Erik Brewer

Polyvinyl alcohol (PVA) is a synthetic polymer that is increasingly being used in biomedical applications due to its excellent biocompatibility, aqueous solubility, low toxicity, and tissue-mimicking properties. The physiochemical properties of PVA hydrogels are widely tunable and allow for a diverse range of tissue-specific applications and delivery methods. In this review, we evaluate the published information on the history of PVA with respect to its safety and efficacy as a biomedical device for orthopedic applications in articular cartilage, fibrocartilage, and intervertebral disc prosthesis. The review includes a classification of the mechanical properties, swelling mechanics, and lubricity and wear properties of the use of PVA in clinical applications, and in vitro and in vivo biocompatibility studies.

Multi-component polymer hydrogels present complex physiochemical interactions that make accurate compositional analysis challenging. This study evaluates three analytical techniques: Nuclear Magnetic Resonance (NMR), Advanced Polymer Chromatography (APC), and Thermogravimetric Analysis (TGA) to quantify polyvinyl alcohol (PVA) and polyethylene glycol (PEG) content in hybrid freeze-thaw derived PVA/PEG/PVP hydrogels. Hydrogels were synthesized using an adapted freeze–thaw method across a wide range of PVA:PEG ratios, with PVP included at 1 wt% to assess potential intermolecular effects. NMR and APC reliably quantified polymer content with low average errors of 2.77% and 2.01%, respectively, and were unaffected by phase separation or hydrogen bonding within the composite matrix. TGA enabled accurate quantification at PVA contents ≤ 62.5%, where PEG and PVA maintained distinct thermal decomposition behaviors. At higher PVA concentrations, increased hydrogen bonding and crystalline restructuring, confirmed by FTIR through shifts near 1140 cm⁻¹ and significant changes in the -OH region, altered thermal profiles and reduced TGA accuracy. Together, these findings establish APC as a high-throughput alternative to NMR for multi-component polymer analysis and outline critical thermal and structural thresholds that influence TGA-based quantification. This work provides a framework for characterizing complex polymer networks in biomedical hydrogel systems.

Multi-component polymer hydrogels present complex physiochemical interactions that make accurate compositional analysis challenging. This study evaluates three analytical techniques: Nuclear Magnetic Resonance (NMR), Advanced Polymer Chromatography (APC), and Thermogravimetric Analysis (TGA) to quantify polyvinyl alcohol (PVA) and polyethylene glycol (PEG) content in hybrid freeze-thaw derived PVA/PEG/PVP hydrogels. Hydrogels were synthesized using an adapted freeze–thaw method across a wide range of PVA:PEG ratios, with PVP included at 1 wt% to assess potential intermolecular effects. NMR and APC reliably quantified polymer content with low average errors of 2.77% and 2.01%, respectively, and were unaffected by phase separation or hydrogen bonding within the composite matrix. TGA enabled accurate quantification at PVA contents ≤62.5%, where PEG and PVA maintained distinct thermal decomposition behaviors. At higher PVA concentrations, increased hydrogen bonding and crystalline restructuring, confirmed by FTIR through shifts near 1140 cm⁻¹ and significant changes in the –OH region, altered thermal profiles and reduced TGA accuracy. Together, these findings establish APC as a high-throughput alternative to NMR for multi-component polymer analysis and outline critical thermal and structural thresholds that influence TGA-based quantification. This work provides a framework for characterizing complex polymer networks in biomedical hydrogel systems.

Injectable polymers offer great benefits compared to other types of implants; however, they tend to suffer from increased mechanical wear and may need a replacement implant to restore these mechanical properties. The purpose of this experiment is to investigate an injectable hydrogel's self-healing ability to augment itself to a previously molded implant. This was accomplished by performing a tensile strength test to examine potential diminishing mechanical properties with increasing time, as well as dye penetration tests to examine the formation of interfacial bonds between healed areas of hydrogels. There were several time points in between injections that were explored, from 0 min between injections all the way up to 48 h in between injections. The tests showed no statistical differences of the increased injection times compared to the single injection for the tensile test. However, our results showed an increase of mechanical breaks at self-healed joints, as well as a linear regression test showed a decrease in dye diffusion rate as time between injections increase. These results show that the hydrogel has strong self-healing abilities, and as time between injections increase, they mechanical properties will slowly decrease. Based on this, the tests can be applied to other injectable implants and a noninvasive solution to a worn-down implant, as well as show scientific backing to a possibly unique and beneficial self-healing property.

Crystallite regions within a hydrogel network contribute to its mechanical strength, which is crucial for use in load‐bearing applications. However, high amounts of crystallinity can negatively impact the ability for hydrogels to be injected, an attractive property that could replace the need for highly invasive surgical procedures. The reversibility of crystallinity and its lasting impact on the injectability of poly(vinyl alcohol) and poly(ethylene glycol) hydrogels was evaluated in this paper. The relative percent crystallinity in hydrogels was evaluated after storage and autoclaving in syringes in weekly intervals using X‐ray diffraction. Results indicate that crystallinity increased over time and significantly decreased after autoclaving for all samples, where postautoclaved samples contained comparable crystallinity percentages to freshly made gels (p > 0.05). Injectability was evaluated using calculated viscosity. Aged samples were able to be injected after autoclaving, yet there was no determination established between viscosity and storage times based on the data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48706.