Thermo-responsive, mechanically robust and 3D printable supramolecular hydrogels

Abstract

In this work, poly(N-isopropylacrylamide) (PNIPAm) grafted and multi-urea linkage segmented linear polyurethane–urea (PUU) copolymers were synthesized using α-dihydroxyl terminated PNIPAm as a chain extender and water as an indirect chain extender, respectively. A series of PUU supramolecular hydrogels were then easily obtained by solution casting and then water swelling of these PUU copolymers. These PUU supramolecular hydrogels show not only thermo-responsive surface wettability, but also robust mechanical performance with tensile strength and elongation at break of 0.2–2.9 MPa and 1100–3000%, respectively, at 37 °C. In addition, temperature responsive and mechanically strong 3D hydrogel scaffolds were also developed by a direct-write 3D printing technique using a methanol solution of the PUU copolymer as the ink. These supramolecular hydrogels are expected to be used as functional biomaterials, especially as elastic substrates for cell sheet cultures under dynamic mechanical stimulation.