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Shape memory polymer foams have been used in a wide range of medical applications, including, but not limited to, vessel occlusion and aneurysm treatment. This unique polymer system has been proven to shape-fill a void, which makes it useful for occlusion applications. While the shape memory polymer foam has superior performance and healing outcomes compared to its leading competitors, some device applications may benefit from longer material degradation times, or degradation-resistant formulations with increased fibrous encapsulation. In this study, biostable shape memory polymer foams were synthesized, and their physical and chemical properties were characterized as an initial evaluation of feasibility for vascular occlusion applications. After characterizing their shape memory behavior in an aqueous environment, degradation of this polymer system was studied in vitro using accelerated oxidative and hydrolytic solutions. Results indicated that the foams did not lose mass under oxidative or hydrolytic conditions, and they maintained high shape recovery in aqueous in vitro models. These degradation-resistant systems have potential for use in vascular occlusion and other wound healing applications that benefit from permanent, space-filling shape memory behavior.

Porous shape memory polymers (SMPs) exhibit geometric and volumetric shape change when actuated by an external stimulus and can be fabricated as foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. These materials have applications in multiple industries such as textiles, biomedical devices, tissue engineering, and aerospace. This review article examines recent developments in porous SMPs, with a focus on fabrication methods, methods of characterization, modes of actuation, and applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1300–1318

Shape memory polymer (SMP) foams were synthesized with three different nanoparticles (tungsten, silicon dioxide, and aluminum oxide) for embolization of cerebral aneurysms. Ultra-low density SMP foams have previously been utilized for aneurysm occlusion, resulting in a rapid, stable thrombus. However, the small cross section of foam struts can potentially lead to fracture and particulate generation, which would be a serious adverse event for an embolic device. The goal of this study was to improve the mechanical properties of the system by physically incorporating fillers into the SMP matrix. Thermal and mechanical characterization suggested minimal changes in thermal transition of the SMP nanocomposites and improved mechanical strength and toughness for systems with low filler content. Actuation profiles of the three polymer systems were tuned with filler type and content, resulting in faster SMP foam actuation for nanocomposites containing higher filler content. Additionally, thermal stability of the SMP nanocomposites improved with increasing filler concentration, and particulate count remained well below accepted standard limits for all systems. Extraction studies demonstrated little release of silicon dioxide and aluminum oxide from the bulk over 16 days. Tungstun release increased over the 16 day examination period, with a maximum measured concentration of approxiately 2.87 μg/mL. The SMP nanocomposites developed through this research have the potential for use in medical devices due to their tailorable mechanical properties, thermal resisitivity, and actuation profiles.