Modification of hydrophilic/ hydrophobic IPNs for enhanced blood compatibility and endothelial cell culture

Abstract

Hydrophilic polyurethane (PU)/ hydrophobic polystyrene (PS) interpenetrating polymer networks (IPNs) were structurally modified for enhanced blood compatibility and endothelial cell culture. Three modification tools were used for enhanced blood compatibility: First, the morphological pattern of PU/ PS IPNs was changed by controlling the polymerization rate and the phase separation kinetics. Second, the PEO chains were grafted on PU/ PS IPNs. Third, the synthesis temperature was controlled to diminish the domain size of PEO-grafted PU/ PS IPNs. Otherwise, the amphiphilic balance of all PS IPNs was controlled, and the collagen immobilization was performed to enhance the adhesion and growth of the human endothelial cells on PU/ PS IPNs. Polyurethane (PU)/ polystyrene (PS) IPNs were simultaneously synthesized at 80 C , controlling the reaction kinetics to change the morphology. Polymerization kinetics of styrene was controlled by the content of initiator, and that of polyurethane by the catalyst concentration. The in-vitro blood-compatibility tests showed that the surface roughness was an important factor on the adsorption of fibrinogens, and platelets. PU/ PS IPNs were grafted with poly(ethylene oxide) (PEO) for enhanced blood compatibility. PEO-grafted PU/ PS JPNs were successfully synthesized changing the length of the pendant PEO chains and the distance between the PEO chains. The hydrophilic and highly concentrated pendant PEO chains could easily prohibit the adsorption of the fibrinogens and the adhesion of the platelets on the surface. The adsorption of the fibrinogens and the platelets was suppressed, as the length of pendant PEO chains, and the grafting density were increased. The effect of the pendant PEO chains on the surface properties of PEO-grafted PU/ PS IPNs was successfully characterized by using AFM techniques recently developed. The compositional mapping showed that the area fraction of the hydrophilic PU-rich phase increased as the PEO-grafting ...