Fabrication and degradation of hierarchical PLA structures via electrospinning and fused filament fabrication

Abstract In the present work, we developed unique structures from polylactic acid (PLA) by combining electrospinning and fused filament fabrication (FFF). The thin layers of fiber mats were used as interleaves between printed infill layers, and hence, we obtained a multi-level porous structure. Due to the known favorable characteristics of the electrospun mats for cell adhesion and growth, these structures may be used as scaffolds in the future. The aim of this study was to test the processing, the structure, and the hydrolytic degradation at a fundamental level. Samples were immersed into phosphate-buffered saline (PBS) solution and incubated at 37 °C for 1, 3, 7, 15, 30 and 60 days. Our findings show that adding 0.15 wt% electrospun fibers results in a significantly higher degree of crystallinity. We found that the embedded fiber mats promoted heterogeneous nucleation, thus improving mechanical properties significantly. Scanning electron microscopy confirmed that fibers fused with the FFF grid in situ, resulting in increased tensile strength and elongation at break. Additionally, the hierarchical structures exhibit better mechanical performance at the potential application temperature (37 °C) than the neat 3D printed samples.