Porous morphology and mechanical properties of poly(lactide-co-glycolide) hollow fiber membranes governed by ternary-phase inversion

Due to the controllable biodegradability and good biocompatibility, poly(lactide-co-glycolide acid) (PLGA) hollow fiber membranes (HFMs) have been successfully used for various biomedical applications, where the morphological and mechanical characteristics of HFMs are of crucial importance. This study focused on the effects of fabrication conditions on the morphology and mechanical performance of PLGA HFMs, which were manufactured by a phase inversion-based dry-jet wet spinning process. The cross-sectional morphology of HFMs was found to be significantly influenced by PLGA concentration of dope fluid. A 5-layered microstructure with macrovoids varied to a 6-layered microstructure with sponge-like microvoids when the PLGA concentration increased from 14% to 22%. Also, Young's modulus and compressive modulus of these PLGA HFMs were found to dramatically increase with PLGA concentration. To understand the underlying mechanism of morphological formation in PLGA HFMs, a physical mass transfer model was developed to describe the mutual diffusion process of PLGA/dimethyl sulfoxide (DMSO)/water ternary system. This model was able to quantify the PLGA distribution within the HFM cross sections by considering the interaction terms of polymer/solvent/nonsolvent in the governing equations, which was validated by the overall agreement between the experimental and numerical results. The present study should be helpful for understanding the formation mechanism of porous morphology during the phase inversion-based dry-jet wet spinning process, which may guide the optimization of PLGA HFMs for their applications as tissue engineered scaffolds.