Fabrication and Characterization of Electrospun Shape Memory Polymer Polyurethane for Biomedical Applications

Abstract

The ability to treat complex medical issues often requires dynamic and versatile biomaterials. Electrospinning is a fabrication technique which enables this type of material through anisotropic mechanical properties, high surface area, and tunable morphologies. This technique enables the production of nano-/microfibers that can mimic the extracellular matrix of various biological tissues. The dynamic response of electrospun materials is broadened with the use of shame memory polymers (SMPs). SMPs are a unique class of polymer which allow for shape change in response to external stimuli. This response can be tuned such that biological conditions, such as body heat, can be the trigger. These materials have already demonstrated their benefit through applications such as shape memory foams for occlusion applications. The combination of the electrospinning fabrication technique with shape memory polymers enables the creation of materials with unique and novel properties that can be beneficial for biomedical applications. Here, we present the fabrication and characterization of an electrospun polyurethane which exhibits the shape memory effect. This system utilizes a click-chemistry crosslinking technique which allows for fabrication in a thermoplastic state with post-fabrication crosslinking into a thermoset for improved mechanical and shape memory properties. We first investigate the parameters important to the electrospinning process as it relates to this polymer system through a design of experiments approach. With the appropriate parameters established, the mechanical and shape memory properties of electrospun materials are evaluated. In relation to this testing, we present a novel technique to improve photoinitiated crosslinking for electrospun materials through mild swelling that preserves fibrous morphology. Finally, degradation and cytotoxicity testing are performed to help determine the material fitness for biomedical applications. Combined, these studies provide a framework to determine appropriate uses of this material. A material with these properties is potentially beneficial for various medical applications, such as vascular anastomosis or tendon repair.