Poly(4-methyl-1-pentene) hollow-fiber membranes with high plasma-leakage resistance prepared via thermally induced phase separation method

Poly (4-methyl-1-pentene) (PMP) hollow-fiber membranes (HFMs) with bi-continuous structure and high plasma-leakage resistance were successfully prepared via thermally induced phase separation using binary diluents of nontoxic paraffin oil (PO) and oleic acid (OA) for oxygenation. The phase separation mechanism of the PMP HFM with 30–40 wt% PMP shifted from solid–liquid to liquid–liquid as the PO/OA mass ratio was increased, changing its flaky crystal structure to a bi-continuous or cellular structure. The effects of the air-gap distance, take-up speed, and PMP concentration on the HFM structure and performance were also investigated. The results showed that a shorter air-gap distance and higher take-up speed reduced the pore size and gas permeability of the membranes. Under the optimal conditions (PMP concentration: 40 wt%, PO/OA mass ratio: 49/11, take-up speed: 60 rpm air-gap distance: 10 mm), PMP HFM exhibited excellent gas permeability (N2 flux: 2.4 mL/(bar·cm2·min) or 533 GPU), mechanical properties (tensile strength: 10.4 MPa; elongation at break: 150.6 %), and plasma-leakage resistance (leakage time: >5900 at an external liquid and internal gas pressures of 0.1 and 0.08 MPa, respectively). Therefore, this study has significant implications for the large-scale production of PMP HFMs.