Ultrafiltration Membranes with a Thin Poly(styrene)‑b‑poly(isoprene) Selective Layer

Ultrafiltration membranes with an 80 nm thick block polymer derived selective layer containing 20 nm cylindrical pores were prepared by removing poly­(lactide) (PLA) from a poly­(styrene)-b-poly­(isoprene)-b-poly­(lactide) (PS-PI-PLA) film onto a microporous polymer support. The block polymer film adopted a core­(PLA)-shell­(PI) cylindrical morphology in which vertically-oriented PLA cylinders were degraded to leave PI-lined channels in a PS matrix. Thanks to the combination of PS and PI in the nanoporous matrix, chemical cross-linking was not needed to provide mechanical stability in the thin film. The membranes showed a hydraulic flux of 165 L m^–2 h^–1 bar^–1 and were able to size-discriminate poly­(ethylene oxide) (PEO) solutes in agreement with theoretical predictions.