Immersion precipitation 3D printing (ip3DP)†
Fabrication of controlled porous materials has gained interest because of their broad range of applications in energy storage, catalysis, biotechnology, and life sciences. The recent development of 3D printing has demonstrated the fabrication of 3D porous materials, albeit with limitations in the printable materials and the simplicity of the methods. In particular, direct dispensing of polymer solutions, solvent-casted 3D printing (SC3DP), requires the printing ink to possess high viscosity and high vapor pressure for 3D modelling. Herein, we introduce a unique and versatile method of 3D printing based on spatially controlled immersion precipitation, termed as immersion precipitation 3D printing (ip3DP). ip3DP offers the capability to fabricate 3D porous models using inks with wide ranges of vapor pressure and viscosity. Using a model ink of acrylonitrile butadiene styrene (ABS) dissolved in acetone (20–60% w/w), we demonstrated that the concentration of the polymer in the ink allowed control over the internal morphologies of the 3D printed structures ranging from complete porous microstructures (with pore sizes ranging from 1–20 μm) to dense nonporous microstructures. The addition of porogens to the printing inks demonstrated the fabrication of microscale pores reaching the surface of the printed filament, allowing the formation of interconnected pores. ip3DP offers an unprecedented route to fabricate micro-to-centimeter structures with controlled internal porosity in thermoplastics and serves as a useful toolkit in 3D printing of hierarchical structures and functional devices.