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 after

each sweep depositing a layer. This study proposes to trigger supramolecular self-assembly during the

process by a gemini imidazolium-based low-molecular-weight gelator, allowing printing of certain

monomers. 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 <50 s, storage modulus =

8.1 kPa and yield stress = 18 Pa, processable using material extrusion 3D printing. Material extrusion 3D

printed objects are usually highly anisotropic, but in this case the gelator network improved the isotropy

by subverting the usual layer-by-layer curing strategy. The monomer in all printed layers was cured

simultaneously during post-processing to form a continuous polymeric network. The two networks then

physically interpenetrate to enhance mechanical performance. The double network hydrogels fabricated

with layers cured simultaneously showed 62–147% increases in tensile properties compared to layer-bylayer

cured hydrogels. The results demonstrated excellent inter- and intra-layered coalescence.