Calcium effect on the membrane preparation of segmented poly (ether/urethane/amide) (PEUN) as a biomedical material

Poly(ether/urethane/amide) (PEUN), a segmented polyurethane, was characterized concerning phase relationship, viscosity in solution, hydraulic permeability, mechanical properties, and in vivo biocompatibility with tissue and blood. PEUN was dissolved at the highest concentration of 0.5% in N,N-dimethylformamide (DMF). Addition of calcium chloride at concentrations up to 3.1% progressively increased the solubility of PEUN in DMF. PEUN2 membrane was prepared by casting from mixtures of PEUN, 3% calcium chloride, and DMF, from which calcium chloride was sufficiently removed. The PEUN2 membrane thus obtained was compared with PEUN membrane which was prepared by casting from DMF solution without the addition of calcium chloride. The water permeability across PEUN2 membrane was higher than that across PEUN membrane. PEUN2 membrane in the swollen state exhibited a lower tensile modulus and much greater elastic property than PEUN membrane. Tissue compatibility of PEUN2 membrane was better than that of PEUN membrane. Thromboresistance of PEUN membrane was good, while PEUN2-coated surface was thrombogenic to some extent in vivo. Our characterization suggested that PEUN2 membrane is more hydrophilic than PEUN membrane, possibly because of the assembly of polar groups on the segments of PEUN molecules which show affinity to calcium chloride in membrane processing.