Solvent-Resistant Nanofiltration Membranes Based on Multilayered Polyelectrolyte Complexes

Abstract

Alternating deposition of oppositely charged polyelectrolyte (PEs) can create stable solvent-resistant nanofiltration (SRNF) membranes with very high flux and selectivity. A new combination of PEs (poly(diallyldimethylammonium chloride) and sulfonated poly(ether ether ketone) is reported from which supported membranes consisting of 5, 10, 15, and 20 bilayers are prepared via the layer-by-layer method. The morphology of the membranes was studied in detail by SEM and AFM, showing rougher membrane surfaces with increasing bilayer number. For the first time, polyelectrolyte complex (PEC) based membranes were also applied in the filtration of organic solvents, where they form an excellent new tool to study the role of charges in solvent filtrations. Due to Donnan exclusion, the multilayered PEC membranes showed very good retentions up to 99% for charged solutes in the pressure-driven filtration of isopropanol solutions. Moreover, they were found to show excellent prospective use in polar aprotic solvents, like dimethylformamide and tetrahydrofuran, which have been extremely troublesome so far for most existing SRNF membranes.

Recent Advances in Polymeric Solvent‐Resistant Nanofiltration Membranes

“…They also stated that negatively charged PE membranes rejected more MO (a type of negative solute) than positively charged dyes. 36 Similar results have been reported in other works 153 indicating that the Donnan effects may also play an important role in separating charged solutes.…”

“…34,[82][83][84][85][86][87][88][89][90][91] Li and co-workers 33-37 studied a series of SRNF membranes fabricated by the self-assembly LBL method. They fabricated PEs composite SRNF membranes by combining polydiallyldimethylammonium chloride polycations with various polyanions, including polyacrylic acid (PAA) 33 , sulfonated poly(ether ether ketone) [34][35][36] , poly(sodium styrene sulfonate), and poly(vinyl sulfate). 37 Their results illustrated that the thickness of PEs composite SRNF membranes affect the permeability of solvents [33][34][35][36][37] and can be adjusted by the number of deposited layers as well as the conformation of the PEs chains.…”

Functional polyelectrolyte multilayer membranes for water purification applications

“…Moreover, the thickness and swelling of LBL assembled polyelectrolyte membranes is affected by many factors including the conformation of the adsorbed polyelectrolyte, the density of the electrostatic charge, the rigidity or flexibility properties of polyelectrolyte, etc. Therefore, the thickness and swelling strongly depends on the preparation condition such as pH and salt concentration of the polyelectrolyte solutions [72]. It is reported that the presence of salt in polyelectrolyte solutions drastically affects the chain configuration in bulk solution [73].…”

“…For charged components electrostatic interactions take place between the components and the membrane surface charges. The molar mass and charge are important parameter of selected dyes because the rejection of charged solutes greatly depends upon charge nature due to Donnan exclusion [72,78,79]. Solute rejection property of developed membranes was evaluated for methyl red, methylene blue, and congo red dyes.…”

Highly conductive, methanol resistant fuel cell membranes fabricated by layer-by-layer self-assembly of inorganic heteropolyacid

“…Multilayered CTS/PTA films were first deposited on negatively charged silicon wafers to study the surface morphology, following the protocol [28]. As seen in Fig.…”