The Modification of Polyethersulfone Membranes with Polyacrylic Acid

Spray coating polymer substrates from a green solvent to enhance desalination performances of thin film composites

“…For example, PES membranes cast from water-miscible solvents such as NMP usually possess thinner skin layers, 14 while highly viscous dope solutions suppress the formation of pores and macrovoids. 16,17 Other methods to control demixing include varying coagulation bath composition 18,19 and temperature, 20 controlling the casting speed, 14 and adding porogens into the dope solution. For example, adding water into the dope solution leads to the formation of larger pores and more porous membranes with water permeances that are 150% higher than those of membranes prepared from dehydrated dope solutions.…”

“…Other methods to control demixing include varying coagulation bath composition 18,19 and temperature, 20 controlling the casting speed, 14 and adding porogens into the dope solution. For example, adding water into the dope solution leads to the formation of larger pores and more porous membranes with water permeances that are 150% higher than those of membranes prepared from dehydrated dope solutions.…”

Effect of the Addition of Polyacrylic Acid of Different Molecular Weights to Coagulation Bath on the Structure and Performance of Polysulfone Ultrafiltration Membranes

“…This technique can contribute to surface modification due to the embedding of hydrophilic polymers or polyelectrolytes into the selective layer, which yields changes in the hydrophilicity, roughness, charge and chemical composition of the membranes. This approach was developed and studied in [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ].…”

“…Polyacrylic acid (PAA) [ 48 , 49 , 53 ], polyethylene imine (PEI) [ 37 , 41 , 43 ], copolymers Praestol 859 [ 47 , 51 ] and Praestol 2540 [ 50 ], poly (diallyldimethylammonium chloride) [ 41 ], chitosan [ 55 ], zwitterionic copolymers [ 56 ], poly (sodium 4-styrenesulfonate) (PSS) [ 40 ], PVP [ 52 ] and PVA [ 54 ] were applied as additives to the coagulant for preparation of flat-sheet and hollow fiber membranes. There are different purposes which can be achieved by the addition of hydrophilic polymers and polyelectrolytes to precipitation medium: Increase in membrane antifouling performance [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 56 ]; Formation of a separation layer after subsequent cross-linking [ 37 , 38 ] or reaction with oppositely charged polyelectrolyte [ 37 , 40 , 41 , 42 , 45 , 46 ]; Creating an intermediate layer for preparation of the composite membrane via interfacial polymerization (IP) technique [ 44 ]; Tailoring membrane surface charge for enhanced separation of charged molecules [ 39 ]. …”

“…Previously, Burts et al [ 48 , 49 ] and Bildyukevich et al [ 53 ] studied the surface modification of polysulfone (PSF) [ 48 , 49 ] and polyethersulfone (PES) membranes [ 53 ] by addition of PAA with a molecular weight of 250 kDa to the coagulant. It was shown that using PAA aqueous solutions as coagulation bath decreased the coagulation rate due to the rise in precipitation medium viscosity and abatement of the mutual diffusion of solvent and coagulant, which yielded a decrease in the pore size of the membrane selective layer [ 48 , 49 ].…”