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

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 the nanoscale size and ordering of hydrophobic cross-linked domains on the mechanical and degradation properties of three-dimensional (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 cross-linkable hydrophobic terminal PPF block lengths. Self-assembled hydrogels were formed by dissolving these amphiphilic PPF-b-PEG-b-PPF copolymers in water and covalently cross-linking 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.

Automated summary

This study investigates the impact of nanoscale size and ordering on the mechanical and degradation properties of amphiphilic hydrogels. By synthesizing ABA triblock copolymers with varying PEG and PPF block lengths, the properties of self-assembled hydrogels were examined and their correlation with mechanical properties was highlighted through various testing methods. Swelling and in vitro degradation tests demonstrated the influence of nanoscale ordering on the degradation timescale.