3D Electrospinning of Macroscopic PLLA Structures.

Electrospinning typically produces 2D fibrous nanofibers with poor heavy metal sorption capabilities and weak mechanical strength without post-processing treatment. Comparably, 3D structures have 99.992% porosity, larger pore sizes, and lower fiber density. In this study, macroscopic 3D poly L-lactic acid (PLLA) structures are fabricated successfully by 3D electrospinning. It is found that the electrospinning solvent system, polymer concentration, phosphoric acid (H3PO4) additive concentration, collector potential, working distance, flow rate, and applied nozzle voltage affected the fiber diameter and 3D structural dimensions. The effects of these variables are investigated, and optimum conditions are obtained. The optimal parameters for the 3D PLLA structure are 0.5 wt.% phosphoric acid additive to the 12 mg mL h-1 PLLA solution, +1 V charged collector, +18 kV nozzle voltage, 4 cm working distance, 4 mL h-1 flow rate, and Dichloromethane (DCM)/ N, N-dimethylformamide (DMF) (6:1) solvent. The structure has a 774 nm average diameter and 2.36 cm height. Scanning electron microscopy showed fiber uniformity at the different sections of the macroscopic 3D PLLA structures. These results expand the possibilities of using PLLA as 3D electrospun biomimetic structures.