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Designing Hydrogen Bonding Polyesters, and Their Use for Enhancing Shape Fidelity of 3D Printed Soft Scaffolds
- Publication Year :
- 2019
-
Abstract
- 3D printing of soft scaffolds allows customization in soft tissue regeneration applications. However, the printing quality is generally low because such materials deform significantly post-printing. Hydrogen bonds when introduced into 3D printing inks, serve as physical crosslinks that can enhance the shape fidelity of 3D printed soft scaffolds. This dissertation will describe our work in examining the effect of hydrogen bonds in polyesters and their impact on the quality of 3D printed scaffolds.In the first part, we present the design of polyesters containing either one or two pendant secondary amide-propyl groups and compare them to a control polyester with one pendant ester-propyl group, to probe the cumulative effects of hydrogen bonding and chain flexibility on their thermal, mechanical and rheological properties. The results showed that hydrogen bonding increased glass transition temperature, Young’s modulus and polymer brittleness. Nevertheless, at higher temperatures, rheometry showed that the polyester containing two amide groups had the shortest chain relaxation time and the lowest zero-shear viscosity. Our results demonstrated the opposing effects of side chain flexibility and hydrogen bonding interaction can be used as a strategy to design materials with desired properties.In another study, secondary amide groups were used to functionalize polycaprolactone (PCL), a commonly used biomaterial by copolymerization of a hydrogen bonding monomer diol, PCL oligomer diol and succinic acid in both statistical and alternating sequences. The introduction of the hydrogen bonding monomer disrupts the microstructure of PCL which results in lower crystallinity, melting point and Young’s modulus, but a more distinct strain hardening. The statistical distribution of the hydrogen bonding monomer along the polymer backbone accelerates the hydrolytic degradation rate.The knowledge gained from the use of hydrogen bonding interactions was incorporated into the design of UV curable polymer inks for 3D printing of soft scaffolds to demonstrate that hydrogen bonds served as physical crosslinks, behaved as a viscosity regulator, reduced the spreading of the extruded filaments and resulted in higher shape fidelity. Rheometry and tensile testing of the UV crosslinked polymers showed that the incorporation of hydrogen bonds did not raise the moduli of the printed soft scaffolds.
- Subjects :
- Polymers
hydrogen bond
chain flexibility
3D printing
shape fidelity
Subjects
Details
- Language :
- English
- Database :
- OpenDissertations
- Publication Type :
- Dissertation/ Thesis
- Accession number :
- ddu.oai.etd.ohiolink.edu.akron1573738707820888