Examination of radio-opacity enhancing additives in shape memory polyurethane foams

Three microparticle additives, tungsten (W), zirconium oxide (ZrO₂), and barium sulfate (BaSO₄) were selected to enhance the radio-opacity in shape memory polymer (SMP) foam biomaterials. The addition of filler causes no significant alterations of glass transition temperatures, density of the materials increases, pore diameter decreases, and total volume recovery decreases from approximately 70 times in unfilled foams to 20 times (4% W and 10% ZrO₂). The addition of W increases time to recovery; ZrO₂ causes little variation in time to shape recovery; BaSO₄ increases the time to recovery. On a 2.00 mean X-ray density (mean X.D.) scale, a GDC coil standard has a mean X.D. of 0.62; 4% W enhances the mean X.D. to 1.89, 10% ZrO₂ to 1.39 and 4% BaSO₄ to 0.74. Radio-opacity enhancing additives could be used to produce SMP foams with controlled shape memory kinetics, low density, and enhanced X-ray opacity for medical materials.