Morphological control and properties of poly(lactic acid) hollow fibers for biomedical applications

Poly(lactic acid) (PLA) hollow‐fiber (HF) membranes were prepared by wet spinning with a phase‐inversion technique. Dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), and 1,4‐dioxane (DIO) were applied as solvents (Ss), and water was applied as a nonsolvent in the precipitation bath. The polymer solution viscosities, PLA–S–water miscibility regions, and precipitation onsets were measured and related to the Hansen solubility and Flory–Huggins interaction parameters. We observed a morphological transition from fingerlike to spongelike pores when DIO was applied as the S instead NMP or DMSO. The water permeabilities of these membranes were not detectable at a transmembrane pressure of 1 bar, and higher pressures caused them mechanical damage. However, the addition of 5 wt % poly(vinyl pyrrolidone) (PVP) induced a higher porosity and water permeabilties from 3.14 to 9.38 L m−2 h−1 bar−1. These membranes were characterized by dialysis, and after 6 h, feed concentration reductions of 2% and 17% for bovine serum albumin and lysozyme, respectively, were observed. In vitro degradation tests showed that a 30% mass loss took place after 90 days of incubation, and a faster initial degradation of spongelike membranes occurred. The spongelike membranes presented a higher maximum stress (12.80 MPa) than the fingerlike membranes (∼6 MPa). With PVP addition, the HFs were less resistant to axial traction and showed a decreased elongation of break from 58% to 23%.