Browsing by Subject "Soft Materials"
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Item Open Access Development and Characterization of Mechanically Robust, 3D-Printable Photopolymers(2017) Sycks, Dalton3D printing has seen an explosion of interest and growth in recent years, especially within the biomedical space. Prized for its efficiency, ability to produce complex geometries, and facile material processing, additive manufacturing is rapidly being used to create medical devices ranging from orthopedic implants to tissue scaffolds. However, 3D printing is currently limited to a select few material choices, especially when one considers soft tissue replacement or augmentation. To this end, my research focuses on developing material systems that are simultaneously 1) 3D printable, 2) biocompatible, and 3) mechanically robust with properties appropriate for soft-tissue replacement or augmentation applications. Two systems were developed toward this goal: an interpenetrating network (IPN) hydrogel consisting of covalently crosslinked poly (ethylene glycol) diacrylate (PEGDA) and ionically crosslinked brown sodium alginate, and semi-crystalline thiol-ene photopolymers containing spiroacetal molecules in the polymer main-chain backbone. In addition to successfully being incorporated into existing 3D printing systems (extrusion-deposition for the PEGDA-alginate hydrogel and digital light processing for the thiol-ene polymers) both systems exhibited biocompatibility and superior thermomechanical properties such as tensile modulus, failure strain, and toughness. This work offers two fully-developed, novel polymer platforms with outstanding performance; further, structure-property relationships are highlighted and discussed on a molecular and morphological level to provide material insights that are useful to researchers and engineers in the design of highly tuned and mechanically robust polymers.
Item Open Access Tensile Fatigue Characterization of High Strength Hydrogels for Soft Tissue Applications(2021) Koshut, William JosephSynthetic cartilage implants have the potential to deeply transform the treatment of articular cartilage degeneration as well as the progression of osteoarthritis in load-bearing applications of various joints in the human body. To reduce patient morbidity and enhance range of motion, surgeons and material scientists alike are looking to synthetic alternatives re-establish articular cartilage function without introducing higher cost and health burdens. These implants are rigorously tested for their compressive and wear properties over longer timeframes, with the first instance of approved human use coming in the 1st metatarsophalangeal (MTP) joint with poly(vinyl alcohol) (PVA) being the predominant polymer in composition. Despite their promise of dissipating stress and providing smooth joint movement, these synthetic cartilage implants are not well-studied for their tensile fatigue properties which are extremely critical to in vivo performance and implant survival. As a synthetic substitute to match the properties of cartilage in human beings, hydrogels are extensively researched due to their potential biocompatibility. This research describes work dedicated to the advanced mechanical study of synthetic hydrogel systems for cartilage-based applications. The materials of interest are designed to have enhanced monotonic tensile properties for supplementary investigation via tensile fatigue testing. Superior mechanical behavior was achieved through the use of bio-friendly additives, freezing-thawing cyclic processing, and fiber reinforcement. Lastly, the long-term failure mechanisms through flaw development for these synthetic hydrogel systems and biological tissue will be explored.