Adsorption Of PSS Research Articles

The application of poly (sodium 4-styrene sulfonate) as an efficient dolomite depressant in the direct flotation of apatite from dolomite

Poly (sodium 4-styrene sulfonate) was tested as a novel and efficient depressant for the selective flotation of apatite and dolomite in this work. The separation performances were evaluated and the interaction mechanisms were uncovered. Flotation results illustrated that PSS strongly depressed dolomite, while it hardly affected the flotation of apatite. Zeta potential and Fourier Transform Infrared Spectrometer results indicated that the adsorption of PSS on dolomite was more favorable than that on apatite, which impeded sodium oleate to adsorb on dolomite surface and rendered it hydrophilic. XPS results indicated that -SO3− groups of PSS strongly complexed with both Ca2+ and Mg2+ sites on dolomite surface, but PSS weakly interacted with apatite surface and hardly affected the adsorption of NaOL on apatite surface. PSS exhibited excellent selectivity and environmental compatibility, which could simplify the flotation processes in upgrading phosphate ores through one-step direct flotation.

Effect of Different Water-Soluble Graphene: (Polystyrene Sulfonate, Titanate Coupling Agent and Glucose)/Reduced Graphene Oxide on the Performance of Magnesium-Air Batteries

Three kinds of water-soluble graphene: (WSG: polystyrene sulfonate, titanate coupling agent and glucose)/reduced graphene oxide were prepared for fabricating magnesium-air batteries with AP65 anode. Corrosion behaviour and discharge performance were investigated. The three kinds of water-soluble graphene added respectively in NaCl solution result in a more negative potential and a lower exchange current density in the potentiodynamic polarization curve of AP65 anode. The comprehensive discharge performance of the magnesium-air battery with the polystyrene sulfonate/reduced graphene oxide (PSS/RGO) is better than other 3 batteries. This is due to non-covalent adsorption of PSS on RGO and π−π interactions formed between PSS and RGO, which prevents graphene from agglomeration. PSS/RGO not only improves the ionic conductivity of solution, but also reduces the anode corrosion. Results of X-ray diffraction, fourier transform infrared spectrophotometer, scanning electron microscope and electrochemical impedance spectroscopy correlate well with the discharge and corrosion performance of AP65 anode in three water-soluble graphene solutions.

Adsorption of Polyions on Flat TiO2 Surface

In this study, the surface properties of Ti/TiO2 substrate before and after the adsorption of polyelectrolytes were investigated. As model polyelectrolytes, strongly charged polycation poly(diallyldimethylammonium) (PDADMA) and strongly charged polyanion poly(4-styrenesulfonate) (PSS) were used. Initially, the bare titanium substrate was characterized by means of ellipsometry, atomic force microscopy (AFM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and measurements of inner surface potential using crystal electrode (CrE). It was shown that the substrate surface is very smooth with the roughness of 3.5 nm and oxide layer thickness of 3.8 nm. After the adsorption of PDADMA and PSS, polyelectrolyte-coated titanium surface was examined using the above-mentioned methods under the same conditions. It was found that both PDADMA cations and PSS anions form a stable polymeric nanofilm on Ti/TiO2 surface that partially covers the surface, without significant impact on the surface roughness. The corrosion protection effectiveness values indicate that the corrosion properties were greatly enhanced upon polyion adsorption and polyelectrolyte coating formation on the flat TiO2 surface. The obtained results were additionally confirmed by inner surface potential measurements. According to the methods employed, PDADMA nanofilm modification offers enhanced corrosion protection to the underlying titanium material in sodium chloride electrolyte solution.

Tuning the excess charge and inverting the salt rejection hierarchy of polyelectrolyte multilayer membranes

Polyelectrolyte multilayers (PEMs) coated on porous membrane supports have shown versatile opportunities for tailoring the resulting membrane characteristics. PDADMAC/PSS multilayers used as a separation layer deliver outstanding NF properties in terms of selectivities and permeances, as well as stability. Charge overcompensation of PDADMAC limits the possibilities of tuning the charge distribution in the PEM. We present a new membrane preparation methodology combining low ionic strength in the polycation and high ionic strength in the polyanion coating solutions, resulting in a PEM build-up with excess negative fixed charges. In contrast to PEMs build from only either low or high ionic strength in the PE coating solutions, this asymmetric approach results in a significant higher adsorption of PSS than PDADMAC for the PEMs, as proved by QCM measurements. The high negative excess charge of the new PEM hollow fiber membranes (PEMMs) leads to Na2SO4 rejections of above 99%. More specifically, the salt rejection hierarchy is inverted, having higher rejections for the monovalent NaCl than for MgCl2. PEMMs with a high amount of negative excess charges are especially promising for anion rejection applications such as phosphate removal from effluents. The achieved high rejections for mono- and divalent phosphate ions and simultaneously high fluxes can compete and even outperform commercial NF membranes. Combining asymmetric low and high ionic strength in the PE coating solutions is therefore an effective way to control the net excess charge and its related salt rejection hierarchy.

Adsorption Behavior of Polyelectrolyte onto Alumina and Application in Ciprofloxacin Removal.

This study aims to investigate the adsorption behavior of a strong polyelectrolyte poly(styrenesulfonate) (PSS) onto alumina particles. Adsorption of PSS onto positively charged alumina surface increased with increasing ionic strength, indicating that non-electrostatic and electrostatic interaction controlled the adsorption. The removal of an emerging antibiotic ciprofloxacin (CFX) from water environment using PSS-modified alumina (PMA) was also studied. The removal of CFX using PMA was much higher than that using alumina particles without PSS modification in all pH ranges of 2–11. The removal of CFX reached 98% under the optimum conditions of pH 6, contact time of 120 min, adsorbent dosage of five milligrams per milliliter and ionic strength 104-M NaCl. The adsorption isotherms of CFX at different salt concentrations fit well with a two-step adsorption model, while the adsorption kinetic fit well with a pseudo-second-order model with a good correlation coefficient (R2 > 0.9969). The CFX-removal from a hospital wastewater using PMA was more than 75%. Our study demonstrates that adsorption of PSS onto alumina to modify the particle surface is important to form a novel adsorbent PMA for CFX-removal from water environments.

Helping Strands: Polyelectrolyte Assists in Surfactant Assembly below Critical Micelle Concentration.

Strongly adsorbing polymer/surfactant (P/S) combinations have been proposed for long-term applications such as emulsion stabilization. However, P/S systems are known to exhibit nonequilibrium behavior despite steady-state surface characteristics. This work examines the coadsorption of dodecyltrimethylammonium bromide and sodium poly(styrene sulfonate) (PSS) using oil/water tensiometry, UV absorption, and vibrational sum frequency spectroscopy. To determine which features do not represent true equilibrium, the molecular details of PSS adsorption are compared for fresh and aged samples. At surfactant concentrations concurrent with bulk precipitation, significant differences between fresh and aged samples indicate that the strong initial coadsorption within this system is a nonequilibrium feature. We conclude that the long equilibration timescales arise from the slow assembly of non-adsorbing polyelectrolyte/micelle complexes below the critical micelle concentration. This study resolves a recent debate regarding system equilibria of surface-active P/S combinations at a water surface.

Dispersion of Graphene in an Aqueous Solution with Poly(sodium 4-styrenesulfonate) Monitored by Capillary Electrophoresis

Graphene was dispersed in an aqueous solution with poly(sodium 4-styrenesulfonate) as a dispersant. The charge of the graphene came to be apparently negative by the adsorption of poly(4-styrenesulfonate) ion (PSS). Two kinds of PSS were examined: the average molecular masses of 70,000 and 1,000,000 (PSS 70,000 and PSS 1,000,000, respectively). Capillary electrophoresis was used to evaluate the dispersion of the apparently anionic graphene in an aqueous solution. A broad signal corresponding to the dispersed graphene was detected in the electropherograms. The effective electrophoretic mobility of the dispersed graphene was somewhat larger at higher concentrations of PSS 70,000, suggesting that the adsorbed amount of PSS 70,000 increased. Even when the separation buffer did not contain PSS, the broad signal of the anionic graphene was still detected. The peak height and/or the peak area, as well as the effective electrophoretic mobility of the graphene decreased little at the reduced applied voltages, i.e., at longer separation/detection time. Therefore, the adsorption of PSS is irreversible or the desorption of PSS from the graphene surface is very slow. Accordingly, the dispersed graphene with PSS would be separated from the matrix PSS by the electrophoretic separation.

Effect of external salt addition on the structural, morphological and electrochemical properties of flexible PEDOT:PSS based LbL multilayered films

This article concerns with the effect of external salt addition on the structural, morphological and electrochemical properties of linear poly(ethylene imine) (LPEI) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) based LbL assembled films that is a cathodic color changing electrode for electrochromic device. For this purpose, cationic and anionic commercial polyelectrolytes (PEs) with/without 0.3 M NaCl were deposited on PET-ITO with automatized dip coating system. From QCM-D, it was found that the multilayer deposition became larger for LbL assembled films obtained from salt-free PEs. While the dissipation change (ΔD) of (LPEI/PEDOT:PSS)10/NaCl (150 × 10−6) exhibited relatively soft/flexible structure compared to the (LPEI/PEDOT:PSS)10 (110 × 10−6), ΔD changes became more obvious during PEDOT:PSS adsorption. Furthermore, it was determined that the film thickness and surface roughness values were highly dependent on the number of deposited bilayers whereas they dropped with the addition of salt to LPEI. The root mean square roughness (Rq) of (LPEI/PEDOT:PSS)10, (LPEI/PEDOT:PSS)20 and (LPEI/ PEDOT:PSS)40 were found to be 28 nm, 41.7 nm and 61.5 nm, respectively, while Rq of (LPEI/PEDOT:PSS)20/NaCl was 14.2 nm. All LbL mutilayered films had hydrophilic character and the average contact angle value of (LPEI/PEDOT:PSS)20/NaCl was found to be 66° due to the presence of salt within the multilayers. In addition, ion transport rate increased if the external salt was added to PE. Concerning the salt effect on colorancy of LbL multilayers, all films showed reversible color changes between blue and transparent/pale blue and (LPEI/PEDOT:PSS)20 exhibited darker blue in the colored state whereas (LPEI/PEDOT:PSS)20/NaCl had more translucent in the bleached state.

Molecular Interactions Leading to the Coadsorption of Surfactant Dodecyltrimethylammonium Bromide and Poly(styrenesulfonate) at the Oil/Water Interface.

The strong synergistic adsorption of mixed polymer/surfactant (P/S) systems at the oil/water interface shows promise for applications such as oil remediation and emulsion stabilization, especially with respect to the formation of tunable mesoscopic multilayers. There is some evidence that a combination of dodecyltrimethylammonium bromide (DTAB) and sodium poly(styrenesulfonate) (PSS) exhibits the adsorption of a secondary P/S layer, though the structure of this layer has long eluded researchers. The focus of this study is to determine whether the DTAB-assisted adsorption of PSS at the oil/water interface occurs as a single layer or with subsequent multilayers. The study presented uses vibrational sum-frequency spectroscopy and interfacial tensiometry to determine the degree of PSS adsorption and orientation of its charged groups relative to the interface at three representative concentrations of DTAB. At low and intermediate DTAB concentrations, a single mixed DTAB/PSS monolayer adsorbs at the oil/water interface. No PSS adsorbs above the system critical micelle concentration. The interfacial charge is found to be similar to that of P/S complexes solvated in the aqueous solution. The surface adsorbate and P/S complexes in the bulk both exhibit a charge inversion at around the same DTAB concentration. This study demonstrates the importance of techniques which can differentiate between coadsorbing species and calls into question current models of P/S adsorption at an oil/water interface.

Regulation of the Stability of Titania Nanosheet Dispersions with Oppositely and Like-Charged Polyelectrolytes.

Charging and aggregation processes of titania nanosheets (TNS) were extensively studied in the presence of oppositely charged or like-charged polyelectrolytes in aqueous dispersions. The surface charge of the TNS was systematically varied by the pH; therefore, positive nanosheets were obtained at pH 4 and negative ones at pH 10. Strong adsorption of poly(styrene sulfonate) (PSS) of high negative line charge density on the TNS was observed at pH 4, leading to charge neutralization and reversal of the original sign of charge of the nanosheets. The adsorption of like-charged poly(diallyldimethylammonium chloride) (PDADMAC) was also feasible through a hydrophobic interaction. The predominating interparticle forces were mainly of the DLVO-type, but additional patch-charge attraction also took place in the case of PSS at low surface coverage. The TNS was found to be hydrophilic at pH 10 and no adsorption of like-charged PSS was possible because of strong electrostatic repulsion between the polyelectrolyte and the surface. The PDADMAC showed high affinity to the oppositely charged TNS surface in alkaline dispersions, giving rise to neutral and positively charged nanosheets at appropriate polyelectrolyte doses. Formation of a saturated PDADMAC layer on the TNS led to high resistance against salt-induced aggregation through the electrosteric stabilization mechanism. These results shed light on the importance of polyelectrolyte concentration, ionic strength, and charge balance on the colloidal stability of TNS, which is especially important in applications, where the nanosheets are dispersed in complex solution containing polymeric compounds and electrolytes.

A highly selective and sensitive electrochemical sensor for tryptophan based on the excellent surface adsorption and electrochemical properties of PSS functionalized graphene

A new green method for the synthesis of poly(sodium 4-styrenesulfonate) functionalized graphene (PSS–graphene) in aqueous solution was realized by using graphene oxide nanosheets (GO) functionalized with PSS and ascorbic acid (AA) as an reducing agent. Various techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and electrochemistry have been utilized to characterize the as-made nanocomposites. The PSS–graphene was used as a modifier to fabricate an electrochemical sensor of tryptophan (Trp). Due to the difference of the adsorption capacity of PSS–graphene for Trp and Tyr, as well as the different charge states of Trp and the other interfering substances, the sensor showed excellent selectivity for Trp. The synergistic amplification of the stronger enrichment and the enhanced electron transfer rate, the signal of Trp on the PSS–graphene modified electrode was about 100-fold enhanced compared to that of the bare GCE. The peak current of Trp is proportional to its concentration in a wide range from 0.04 to 10.0 µmol L−1 with detection limit of 0.02 µmol L−1. Further, the proposed sensor was applied for the detection of Trp in human serum samples. Favorable results revealed that this work provided a new design strategy and a valuable platform for highly selective and sensitive determination of Trp in complex samples.

Adsorption of poly(styrenesulfonate) onto different-sized alumina particles: characteristics and mechanisms

We report the adsorption characteristics and mechanisms of a strong polyanion, poly(styrenesulfonate), PSS, onto α-Al2O3 with large size (L-Al2O3) and small size (S-Al2O3) in this paper. Some effective conditions to the adsorption of PSS onto L-Al2O3 and S-Al2O3 such as adsorption time, pH, mass ratio of PSS to α-Al2O3, and ionic strength were systematically studied. Maximum adsorption capacities of PSS onto both L-Al2O3 and S-Al2O3 were achieved with adsorption time 120 min, mass ratio of PSS to α-Al2O3 20 mg/g, and ionic strength 50 mM NaCl. The PSS adsorption onto S-Al2O3 significantly decreased with increasing pH from 4 to 9 while PSS adsorption onto L-Al2O3 decreased insignificantly in the pH range 4–9. Adsorption of PSS onto both L-Al2O3 and S-Al2O3 increased with increasing salt from 0 to 50 mM NaCl, indicating that electrostatic and none-lectrostatic interactions controlled adsorption at low ionic strength. However, adsorption of PSS was independent on the ionic strength at salt concentration higher than 50 mM. The changes in surface charge after PSS adsorption onto L-Al2O3 and S-Al2O3 were determined by zeta potential while the differences of surface functional groups before and after PSS adsorption were characterized by Fourier-transform infrared spectroscopy (FT-IR). The zeta potential as a function of the mass ratio of PSS to L-Al2O3 and S-Al2O3 agreed well with the adsorption capacity against the mass ratio. Adsorption mechanisms of PSS onto L-Al2O3 and S-Al2O3 were also discussed based on the changes in zeta potential, the differences of surface functional groups, and adsorbed amount as a function of the mass ratio of PSS to α-Al2O3.

Poly(sodium 4-styrenesulfonate) Stabilized Janus Nanosheets in Brine with Retained Amphiphilicity.

Maintaining colloidal stability in unfriendly environments while retaining surface chemical properties is challenging for fundamental science and crucial for many applications. Here, we report for the first time that by using a low concentration of poly(sodium 4-styrenesulfonate) (PSS), graphene-based amphiphilic Janus nanosheets (AJNs) can be stabilized in high salt brine (3 wt % NaCl and 0.5 wt % CaCl2), whereas the interfacial behavior of the nanosheets is not affected. The adsorption of PSS on the hydrophilic and hydrophobic surfaces of AJNs in brine was investigated experimentally and by molecular dynamics simulations. Simulations further showed that the spatial configuration of absorbed PSS molecules with sulfonate functional groups facing outward favored the generation of electrosteric repulsive interactions. Calculations of the interaction energy between PSS molecules and the nanosheet revealed surface charge as a key parameter to stabilize AJNs in the salt environment, as demonstrated by the case of graphene oxide with higher surface charge. Simulations were also used to examine the interfacial behavior of graphene-based AJNs in biphasic systems. The AJNs, which exhibited asymmetry in surface wettability, remained at the oil/brine interface because of PSS detachment from the hydrophobic surface. The results were subsequently experimentally confirmed, consistent with our previously reported graphene-based AJN fluid prepared in fresh water. The process was thermodynamically supported by the demonstrated negative change of Gibbs free energy. We believe that such a strategy could benefit for the stabilization of other AJNs with surface chemical accessibility under harsh conditions.

Design of polyelectrolyte core-shells with DNA to control TMPyP binding

The interaction of DNA with 5,10,15,20-tetrakis(4-N-methylpyridiniumyl)porphyrin (TMPyP) in polyelectrolyte core-shells obtained via layer by layer adsorption of poly(sodium 4-styrenesulfonate), PSS, and poly(allylamine hydrochloride), PAH, polyelectrolytes was followed by steady state, time resolved fluorescence and by Fluorescence Lifetime Imaging Microscopy (FLIM). Our results show that DNA adsorption onto polyelectrolyte core-shell changes the TMPyP interaction within PSS/PAH core-shells structure and increase significantly the TMPyP uptake. Specific DNA/TMPyP interactions are also altered by DNA adsorption favouring porphyrin intercalation onto GC pair rich regions. Circular dichroism (CD) spectra reveal that DNA undergoes important conformational changes upon adsorption onto the core-shell surface, which are reverted upon TMPyP encapsulation.

Adsorption of Polyanion onto Large Alpha Alumina Beads with Variably Charged Surface

Adsorption of strong polyelectrolyte, poly(styrenesulfonate), PSS, of different molecular weights onto large α-Al2O3 beads was systematically investigated as functions of pH and NaCl concentrations. The ultraviolet (UV) absorption spectra of PSS at different pH and salt concentrations confirmed that the structure of PSS is independent of pH. With the change of molecular weight from 70 kg/mol (PSS 70) to 1000 kg/mol (PSS 1000), adsorption amount of PSS increases and proton coadsorption on the surface of α-Al2O3 decreases at given pH and salt concentration. It suggests that higher molecular weight of PSS was less flat conformation than lower one. The adsorption density of PSS 70 and PSS 1000 decreases with decreasing salt concentrations, indicating that both electrostatic and nonelectrostatic interactions are involved. Experimental results of both PSS 70 and PSS 1000 adsorption isotherms onto α-Al2O3 at different pH and salt concentrations can be represented well by two-step adsorption model. The effects of molecular weight and salt concentration are explained by structure of adsorbed PSS onto α-Al2O3. The influence of added SDS on the isotherms is evaluated from the sequential adsorption. The SDS uptake onto α-Al2O3 in the presence of hemimicelles can prevent the adsorption of PSS at low concentration so that adsorption of PSS reduces with preadsorbed SDS.

Dispersion Characteristics and Aggregation in Titanate Nanowire Colloids.

Titanate nanowires (TiONWs) are synthesized through the hydrothermal method and characterized in acidic aqueous dispersions by using electrophoresis, dynamic light scattering, and atomic force microscopy. The TiONWs have a rodlike shape with an average length of about 600 nm and a thickness of 35 nm. They are positively charged under the conditions used. Their surface charge properties and aggregation are investigated in the presence of oppositely charged poly(styrene sulfonate) (PSS) polyelectrolyte. Charge neutralization followed by a subsequent charge reversal process is observed, which is attributed to the adsorption of PSS. The colloids are unstable near the charge neutralization point and stable at lower and higher PSS doses, in good qualitative agreement with the theory developed by Derjaguin, Landau, Verwey, and Overbeek (DLVO). The nanowires prefer to align along the walls, leading to "spaghetti-like" oriented aggregates. The aggregation processes of bare and PSS-coated TiONWs are monitored at different concentrations of an inert electrolyte; slow aggregation is found at low salt levels, whereas aggregation is rapid beyond the critical coagulation concentration, as predicted by the DLVO theory, which describes the colloid stability of the TiONWs adequately in all the systems investigated. Coating of the nanowires with the polyelectrolyte leads to a critical coagulation concentration 75 times higher than that of the bare titanates, indicating the enormous stabilizing effect of PSS.

Nanoflake Patterning of Self-Assembled Multilayer Films

Nanopatterning has attracted much attention because of its growing use in designing nanoelectronic and optoelectronic devices. Development of a facile route to nanopatterning is a persistent goal in nanotechnology. Originating from positively charged polyethyleneimine (PEI) and negatively charged poly(4-styrenesulfonate) (PSS), we successfully designed separable nanoflake patterning using layer-by-layer self-assembly technique by sequential adsorption of PEI and PSS. The morphology and size of the nanopatterning can be controlled by adjusting the number of bilayers in the film. Electrochemical measurements reveal that the (PEI/PSS) nanoflakes have good electroactivity and permeability for the electrolytes undergoing redox reaction. By controlling the distribution of surface charges on substrates, nanopatterning can be facilely achieved by self-assembly method.

Enhancing the catalytic activity of Pt nanoparticles using poly sodium styrene sulfonate stabilized graphene supports for methanol oxidation

Pt NPs were in situ synthesised on poly(sodium styrene sulfonate) functionalized graphene supports (PSS–G) in aqueous solution. We investigate the reduction of graphene oxide, PSS adsorption on reduced graphene, and Pt NP functionalization by X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure studies (XAFS), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The as-prepared Pt on PSS–G sample (Pt–PSS–G) was used directly as a catalyst ink without further treatment. The use of PSS as a stabilizer prevents stacking of reduced graphene sheets, binds Pt NPs, and promotes mass transport of reaction species. The as-prepared Pt–PSS–G exhibits higher activity and stability for methanol oxidation reaction than Pt NPs supported on pristine graphene sheets (Pt–G). The higher activity is due to the presence of Pt NPs on the surface of the PSS–G support, which provides an integrated electron and mass transport pathway for every Pt NP. This work realizes both scalable and greener production of highly efficient catalysts, and would be valuable for practical applications of graphene based fuel cell catalysts.

Solvothermal synthesis of core–shell ZnO hollow microhemispheres

Core–shell ZnO hollow micro-hemispheres with core-nanoparticles and hexagonal nanoplates at the outer layer were synthesized through a facile solvothermal route assisted by poly(styrene sulfonic acid) sodium salt (PSS). The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results indicate that PSS and the starting content of the reactants have influence on the morphologies of ZnO. To investigate the formation process of ZnO hollow micro-hemispheres, the ZnO products collected at different times were characterized by XRD and SEM. The growth mechanism of the hollow ZnO micro-hemispheres may be attributed to the preferred adsorption of PSS on (001) plane of ZnO and the Ostwald ripening process.

Atomistic Study of Surface Effects on Polyelectrolyte Adsorption: Case Study of a Poly(styrenesulfonate) Monolayer

Extensive all-atom molecular dynamics simulations have been performed to investigate the effect of surface features on the adsorption of poly(styrenesulfonate) (PSS) oligomers on top of a modified graphite substrate. In particular, we have investigated hydrophilic and hydrophobic model surfaces, accompanied by a variable surface charge density σs in the range 0−0.164 C/m2. Our results demonstrate that short-range interactions originating from the adsorbing substrate play a significant role in the layer structure of the adsorbed PSS, and they alone are already sufficient to induce a stable PSS adsorption layer. The presence of additional hydrophilic hydroxyl groups and charges on the adsorbing surface can further enhance the adsorption of PSS sulfonate groups at lower σs, whereas for the case of σs = 0.164 C/m2, the influence of the surface hydroxyl groups becomes negligible compared to that of the surface charges. The adsorbed PSS chains show mostly conformations where the PSS backbones are approximately parallel to the adsorbing surface. In some case, however, also the PSS backbones stand on top of the surface. Both the obtained surface charge overcompensation and the surface coverage are in good agreement with a previous experimental work [Ahrens et al. Macromolecules 2001, 34, 4504−4512]. Between the first PSS adsorption layer and the adsorbing substrate, we always find a water-rich region. The orientation of the water molecules in this region depends crucially on the features of the adsorbing surface. Our simulations suggest that the water-involved hydrogen bondings play a dominant role in determining the orientation of the water molecules. We also observe a decrease of the dielectric constant of water in the region close to the adsorbing surface in all of the investigated systems that is more pronounced for the hydrophilically modified surface and moreover increases with rising surface charge density. We suggest that this effect could lead to an electrostatic stabilization of the monolayer surface.