Thermoplastic PCL- b -PEG- b -PCL and HDI Polyurethanes for Extrusion-Based 3D-Printing of Tough Hydrogels

摘要

Novel tough hydrogel materials are required for 3D-printing applications. Here, a series of thermoplastic polyurethanes (TPUs) based on poly(?-caprolactone)- b -poly(ethylene glycol)- b -poly(?-caprolactone) (PCL- b -PEG- b -PCL) triblock copolymers and hexamethylene diisocyanate (HDI) were developed with PEG contents varying between 30 and 70 mol%. These showed excellent mechanical properties not only when dry, but also when hydrated: TPUs prepared from PCL- b -PEG- b -PCL with PEG of Mn 6 kg/mol (PCL 7 -PEG 6 -PCL 7 ) took up 122 wt.% upon hydration and had an E-modulus of 52 ± 10 MPa, a tensile strength of 17 ± 2 MPa, and a strain at break of 1553 ± 155% in the hydrated state. They had a fracture energy of 17976 ± 3011 N/mm 2 and a high tearing energy of 72 kJ/m 2 . TPUs prepared using PEG with Mn of 10 kg/mol (PCL 5 -PEG 10 -PCL 5 ) took up 534% water and were more flexible. When wet, they had an E-modulus of 7 ± 2 MPa, a tensile strength of 4 ± 1 MPa, and a strain at break of 147 ± 41%. These hydrogels had a fracture energy of 513 ± 267 N/mm 2 and a tearing energy of 16 kJ/m 2 . The latter TPU was first extruded into filaments and then processed into designed porous hydrogel structures by 3D-printing. These hydrogels can be used in 3D printing of tissue engineering scaffolds with high fracture toughness.