Clustering and Hierarchical Organization of 3D Printed Poly(propylene fumarate)-block-PEG-block-poly(propylene fumarate) ABA Triblock Copolymer Hydrogels

Abstract

Hydrogels are deployed widely in all areas of regenerative medicine, including bioprinting. The transport and mechanical properties exhibited by hydrogel assemblies are controlled by their organization and hierarchical assembly. This paper points out the role of nanoscale size and ordering of hydrophobic crosslinked domains on the mechanical and degradation properties of 3D printed amphiphilic hydrogels. A series of six poly(propylene fumarate)-block-poly(ethylene glycol)-block-poly(propylene fumarate) (PPF-b-PEG-b-PPF) ABA triblock copolymers were synthesized by varying both the water-soluble PEG block and the crosslinkable hydrophobic terminal PPF block lengths. Self-assembled hydrogels were formed by dissolving these amphiphilic PPF-b-PEG-b-PPF copolymers in water and covalently crosslinking the PPF units via digital light processing (DLP) additive manufacturing. Differential scanning calorimetry (DSC), in situ diffuse reflectance infrared spectroscopy (DRIFTS-IR) measurements, small-angle neutron scattering (SANS) and compressive measurements highlight how structural properties correlate with mechanical properties within this hydrogel system. Finally, swelling and in vitro degradation tests showed the influence of the nanoscale ordering on the degradation timescale.

Tunable Thermal-Induced Degradation in Fully Bio-Based Copolyesters with Enhanced Mechanical and Water Barrier Properties

“…As the high energy stability of CC in FA, numerous FA polymers have been explored, introducing reactive double bonds into the main chain. For example, poly­(propylene fumarate) (PPFu) has attracted extensive interest due to its outstanding mechanical, biodegradable, and biocompatible properties which endow PPFu-based materials with great potential for a wide range of applications in bone cements, drug release, and porous scaffolds. − Poly­(butylene fumarate) (PBFu) also achieved amazing popularity due to its semicrystalline nature and high melting temperature of 130 °C. Moreover, some FA-based copolyesters have been reported so far.…”

Block Copolymers in 3D/4D Printing: Advances and Applications as Biomaterials

“…It was shown that size, connectivity, and phase ordering changes resulted from aggregation mechanisms driven by the length of the blocks. The importance of these nanoscale ordering can also be seen in the authors’ swelling and in vitro tests [ 91 ].…”

Thiol-Based Three-Dimensional Printing of Fully Degradable Poly(propylene fumarate) Star Polymers

“…Polypropylene fumarate (PPF) is a biodegradable aliphatic polyester with an alkene bond in the backbone, lending it to photochemical cross-linking. , It has been used in a number of preclinical applications, including vascular stents, nerve grafts, and for cartilage and bone tissue engineering. − The molecular architecture of PPF has been varied from linear to star-shaped polymers , as well as combined with other monomers to yield block, − gradient, , and random copolymers. Star-shaped PPF possesses a lower viscosity at very high molecular weight compared to linear PPF-based polymers.…”