Multiscale enhancement of mechanical and thermal properties in Co3O4 reinforced TPMS-based epoxy nanocomposites via additive manufacturing

Abstract

This study investigates the design, fabrication, and comprehensive characterization of epoxy-based nanocomposites reinforced with cobalt oxide (Co3O4) nanoparticles using stereolithography (SLA), a prominent vat photopolymerization additive manufacturing technique. Composite formulations containing 0.05 to 0.25 wt.% Co3O4 were prepared via sequential probe sonication, and ultrasonic bath treatment to ensure homogeneous nanoparticle dispersion within the photosensitive epoxy resin. Both solid specimens and architected structures based on triply periodic minimal surface (TPMS) topologies, specifically gyroid and Kelvin lattices, were fabricated to assess the synergistic influence of reinforcement content and lattice geometry on multifunctional performance. Mechanical tests including tensile, flexural, compressive, and Shore D hardness evaluations were conducted alongside thermogravimetric analysis and thermal conductivity measurements. The results revealed that 0.10 wt.% Co3O4 yielded optimal enhancements in mechanical strength and thermal conductivity without causing detrimental agglomeration. Gyroid lattices exhibited superior compressive strength and extended plateau behavior compared to Kelvin counterparts, owing to smoother load redistribution and delayed densification. Fractographic analysis further corroborated these findings, showing improved crack deflection and interfacial adhesion at the optimal filler level. This work demonstrates the efficacy of integrating nanoscale reinforcement with topological optimization in SLA-based photopolymer composites, offering a promising route toward lightweight, mechanically robust, and thermally functional materials for structural applications.