Charged Mosaic Membrane Research Articles

Transport Behavior of Electrolytes Through Charged Mosaic Composite Membranes

Abstract The first part of this article reviews the strong acid/strong base type charged mosaic composite membrane. A template pattern with alternating poly(4-vinylpvridine) (P4VP)/poly(vinyl alcohol) (PVA) lamellae was fabricated upon a microporous membrane by casting of poly[4-vinylpyridine (4VP)-g-vinyl alcohol (VA)] graft copolymer from a water/l-propanol mixture. After a treatment involving the binding of the microporous membrane with the graft copolymer and also domain fixing of the PVA phases, a dilute solution of poly[sodium p-styrenesulfonate (SSS)-g-VA] graft co-polymer/P4VP binary blend was cast on this template surface. After chemical treatments (introduction of a positive charge and domain fixing of ion-exchange regions), we examined the transport of KCl and selective transport of a KCl-sucrose mixture through the charged mosaic composite membrane. The second section reviews the weak acid strong base type charged mosaic composite membrane. In this type, the charged mosaic regions were compose...

The desalination of a mixed solution of an amino acid and an inorganic salt by means of electrodialysis with charge-mosaic membranes

A new electrodialysis with charge-mosaic membranes was proposed to achieve efficient desalination of a mixed solution of an amino acid and an inorganic salt. For such a mixed solution, the conventional electrodialytic desalination with both cation-and anion-exchange membranes had resulted in a considerable loss of the amino acid through the membranes. In this method, however, the amino acid in the desalination channel of the electrodialyzer migrates away from the membranes so that the permeation loss of the amino acid through the membrane can be prevented. Batchwise desalination experiments by this method were carried out with a glutamic acid or arginine solution including NaCl under the condition of constant electric current density. Similar experiments by the conventional method were also carried out. As a result of comparing both methods, the amino acid loss in this method became much smaller than that in the conventional one. It was confirmed that this method was very useful for the desalination of an amino acid solution. The effects of operating conditions on the desalination process are also discussed.

Microstructure of charged mosaic membranes constructed by phase growth

AbstractA template pattern with alternating poly(4‐vinylpyridine) (P4VP)/poly(vinyl alcohol) (PVA) lamellae was fabricated upon a cross‐linked PVA film by casting of poly[4‐vinyl‐pyridine (4VP)‐g‐vinyl alcohol (VA)] graft copolymer. After a treatment involving the binding of a PVA film with the graft copolymer and also domain fixing of the PVA phases, a dilute solution of poly[acrylic acid (AA)‐benzyl N,N‐dimethyldithiocarbamate (DMTC)] copolymer/P4VP binary blend was cast on this template surface. The microstructure of binary blend was observed from scanning electron microscopy (SEM) by wet‐etching of films after domain fixing of one component of the binary blend. The poly(AA‐DMTC) copolymer/P4VP binary microdomains formed by phase growth were oriented perpendicularly to the film surface. We also fabricated these charged mosaic regions on a microporous poly(vinyl chloride) (PVC) membrane, and carried out the surface analysis by X‐ray photoelectron microscopy (XPS). Finally, we examined the transport of KCl through the charged mosaic composite membranes. © 1994 John Wiley & Sons, Inc.

Charge-mosaic membrane from gamma-irradiated poly (styrene—butadiene—4-vinylpyridine) triblock copolymer. II. Prelimineary dialysis test

In the present paper the variations of the physicochemical properties of a charge-mosaic membrane with the pH of solution were investigated. Charge-mosaic membranes with a well-defined domain structure and strong mechanical and chemical stability were prepared from irradiated poly (styrene—butadiene—4-vinylpyridine) triblock copolymer. The membrane conductivity (or salt flux) of the charge-mosaic membrane increases with pH in the pH range 2–6) and reaches a maximum at pH 6. On further increase of the pH (in the range 6–10), the membrane conductivity (or salt flux) decreases again. However, the amount of non-electrolyte (protein or sucrose) flux through membrane could not be detected over the whole pH range studied. The remarkable effect of pH on the membrane properties can be illustrated by an analysis of the microstructure of the charge-mosaic membrane and by the amount of the hydrogen and hydroxyl ions formed at the different pHs. Dialysis coefficients determined from a mixed solution of 0.1 N KCl and 0.1 g/100 ml protein (or 0.1 N KCl and 0.1 N sucrose) were 1.07 × 10 −8 mol/cm 2-sec and 1.10 × 10 −8 mol/cm 2-sec respectively. The high salt permeability seems to originate from the well-defined domain structure in the precursor film (cast from a mixed solution of n-butyralydehyde and chloroform) and indicates that the transport of salt through these charge-mosaic membranes occurs by a mechanism typical for such a membrane.

モザイク荷電膜の設計と機能

Charge-mosaic membranes were fabricated from pentablock copolymers of the BABCB type, poly (isoprene-b-styrene-b-butadiene-b- (4-vinylbenzyl) dimethylamine-b-isoprene), by selectively introducing anion-and cation-exchange groups into the micro-separated phases. The three-layer lamellar structure of the starting pentablock copolymer films was not disturbed by the modification. The resulting membranes showed negative osmosis for aqueous solutions of salts and highly selective transport for sodium chloride in mixed solutions of low-molecular weight organic non-electrolytes and sodium chloride when the membranes were applied to dialysis process. The selectivity was much higher than those for conventional porous membranes, reverse osmosis membrane and dialysis membrane. On the other hands, the membrane exhibited an apparent piezodialytic effect in the region of low salt concentration (<0.01M) when they were applied to piezodialytic process. The salt enrichment increased with increasing applied hydrostatic pressure difference or decreasing salt concentration. These data and recent new challenges in the membrane fabrication make us expect the advent of some practical uses of charge-mosaic membranes in the future.

Charge-mosaic Membrane

I. INTRODUCTION Charge-mosaic membranes composed of cation-and anion-permeable micro­ domains have been of interest in membrane technology because of their unique transport properties. Figure 1 shows the two types of three-dimensional struc­ ture characteristic of the membrane. Homogeneous cation-or anion-exchange membranes allow their counterions to pass through the membrane but retard the permeation of electrolytes. Since charge-mosaic membranes have respec­ tive pathways for anions and cations, they have high permeability for electro­ lytes and can thus be used for the dialytic and piezodialytic separation of electrolytes from mixed aqueous solutions of electrolytes, such as sodium chlo­ ride, and nonelectrolytes, such as sugar.

Weak acid-strong base type charge-mosaic membrane. I. Carboxylic acid-quaternary amine system

A film prepared from a pentablock copolymer, poly [isoprene-b-styrene-b-isoprene-b-(4-vinylbenzyl)dimethylamine-b-isoprene] (ISIAI), was subjected to chemical modification in three steps: the A block was quaternized, the I block was cross-linked, and the S block was acylated. The threelayer lamellar structure of the original film was retained even after these processes. The resulting membrane behaved as a charge-mosaic membrane at higher pH values and as an anion-exchange membrane at lower pH values, the behavior corresponding to the degree of dissociation of the carboxyl group. This weak acid-strong base type charge-mosaic membrane exhibited quite high ion selectivity in comparison with previous strong acid-strong base type charge-mosaic membranes.

Synthesis and properties of 4‐vinyl pyridine grafted SBS used as charged mosaic membrane

AbstractThe grafting of 4‐vinyl pyridine onto styrene‐butadiene‐styrene triblock copolymer by irradiation was studied. Cationic and anionic groups were introduced by sulfonation and methylation to obtain a charged mosaic membrane.The experiments showed an increased rate of grafting with the increase of irradation dose. The best concentration of monomer was at 20%.After grafting, the contact angle and the water content were tested and morphology studies were performed.Furthermore, the tensile strength of this membrane increased with increased percentage of grafting. After testing, the charged mosaic membrane had a reduced potential. Its anionic and cationic exchange capacitites were between 0.12 to 0.13 meq/g, and 0.24 to 0.343 meq/g, respectively. The ratio of exchanged capacity was up to 0.509. KCI and urea can be separated by dialysis. In the determination of a piezodialysis, the salt enrichment reached a percentage of 10.3.

Preparation of charge-mosaic membranes by radiation-induced graft copolymerization of PE films with styrene and 4-vinylpyridine: II. Effects of pre-irradiation dosage, atmosphere, storage time and storage temperature of grafting of 4-vinylpyridine onto PE films

The graft copolymerization of 4-vinylpyridine onto LDPE films pre-irradiated with a 1.2 MeV electron beam, was carried out in the vapor phase as the second step in the preparation of charge-mosaic membranes. The effects of pre-irradiation dosage, atmosphere, storage time and storage temperature of PE films on the grafting process were studied by measuring the rate of free radical decay under different conditions. The results of ESR study show that: (1) The free radicals, created in the course of pre-irradiation, decrease stepwise with different decay constants. At first, they decay rapidly, but afterwards they decay more and more slowly. (2) At different temperatures, free radicals have different decay constants but they have almost the same decay characteristics as described above. (3) Sampling pre-irradiated PE films during the fast decay period may cause a pronounced error in the percentage graft, so that the standard deviation is much larger. On the other hand, sampling pre-irradiated PE films during the slow decay period greatly improves the precision of the percentage graft, so the standard deviation is much smaller. (4) For the above reason, the optimum storage time of pre-irradiated PE films at 5°C may be considered to be in the range of 48–120 h after the free radicals have been created. The results of graft copolymerization of pre-irradiated PE films with 4-vinylpyridine in the gaseous phase at different temperatures showed that: (1) At higher grafting temperatures, the grafting rate of 4-vinylpyridine onto PE films is much higher than the swelling rate of PE films by monomer vapor. As the grafted macromolecular chains propagated surround the activated sites very quickly, there is a local thickening effect, and the resulting graft copolymer looks rough. (2) At lower grafting temperatures, the grafting rate of 4-vinylpyridine seems to be comparable with the swelling rate of PE films by monomer vapor; an even and smooth copolymeric film can be obtained.

Preparation and characterization of 4-vinyl pyridine-grafted SBS triblock copolymer

Study on the graft of 4-vinyl pyridine to styrene-butadiene-styrene triblock copolymer by solution polymerization shows that the catalyst concentration, temperature, and reaction time are the major influencing factors. Graft efficiency increases with temperature and time but levels off when temperature is higher than 65°C. Increasing concentration of catalyst also promotes graft, but when it is higher than 1.0 × 10−2M, the reaction system begins to gel. A cast film of the graft copolymer was dried, cross-linked with S2Cl2 in nitromethane solution, sulfonated, and chloromethylated. The water content of the membrane is 13.5%. Its anionic and cationic exchange capacities are 0.066 mEq per dry gram and 0.273 mEq per dry gram, respectively. The anionic-cationic capacity ratio is thus 0.26. The nitrogen content of the graft copolymers was determined with a CHN elemental analyzer, and qualitative analysis was carried out with infrared spectroscopy. Transmitting electronic microscopy was used to study the morphology and feasibility of preparing a charged mosaic membrane for piezodialysis.

Charge mosaic membranes: Microdomain fixing of (polystyrene–poly‐4‐vinylpyridine) sequential copolymers prepared by macromonomer methods

AbstractPolystyrene (PST) macromonomers having several allyl groups at the ends were synthesized by the mechanical scission reaction of the main chain in the presence of diallylmalonic acid diethyl ester (DAME). Photosensitive benzophenone groups were introduced on a PST macromonomer molecule by the reaction of these PST macromonomers with benzoyl chloride. The palm‐treelike (PST–poly‐4‐vinylpyridine (P4VP)) sequential copolymers with different compositions were prepared by the radical copolymerization of PST macromonomer with 4VP. The morphological observation of these sequential copolymers was carried out by the transmission electron microscopy. The PST block microdomains were fixed by photocrosslinks (UV irradiation) in the presence of mono‐ and bifunctional unsaturated compounds in the state of mesomorphic structures. The microdomain fixing of P4VP blocks was carried out by using the vapor of 1, 4‐dibromobutane (DBB). After subsequent chemical modifications (quaternization of residual P4VP blocks and sulfonation of PST blocks), the effect of microdomain fixings was elucidated from the moisture content of positive and negative regions. These results are discussed in some detail.

Artificial Membranes from Multiblock Copolymer IV. Four-Component Pentablock Copolymers of the DSD′AD Type Usable to Fabricate a Charge-Mosaic Membrane

Four-component pentablock copolymers of the DSD′AD type, poly(isoprene-b-styrene-b-butadiene-b-(4-vinylbenzyl)imethylamine-b-isoprene) and poly(butadiene-b-styrene-b-isoprene-b-(4-vinylbenzyl)dimethylamine-b-butadiene), were prepared by a sequential anionic polymerization and the morphologies of the films cast from benzene, dioxane, and cyclohexane solutions of the samples were studied by electron microscopy and viscoelastic spectrometry. Three-layer lamellar structures were observed for the benzene- and dioxane-cast films just like as the case for ISIAI pentablock copolymers. Charge-mosaic membranes prepared by quaternizing, cross-linking, and sulfonating the films exhibited better refined microstructures and better performance than those prepared from ISIAI block copolymers.

Artificial membranes from multiblock copolymers. 3. Preparation and characterization of charge-mosaic membranes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTArtificial membranes from multiblock copolymers. 3. Preparation and characterization of charge-mosaic membranesYoshiyuki Miyaki, Hiroshi Nagamatsu, Minoru Iwata, Koji Ohkoshi, Kazunori Se, and Teruo FujimotoCite this: Macromolecules 1984, 17, 11, 2231–2236Publication Date (Print):November 1, 1984Publication History Published online1 May 2002Published inissue 1 November 1984https://doi.org/10.1021/ma00141a006RIGHTS & PERMISSIONSArticle Views224Altmetric-Citations48LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

モザイク荷電膜 その設計思想

In order to prepare charge-mosaic membranes, many attempts have been made by many authors. In this article a historical survey is presented on the development of the methods for fablicating such membranes. A multiblock copolymer method is considered to be one of the most promising methods. Suitably designed ISIAI-type pentablock copolymers consisting of isoprene (I), styrene (S), and 4-vinylbenzyldimethylamine (A) with a three-layer-lamellar structure are stable to chemical treatments and successfully give a charge-mosaic membrane which shows a piezodialytic effect and a very high salt permeability. This membrane is useful for desalination of aqueous solutions containing organic substances of low molecular weights.

Separation of mixtures of sodium and potassium ions by charge mosaic dialysis

Charge mosaic membranes contain a mixture of anionic and cationic elements separated by thin neutral regions. In order to maintain eloctroneutrality, the overall flux of salts from electrolytic solutions through such membranes must occur with equal transport of cationic and anionic charge. The flux rate depends on the resistivities of the exchange elements and the solution composition. It is shown that Na + and K + can have vastly different relative transport rates depending on the selection of the membrane formulation and the receiver composition. The effect is attributed to ionic polarization of the membrane.

Piezodialytic transport across charge-mosaic membranes

The study reported in this paper is a continuation of a study presented earlier'*/Proceedings of the Internat, Congress on Desalination and water Re-use, Nice, France, Oct. 21-27, 1979, Water for life, Vol. III Part 3/. The title membranes were prepared on the basis of polyethylene modified with the copolymers of styrene, 4-vinyl-pyridine and 2-vinyl-benzene. They were designed for the piezodialytic desalination and concentration of brakish waters and seawater. Symmetric and asymmetric electrolytes, KCl, MgCl 2,Mncl 2 CaCl 2 and Na 2So 4, /of an initial concentration between 0.05 and 0.5 M/ contained in brackish waters were concentrated, and the results obtained are discussed. The investigations were carried out in a laboratory system which permitted a recirculation of the liquid under study, and a mixing in the dialysate cell. The pressure at which the electrolytes were concentrated varied from 10.3 to 15.3 Pa /100 to 150 atm/ and was kept constant throughout each measurement. The applicability of the membranes in question to a dialytic concentration was estimated, in terms of the coefficient α which describes the concentration effect. The concentration effect depends on the degree of crosslinking in the ion-exchange elements, on the type concentration of the electrolyte and the value of pressure difference. For electrolytes of an initial concentration of 0.5 M no concentration effect was obtained. In the case of asymmetric electrolytes /but only for an initial concentration of 0.05 M/ the concentration effect was insignificant The experimental results indicate that the concentration effect decreases with the increase in electrolyte concentration and in the pressure applied.

Piezodialytic transport across charge-mosaic membranes

Three membrane series differing in capacity and crosslinkage of both cation- and anion-exchange resins have been studied to determine the apparent diffusion coefficient of salts as well as the osmotic transport of water through the membranes. The study have covered pressure tests to obtain hydrodynamic permeability coefficient of the membranes, salt enrichment coefficient, volume flux and salt flux for NaCl solution in concentration over the range of 0.05 to 0.25 M. Permeate concentration was 2.75 to 3.95 times higher than that of feed solution.

Transport properties of charge-mosaic membranes I. Theoretical models

Charge-mosaic membranes are currently being considered for a number of practical applications, most notably “piezodialysis“ desalination. In Part I of this series the properties of the charge-mosaic are subjected to a nonequilibrium thermodynamic analysis, with emphasis on the role of the electrical resistance in the solutions bathing the membrane. Four regimes of operation are delineated by the analysis: (i) membrane control, (ii) solution control, (iii) co-ion leakage control, and (iv) polarization control. For a charge-mosaic operating in the regime of membrane control, the “complete” phenomenological coefficients are essentially concentration-independent, hence the flows may be expressed as linear functions of the global forces. If the membrane operates instead in the regime of solution control, the relationships are not linear but the coefficients are still directly calculable.

Geometric effects in piezodialysis through charge-mosaic membranes

An explicit but highly schematic theory of the effect of the heterogeneity of charge-mosaic membranes on piezodialysis is given. An effect exists because the ions being transported through different parts of the membrane leave the feed bath at different points and also arrive in the filtrate bath at different points. The effect is always to reduce the salt flux through the membrane. The amount of reduction has been calculated for two geometric arrangements of the parts of the mosaic membrane, namely, alternating strips and a checkerboard of squares.

Ionic membranes for water desalination. I. Charge mosaic membranes from blends of random copolymers

AbstractThe incompatibility of polymers was used in order to prepare films with regular phase separation. The conversion of the separate phases into polyelectrolytes of different charge should lead to the preparation of charge mosaic membranes for piezodialysis.Copolymers of suitable monomers with 20–45 mole‐% butadiene content were synthesized which could be cross‐linked with sulfur monochloride. The comonomers were: styrene, 2‐vinyl pyridine, 4‐vinyl pyridine, methacrylic acid, methyl methacrylate and 2‐chloroethyl methacrylate.After conversion into the ionic form cross‐linked films of these copolymers showed salt rejections in the range of 26–78 % and water permeabilities of 40–43 [1· mm· m−2· day−1], respectively. These films can be used as anion and cation exchange membranes for water desalination.Mixtures of poly (2‐vinyl pyridine‐co‐butadiene) and poly (styrene‐co‐butadiene) yielded films with regular phase separation. After cross‐linking and conversion into the ionic form these charge mosaic membranes were porous and had poor mechanical strength. Despite these unfavourable properties a salt enrichment of 4.8 % was found in one case.