| dc.description.abstract | Shape memory polymers are a class of smart materials that have the capability to transition from a mechanically programmed secondary shape to their original shape. This unique shape change behavior is useful for medical applications such as sutures and self-expanding stents. Polyurethane SMP foams have been studied as an implantable material for embolic applications due to their high surface area to volume ratio, known biocompatibility, and tunable mechanical properties. Passive actuation of SMP foam in physiological conditions is dependent on factors such as hydrophobicity and transition temperature of the polymer, which affect plasticization by water and shape recovery.
This research focuses on altering the chemical structure of the foam matrix to control the glass transition temperature (Tg) and actuation time. Incorporation of nano-fillers into the foam matrix was used to induce radio-opacity and enhance mechanical properties such as toughness and tensile strength. Further, the effect of filler concentration and dispersion within the liquid phase on mechanical toughness was evaluated. Lower filler concentrations yielded nanocomposites with improved mechanical properties and thermal stability, with tunable actuation profiles and shape recovery.
Control over the cell morphology was achieved by synthesizing a siloxane-glycol amphiphile to serve as a foaming surfactant. Changes in foam morphology and cell size due to changes in chemical structure and concentration of the surfactant were studied. This work provided enhanced control over the foam morphology and the chemical, thermal, and mechanical properties of the SMP foam for use in medical applications, specifically as vascular embolic agents. | en |
