Composite membranes with hydrophilic nanopores derived from the self-assembly of block copolymer supramolecular complexes

Selective composite membranes with high and controlled porosity have been fabricated using patterned silicon microsieves as support and nanoporous polystyrene-block-poly(ethylene oxide) (PS-b-PEO) membranes as selective layer. The desired morphology of the block copolymer layer is obtained by a supramolecular approach based on the hydrogen bonding of the PEO block with resorcinol. The formation of PS-b-PEO/resorcinol complexes allows to easily control the self-assembly of the block copolymer and to obtain normally oriented PEO/resorcinol nanocylinders by spin coating PS-b-PEO/resorcinol solutions. In a further step resorcinol works as a porogen and by its selective dissolution densely packed, normally oriented nanochannels coated by PEO chains have been obtained. These hydrophilic nanochannels have a diameter of approximately 20 nm and cross the membranes from top to bottom. The nanoporous polymer layer is crack-free and well adheres to the support microsieve. The composite membrane is permeable to methylene blue while blocks larger molecules, such as bovine serum albumin.