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

Abstract

<p>The variety of UV-curable monomers for 3D printing is limited by a requirement for rapid curing after</p><p>each sweep depositing a layer. This study proposes to trigger supramolecular self-assembly during the</p><p>process by a gemini imidazolium-based low-molecular-weight gelator, allowing printing of certain</p><p>monomers. The as-printed hydrogel structures were supported by a gelator network immobilising monomer:</p><p>water solutions. A thixotropic hydrogel was formed with a recovery time of <50 s, storage modulus =</p><p>8.1 kPa and yield stress = 18 Pa, processable using material extrusion 3D printing. Material extrusion 3D</p><p>printed objects are usually highly anisotropic, but in this case the gelator network improved the isotropy</p><p>by subverting the usual layer-by-layer curing strategy. The monomer in all printed layers was cured</p><p>simultaneously during post-processing to form a continuous polymeric network. The two networks then</p><p>physically interpenetrate to enhance mechanical performance. The double network hydrogels fabricated</p><p>with layers cured simultaneously showed 62–147% increases in tensile properties compared to layer-bylayer</p><p>cured hydrogels. The results demonstrated excellent inter- and intra-layered coalescence.</p>