PEO-grafting on PU/PS IPNs for enhanced blood compatibility--effect of pendant length and grafting density

Polyurethane (PU) homopolymers and PU/polystyrene (PS) interpenetrating polymer networks (IPNs) were successfully synthesized changing the length of the pendant poly(ethylene oxide) (PEO) chains and the grafting density of PEO chains. All the PU/PS IPNs had the microphase-separated structures in which the PS-rich phase domains were dispersed in the matrix of the PU-rich phase. The domain size decreased a little, as the degree of grafting with PEO chains was increased. The water swelling ratio increased, and the interfacial energy decreased, as the length of the pendant PEO chains, and the grafting density of PEO chains of the PEO-grafted PU/PS IPNs were increased, since the mobile hydrophilic pendant PEO chains effectively induced and absorbed the water, when they were contacted with water. The hydrophilic and highly concentrated pendant PEO chains could easily prohibit the adhesion of the fibrinogens and the platelets on the surface, and the blood compatibility of IPNs was enhanced by increasing of grafting with PEO chains. The adsorption of the fibrinogens and the platelets was suppressed, as the length of pendant PEO chains, and the grafting density were increased.