Blood compatibility of hydrophilic polyurethane and hydrophobic polystyrene IPNs

Abstract

Effect of the degree of phase separation in PU/PS IPNs on blood compatibility was investigated. The degree of phase separation was controlled by varying the synthesis pressure and the chemical affinity between PU and PS components. Two types of polyurethane were synthesized to vary the chemical affinity. One is using poly(ethylene glycol), the other is using poly(tetramethylene ether)glycol as the polyol component in the PU synthesis. The synthesis pressure was varied from atmospheric up to 5,000kg/㎠. All IPNs exhibited microphase separated structure with PS domain dispersed in continuous PU matrix. PS domain sizes decreased as synthesis pressure increased. Dielectric relaxation and DSC analysis demonstrated enhanced intermixing between two component networks as synthesis pressure was increased. Water swelling ratio decreased as synthesis pressure was increased, which indicates reduced hydrophilicity of IPNs synthesized under high pressure. With increase in synthesis pressure, underwater contact angle decreased and surface-water interfacial energy increased. The number of adhered platelets on PU/PS IPN surfaces decreased, and the platelet deformation was reduced as the domain size decreased. Among IPNs investigated in this study, PTMG based PU/PS IPNs synthesized at 5,000kg/㎠(TX5000) showed the lowest platelet adhesion and deformation, the smallest PS domain size(less than 0.01㎛)and the highest surface-water interfacial energy.