Synthesis and characterisation of a 3D-printable gelatin – epoxy amine double network hydrogel

There is a current need for the development of robust smart materials for a variety of medical, consumer, and manufacturing applications. In addition, these materials require the ability to act as 3D printable inks to undergo rapid prototyping. A UV curable gelatin-epoxy amine double network hydrogel with water content of 80% can be simply produced by a one-pot synthesis. This synthesis method can be performed by methacrylating the individual networks by either a one-step process (simultaneously) or a two-step process (independently). It was found that the two-step process is more effective in producing a mechanically robust material, capable of exhibiting a compressive stress at failure of 2.5 ±0.2 MPa. Significantly, a new 3D printing method has been developed to allow the material to be cured post printing resulting in no significant loss in mechanical strength compared to gels prepared by casting. This method uses the entanglement of gelatin (below 37°C) to give support to the individual printed layers of the structure eliminating the need for UV curing after each layer is printed. Post printing, the structure can be UV cured to increase the mechanical strength of the material to that of the hydrogels prepared by casting. It is envisage that this new printing method in conjunction with new hydrogel chemistries can be utilised to fabricated new materials for applications ranging from biomedical devices to soft robotics.