An Imidazolium-Based Supramolecular Gelator Enhancing Interlayer Adhesion in 3D Printed Dual Network Hydrogels

The variety of UV-curable monomers for 3D printing is limited by a requirement for rapid curing aftereach sweep depositing a layer. This study proposes to trigger supramolecular self-assembly during theprocess by a gemini imidazolium-based low-molecular-weight gelator, allowing printing of certainmonomers. The as-printed hydrogel structures were supported by a gelator network immobilising monomer:water solutions. A thixotropic hydrogel was formed with a recovery time of 8.1 kPa and yield stress = 18 Pa, processable using material extrusion 3D printing. Material extrusion 3Dprinted objects are usually highly anisotropic, but in this case the gelator network improved the isotropyby subverting the usual layer-by-layer curing strategy. The monomer in all printed layers was curedsimultaneously during post-processing to form a continuous polymeric network. The two networks thenphysically interpenetrate to enhance mechanical performance. The double network hydrogels fabricatedwith layers cured simultaneously showed 62–147% increases in tensile properties compared to layer-bylayercured hydrogels. The results demonstrated excellent inter- and intra-layered coalescence.</p