxidation, as detected by ESCA, and the formation of peroxides and hydroperoxides. The amount of oxygen-bearing moietie s, as detected by FT-IR, was increased when a microporous membrane wit h a large surface area was used. Ozonation for an extended period of t ime, 1-2 h, resulted in a degradation of microporous PP, observed with SEM as an enlargement of pores and brittle characteristics of the mat erial. The molecular weight of PP was dramatically reduced after as li ttle as 5 min of ozonation. Exposure to ozone for longer periods of ti me contributed to further reductions of the molecular weight and gradu al modification of chemical composition of polypropylene, restricted, however, to the surface or intercrystalline amorphous regions. It was possible to graft 2-hydroxyethylemthacrylate (HEMA) to the ozonated sa mples, such that the graft copolymer acted as continiuous matrix conse quently linked to and reinforced by the PP crystals. (C) 1997 John Wil ey & Sons, Inc.