Negatively Charged Porous Thin Film from ABA Triblock Copolymer Assembly

Abstract

The preparation of well-arranged nano-porous thin films from an ABA triblock copolymer of polystyrene- block -poly(sodium 4-styrenesulfonate)- block -polystyrene (PS-PNaSS-PS) is reported. This copolymer was self-assembled in a N , N -dimethylformamide (DMF)/water mixture and the resulting micellar solution was used to prepare thin films via the compact packing of the flower-like micelles using spin coating method. The films were characterized by several microscopy techniques such as TEM, AFM, and SEM. Permeation test was performed to highlight the interconnected porous nature of the polymeric network obtained. Under applied water pressure, the micellar morphology was altered and a partial fusion of the micelles was observed that resulted in a change in the water permeability. Such hydrophilic nanoporous thin films with negatively charged interface could find applications in membrane filtration.

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

“…This shows that the electrostatic repulsion of Mg 2+ by the membrane was much higher than that of Na + , hence why the high rejection of MgCl 2 was observed. It can be concluded that the composite membranes in this study possess negatively charge surfaces due to the AlO 4 tetrahedra interactions with the SiOH of ZSM-22 nanoadditives [ 84 , 86 , 87 ].…”

“…This assessment led to cheaper water softening applications using lower applied pressure (<1 bar) in the NF or RO membrane systems. The interaction of these solutes with the composite membrane matrix containing negatively charge nanoadditives, as opposed to size exclusion, was also a possible mode for membrane rejection [84,85]. The relatively high charge on divalent Mg ion means it is strongly attracted to the negatively charged membrane surface than the monovalent Na ion, resulting in the different observed rejection profiles.…”

Polymerizations by RAFT: Developments of the Technique and Its Application in the Synthesis of Tailored (Co)polymers

“…Their systematic study, investigated the effect of solvent mixtures, solvent mixture ratios, molecular weights, block ratios, and polymer concentration. [ 245–247 ] It was shown that independent of the block ratios aggregates of different morphologies could be prepared depending on the solvent mixture ratios (THF/H 2 O). At constant polymer concentrations, different type of morphologies could be prepared (spheres, short worms, and vesicles).…”

“…[ 245,246 ] They also demonstrated that when the block ratios were even (PS 5k ‐PNaSS 5k ‐PS 5k , PS 10k ‐PNaSS 10k ‐PS 10k ) depending on the choice of organic solvent (THF or DMF) hydrophobic LCVs or hydrophilic spheres could be prepared. [ 246,247 ] All these colloidaly stable aggregates were used to make porous thin film membranes on a solid support via spin‐coating. Image analysis and filtration tests suggested that the pore size of these porous thin films were in the range of 10–30 nm making these membranes suitable for ultrafiltration.…”

Deposition of Thin Alumina Films Containing 3D Ordered Network of Nanopores on Porous Substrates

“…Nanoporous thin films are widely used for various applications such as energy conversion and storage [ 1 , 2 , 3 , 4 ], the selective separation of molecules [ 5 , 6 , 7 ] and filtration [ 8 , 9 , 10 ]. Commercially available nanoporous membranes generally exhibit broad size distributions and relatively large thickness.…”