New approach to 3D-print methacrylic acid/polyethylene glycol diacrylate-based membranes based on polymerization induced phase separation

We present a novel freeform fabrication strategy for polymer membranes via 3D printing, in which porosity is generated through a polymerization-induced phase separation mechanism. The approach employs a vat-photopolymerization compatible formulation to produce a macroporous network with coexisting mesoporosity. Hydrophilic flat-sheet membranes (400 μm thick) were fabricated and subjected to post-treatments involving CO 2 supercritical drying and solvent exchange. The resulting membranes exhibited permeance of up to 36 and 29 LMH.bar −1 , respectively, under a transmembrane pressure of 2 bar. An in-depth evaluation was conducted on membranes produced from photocurable formulations containing methacrylic acid (MA, 30 vol%) and polyethylene glycol diacrylate (PEGDA, 20 vol%), with varying ratios of 1-butanol and 2-phenoxyethanol as porogens. SEM analysis revealed a porous morphology throughout the membrane cross-section. The top-performing sample exhibited the highest specific surface area of 12.8 m 2 /g and the smallest mean pore diameters of 45 nm and 42 nm, as determined by adsorption branches of Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses, respectively. Pore size distribution was compared with liquid-liquid displacement method, which revealed mean pore size of 8.8 nm, with a small quantity of pores of approximately 121 nm, which were in better agreement with pure water flux values. The influence of post-polymerization porogen removal methods—solvent exchange and supercritical drying—was also assessed. Post-treated membranes demonstrated lower compaction factors and more stable flux over time and under increasing pressure. This technique offers a promising route for the customized design of membrane geometries and architectures tailored to specific separation challenges. We further demonstrate such concept by printing textured membranes with wavy and rugged surface profiles. • Flat-sheet membranes were 3D-printed using different resin formulations for comparative evaluation. • Macroporous and mesoporous architectures were successfully achieved through polymerization-induced phase separation. • The ratio of 1-butanol to 2-phenoxyethanol significantly influenced specific surface area and pore size distribution. • Post-fabrication treatments reduced membrane compaction and enhanced structural stability. • The membranes exhibited high pure water flux, demonstrating their potential for efficient filtration applications.