Browsing by Subject "Hydrogel"
Now showing items 1-2 of 2
-
(2024)4D printing is becoming increasingly investigated as it is emerging as a pioneering method for biofabrication. By implementing programmable shape changing thermoresponsive hydrogels in bioink formulations, a 4D response can be achieved, which can be manipulated to print artificial organs and tissues. The limited selection of biocompatible thermoresponsive hydrogels, accompanied by the mechanical weakness of hydrogels have restricted the mainstream application of this technology in the field of bioprinting. The most commonly studied thermoresponsive polymer is poly(N-isopropylacrylamide), but it is understood that the monomer N-isopropylacrylamide exhibits cytotoxicity at low concentrations. The primary goal of this study is to investigate poly(2-substituted-2-oxazoline) macromonomers as potential alternatives to poly(N-isopropylacrylamide), and the secondary goal is to investigate microgels as an additive in crosslinked networks to enhance hydrogel mechanical strength. The results in this work indicate that poly(2-n-propyl-2-oxazoline-co-2-ethyl-2-oxazoline) is a promising candidate for 4D printing, because it’s LCST can be fine-tuned by altering the monomer ratio. However, it still requires further investigation as it requires an acrylamide comonomer to crosslink, and it also has compatibility issues with commercial printing additives like Pluronic F127. The addition of 2 wt.% microgel also showed promise as it enhanced the hydrogels mechanical strength over threefold.
-
Synthesis and MEW Processing of Polyoxazine Based, Reversibly Crosslinking, Dual Network Hydrogels (2023)A polyoxazine based reversibly crosslinking hydrogel material developed for MEW was modified to increase its resistance to thermal degradation and impart control over its swelling properties. A portion of side chain functionalized Diels-Alder crosslinking moieties was replaced by hydrophobic octyl groups to induce the formation of a dual network hydrogel of equal crosslink density upon swelling. This modification was found to have no negative effects on the processing behavior of the material and was able to produce MEW printed scaffolds with equal stacking accuracy and fiber shape fidelity at processing temperatures 20˚C lower than a fully chemically crosslinked material. The thermal degradation of this dual network crosslinked material was significantly reduced, showing minuscule increases in viscosity when held at processing temperatures for several hours. The swelling of the dual network hydrogel was found to be similar to that of fully chemically crosslinked hydrogels despite consisting of significantly fewer chemical crosslinks, demonstrating another potential avenue of control over this material property. Finally, promising alterations in mechanical properties were observed in the dual-network hydrogel versus chemically crosslinked hydrogels, along with observations of water induced crystallization attributed to the octyl chains.
Now showing items 1-2 of 2