Fabrication of Shape Memory Polymer Nanocomposite Foams with Surface Modified Nanoparticle Fillers

Abstract

Every year, 30,000 individuals in the United States will suffer from a ruptured cerebral aneurysm. The Biomedical Device Laboratory seeks to improve on current aneurysm treatment by using a low-density, high-volume shape memory polymer (SMP) polyurethane foam-over-coil device to fully occlude aneurysms via minimally invasive surgery using a microcatheter. Due to the SMP foam’s low density, it is susceptible to tearing, which would be a serious adverse event during aneurysm treatment. The potential for tearing can be reduced by improving the foam’s mechanical properties. Incorporating aluminum oxide nanoparticle filler into the foam has been previously shown to improve mechanical properties, but the limited bonding between the nanoparticles and the polymer may cause excessive particulate leaching. Bonding between the nanoparticles and foam can be improved by altering the surface chemistry of the nanoparticles by applying a silane coupling agent. Nanoparticles modified with a silane coupling agent can form a strong urea linkage with the polyurethane foam that improves upon the secondary bonding of unmodified nanoparticles with the polyurethane foam. This increased bonding is hypothesized to improve the foam’s mechanical properties and decrease the potential for excessive particulate leaching as compared to foams loaded with unmodified nanoparticles.