Functional Polyesters for Biomedical and Industrial Applications

Advances in polymer science impact a range of materials applications, from medical technology to commodity plastics. This dissertation describes the development of radiopaque biomaterials and supramolecular engineering polymers accomplished via synthesis, characterization, and elucidation of the structure-property relationships of functionalized polyesters. Computed tomography (CT) generates detailed images for diagnosing diseases and monitoring implants. While metallic implants are easily visualized by CT, polymeric implants, absent of high Z elements, lack radiocontrast. Nevertheless, replacing metal-based implants with polymeric materials has many advantages: biodegradability, increased biocompatibility, and tunable thermal and mechanical properties. Additionally, blood pool imaging utilizes CT contrast agents, which are rapidly excreted and renally toxic. Designing polymeric biomaterials capable of long-lasting x-ray contrast could lead to safer, more effective implants and contrast agents. In Chapters 2 and 3, a single iodinated monomer was used to synthesize and evaluate a variety of aliphatic, radiopaque polyesters. These polymers exhibited high radiocontrast, tunable thermal and mechanical properties, low cytotoxicity, and they were easily processed into both nanoparticles and thermosets. The nanoparticles showed good continual contrast with no uptake into the kidneys. Additionally, copolymer thermosets served as stable, biocompatible and degradable, inherently radiopaque shape memory materials. While the functionalization of a unique monomer was highlighted in the first part, Chapter 4 focuses on polyester endgroup functionalization. The benefits of supramolecular polymers include recyclability, self-healing, and processability. While the effect of the supramolecular ureidopyrimidinone (UPy) endgroup has been investigated on many low-performing polymers, this moiety has not been broadly investigated with higher performance materials. High molecular weight engineering plastics have excellent mechanical properties, but they can be difficult to process. By end-functionalizing low molecular weight engineering polymers with a supramolecular moiety, issues involving processability could be overcome while maintaining robust mechanical properties. Herein, the structure-property relationships of end-functionalized glycol-modified poly(ethylene terephthalate) (PETG) of various molecular weights were investigated using the UPy group and various linkers. By taking advantage of the unique thermal properties of PETG, this system serves as the first example of a supramolecular engineering polymer with enhanced thermal and mechanical properties that also shows improved melt viscosity at temperatures suitable for non-degradative processing.