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

Abstract

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.

Shape memory polymers with enhanced visibility for magnetic resonance- and X-ray imaging modalities

“…[31–32] TEA, HPED and TMHDI were reacted to form a prepolymer prior to foaming. The isocyanate index of this prepolymer (NCO/OH ratio) was approximately 2.5; the prepolymer was cured at 50°C for 36 hours to increase viscosity and network formation prior to foaming.…”

“…[31] Dynamic mechanical analysis (DMA) was performed using a Q800 TA DMA (TA Instruments, New Castle, DE) were equilibrated at 20°C for 15 minutes and then ramped to 120°C at a rate of 2°C/min for dry samples, and wet samples were equilibrated at 25°C and then ramped at a rate of 1° C/min to 70°C. [31] Thermogravimetric analysis (TGA) using the TA Q50–0408 (TA Instruments, New Castle, DE) was performed on samples (12.5 mg +/− 2.5mg) by heating from room temperature to 500°C at 20°C/min. [31] Specific heating cycles are discussed in greater detail in Supplemental Materials.…”

“…[31] Thermogravimetric analysis (TGA) using the TA Q50–0408 (TA Instruments, New Castle, DE) was performed on samples (12.5 mg +/− 2.5mg) by heating from room temperature to 500°C at 20°C/min. [31] Specific heating cycles are discussed in greater detail in Supplemental Materials.…”

“…[31, 33–34] The samples were cut to 6 mm in diameter and 1 cm in length. The samples were then threaded over wire radially compressed to the smallest possible diameter (approximately 1 mm) using a ST 150–42 stent crimper (Machine Solutions, Flagstaff, AZ).…”

“…Volume expansion was calculated using Equation 1, and volume recovery was calculated using Equation 2. [31,33–34]…”