Morphological, Electrical, and Chemical Characteristics of Poly(sodium 4-styrenesulfonate) Coated PVDF Ultrafiltration Membranes after Plasma Treatment

Abstract

A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinylidene fluoride) (PVDF), was recovered with a negatively-charged polyelectrolyte (poly(sodium 4-styrenesulfonate)) (PSS), and the effects on its electric, chemical, and morphological properties were analyzed. Atomic force microscopy (AFM), liquid–liquid displacement porometry, Electrical Impedance Spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the modifications induced by the deposition of PSS on the PVDF positively-charged membrane and after its treatment by a radio frequency Ar-plasma. These techniques confirmed a real deposition and posterior compaction of PSS with increasing roughness and decreasing pore sizes. The evolution of the electric resistances of the membranes confirmed crosslinking and compaction with shielding of the sulfonated groups from PSS. In this way, a membrane with a negatively-charged active layer and a pore size which was 60% lower than the original membrane was obtained. The composition of the additive used by manufacturers to modify PVDF to make it positively charged was obtained by different procedures, all of which depended upon the results of X-ray photoelectron spectroscopy, leading to fairly consistent results. This polymer, carrying positive charges, contains quaternary nitrogen, as confirmed by XPS. Moreover, Raman spectroscopy confirmed that PVDF changes from mostly the β to the α phase, which is more stable as a substrate for the deposited PSS. The aim of the tested modifications was to increase the retention of divalent anions without reducing permeability.

One-Step Preparation of Antifouling Polysulfone Ultrafiltration Membranes via Modification by a Cationic Polyelectrolyte Based on Polyacrylamide

“…The approaches utilized for the design of antifouling membranes involve (1) membrane polymer modification (pre-modification) [11], (2) blending of the membrane polymer with a modifying agent (additive) [12][13][14] and (3) surface modification after membrane preparation (post-modification) [15]. Grafting [5,7,[15][16][17][18][19][20] and coating [21,22] are the most important and frequently utilized membrane surface modification methods.…”

“…Coating can be performed via the Langmuir-Blodgett technique, layer-by-layer deposition, copolymer adsorption, surfactant adsorption, salting-out effects and bio-adhesion [21]. Coatings feature more benefits compared to grafting due to the possibility to apply it to the existing installed membrane systems and modules via static or dynamic adsorption techniques.…”

“…Moreover, the coating does not change the structural properties and mechanical strength of the membranes, less expensive additional equipment is needed and the modification time is usually not too long [22]. In contrast, grafting significantly changes membrane surface chemistry and physicochemical properties and requires excessive application of chemical solvents and various monomers [21,22]. However, both of these approaches are multi-step membrane formation techniques leading to the substantial increase of membrane cost.…”

Chemiluminescent Poly(sodium 4-styrenesulfonate)-Encapsulated Acridinium Sulfonamide-Functionalized CoFe2O4 Nanoparticles for Detection of Cholesterol

“…Moreover, as shown in Figure B, compared to the C 1s spectrum of CoFe 2 O 4 NPs (bottom), a new peak located at 286.8 eV was found in the spectrum of CoFe 2 O 4 /AS NPs (middle), which was assigned to N–CO, confirming that AS was modified on the surface of CoFe 2 O 4 NPs by amide bond. In addition, an additional peak located at 288.7 eV was found in CoFe 2 O 4 /AS/PSS NPs (top), which was assigned to the C–S bond from PSS, further demonstrating the successful synthesis of CoFe 2 O 4 /AS/PSS NPs. Then, the Fe 2p, Co 2p, and S 2p spectra of CoFe 2 O 4 /AS/PSS NPs were investigated in detail.…”

Freestanding Activated Carbon Nanocomposite Electrodes for Capacitive Deionization of Water

“…This polymer binder addition can lower electrical conductivity of the electrode as resistance builds up due to reduced electrical contact between the carbon particles. To offset this, additional highly conductive carbon materials can be added at low concentrations to improve electrode performance [ 13 ]. Furthermore, manufacturing the electrode might require high temperature treatment that could result in poor bonding between different carbon precursors.…”