Polyurethane-maleamides for cardiovascular applications: synthesis and properties

Several polyurethane-maleamides (PUMAs) containing polyether or polycarbona te soft segments, and aromatic or aliphatic hard segments were synthesized by solution or bulk polymerization, using maleic acid (MA) or a mixture of MA and butanediol as chain extenders. Using this process, activated double bonds are introduced into the polymer chains and the base polyurethanes may undergo further modification via specific grafting, thus improving their t issue compatibility. PUMAs chemicophysical properties were evaluated by gel permeation chromatography (GPC), intrinsic viscosity analyses, differentia l scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-I R) and tensile mechanical tests. Polycarbonate diol (PCU)-based PUMAs showe d higher molecular weights than polyether diol (PEU)-based ones. The use of butanediol in mixture with maleic acid led to an increase of molecular wei ghts. FT-IR confirmed the presence of the bands related to the amide groups and to the conjugated double bond, yet more evident for the polymer obtain ed in solution. The higher crystallinity shown by this polymer was also ind icative of a better phase separation. All the PCU-PUMAs exhibited similar t ensile properties with a higher stiffness than PEU-PUMAs. Among the PEU-PUM As, the highest tensile properties were shown by the polymer obtained in so lution, and by the one derived from a mixture of maleic acid and butanediol . (C) 1999 Kluwer Academic Publishers.