Fused deposition modeling of hierarchical porous polyetherimide assisted by an in-situ CO2 foaming technology

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 mu m and cell density of 10(10)(-11) cells/cm(3) 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.