Sulfonic Chains Research Articles

Adsorption mechanism and interactions of coal particles modified with a novel hyperbranched dispersant

This account, a hyperbranched dispersant (Es-SAF-DBM-PSS) was assembled with the skeleton of Es-SAF-DBM (the functional modification of hydroquinone-based sulfonated acetone formaldehyde (SAF)) and numbers of linear polystyrene sodium sulfonate (PSS) chains by single electron transfer living radical polymerization (SET-LRP) in the system of PhBr2m4/Cu wire/PMDETA. The structure of the synthesized Es-SAF-DBM-PSS was detected by FTIR, 1H NMR, XPS, UV and GPC. Series of tests about the polymerization kinetics of Es-SAF-DBM-PSS were executed. Effects of temperatures and initiator concentration on the apparent polymerization rate were investigated, the results showed the low activation energy and higher initiation rate fitted the characteristic of SET-LRP. The rheological behaviors of Es-SAF-DBM-PSS as dispersant applied to coal water slurry (CWS) were tested. The following results were found as expected: the best usage of Es-SAF-DBM-PSS was only 0.3%, maximum coal content reached 63.7%, the viscosity dropped as low as 1000mPa·s. And the penetration ratio of slurry mixed with Es-SAF-DBM-PSS was still 100% even after 35days. Adsorption mechanism and interparticle interactions of coal particles modified with Es-SAF-DBM-PSS were investigated by Langmuir equation, dynamic equations and extended Derjaguin-Landau-Verwey-Overbeek (eDLVO) theory, the results showed the excellent dispersion and stability performance of Es-SAF-DBM-PSS were mainly related to the specific hyperbranched structure.

Oxide vacancy passivation through interface engineering of Tetraphenylethylene-Based Small-Molecule with sulfonate functional group for efficient organic photodetector

In this study, an alcohol-soluble tetraphenylethylene (TPE) unit-based luminogen with sulfonate chains is developed as a passivation layer for the oxygen vacancies of zinc oxide (ZnO) to obtain efficient organic photodetectors (OPDs). Given that the TPE-4 is designed to have four sulfonate chains, it can effectively fill the oxygen vacancy in ZnO, as confirmed by the results of X-ray photoelectron spectroscopy. The OPD device with the combination of ZnO and TPE-4 buffer layer exhibited decreased dark current and increased photocurrent owing to the prevention of trap-assisted recombination and shunt leakage caused by oxygen vacancies, as proved by electrical analysis. Moreover, the TPE-4 buffer layer exhibited excellent noise attenuation, leading to a signal-to-noise ratio of 50.35 dB and high device speeds of 0.77 μs and 137 kHz. The proposed TPE-based luminogen, designed to highlight the advantages of the widely used metal oxide layer while compensating for its limitations, is an effective strategy for realizing excellent photodetectors through chemical bonding.

Complexation and organization of doxorubicin on polystyrene sulfonate chains: impacts on doxorubicin dimerization and quenching.

Anthracycline doxorubicin hydrochloride (DX) is a positively charged fluorescent drug, which in water self-associates into non-fluorescent antiparallel dimers upon increasing concentration and/or ionic strength. The positive charge of DX allows for complexation with negatively charged polymers and drug carriers. The fluorescence of DX following complexation with polyanion polystyrene sulfonate (PSS) is studied here. The fluorescence emission of DX decreases in the presence of PSS, being almost completely quenched when the ratio (R) of PSS monomers-to-DX molecules is larger than 10. Increasing R values over 30 results in a progressive recovery of fluorescence. The circular dichroism of PSS-DX complexes shows inverted characteristic bands of DX dimers suggesting the presence of parallel dimers at a concentration of DX below dimerization in water. Molecular dynamics studies corroborate a preferential orientation of DX into parallel dimers when interacting with PSS and show that DX molecules interact with a binding pocket of PSS monomers rather than with one single monomer. Increasing the ionic strength results in a recovery of fluorescence without an apparent release of DX from the PSS-DX complex as shown by DOSY NMR. PSS acts as a template for concentrating DX, triggering dimerisation and orienting DX molecules with their charged groups facing the negatively charged PSS monomers.

Enhancing Hybrid Upconversion Nanosystems via Synergistic Effects of Moiety Engineered NIR Dyes.

Hybrid upconversion nanosystems have been reported to improve the low absorption efficiency of lanthanide-doped upconversion nanoparticles (UCNPs). However, the low quantum yield and poor photostability of NIR dyes pose challenges for practical uses. Here, we introduce a bulky moiety, 4-(1,2,2-triphenylvinyl)-1,1'-biphenyl (TPEO), to enhance its quantum yield by suppressing the bond rotation and improve the stability by deactivating the photoinduced oxidization. Compared with the conventional IR806, the formed NIR dye, TPEO-Cy, has been characterized to deliver three times higher quantum yield and seven times better photostability. Moreover, we take advantage of the strong affinity of sulfonate chains on the TPEO-Cy to bind to the surface of UCNPs. Taking together the synergistic effect, we have achieved a 242-fold upconversion emission enhancement over the benchmark of IR806-sensitized system and an ∼800 000-fold increase than the bare UCNPs. Our design of the NIR dyes suggests a new scope to search for more efficient upconversion nanohybrids.

Nafion membrane channel structure studied by small-angle X-ray scattering and Monte Carlo simulations

The structure of Nafion 117 membranes was studied through SAXS experiments and 2D pattern simulations. Measurements were taken for different moisture conditions by synchrotron radiation, and for different temperatures through X-ray tube irradiation. The experimental profiles were fitted through simulations based on a new structural model including: the amorphous polymer matrix, polymer crystallites, and inverse core-shell type channels conformed by water cylinders and sulfonic chains. The geometrical parameters intervening in the simulation of the SAXS patterns were optimized for each experimental condition. This approach allowed the proper description of the experimental SAXS profiles for the various moisture conditions studied. In addition, a recent lamelar model was also included in the assessments, and the corresponding performances were discussed.

Discovery of an Orally Bioavailable Dual PI3K/mTOR Inhibitor Based on Sulfonyl-Substituted Morpholinopyrimidines.

The discovery and optimization of a series of 2-morpholino-pyrimidine derivatives containing various sulfonyl side chains at the C4 position led to the identification of compound 26 as a potent dual PI3K/mTOR inhibitor. It exhibited high inhibitory activity against PI3Kα/β/γ/δ (IC50 = 20/376/204/46 nM) and mTOR (IC50 = 189 nM), potent functional suppression of AKT phosphorylation (IC50 = 196 nM), and excellent antiproliferative effects on a panel of cancer cells. Enzymic data and modeling simulation indicate that a cyclopropyl ring on the C4 sulfone chain and a fluorine on the C6 aminopyridyl moiety are responsible for its maintained PI3K activity and enhanced mTOR potency, respectively. Furthermore, compound 26 exhibited higher efficiency in the HT-29 colorectal carcinoma xenograft model at the daily dose of 3.75 and 7.5 mg/kg relative to BKM120 at the dose of 15 and 30 mg/kg.

Study to improve an amphoteric sulfonate alkyl ester surfactant by mixing with nonionic surfactant to reduce brine\u2013waxy oil interfacial tension and to increase oil recovery in sandstone reservoir: T-KS field, Indonesia

Crude oil with a high wax content and high pour point can be very challenging when enhanced oil recovery by surfactant flooding is to be applied. High wax content in crude oil will lead to high intermolecular interaction because of the increasing cohesion forces. It causes interfacial (IFT) tension between oil and brine to be high. Hence, oil recovery is relatively low. This paper presents formulation of an amphoteric sulfonate alkyl ester (SAE) surfactant with a nonionic surfactant (ester group) to reduce oil–brine IFT in waxy oil of T-KS field, in Indonesia. The ion–dipole forces may occur between SAE surfactant and nonionic cosurfactant molecules. The forces cause sulfonate chain to be attracted to oil phase. The formulated surfactant produces low interfacial tension between brine and waxy oil of T-KS oil field. Its ability to displace remaining oil in the pore space was also tested using coreflood tests. These tests demonstrate considerably good incremental recovery.

Static structure of sodium polystyrene sulfonate solutions obtained through a coarse-grained model

ABSTRACTWe present a model based on effective pair interactions to describe the arrangement of sodium polystyrene sulfonate chains in suspension. The potential functions are obtained from the analysis of all-atom simulations and they are the main ingredient of a Brownian dynamics simulation. The resulting configurations are used to reconstruct the corresponding scattering intensity spectra that have the main features of experimental patterns. This coarse-grained model in conjunction with the reconstruction scheme allows us to gain some insights on the structural properties of a polyelectrolyte in solution.

Synthesis and Morphology Study of SEBS Triblock Copolymers Functionalized with Sulfonate and Phosphonate Groups for Proton Exchange Membrane Fuel Cells

Aromatic rings of poly(styrene-b-(ethylene-r-butylene)-b-styrene) triblock copolymer (SEBS) were functionalized with various acid functional groups for proton exchange membrane (PEM) applications. Three different acid functional groups (fluoroalkylsulfonic acid, arylsulfonic acid, and arylphosphonic acid) were introduced into SEBS via borylation of aromatic C–H bonds and Suzuki coupling reactions. The incorporation of acid side groups selectively into the polystyrene block of SEBS created nanometer-scale phase separated morphology composed of hydrophilic and hydrophobic domains in which the morphology structures and interdomanin distances are dependent on the chemical structure of acid side chains. Despite high ion exchange capacity value, the aryl phosphonated polymer (SEBS-P) showed the lowest water uptake and significantly lower proton conductivity compared to sulfonated SEBS PEMs because of the low acidity of phosphonic acid. Compared to aryl sulfonated SEBS-S2, fluoroalkyl sulfonated SEBS-S1 showed better proton conductivity at low relative humidity condition (<50%), which is ascribed to the stronger acidity and more compact ionic domains. Morphology study of SEBS-S1 indicates that due to both hydrophobic and oleophilic nature of fluoroalkyl chains, fluoroalkyl sulfonate chains of SEBS-S1 induced more dense ionic self-aggregation.

Study of sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups as ion conductive binder in lithium-ion batteries

In an attempt to reduce the Li+ concentration polarization and electrolyte depletion from the electrode porous space, sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups (SPEEK-FSA-Li) is prepared and attempted as ionic conductivity binder. Sulfonated aromatic poly(ether ether ketone) exhibits strong adhesion and chemical stability, and lithiated fluorinated sulfonic side chains help to enhance the ionic conductivity and Li+ ion diffusion due to the charge delocalization over the sulfonic chain. The performances are evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, charge–discharge cycle testing, 180° peel testing, and compared with the cathode prepared with polyvinylidene fluoride binder. The electrode prepared with SPEEK-FSA-Li binder forms the relatively smaller resistances of both the SEI and the charge transfer of lithium ion transport. This is beneficial to lithium ion intercalation and de-intercalation of the cathode during discharging–charging, therefore the cell prepared with SPEEK-FSA-Li shows lower charge plateau potential and higher discharge plateau potential. Compared with PVDF, the electrode with ionic binder shows smaller decrease in capacity with the increasing of cycle rate. Meanwhile, adhesion strength of electrode prepared with SPEEK-FSA-Li is more than five times greater than that with PVDF.

Biodiesel from Citrullus colocynthis oil: sulfonic-ionic liquid-catalyzed esterification of a two-step process.

Biodiesel was prepared from Citrullus colocynthis oil (CCO) via a two-step process. The first esterification step was explored in two ionic liquids (ILs) with 1,3-disulfonic acid imidazolium hydrogen sulfate (DSIMHSO4) and 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate (MSIMHSO4). Both ILs appeared to be good candidates to replace hazardous acidic catalyst due to their exceptional properties. However, the two sulfonic chains existing in DSIMHSO4 were found to increase the acidity to the IL than the single sulfonic chain in MSIMHSO4. Based on the results, 3.6 wt% of DSIMHSO4, methanol/CCO molar ratio of 12 : 1, and 150°C offered a final FFA conversion of 95.4% within 105 min. A 98.2% was produced via second KOH-catalyzed step in 1.0%, 6 : 1 molar ratio, 600 rpm, and 60°C for 50 min. This new two-step catalyzed process could solve the corrosion and environmental problems associated with the current acidic catalysts.

Blue-Emitting Self-Assembled Polymer Electrolytes for Fast, Sensitive, Label-Free Detection of Cu(II) Ions in Aqueous Media

We have developed a light-emitting material based on nonconjugated block copolymers that contain polystyrene sulfonate (PSS) chains. The confinement of the PSS chains within nanosized domains appeared to be a powerful means of achieving enhanced fluorescence signals. High fluorescence quantum yield, with a maximum value of 37%, was obtained by adjusting the types of self-assembled morphologies of PSS-containing block copolymers; in contrast, the fluorescence quantum yield was merely 5% for the PSS homopolymer lacking organization. The wavelength of fluorescence emission was tunable by rational molecular design. In addition, significant self-quenching behavior was not noticed in diverse forms of this material such as solutions, thin films, and free-standing membranes. Notably, the light-emitting self-assembled block copolymer electrolytes exhibited high sensitivity toward Cu(2+) ions, with a detection limit of parts per billion levels, rapid response time of ≤1 min, and insignificant interference of other competitive metal ions.

Giant hollow fiber formation through self-assembly of oppositely charged polyelectrolyte brushes and gold nanoparticles

We report on the use of binary mixtures of oppositely charged gold nanoparticles (AuNPs) and spherical polyelectrolyte brushes (SPBs), consisting of a polystyrene core onto which long polystyrene sulfonate chains are grafted, as a simple model system to investigate the influence of directional interactions on self-assembly. We demonstrate that the mixing ratio, i.e., the number of AuNPs per SPB, has a profound influence on self-assembly. In particular we report on the formation of giant hollow fibers, and present a thorough characterization of these nanostructures. We speculate that the adsorption of a few AuNPs on the SPBs appears to direct the tubular self-assembly, and discuss the analogy to the case of modified proteins such as tubulin under the action of nucleotides.

Mechanically and structurally robust sulfonated block copolymer membranes for water purification applications

The effective removal of ionic pollutants from contaminated water using negatively charged nanofiltration membranes is demonstrated. Block copolymers comprising polystyrene (PS) and partially hydrogenated polyisoprene (hPI) were synthesized by varying chain architectures. A one step procedure of cross-linking (hPI blocks) and sulfonation reactions (PS chains) was then carried out, which was revealed as an effective method to enhance mechanical integrity of membranes while hydrophilic sulfonated chains remain intact. In particular, the control of chain architecture allows us to create a synergetic effect on optimizing charge densities of the membrane, water permeability, and mechanical integrity under water purification conditions. The best performing membrane can almost completely (>99%) reject various divalent cations and also show NO3− rejection > 85% and Na+ rejection > 87%. Well defined nanostructures (tens of nanometers) as well as the periodically arranged water domains (a few nanometers) within hydrophilic phases of the hydrated membranes were confirmed by in situ neutron scattering experiments.

Atomistic Simulations of Dilute Polyelectrolyte Solutions

The properties of short chains of poly-(styrene)-co-(styrene sulfonate) are studied using atomistic molecular dynamics simulations with explicit solvent. We study single 8-mers and 16-mers with two species of counterions, Na(+) and Mg(2+), and for various degrees of sulfonation, f. We find that single trajectories do not efficiently sample configurational space, even for fairly long 100-ns simulations, because of rotational barriers caused by nonbonded interactions. Hamiltonian replica exchange molecular dynamics (HREMD) simulations or averages over multiple trajectories are required in order to obtain equilibrium properties. A polystyrene sulfonate chain adopts collapsed conformations at low f, in which the sulfonate groups are located outside the globule and benzene rings form the inner region, and adopts extended conformations as f is increased. Interestingly, the pair correlation functions between side groups of polystyrene chains are not sensitive to f and species of counterion, i.e., the balance of electrostatic repulsion between charged groups and hydrophobic attraction between benzene rings is achieved by conformational change in a way preserving pair correlations between side groups in a polymer chain. For Na(+) counterions, no localization is observed in the simulations. For Mg(2+) counterions, there is a large free energy barrier to contact pair formation between the sulfonate groups and the Mg(2+) counterions. As a consequence we do not observe the formation or breaking of contact pairs during the course of a simulation. The simulations provide insight into the important interactions and correlations in polyelectrolyte solutions.

Detailed Molecular Dynamics Simulations of a Model NaPSS in Water

Hydrophobic polyelectrolytes are known to form necklace-like structures of dense beads connected by strings of monomers. This structure appears as a result of optimization of the electrostatic and short-range interactions. To elucidate the effect of counterion condensation and solvent on polyelectrolyte conformations, we performed two sets of molecular dynamics simulations of model poly(styrene)-co-styrene sodium sulfonate (NaPSS) chains with the degree of polymerization N = 16-64 and fraction of charged monomers f = 0.25-1 in aqueous solutions: (1) water molecules were considered explicitly using the TIP3P-PME model and (2) water molecules were modeled as a dielectric continuum with the dielectric constant 77.73. Our simulations showed that with increasing fraction of sulfonated groups f a polystyrene sulfonate chain adopts an elongated conformation. There is a transition between collapsed and elongated states which is manifested in the change of the scaling dependence of the chain size on the degree of polymerization. The effect of the water-ion interactions on counterion condensation was analyzed by comparing the radial distribution functions between the sulfonated groups and counterions for chains with different f values. In the case of the collapsed NaPSS chains, it was found that ionized groups are located at the globular surface.

Synthesis and characterization of poly(acrylic acid‐co‐acrylamide)/hydrotalcite nanocomposite hydrogels for carbonic anhydrase immobilization

AbstractTo combine the advantages of a biopolymer with hydrotalcite in an enzyme immobilization system, the intercalation polymerization was used to prepare poly(acrylic acid‐co‐acrylamide)/hydrotalcite (PAA‐AAm/HT) nanocomposite hydrogels using sodium methyl allyl sulfonate as intercalation agent. Transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy results revealed that sodium methyl allyl sulfonate chains entered into the interlayer of HT, the interaction between them has taken place, and HT was dramatically exfoliated into nanoscale and homogeneously dispersed in the PAA‐AAm matrix. Transmission electron microscopy and cryo scanning electron microscope results showed that dried hydrogels were regular spherical particles, and swollen hydrogels revealed homogeneous porous network structures. Then, PAA‐AAm/HT nanocomposite hydrogels were used to immobilize carbonic anhydrase (CA), and the CO2 hydration activities of free enzyme and immobilized enzyme were evaluated. Results showed that immobilized CA retained the majority of the enzyme activity. The reason may be the formation of a microenvironment almost all of which is composed of free water inside the porous network structures. Therefore, the immobilized CA is of great potential in the removal of trace CO2 from the closed spaces. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3232–3240, 2009

Modification of poly(butylene terephthalate) by reaction with 1,4-butane sultone; synthesis and thermal characterization of new telechelic PBT ionomers

AbstractNew telechelic poly(butylene terephthalate) (PBT) ionomers, characterized by the presence of some aliphatic sulfonated chain ends, were prepared by reaction with the 1,4-butane sultone. Two methods of synthesis were compared and the final polymers, containing different percentages of ionic groups, were characterized, with particular attention to the thermal properties. Thermogravimetric analysis shows that the presence of ionic groups does not modify the thermal stability of PBT. The differential scanning calorimetry indicates that the crystalline phase and the crystallinity degree of PBT do not change in the presence of ionic chain ends, whereas the crystallization rate was found to be strongly modified. The ionomers crystallize at very high rate, due to the nucleating effect of the ionic aggregations formed in the melt.

Structural study of coacervation in protein-polyelectrolyte complexes

Coacervation is a dense liquid-liquid phase separation and herein we report coacervation of protein bovine serum albumin (BSA) in the presence of polyelectrolyte sodium polystyrene sulfonate (NaPSS) under varying solution conditions. Small-angle neutron scattering (SANS) measurements have been performed on above protein-polyelectrolyte complexes to study the structural evolution of the process that leads to coacervation and the phase separated coacervate as a function of solution pH , protein-polyelectrolyte ratio and ionic strength. SANS study prior to phase separation on the BSA-NaPSS complex shows a fractal structure representing a necklace model of protein macromolecules randomly distributed along the polystyrene sulfonate chain. The fractal dimension of the complex decreases as pH is shifted away from the isoelectric point ( approximately 4.7) of BSA protein, which indicates the decrease in the compactness of the complex structure due to increase in the charge repulsion between the protein macromolecules bound to the polyelectrolyte. Concentration-dependence studies of the polyelectrolyte in the complex suggest coexistence of two populations of polyelectrolytes, first one fully saturated with proteins and another one free from proteins. Coacervation phase has been obtained through the turbidity measurement by varying pH of the aqueous solution containing protein and polyelectrolyte from neutral to acidic regime to get them to where the two components are oppositely charged. The spontaneous formation of coacervates is observed for pH values less than 4. SANS study on coacervates shows two length scales related to complex aggregations (mesh size and overall extent of the complex) hierarchically branched to form a larger network. The mesh size represents the distance between cross-linked points in the primary complex, which decreases with increase in ionic strength and remains the same on varying the protein-polyelectrolyte ratio. On the other hand, the overall extent of the complex shows a similar structure irrespective of varying ionic strength and protein-polyelectrolyte ratio. A large fraction ( approximately 50%) of protein-polyelectrolyte complexes is also found to be free in the supernatant after the coacervation.

Visualization of Hydrophobic Polyelectrolytes Using Atomic Force Microscopy in Solution

We have used atomic force microscopy to study the morphology of hydrophobic polyelectrolytes adsorbed on surfaces. The polyelectrolytes consisted of polystyrene sulfonate (PSS) chains made with three charge densities: 32%, 67%, and 92%. They were adsorbed on two types of surfaces: mica, and phospholipid bilayers made of mixed neutral and cationic lipids. We show that the chains with a low charge density (32%) are collapsed in spherical globules while highly charged chains (67% and 92%) are fully extended. End-to-end distances and contour lengths of the extended chains were measured. Statistical analysis shows that the persistence length of these chains depends on the surface where they adsorb. On lipid bilayers, highly ordered monolayers are formed upon increase of the proportion of cationic phospholipids. These results show that highly charged PSS chains behave in a similar manner than the stiffer, hydrophilic DNA when adsorbed on surfaces. It could lead to the design of new types of nanostructured surfaces using polyelectrolyte molecules synthesized with specific properties.