Sulfonated polymerized liquid crystal nanoporous membranes for water purification

New isoporous nanofiltration composite membranes were fabricated by photo-polymerization of thin films of the hexagonal columnar mesophase of the supramolecular complex 4₃TB. This was followed by deposition on a polyether sulfone macro-porous support and removal of the template molecule. The membranes had an average permeability of 2.3 L m^-2 h^-1·bar^-1 and a sharp molecular weight cut-off of around 5000 g mol^-1 based on PEG filtration. The full rejection of Bovine Serum Albumin and Green fluorescence proteins and their flux recovery suggested the absence of defects on the LC layer of the membrane. The filtration of charged molecules presented total rejection for molecules larger than 1000 g mol^-1 and a size-charge selectivity with higher rejection for cationic molecules due to ionic interactions with the pore walls. These interactions mean absorption within the membrane, which has an effect on the rejection of neutral solutes such as Riboflavin and PEG 3000, being less relevant for smaller molecules.