Preparation and properties of a biomaterial: HEMA grafted SBS by gamma-ray irradiation.

Solvent-cast films of styrene-butadiene-styrene triblock copolymer (SBS) were synthesized and a poly(2-hydroxyethyl methacrylate) (PHEMA) layer was grafted onto these films using Co 60 gamma-ray irradiation. The IR absorption spectrum of the graft copolymer was taken and its surface morphology studied by a scanning electron microscope. The degree of grafting and the mechanical properties of SBS, SBS-g-HEMA, and PHEMA were measured. In order to study its biocompatibility, contact angle and blood clotting time experiments were performed. The degree of grafting was related to the soaking time, film thickness and total irradiation dosage. However, it levelled off at 7% when the total dosage reached 1 Mrad. It was found that the mechanical properties of SBS-g-HEMA were the same as those of SBS and were superior to those of PHEMA. The blood compatibility of SBS-g-HEMA as measured by the Lee-White clotting test was better than that of SBS and polystyrene and was quite similar to that of PHEMA.