Water-soluble Polyelectrolyte Research Articles

Potentiometric sensors for the determination of water-soluble polyelectrolytes

Potentiometric sensors for the analysis of water-soluble polyelectrolytes with different molecular masses were proposed. The surface morphology of polyvinyl chloride sensor membranes and chemical analytical characteristics of ready devices were studied. Selectivity coefficients of the sensors were calculated.

A Micellar Route to Layer-by-Layer Assembly of Hydrophobic Functional Polymers

We demonstrate a general approach to introduce hydrophobic functional polymers into a multilayer film using the layer-by-layer (LBL) assembly method that normally works for water-soluble polyelectrolytes. To this end, two new amphiphilic diblock copolymers each containing a hydrophobic side-chain liquid crystalline polymer (SCLCP) were synthesized using atom transfer radical polymerization, followed by a modification reaction. They are poly(acrylic acid)-b-poly{6-[4-(4′-cyanophenyl)phenoxy]hexyl methacrylate} (PAA-b-PCMA) and quaternized poly(4-vinyl pyridine-b-poly{6-[4-(4-ethyloxyphenylazo)phenoxy]hexyl methacrylate} (QP4VP-b-PAMA). We show that through the use of their micelles in aqueous solutions, which have a polycation (QP4VP-b-PAMA) or a polyanion (PAA-b-PCMA) corona, the two hydrophobic SCLCPs can be LBL assembled. The characterization results indicate that the LC phases are retained in the film, and that the SCLCPs are subjected to confinement effects inside the nanodomains defined by the core regions of the micelles. This micellar route to LBL assembly of hydrophobic functional polymers is general and offers new possibilities of designing nanostructured materials.

Water-Soluble Polyelectrolytes for FRET-based DNA Detection

Two conjugated polyelectrolytes with same electronic structure with/without molecular spacer (or bumper) are compared in functioning as a donor in fluorescence resonance energy transfer (FRET) to a fluorescein-labeled single-stranded DNA (ssDNA-Fl). Fluorescence quenching of the acceptor (Fl) in the polymer/ssDNA-Fl electrostatic complex is a main concern to improve detection sensitivity. This study can show one important example of structure-property relationships for the FRET-based biosensing assays. Structure modification such as molecular bumper can fine-tune the competition between energy transfer and electron transfer quenching in FRET-based DNA sequence detection.

Template synthesized high conducting silver chloride nanoplates

Silver chloride was synthesized using a water-soluble polyelectrolyte as a capping agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and differential scanning calorimetry (DSC) were employed to characterize morphology, structure and phase transition of as-prepared silver chloride. XRD, SEM and AFM confirms the formation of nanoplates of AgCl with a polygonal edge of diameter ∼ 250–300 nm. These nanoplates are found to be thermally stable up to its melting temperature (∼ 455 °C) with smaller value of melting enthalpy and higher room temperature conductivity values compared to pristine silver chloride ( σ Nanoplate / σ Pristine ≈ 10 4).

Comment on “Schottky contact on a ZnO (0001) single crystal with conducting polymer” [Appl. Phys. Lett. 91, 142113 (2007)

Poly 3,4-ethylenedioxythiophene doped with poly 4styrenesulfonate PEDOT:PSS has become one of the most widely studied conducting polymers in both academia and industry due to its several advantages, such as high work function, high conductivity, high stability in the oxidized state, and the ability to incorporate water-soluble polyelectrolyte dopants. In a letter in this journal, Nakano et al. reported that high quality Sckottky junctions were formed on a ZnO single crystal by employing a simple technique of spin coating PEDOT:PSS as the metal electrode. This information was very helpful for the fabrication of ZnO-based Schottky diodes. However, we found that the energy band diagram of the PEDOT:PSS/ZnO Schottky junction might be questionable for the argumentation in this letter. In this comment, we point out the mistake of their analysis of the observed result by current density-voltage J-V and capacitance-voltage C-V measurements. Nakano et al. pointed out that the Schottky barrier height b was directly determined from C-V and J-V measurements. In general, b determined from J-V measurements b JV for inorganic semiconductors is close to b determined from C-V measurements b CV based on the neglect of the image-force lowing. Among the J-V methods, the barrier height is most commonly calculated from the current density Js, determined by an extrapolation of the ln J versus V curve to V=0. The barrier height so determined is b JV for zero bias. In addition, the net current density under forward bias is J=Js→m—Jm→s where Js→m is the current from the semiconductor to the metal and Jm→s is the current from the metal to the semiconductor , meaning that the presence of the interfacial dipole may affect the injection of current from the metal semiconductor to the semiconductor metal and b JV is related to . Among the C-V methods, the barrier height is most commonly calculated from the intercept voltage, determined by an extrapolation of the 1 /C2 versus V curve to 1 /C2=0. The barrier height so determined is b CV

An Effective Hydrothermal Route for the Synthesis of Multiple PDDA-Protected Noble-Metal Nanostructures

In this article, we demonstrate an effective hydrothermal route for the synthesis of multiple PDDA-protected (PDDA = poly(diallyl dimethylammonium) chloride) noble-metal (including silver, platinum, palladium, and gold) nanostructures in the absence of any seeds and surfactants, in which PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. Under optimal experimental conditions, Ag nanocubes, Pt and Pd nanopolyhedrons, and Au nanoplates can be obtained, which were characterized by transmission electron microscopy , scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. More importantly, the nanostructures synthesized show potential applications in surface-enhanced Raman scattering and electrocatalysis, in which Ag nanocubes and Pt nanopolyhedrons were chosen as the examples, respectively.

Living Photolytic Ring-Opening Polymerization of Amino-Functionalized [1]Ferrocenophanes: Synthesis and Layer-by-Layer Self-Assembly of Well-Defined Water-Soluble Polyferrocenylsilane Polyelectrolytes

Facile synthetic routes have been developed that provide access to cationic and anionic water-soluble polyferrocenylsilane (PFS) polyelectrolytes with controlled molecular weight and narrow polydispersity. Living photolytic ring-opening polymerization of amino-functionalized [1]ferrocenophane (fc) monomers [fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}] (3), [fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2)] (10), [fcSiMe(C[triple chemical bond]CCH(2)NMe(2))] (14), and [fcSiMe(p-C(6)H(4)CH(2)NMe(2))] (20) yielded the corresponding polyferrocenylsilanes [(fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)})(n)](5), [(fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2))(n)] (11), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(2))}(n)] (15), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(2))}(n)] (21) with controlled architectures. Further derivatization of 5, 15, and 21 generated water-soluble polyelectrolytes [(fcSiMe{C[triple chemical bond]CCH(2)N(CH(2)CH(2)CH(2)SO(3)Na)(2)})(n)] (6), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(3)OSO(3)Me)}(n)] (7), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(3)OSO(3)Me)}(n)] (22), respectively. The polyelectrolytes were readily soluble in water and NaCl aqueous solutions, with 6 and 22 exhibiting long-term stability in aqueous media. The PFS materials 6 and 22, have been utilized in the layer-by-layer (LbL) self-assembly of electrostatic superlattices. Our preliminary studies have indicated that films made from controlled low molecular-weight PFSs possess a considerably thinner bilayer thickness and higher refractive index than those made from PFSs that have an uncontrolled high molecular-weight. These results suggest that the structure and optical properties of LbL ultra-thin films can be tuned by varying polyelectrolyte chain length. The water-soluble low molecular weight PFSs are also useful materials for a range of applications including LbL self-assembly in highly confined spaces.

Contribution of flow field flow fractionation with on line static and dynamic light scattering to the study of hydrosoluble polyelectrolyte complexes

Water soluble polyelectrolyte complexes (PECs) formed between polyaspartate (anionic polymer) and poly(trimethylammonium propyl methacrylamide chloride) (cationic polymer) were studied by flow field flow fractionation with on-line coupling multi-angle laser light scattering–quasi elastic light scattering–differential refractive index determination (F4/MALLS/QELS/DRI). The separation technique permits to characterize polydisperse PECs. The molar mass of the polycation (PC) influences the stiffness of the PECs and the proportion between single PECs (i.e. nPA/1PC) and multiple PECs (i.e. nPA/n’PC). High ionic strength with NaCl (>0.1 M) tends to break the multiple PECs while CaCl 2 destroys PECs and leads to the formation of complexes polyaspartate/Ca 2+. The studied PECs can be used as inhibitors to the calcite formation in the drilling fluids.

Complexation of sodium 2-acrylamido-2-methylpropanesulfonate-monoethanolamine vinyl ether copolymer with polyelectrolytes in aqueous medium

A new water-soluble polyelectrolyte—the copolymer of sodium 2-acrylamido-2-methylpropanesulfonate and monoethanolamine vinyl ether—has been synthesized by free-radical copolymerization. The concentration behavior of the reduced viscosity of copolymer solutions that is typical for polyelectrolytes has been revealed. The reactivity ratios of the monomers have been measured. These values indicate a lower reactivity of monoethanolamine vinyl ether than that of sodium 2-acrylamido-2-methylpropanesulfonate. The complexation of this copolymer with poly(acrylic acid) and poly(N,N-dimethyl-N,N-diallylammonium chloride) has been studied. It has been found that the copolymer demonstrates the polyampholytic behavior and is able to form interpolymer complexes both with polycations and polyanions. It has been established that the polycomplex of the copolymer with polyacrylic acid has the unfolded structure due to the presence of sulfonate groups uninvolved in complexation, while the complex of the copolymer with poly(N,N-dimethyl-N,N-diallylammonium chloride) is compact owing to enhancement of hydrophobic interactions, and the sizes of its species are of the order of 80 nm.

Dispersion of Single-Walled Carbon Nanotubes in Water with Polyphosphazene Polyelectrolyte

A polyphosphazene polyelectrolyte was prepared as a dispersing agent of SWNTs in water. Poly(organophosphazene) was prepared by sequential treatment of poly(dichlorophosphazene) with sodium 4-phenylphenoxide, sodium phenoxide, and sodium trifluoroethoxide in THF. Their substitution percentages were 60, 24, and 16%, respectively. A water-soluble polyphosphazene polyelectrolyte was obtained by sulfonation of aromatic rings by using fuming sulfuric acid. SWNTs were dispersed in an aqueous polymer solution by sonication to give a black homogeneous dispersion. The supramolecular association between the nanotube and the sulfonated polyphosphazene was investigated by TEM, SEM, and AFM. The SEM image of the cleaved edge of the bucky paper, obtained by filtration of the dispersion of SWNTs, showed the nanotubes uniformly wrapped with the polymer. Their diameters were about 30 nm, suggesting small bundles of SWNTs rather than individual SWNTs. Individual SWNTs coated with the polymer were also observed by TEM. The total diameter of the coated tube was about 10 nm and a polymer layer thickness was lager than 4 nm.

Dendritic superstructure formation of polyaniline prepared using a water-soluble polyelectrolyte copolymer as the support matrix

In this letter, we report a dendritic superstructure formation of polyaniline (PANi) via a chemical oxidation approach using ammonium peroxydisulfate (APS) as the oxidant and a water-soluble polyelectrolyte copolymer as the dopant and support matrix. The morphology and the reaction conditions have been correlated, and a possible formation mechanism was proposed. It is suggested that the complex formation between the polyelectrolyte and aniline oligomer functions as nuclei which directs the further growth of polyaniline to dendritic superstructure.

Solid electrolyte of fully conjugated, water–soluble rigid-rod polymer with articulated backbone for isotropic ionic conductivity

An intractable and fully conjugated, aromatic, heterocyclic rigid-rod polymer poly[1,7- dihydrobenzo[1,2-d:4,5-d′] diimidazo-2,6-diyl-(2-sulfo)- p-phenylene] (sPBI) was derivatized with isophthalic acid for an articulated rigid-rod polymer asPBI. This molecular backbone alternation significantly changed the intrinsic viscosity [ η] of sPBI from 9.4 dL/g to 1.1 dL/g for asPBI containing minute (1/50 molar ratio) articulation moiety indicating more a coil-like polymer for asPBI. Both sPBI and asPBI were reacted with 1,3-propanesultone in dimethylsulfoxide containing lithium hydroxide for water–soluble polyelectrolytes sPBI-Li + and asPBI-Li +, respectively. The polyelectrolytes were dissolved in aqueous solution with up to 5 wt.% of LiI dopant and cast into films. Direct-current conductivity ( σ) was measured at room-temperature parallel to the film surface yielding σ ∥=3.2 × 10 −3 S/cm and 2.8 × 10 −3 S/cm for sPBI-Li + and asPBI-Li + (1/15), respectively. X-ray scattering and electron microscopy suggested that the cast films of sPBI-Li + was in-plane isotropic but out-of-the plane anisotropic, and of asPBI-Li + was three-dimensionally isotropic. It suggested that cast films of asPBI-Li + having articulated backbone acquired an isotropic microstructure as well as an isotropic room-temperature σ superior to those of other solid polyelectrolytes.

Adsorption of water-soluble polyelectrolytes of varied nature on mineral adsorbents

The adsorption behavior of water-soluble polyelectrolytes on mineral and synthetic adsorbents was analyzed. The effect of ionic strength, pH value, and hydrophobic interaction on the adsorption transfer of macrochains to the solid surface, determined by the conformation state of the macrochains and the electrokinetic potential of the adsorbent, was studied for model and industrial polyelectrolytes and adsorbents of varied acid-base nature.

Alginate polyelectrolyte complexes with cationic hydroxyethyl cellulose derivatives: Role of the block structure

It was shown that the block structure of alginate significantly affects the mechanism of formation and properties of its water-soluble polyelectrolyte complexes with cationic derivatives of hydroxyethyl cellulose. Alginate that contains residues of only mannuronic acid remains in solution in the form of coils, and the incorporation of guluronic acid residues gives rise to formation of a network structure. A difference in the structure of polyelectrolyte complexes is explained by different rigidities of blocks formed by residues of mannuronic and guluronic acids having different conformations of the pyranose ring.

Reversible Hydrogels from Self-Assembling Genetically Engineered Protein Block Copolymers

A series of triblock protein copolymers composed of a central water-soluble polyelectrolyte segment flanked by two coiled-coil domains was synthesized by genetic engineering methods. The copolymers self-assembled into reversible hydrogels in response to changes in temperature, pH, and the presence or absence of denaturating agent (guanidine hydrochloride, GdnHCl). Hydrogel formation was concentration-dependent, and the concentration needed for hydrogel formation correlated with the oligomerization state of the coiled-coil domains in the protein copolymers. The morphology of the hydrogels, as determined by scanning electron microscopy (SEM), indicated the presence of porous interconnected networks. The thermal stabilities and self-assembling properties of the protein copolymers were successfully controlled by manipulating the amino acid sequences of the coiled-coil domains. The stimuli responsiveness and reversibility of the hydrogel self-assembly suggest that these protein copolymers may have potential in biomedical applications.

Control of Charge Densities for Cationic Latex Particles

We report a systematic investigation, together with a new method, on controlling cationic charge densities of latex particles. A covalently bonded charge density up to 100 μequiv/g was achieved on the basis of copolymers of glycidyl methacrylate (GMA) and butyl methacrylate (BMA) by either surfactant-free or nonionically stabilized emulsion polymerization, followed by the aminolysis of epoxy groups into quaternary ammonium groups. The cationic charge density was successfully controlled by adjusting the ratio between epoxy and amino groups. It was found that the formation of disadvantageous water-soluble polyelectrolytes was negligible. Cationic charges were also introduced to latex particles by using cationic azo initiators and/or copolymerization with cationic or amine-containing comonomers, but colloidal titrations showed that controlled formation of highly charged cationic latex particles without the formation of water-soluble polyelectrolytes was only achievable for the aminolysis approach.

Concentration of Inorganic Salts in the Permeate during Nano- or Ultrafiltration Promoted by Water-Soluble Polyelectrolytes in the Feed Solution

Nano- or ultrafiltration of inorganic salts in the presence of a polyelectrolyte in the feed solution is investigated in this work. The membranes are completely impermeable to the polyelectrolyte. At low concentrations of polyelectrolyte, a gel layer on the membrane surface is not formed. At such polyelectrolyte concentrations, the concentration of inorganic salt in the permeate stream can be higher than that in the feed solution. This salt concentration effect is the reverse of what is obtained with conventional membrane processes, where the permeate salt concentration is lower than, or equal to, the salt concentration in the feed solution. It is shown that, in the nano- or ultrafiltration of inorganic salts in the presence of a polyelectrolyte, the ratio of the salt concentration in the permeate to that in the feed is improved when the initial salt concentration in the feed solution is low. Concentration polarization has a negative impact on this concentrating effect. A theory that elucidates the observed phenomenon is presented, together with experimental data for potassium chloride solutions and N,N-dimethyl-N-2-propenyl-2-propen-1-aminium chloride homopolymer filtered on an ultrafilter with a pore size of 5 nm.

Tailoring Photonic Crystals with Nanometer-Scale Precision Using Polyelectrolyte Multilayers

In this paper, we describe a rapid, accurate, and convenient method for postsynthetically tuning the optical properties of colloidal photonic crystals. High quality photonic crystal films are first synthesized and then coated iteratively with layers of water-soluble polyelectrolytes. The coating process results in nanometer-scale shifts in the photonic stop band, a process which has been monitored by theoretical modeling. The results suggest a fundamentally different, reproducible layering mechanism inside the confined spaces of the colloidal crystal where polyelectrolyte multilayers are less densely packed.

Synthesis and biologically relevant properties of polyphosphazene polyacids.

Polyphosphazene polyacids show potential as immunostimulating compounds and materials for microencapsulation. Their synthesis requires multistep chemical transition from a hydrolytically unstable macromolecular precursor, poly(dichlorophosphazene), to a water-soluble polyelectrolyte. Insufficient synthetic control in these reactions can lead to molecular weight variations and formation of macromolecules with "structural defects" resulting in significant variations in polymer performance. Simple and reproducible "one pot-one solvent" method is reported for the preparation of polyphosphazene polyacids-poly[di(carboxylatophenoxy)phosphazene] and its copolymers. Molecular weight characteristics and polymer compositions were studied as a function of reaction parameters. Macromolecular byproducts, incompletely substituted polymers containing hydroxyl groups and partially deprotected polymers containing propyl ester functionalities, were synthesized and characterized. It was demonstrated, that the presence of such groups can affect polymer characteristics, such as hydrolytic degradation profiles, immunostimulating activity, and microsphere forming properties. In vivo studies showed that the immunostimulating activity of polyphosphazene polyacids correlates with the content of acid functionalities in the polymer.

Water-soluble polyelectrolyte complexes formed by poly(diallyldimethylammonium chloride) and poly(sodium acrylate-co-sodium 2-acrylamido-2-methyl-1-propanesulphonate)-graft-poly(N,N-dimethylacrylamide) copolymers

Water-soluble polyelectrolyte complexes formed by poly(diallyldimethylammonium chloride) and poly(sodium acrylate-co-sodium 2-acrylamido-2-methyl-1-propanesulphonate)-graft-poly(N,N-dimethylacrylamide) copolymers