Tunable dual-curing acrylic/epoxy systems for 3D printing with enhanced joint performance via carbon nanotubes

This study presents a novel dual-curing strategy for low-viscosity, high-performance acrylic/epoxy systems, which enables precise control over the final density of the co-network structure and its thermo-mechanical properties. Unlike conventional acrylate/epoxy dual-curing systems, this new strategy incorporates a long chain extender (polyethylene glycol) covalently bonded within the epoxy network to specifically reduce the crosslinking density achieved in the second curing stage. This allows for fine-tuning of the material's mechanical properties, facilitating adjustments to the elastic modulus from 3 MPa to 2500 MPa and achieving maximum tensile strength values of 80 MPa, while maintaining a low viscosity of less than 35 mPa s, making it ideal for 3D printing vat photopolymerization applications. Additionally, the material exhibits good thermal stability and excellent printed components resolution, thereby opening a wide range of design options for achieving optimal configurations related to mechanical preferences and precise geometric accuracy. The work further includes an analysis of tensile strength in bonded joints, which is a crucial parameter in structural design, particularly for the fabrication of large parts through bonding. Moreover, the project proposes the incorporation of functionalized multi-walled carbon nanotubes (MWCNT-COOH) to enhance interfacial adhesion between phases.