Direct Ink Writing (DIW)-based 3D printing of microscale porous structures using an acrylic resin–fumed silica composite

Control of porosity in extrusion printing with resins remains challenging despite the availability of high-resolution DLP/SLA resins. In this work, we adapt an off-the-shelf 405 nm UV-curable acrylic resin for extrusion-based additive manufacturing by tuning rheology with fumed silica and evaluate the effects of silica loading and printing parameters on the dimensional accuracy, microstructure, mechanical performance, and wetting behaviour. Resin formulations were prepared by mixing a commercially available resin with incremental additions of fumed silica (0–9.12 w/w%). After establishing the working curve, the resin–silica mixtures were printed layer-by-layer, important printing parameters such as layer height, print speed and curing time were optimized for shape retention. Rheological characterization showed pronounced shear-thinning and a monotonic viscosity increase with silica content; an ~ 8 w/w% silica loading gave the best balance between printability and shape fidelity. The 3D printed Composite exhibited a multilayer, multiporous architecture arising from alternating layer orientations and post-extrusion spreading. SEM confirmed uniform dispersion of fumed silica across flat and fractured surfaces, while mechanical testing revealed decrease in stiffness and strength for porous samples in comparison with non-porous material. Drop-spreading experiments demonstrated that larger pores and front-side orientations promote rapid wetting and complete spreading, whereas smaller pores limit wetting. The ability to print non-porous, regular porous as well gyroid porous structures was demonstrated. The study’s novelty lies in demonstrating that DLP-grade UV resins can be repurposed for extrusion printing through rheological tuning with fumed silica, enabling tuneable porosity. Moreover, we discuss process constraints, the principal sources of error (material flow/spreading, curing strategy), potential applications (filtration, scaffolds, microfluidics).