LAUSR

Abstract This work provides a novel approach to manufacture hierarchical porous parts via an in-situ foaming fused deposition modeling (FDM) method. The cell nucleation, growth, and stabilization occurred as the CO2-saturated polyetherimide (PEI) filament was heated, and the layer-by-layer deposition of porous strands was controlled by a planned path. The microporous structure with cell size of 2–30  μ m and cell density of 1010−11 cells/cm3 was generated inside and on the surface of the porous PEI strand, and the macroporous structure with size of about 1–50 mm was constructed within the porous PEI honeycombs and cylinder. The compressed CO2 exhibited extremely slow diffusivity in PEI filaments, and the stable CO2 content ensured that the hierarchical porous PEI part could be 3D printed with high accuracy for a long time.