In water treatment processes and conditioning drinking water, PEs are widely used;however, their environmental impact is still doubtful, since residual concentrations increase organic matter content and represents a p...In water treatment processes and conditioning drinking water, PEs are widely used;however, their environmental impact is still doubtful, since residual concentrations increase organic matter content and represents a potential health hazard. This paper demonstrates a multiparametric study of two colloidal titration methods: spectrophotometric and zeta potential end point detection. The first one was optimized to guarantee the accuracy of cationic commercial PE quantification. It includes the indicator dose optimization using analytical criteria for competing equilibria, a calibration curve for two ranges of CPE concentration (1 - 5 ppm and 5 - 100 ppm) and the interference study of flocculant and Sn in the CPE quantification. The second method provides a physicochemical validation of the electric surface phenomena occurring during the colloidal titration and the end point detection. As an additional contribution the zeta potential titration was discussed and proposed as an alternative method for quantifying CPE when the sample is metal free.展开更多
The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymer...The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymers from the Praestol and Organopol series have been studied. The PCCs that spontaneously formed during mixing of sols of a high-basicity aluminum polyhydroxochloride (APHC) with aqueous solutions of the copolymers exhibit high flocculating ability under the conditions of gravity sedimentation of the model kaolin dispersion with Сd = 8 g/dm3, and their efficiency exceeds both that of the copolymers and the earlier obtained PCCs with nonionogenic polyacrylamide (PAA). In contrast to weakly charged polycationites, the fully charged KF-99 polyelectrolyte does not form PCCs and the products of its mixing with APHC do not reveal an increased flocculating effect.展开更多
The self-assembling behavior of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS)and hydrophobic comonomers possessing dodecyl groups linked by various spacer bonds was discussed with a focus ...The self-assembling behavior of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS)and hydrophobic comonomers possessing dodecyl groups linked by various spacer bonds was discussed with a focus on theeffect of the spacer. The characterization of association behavior of such polymers in water using quasielastic light scattering,capillary electrophoresis, NMR relaxation, various fluorescence, and viscoelastic methods was described. These copolymersform a variety of self-assembled nanostructures depending on the type of the spacer. Random copolymers of AMPS and N-dodecylmethacrylamide show a strong preference for intrapolymer self-association even in concentrated aqueous solutionsforming single-macromolecular self-assemblies (unimolecular micelles). In contrast, random copolymers of AMPS anddodecyl methacrylate are prone to undergo interpolymer associations yielding multipolymer micelles. In random copolymersof AMPS and a methacrylate substituted a nonionic surfactant (HO(CH_2CH_2O)_(25)C_(12)H_(25)) (C_(12)E_(25)), dodecyl groups are muchless restricted by the polymer backbone because they are linked via a long, flexible hydrophilic spacer. Thus, the polymer-bound C_(12)E_(25) surfactant moieties form micelles similar to those formed by discrete surfactants, but they are bridged bypolymer chains forming a network structure.展开更多
In this paper is describing the physicochemical behavior of polyelectrolytes (PEs) used in waste water treatment with mono-, di- and trivalent metal ions as K+, Mg2+, Zn2+, Fe3+, Sn2+, Cd2+, Pb2+, Cu2+, Ni2+, Al3+ and...In this paper is describing the physicochemical behavior of polyelectrolytes (PEs) used in waste water treatment with mono-, di- and trivalent metal ions as K+, Mg2+, Zn2+, Fe3+, Sn2+, Cd2+, Pb2+, Cu2+, Ni2+, Al3+ and Cr3+. A coagulant polyelectrolyte Poly(vinyl sulfate) potassium salt (PVSK), and a commercial available Flocculant Trident 2756, were used as models for the study. The colloidal titration UV-Vis spectroscopy technique was successfully implemented in order to evaluate the complexation of PEs with Toluidine Blue O (OTB) and the ability of different metal ions to displace the OTB from the PE-OTB complex and form the PE-metal ion complex. From the experiments was concluded that PVSK has a high affinity for Al3+ and Mg2+ while the Flocculant has the highest affinity for Sn2+ followed by Zn2+and Mg2+. The absorbance profiles of polyelectrolyte-OTB complex (Absorbance vs. Metal/PE) were used to calculate association constants. On the other hand, the mass balance of OTB and its absorbance profiles were used to calculate the association constants of polyelectrolyte-metal ion complexes. Thus metal ions with the highest affinities have the highest association constant. Metal ions with the highest affinities present the highest values of association constant.展开更多
Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly...Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.展开更多
Polyelectrolytes are charged polymers comprising macromolecules in which substantial portions of the constituent units contain cationic(e.g.,pyridinium,ammonium)or anionic(e.g.,sulfonate,carboxylate)groups,which posse...Polyelectrolytes are charged polymers comprising macromolecules in which substantial portions of the constituent units contain cationic(e.g.,pyridinium,ammonium)or anionic(e.g.,sulfonate,carboxylate)groups,which possess special functions from the features of counterions,such as dissociation to charged species,mechanical stability,phase behavior,etc.Therefore,functional polyelectrolytes have been widely applied in many fields.In this perspective,we present some progresses in the studies of poly(polyoxometalate)s,denoted as poly(POM)s,as a kind of new charged polymers/polyelectrolytes,by covalent bonding between the inorganic polyoxometalate(POM)clusters and the organic polymer chains.According to the distinct positions of POMs in polymer chain and functions of poly(POM)s,they are divided into the following four categories:crosslinked poly(POM);side-chain poly(POM);backbone poly(POM),including poly(POM)-conjugated polymer hybrid and block poly(POM)-polymer;and POM-based covalent organic framework(PCOF).This perspective introduces the synthesis methods of poly(POM)polyelectrolytes and their macromolecular and aggregate structural characteristics,while also focusing on their properties and functions.Their application areas include catalysis,thermal resistance,optical functions,fuel cells and batteries,etc.展开更多
We utilize molecular dynamics simulations to investigate the microstructures of ions and polyelectrolytes in aqueous solutions under external electric fields.By focusing on the multi-body interactions between ionic co...We utilize molecular dynamics simulations to investigate the microstructures of ions and polyelectrolytes in aqueous solutions under external electric fields.By focusing on the multi-body interactions between ionic components and H_(2)O molecules,as well as their responses to the external electric fields,we clarify several nontrivial molecular features of the ionic and polyelectrolyte solutions,such as the solvations of cations and anions,clustering of the ions,and dispersions/aggregations of polyelectrolyte chains,as well as the corresponding responses of H_(2)O molecules in these contexts.Our simulations illustrate the variations in structures of ionic solutions caused by reversing the charge sign of the ions,and elucidate the disparity in structures between anionic and cationic polyelectrolyte solutions in the presence of the external electric fields.This work clarifies the mechanism for the alternations in complex multi-body interactions in aqueous solutions caused by the application electric field,which can contribute to the fundamental understanding of the physical and chemical natures of ion-containing and charged polymeric systems.展开更多
The counterion-mediated hydrogen bonding(CMHB)is related to the hydrogen bonding between bound counterions and polyelectrolyte chains in polyelectrolyte systems,where the counterions can both electrostatically bind to...The counterion-mediated hydrogen bonding(CMHB)is related to the hydrogen bonding between bound counterions and polyelectrolyte chains in polyelectrolyte systems,where the counterions can both electrostatically bind to the charged groups of polyelectrolyte chains and act as hydrogen bond donors or acceptors to form hydrogen bonds with the hydrogen bond sites associated with polyelectrolyte chains simultaneously.A large number of literatures illustrate that strong polyelectrolytes(SPs)are insensitive to pH,which severely limmits the applications of SPs as smart materials.However,our studies have demonstrated that the CMHB makes SPs pH-responsive.This perspective discusses the mechanism of pH responsiveness of SPs and the pH-tunable properties of SPs,based on the pH-controlled CMHB effect.The future research directions on the pH responsiveness of SPs are also discussed here.It is anticipated that the study of the pH responsiveness of SPs not only will provide a new understanding of the fundamental properties of SPs,but also will greatly expand the applications of SPs in the field of smart materials.展开更多
We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are neutral.The electrostatic complexat...We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are neutral.The electrostatic complexation between oppositely charged polymers drives the formation of many ordered phases.The microstructures and phase diagrams are calculated using self-consistent field theory(SCFT)based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged monomers.The effects of the charge ratio,representing the ratio of charges from the homopolymer over all charges from polymers in the system,on the ordered structure are systematically studied,both for hydrophobic and hydrophilic A blocks.The charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer concentration.We also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed,and the results are in good agreement with experiments.These studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems.展开更多
The rheological properties of three different microstructures of hydrophobically modified alkalisoluble polymers (telechelic, multisticker and combined) in the presence of various concentrations of anionic surfactant ...The rheological properties of three different microstructures of hydrophobically modified alkalisoluble polymers (telechelic, multisticker and combined) in the presence of various concentrations of anionic surfactant and salt (NaCl) were investigated. Associative polymers containing both ionic sites and small number of hydrophobic groups were obtained, and their thickening properties in aqueous solutions, were investigated. Solution polymerization was used for obtaining the different polymers. Relationships between hydrophobe, sodium dodecyl sulfate (SDS) and NaCl concentration are proposed. Owing to the competition between attractive hydrophobic interaction and repulsive electrostatic interactions, such hydrophobically modified polymers exhibit various rheological behaviors in aqueous solutions, depending on microstructure of polyelectrolyte, SDS and NaCl concentrations.展开更多
The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s ...The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance.Thus,solution-processable poly(POM)s are expected to be used as key materials in advanced devices.Further understanding of poly(POM)s will optimize the preparation process and improve device performance.Herein,we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy.Compared with traditional polymers,individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants.Thus,cluster aggregates with diverse shapes were observed.Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined,and studying the aggregate shapes revealed the presence of a curved semirigid chain in solution.Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing.Fundamental insight is critical to understanding the formation of poly(POM)films from solutions as key functional materials,especially for fuel and solar cells.展开更多
A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit...A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.展开更多
It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute...It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect. According to this theory, we have reviewed the previous viscosity data of derivatives of poly-2- vinylpyridine reported by Maclay and Fuoss first. Then, the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further. The solute adsorption behaviors and structural information of polymers have been discussed carefully.展开更多
Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observedwith fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),d...Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observedwith fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C_(12)E_8) wereallowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalenelabeled copolymers. The relative excimer emission intensity I_E/I_M of a cationic probe l-pyrenemethylamine hydrochloride(PyMeA·HCl) and the non-radiative energy transfer (NRET) I_(Py)/I_(Np) of naphthalene to pyrene for labeled polyelectrolyteswere chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightlyhigher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-boundpolyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to itsweaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescenceresults, nonionic surfactant C_(12)E_8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted themicelle formation for C_(12)E_8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyllabeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of thepolyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymer-surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.展开更多
We present a method of constructing composites composed of conjugated polyelectrolytes(CPEs)and singlewalled carbon nanotubes(SWCNTs)to obtain a high-performing flexible thermoelectric generator.In this approach,three...We present a method of constructing composites composed of conjugated polyelectrolytes(CPEs)and singlewalled carbon nanotubes(SWCNTs)to obtain a high-performing flexible thermoelectric generator.In this approach,three kinds of polymers,namely,poly[(1,4-(2,5-didodecyloxybenzene)-alt-2,5-thiophene](P1),poly[(1,4-(2,5-bis-sodium butoxysulfonate-phenylene)-alt-2,5-thiophene](P2),and poly[(1,4-(2,5-bis-acid butoxysulfonic-phenylene)-alt-2,5-thiophene](P3)are designed,synthesized and complexed with SWCNTs as thermoelectric composites.The electrical conductivities of the CPEs/SWCNTs(P2/SWCNTs,and P3/SWCNTs)nanocomposites are much higher than those of non-CPEs/SWCNTs(P1/SWCNTs)nanocomposites.Among them,the electrical conductivity of P2/SWCNTs with a ratio of 1:4 reaches 3686 S·cm^(-1),which is 12.4 times that of P1/SWCNTs at the same SWCNT mass ratio.Moreover,CPEs/SWCNTs composites(P2/SWCNTs)display remarkably improved thermoelectric properties with the highest power factor(PF)of 163μW·m^(-1)·K^(-1).In addition,a thermoelectric generator is fabricated with P2/SWCNTs composite films,and the output power and power density of this generator reach 1.37μW and 1.4 W·m;(cross-section)at△T=70 K.This result is over three times that of the thermoelectric generator composed of non-CPEs/SWCNTs composite films(P1/SWCNTs,0.37μW).The remarkably improved electrical conductivities and thermoelectric properties of the CPEs/SWCNTs composites(P2/SWCNTs)are attributed to the enhanced interaction.This method for constructing CPEs/SWCNTs composites can be applied to produce thermoelectric materials and devices.展开更多
Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developed from acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, ...Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developed from acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, poly(acryloyl chloride), was prepared by free radical polymerization of acryloyl chloride. The azo polyelectrolytes were prepared by an esterification reaction between the precursor polymer and corresponding azo chromophores containing a reactive hydroxyl group, followed by hydrolysis of the unreacted acyl chloride groups. The epoxy based precursor polymer was prepared by the reaction between 1,4-cyclohexanedimethanol diglycidyl ether and aniline, and postfunctionalized by azo coupling reaction to form azo polymers containing chromophores with ionizable groups. The polyelectrolytes were characterized by elemental analysis, H-1-NMR, IR and UV-Vis spectroscopy. The photodynamic and photoresponsive properties, as well as self-assembly of these azo polyelectrolytes are reported in this paper([1]).展开更多
The adsorption amount of poly(styrene sulfonate) and poly(dimethyldiallyl ammonium chloride) (PSS/PDDA) self-assembled multilayer membranes in designed dipping solvents were measured by UV-Vis-spectroscopy and quartz ...The adsorption amount of poly(styrene sulfonate) and poly(dimethyldiallyl ammonium chloride) (PSS/PDDA) self-assembled multilayer membranes in designed dipping solvents were measured by UV-Vis-spectroscopy and quartz crystal microbalance (QCM). Intrinsic viscosities of PSS and PDDA in corresponding dipping solvents were determined by an Ubbelohde viscometer. It is found that the adsorption amount of PSS/PDDA self-assembled multilayer membranes built up in different dipping solutions, added salt concentration, pH of solution and solvent quality, respectively changed oppositely with the corresponding intrinsic viscosity of PSS and PDDA in dipping solvents. A negative relation between the adsorption amount and intrinsic viscosity was revealed, and explained in term of the concept of excluded volume of polymer molecule in dilute solutions.展开更多
The rheological behavior of polyhexamethylene guanidine hydrochloride (PHGC) and polyhexamethylene guanidine stearate (PHGS) has been investigated using the capillary rheometer. It is shown that the polyelectrolyte me...The rheological behavior of polyhexamethylene guanidine hydrochloride (PHGC) and polyhexamethylene guanidine stearate (PHGS) has been investigated using the capillary rheometer. It is shown that the polyelectrolyte melts are non-Newtonian of shear-thinning fluid. The melt viscosity, die flow activation energy and the flow temperature are high even if the molecular weight is not high. The melting viscosity of PHGC is higher than that of PHGS at the same experimental conditions. By comparison with the case of PHGS the non-Newtonian index of PHGC is smaller, the flow activation energy and die flow temperature of PHGC are higher, which was caused by the difference in their molecular structure.展开更多
文摘In water treatment processes and conditioning drinking water, PEs are widely used;however, their environmental impact is still doubtful, since residual concentrations increase organic matter content and represents a potential health hazard. This paper demonstrates a multiparametric study of two colloidal titration methods: spectrophotometric and zeta potential end point detection. The first one was optimized to guarantee the accuracy of cationic commercial PE quantification. It includes the indicator dose optimization using analytical criteria for competing equilibria, a calibration curve for two ranges of CPE concentration (1 - 5 ppm and 5 - 100 ppm) and the interference study of flocculant and Sn in the CPE quantification. The second method provides a physicochemical validation of the electric surface phenomena occurring during the colloidal titration and the end point detection. As an additional contribution the zeta potential titration was discussed and proposed as an alternative method for quantifying CPE when the sample is metal free.
文摘The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymers from the Praestol and Organopol series have been studied. The PCCs that spontaneously formed during mixing of sols of a high-basicity aluminum polyhydroxochloride (APHC) with aqueous solutions of the copolymers exhibit high flocculating ability under the conditions of gravity sedimentation of the model kaolin dispersion with Сd = 8 g/dm3, and their efficiency exceeds both that of the copolymers and the earlier obtained PCCs with nonionogenic polyacrylamide (PAA). In contrast to weakly charged polycationites, the fully charged KF-99 polyelectrolyte does not form PCCs and the products of its mixing with APHC do not reveal an increased flocculating effect.
文摘The self-assembling behavior of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS)and hydrophobic comonomers possessing dodecyl groups linked by various spacer bonds was discussed with a focus on theeffect of the spacer. The characterization of association behavior of such polymers in water using quasielastic light scattering,capillary electrophoresis, NMR relaxation, various fluorescence, and viscoelastic methods was described. These copolymersform a variety of self-assembled nanostructures depending on the type of the spacer. Random copolymers of AMPS and N-dodecylmethacrylamide show a strong preference for intrapolymer self-association even in concentrated aqueous solutionsforming single-macromolecular self-assemblies (unimolecular micelles). In contrast, random copolymers of AMPS anddodecyl methacrylate are prone to undergo interpolymer associations yielding multipolymer micelles. In random copolymersof AMPS and a methacrylate substituted a nonionic surfactant (HO(CH_2CH_2O)_(25)C_(12)H_(25)) (C_(12)E_(25)), dodecyl groups are muchless restricted by the polymer backbone because they are linked via a long, flexible hydrophilic spacer. Thus, the polymer-bound C_(12)E_(25) surfactant moieties form micelles similar to those formed by discrete surfactants, but they are bridged bypolymer chains forming a network structure.
文摘In this paper is describing the physicochemical behavior of polyelectrolytes (PEs) used in waste water treatment with mono-, di- and trivalent metal ions as K+, Mg2+, Zn2+, Fe3+, Sn2+, Cd2+, Pb2+, Cu2+, Ni2+, Al3+ and Cr3+. A coagulant polyelectrolyte Poly(vinyl sulfate) potassium salt (PVSK), and a commercial available Flocculant Trident 2756, were used as models for the study. The colloidal titration UV-Vis spectroscopy technique was successfully implemented in order to evaluate the complexation of PEs with Toluidine Blue O (OTB) and the ability of different metal ions to displace the OTB from the PE-OTB complex and form the PE-metal ion complex. From the experiments was concluded that PVSK has a high affinity for Al3+ and Mg2+ while the Flocculant has the highest affinity for Sn2+ followed by Zn2+and Mg2+. The absorbance profiles of polyelectrolyte-OTB complex (Absorbance vs. Metal/PE) were used to calculate association constants. On the other hand, the mass balance of OTB and its absorbance profiles were used to calculate the association constants of polyelectrolyte-metal ion complexes. Thus metal ions with the highest affinities have the highest association constant. Metal ions with the highest affinities present the highest values of association constant.
基金Supported by the National Basic Research Program of China(2015CB655301)the Natural Science Foundation of China(21825803)+2 种基金and the Natural Science Foundation of Jiangsu Province(BK20150063)the Program of Excellent Innovation Teams of Jiangsu Higher Education Institutionsthe Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.
基金supported by the Natural Science Foundation of Shandong Province of China(No.ZR2023QB278)the National Natural Science Foundation of China(No.92061120).
文摘Polyelectrolytes are charged polymers comprising macromolecules in which substantial portions of the constituent units contain cationic(e.g.,pyridinium,ammonium)or anionic(e.g.,sulfonate,carboxylate)groups,which possess special functions from the features of counterions,such as dissociation to charged species,mechanical stability,phase behavior,etc.Therefore,functional polyelectrolytes have been widely applied in many fields.In this perspective,we present some progresses in the studies of poly(polyoxometalate)s,denoted as poly(POM)s,as a kind of new charged polymers/polyelectrolytes,by covalent bonding between the inorganic polyoxometalate(POM)clusters and the organic polymer chains.According to the distinct positions of POMs in polymer chain and functions of poly(POM)s,they are divided into the following four categories:crosslinked poly(POM);side-chain poly(POM);backbone poly(POM),including poly(POM)-conjugated polymer hybrid and block poly(POM)-polymer;and POM-based covalent organic framework(PCOF).This perspective introduces the synthesis methods of poly(POM)polyelectrolytes and their macromolecular and aggregate structural characteristics,while also focusing on their properties and functions.Their application areas include catalysis,thermal resistance,optical functions,fuel cells and batteries,etc.
基金supported by the Major Science and Technology Projects for Independent Innovation of China FAW Group Co., Ltd. (No. 20220301018GX)the National Natural Science Foundation of China (Nos. 9237210012, 22073094 and 21474109)+2 种基金the Science and Technology Development Program of Jilin Province (Nos. 20240602003RC and 20210402059GH)the State Key Laboratory of Molecular Engineering of Polymers (Fudan University) (No. K2023-08)the Program for Young Scholars in Regional Development of CAS
文摘We utilize molecular dynamics simulations to investigate the microstructures of ions and polyelectrolytes in aqueous solutions under external electric fields.By focusing on the multi-body interactions between ionic components and H_(2)O molecules,as well as their responses to the external electric fields,we clarify several nontrivial molecular features of the ionic and polyelectrolyte solutions,such as the solvations of cations and anions,clustering of the ions,and dispersions/aggregations of polyelectrolyte chains,as well as the corresponding responses of H_(2)O molecules in these contexts.Our simulations illustrate the variations in structures of ionic solutions caused by reversing the charge sign of the ions,and elucidate the disparity in structures between anionic and cationic polyelectrolyte solutions in the presence of the external electric fields.This work clarifies the mechanism for the alternations in complex multi-body interactions in aqueous solutions caused by the application electric field,which can contribute to the fundamental understanding of the physical and chemical natures of ion-containing and charged polymeric systems.
基金supported by the National Natural Science Foundation of China(Nos.22273098,52033001,22373003 and 22103002)the Fundamental Research Funds for the Central Universities(No.WK2480000007).
文摘The counterion-mediated hydrogen bonding(CMHB)is related to the hydrogen bonding between bound counterions and polyelectrolyte chains in polyelectrolyte systems,where the counterions can both electrostatically bind to the charged groups of polyelectrolyte chains and act as hydrogen bond donors or acceptors to form hydrogen bonds with the hydrogen bond sites associated with polyelectrolyte chains simultaneously.A large number of literatures illustrate that strong polyelectrolytes(SPs)are insensitive to pH,which severely limmits the applications of SPs as smart materials.However,our studies have demonstrated that the CMHB makes SPs pH-responsive.This perspective discusses the mechanism of pH responsiveness of SPs and the pH-tunable properties of SPs,based on the pH-controlled CMHB effect.The future research directions on the pH responsiveness of SPs are also discussed here.It is anticipated that the study of the pH responsiveness of SPs not only will provide a new understanding of the fundamental properties of SPs,but also will greatly expand the applications of SPs in the field of smart materials.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.22073002,51921002 and 22373008).
文摘We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are neutral.The electrostatic complexation between oppositely charged polymers drives the formation of many ordered phases.The microstructures and phase diagrams are calculated using self-consistent field theory(SCFT)based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged monomers.The effects of the charge ratio,representing the ratio of charges from the homopolymer over all charges from polymers in the system,on the ordered structure are systematically studied,both for hydrophobic and hydrophilic A blocks.The charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer concentration.We also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed,and the results are in good agreement with experiments.These studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems.
文摘The rheological properties of three different microstructures of hydrophobically modified alkalisoluble polymers (telechelic, multisticker and combined) in the presence of various concentrations of anionic surfactant and salt (NaCl) were investigated. Associative polymers containing both ionic sites and small number of hydrophobic groups were obtained, and their thickening properties in aqueous solutions, were investigated. Solution polymerization was used for obtaining the different polymers. Relationships between hydrophobe, sodium dodecyl sulfate (SDS) and NaCl concentration are proposed. Owing to the competition between attractive hydrophobic interaction and repulsive electrostatic interactions, such hydrophobically modified polymers exhibit various rheological behaviors in aqueous solutions, depending on microstructure of polyelectrolyte, SDS and NaCl concentrations.
基金by the National Natural Science Foundation of China(Nos.21334003 and 21674052).
文摘The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance.Thus,solution-processable poly(POM)s are expected to be used as key materials in advanced devices.Further understanding of poly(POM)s will optimize the preparation process and improve device performance.Herein,we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy.Compared with traditional polymers,individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants.Thus,cluster aggregates with diverse shapes were observed.Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined,and studying the aggregate shapes revealed the presence of a curved semirigid chain in solution.Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing.Fundamental insight is critical to understanding the formation of poly(POM)films from solutions as key functional materials,especially for fuel and solar cells.
文摘A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.
基金financially supported by the National Natural Science Foundation of China(Nos.50633030 and 51073077)
文摘It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect. According to this theory, we have reviewed the previous viscosity data of derivatives of poly-2- vinylpyridine reported by Maclay and Fuoss first. Then, the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further. The solute adsorption behaviors and structural information of polymers have been discussed carefully.
基金The project was supported by the National Natural Science Foundation of China (No. 29725411, No. 29804003, No. 90206010) and Natural Science Foundation of Guangdong Province (015036).
文摘Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observedwith fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C_(12)E_8) wereallowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalenelabeled copolymers. The relative excimer emission intensity I_E/I_M of a cationic probe l-pyrenemethylamine hydrochloride(PyMeA·HCl) and the non-radiative energy transfer (NRET) I_(Py)/I_(Np) of naphthalene to pyrene for labeled polyelectrolyteswere chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightlyhigher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-boundpolyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to itsweaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescenceresults, nonionic surfactant C_(12)E_8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted themicelle formation for C_(12)E_8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyllabeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of thepolyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymer-surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.51803126 and 21704065)the Natural Science Foundation of Guangdong Province,China(Grant No.2018A0303130157)。
文摘We present a method of constructing composites composed of conjugated polyelectrolytes(CPEs)and singlewalled carbon nanotubes(SWCNTs)to obtain a high-performing flexible thermoelectric generator.In this approach,three kinds of polymers,namely,poly[(1,4-(2,5-didodecyloxybenzene)-alt-2,5-thiophene](P1),poly[(1,4-(2,5-bis-sodium butoxysulfonate-phenylene)-alt-2,5-thiophene](P2),and poly[(1,4-(2,5-bis-acid butoxysulfonic-phenylene)-alt-2,5-thiophene](P3)are designed,synthesized and complexed with SWCNTs as thermoelectric composites.The electrical conductivities of the CPEs/SWCNTs(P2/SWCNTs,and P3/SWCNTs)nanocomposites are much higher than those of non-CPEs/SWCNTs(P1/SWCNTs)nanocomposites.Among them,the electrical conductivity of P2/SWCNTs with a ratio of 1:4 reaches 3686 S·cm^(-1),which is 12.4 times that of P1/SWCNTs at the same SWCNT mass ratio.Moreover,CPEs/SWCNTs composites(P2/SWCNTs)display remarkably improved thermoelectric properties with the highest power factor(PF)of 163μW·m^(-1)·K^(-1).In addition,a thermoelectric generator is fabricated with P2/SWCNTs composite films,and the output power and power density of this generator reach 1.37μW and 1.4 W·m;(cross-section)at△T=70 K.This result is over three times that of the thermoelectric generator composed of non-CPEs/SWCNTs composite films(P1/SWCNTs,0.37μW).The remarkably improved electrical conductivities and thermoelectric properties of the CPEs/SWCNTs composites(P2/SWCNTs)are attributed to the enhanced interaction.This method for constructing CPEs/SWCNTs composites can be applied to produce thermoelectric materials and devices.
基金This work was supported by National Natural Foundation of China (No. 59873013).
文摘Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developed from acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, poly(acryloyl chloride), was prepared by free radical polymerization of acryloyl chloride. The azo polyelectrolytes were prepared by an esterification reaction between the precursor polymer and corresponding azo chromophores containing a reactive hydroxyl group, followed by hydrolysis of the unreacted acyl chloride groups. The epoxy based precursor polymer was prepared by the reaction between 1,4-cyclohexanedimethanol diglycidyl ether and aniline, and postfunctionalized by azo coupling reaction to form azo polymers containing chromophores with ionizable groups. The polyelectrolytes were characterized by elemental analysis, H-1-NMR, IR and UV-Vis spectroscopy. The photodynamic and photoresponsive properties, as well as self-assembly of these azo polyelectrolytes are reported in this paper([1]).
基金supported by the NNSFC(Nos.20574059,50633030)the Major State Basic Research Program of China(No.9732003C8615700).
文摘The adsorption amount of poly(styrene sulfonate) and poly(dimethyldiallyl ammonium chloride) (PSS/PDDA) self-assembled multilayer membranes in designed dipping solvents were measured by UV-Vis-spectroscopy and quartz crystal microbalance (QCM). Intrinsic viscosities of PSS and PDDA in corresponding dipping solvents were determined by an Ubbelohde viscometer. It is found that the adsorption amount of PSS/PDDA self-assembled multilayer membranes built up in different dipping solutions, added salt concentration, pH of solution and solvent quality, respectively changed oppositely with the corresponding intrinsic viscosity of PSS and PDDA in dipping solvents. A negative relation between the adsorption amount and intrinsic viscosity was revealed, and explained in term of the concept of excluded volume of polymer molecule in dilute solutions.
文摘The rheological behavior of polyhexamethylene guanidine hydrochloride (PHGC) and polyhexamethylene guanidine stearate (PHGS) has been investigated using the capillary rheometer. It is shown that the polyelectrolyte melts are non-Newtonian of shear-thinning fluid. The melt viscosity, die flow activation energy and the flow temperature are high even if the molecular weight is not high. The melting viscosity of PHGC is higher than that of PHGS at the same experimental conditions. By comparison with the case of PHGS the non-Newtonian index of PHGC is smaller, the flow activation energy and die flow temperature of PHGC are higher, which was caused by the difference in their molecular structure.
