On imparting radiopacity to a poly(urethane urea)

A poly(urethane urea) (PUU) synthesized from 2,4-toluene diisocyanate (TDI) and polyethylene glycol (PEG) with ethylenediamine (ED) as the chain extender was rendered radiopaque by attaching 3,4,5-triiodobenzoic acid (TIB) onto the polymer backbone. The radiopaque polyurethane obtained was characterized by infra red (IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-radiography. By optimizing the reaction conditions, it was possible to carry out the modification without adversely affecting the properties of the starting polymer significantly. IR spectral evidence suggested that the hydrogen bonded structure of PUU remained undisrupted even after modification. However, the product exhibited altered thermal characteristics when compared to the parent polymer. Degradation characteristics as observed from the TGA remained unchanged, while one of the glass transitions got shifted to a lower temperature. The observed changes in thermal characteristics were explained on the basis of possible inter-phase mixing and the changes in the close packing of the polymer chains by the introduction of bulky iodine atoms.