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.