A new biomedical polyurethane with a high modulus based on 1,4-butanediisocyanate and epsilon-caprolactone

A new approach to the synthesis of biomedical polyurethanes based on epsilon-caprolactone and 1,4-butanediisocyanate with a high modulus, has been developed. By chain extending an epsilon-caprolactone prepolymer with a long uniform-size diisocyanate block, a segmented polyurethane with uniform-size hard segments was obtained. It shows excellent mechanical properties; an extremely high modulus of 105 MPa and a tensile strength of 35 MPa. The polymer is soluble at high concentrations in various volatile solvents such as chloroform and 1,4-dioxane. By a combination of salt-leaching and freeze-drying, porous materials have been obtained in which macropores ranging in size from 150-300 microm are highly interconnected by micropores. The material shows a sufficiently high compression modulus of 200 kPa and appears to be suitable for biomedical applications such as meniscal prostheses.