HIGH-MOLECULAR-WEIGHT POLYURETHANES AND A POLYURETHANE UREA BASED ON 1,4-BUTANEDIISOCYANATE

New biomedical polyurethanes and a polyurethane urea based on epsilon- caprolactone and 1,4-butanediisocyanate have been developed. On degrad ation, only non-toxic products are produced. The polyurethane urea wit h poly(epsilon-caprolactone) soft segments and butanediisocyanate/buta nediamine hard segments shows a high tensile strength, a high modulus and a high resistance to tearing but as a result of the strong interac tions between the solvent and the polymer processing is difficult. Whe n butanediamine is replaced by butanediol in the chain extension step, a processible polyurethane is obtained but the polymer lacks the desi red mechanical properties for biomedical applications. By chain extend ing with a longer urethane diol block, a processible polymer was obtai ned with mechanical properties comparable to the polyurethane urea. Th is polyurethane has been made porous and can be used as a meniscal pro sthesis.