PLATELET-ADHESION ONTO SEGMENTED POLYURETHANE SURFACES MODIFIED BY PEO-CONTAINING AND SULFONATED-PEO-CONTAINING BLOCK-COPOLYMER ADDITIVES

Polyethylene oxide (PEG) surfaces were prepared by the addition of PEG -and sulfonated PEO-containing amphiphilic block copolymers as surface -modifying additives in a segmented polyurethane (PU). PEO-PPO-PEO tri block copolymers (Pluronics) with different PEO chain lengths (from 2 to 80) were used as additives. The prepared film surfaces were charact erized by the measurement of dynamic water contact angles and electron spectroscopy for chemical analysis. It was observed that the PU films containing 10 wt % of PEO additives were surface-saturated with the a dditives regardless of their PEO chain length, but the PEO chains were more projected from the film surfaces containing the additives with l onger PEO chains. The water absorption of the films increased largely with the increasing PEO chain length of the additives. The addition of PEO additives produced film surfaces that were in a gel-like state. T he films demonstrated some extraction of the PEO additives. However, t he additives with higher molecular weights were entrapped more stably into the PU matrix. The mechanical properties (tensile strength and el ongation) of the films were changed by the addition of PEO additives, but the differences were not significant compared to the control PU. T he platelet adhesion on the film surfaces decreased with increasing PE O chain length of the additives. The film surface containing additives with long PEO chains (chain length of 80) was particularly effective in preventing platelet adhesion. The effect of negatively charged sulf onate groups on the prevention of platelet adhesion appeared only on t he film surfaces containing additives with short PEO chains. For longe r PEO chains, the chain mobility effect was more dominant than the neg ative charge effect on the prevention of platelet adhesion. (C) 1998 J ohn Wiley & Sons, Inc.