Effect Of Polymer Adsorption Research Articles

Synergistic effects of potassium alginate and silicates co-inhibition performance in shale hydration

High performance hydration inhibitors are recognized as an attractive solution to address wellbore instability associated with water-based drilling fluids. Nevertheless, conventional inhibitors still face a dilemma regarding the balance between inhibition performance and compatibility, including rheological and filtration properties. Herein, we proposed an organic–inorganic composite inhibitor that combines polymer adsorption and ion intercalation to provide synergistic inhibition properties. The results demonstrated that the composite inhibitors reduced the clay swelling rate from 50.7 to 22.4 % and increased shale recovery from 71.4 to 90.2 % compared with that in K2SiO3 solution, revealing the synergistic inhibition properties between ion exchange and film coating effect. In addition, the hydrogen bonding interaction between potassium alginate (PA) and clay particles effectively alleviates performance deterioration of base fluids containing K2SiO3, as evidenced by the apparent viscosity increased from 14.0 to 35.5 mPa·s, plastic viscosity increased from 4.0 to 25.0 mPa·s and filtration loss reduced from 35.2 to 20.4 mL after rolling at 120 °C. The intermolecular interaction between clay and PA facilitates the adsorption of polysaccharide chains onto clay surface, which was confirmed by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Moreover, X-ray diffraction (XRD), zeta potential and particle size distribution verified the suppression of electric double layers caused by K+ ions intercalation. This study validates the feasibility of organic–inorganic hybrid materials as shale hydration inhibitors, utilizing the synergistic effects of polymer adsorption and cation intercalation. Furthermore, the study highlights the great potential of combining PA with silicates to maintain wellbore stability.

Interfacial Effects and the Nano-Scale Disruption in Adsorbed-Layer of Acrylate Polymer-Tween 80 Fabricated Steroid-Bearing Emulsions: A Rheological Study of Supramolecular Materials

The effect of polymer adsorption on the stability and viable shelf life of 55 μm diameter oil-in-water (O/W) emulsions containing the steroid, betamethasone 21-phosphate was investigated. Two acrylate polymers, Carbopol® 971P and 974P, were added in the role of emulsion stabilizers to a model system, representing a non-ionic low molecular weight surfactant-stabilized emulsion (topically applied medicinal cream). For the purposes of this study the dosage of the viscosifier was maintained below 1% w/v and consequently, the consistency of the emulsion was measured in the diluted form. One of the polymers was responsible for elevated degrees of droplet creaming and coalescence and this was closely linked to its surface tension lowering capacity. This lowering was seen at 62 mN/m compared to the routine values at equivalent concentrations of 68 mN/m and 35 mN/m for the betamethasone drug and non-ionic surfactant-Tween 80, respectively. The same polymer also demonstrated a predisposition to form low-micron and greater sized aggregates of nanoparticles that led to extensive flocculation and the formation of a sedimentary precipitate, formed from an amalgam of the components found in the creamed droplet layer.

Interplay between Interparticle Potential and Adsorption Structure in Nanoparticle Dispersions with Polymer Addition as Displayed by Small-Angle Scattering.

The effect of polymer adsorption on the dispersion stability of particles is an important subject applicable to various manufacturing processes. In this study, small-angle scattering was used to examine the relationship between interparticle potential and polymer adsorption in dispersions of nanoparticles with an 81 Å radius containing two types of polymers. Small-angle X-ray scattering (SAXS) measurements in a silica/polyacrylamide (PAAm) system showed an increase in interparticle attractive interactions as PAAm concentration was increased. In a silica/poly(ethylene oxide) (PEO) system, the correlation between PEO concentration and interparticle potential strength became negligible at higher concentrations. Hence, the contrast variation small-angle neutron scattering (CV-SANS) method was employed to evaluate the interparticle potential and polymer adsorption simultaneously. CV-SANS revealed that PAAm was adsorbed to silica particles with a polymer shell layer thickness of 186 Å. The attractive potential observed in the absorbed layer region can be attributed to bridging PAAm molecules between the silica particles. By contrast, CV-SANS of the silica/PEO system indicated a low-polymer-concentration layer with a thickness of 34 Å around silica particles, indicating weak adsorption of PEO molecules. Negligible interaction between PEO and silica particles was assumed to be the origin of the depletion stabilization from excess polymer addition. Thus, quantitative analyses conducted using SAXS and CV-SANS measurements for the first time clearly demonstrated a difference in the adsorption structure of the polymer, which induces changes in the interaction potential between nanoparticles.

Numerical investigation of carbonate acidizing with gelled acid using a coupled thermal–hydrologic–chemical model

In this work, an experiment-based rheological model that accounts for the influence of polymer concentration, shear-thinning behavior, and temperature variation on the in-situ viscosity of gelled acid is developed. On the basis of the rheological model, we present a thermal–hydrologic–chemical coupled model that describes the dissolution process of carbonate acidization with gelled acid. A sensitivity analysis of the dissolution dynamic regarding the temperature variation, polymer adsorption, and non-Newtonian behavior of the injected acid is carried out. The comparison of acidization curves and dissolution patterns obtained by injecting gelled acid and HCl is conducted. It is found that the optimal dissolution regime for gelled acid has a much wider range than neat HCl. It is observed from the numerical simulations that reservoir temperature and rheological parameters of the acid are key factors that affect acidizing efficiency, while the effect of polymer adsorption can be ignored. In addition, several recommendations for optimal stimulation of carbonates with gelled acids are provided.

Biopharmaceutical Understanding of Excipient Variability on Drug Apparent Solubility Based on Drug Physicochemical Properties: Case Study\u2014Hypromellose (HPMC)

Identification of the biopharmaceutical risks of excipients and excipient variability on oral drug performance can be beneficial for the development of robust oral drug formulations. The current study investigated the impact of Hypromellose (HPMC) presence and varying viscosity type, when used as a binder in immediate release formulations, on the apparent solubility of drugs with wide range of physicochemical properties (drug ionization, drug lipophilicity, drug aqueous solubility). The role of physiological conditions on the impact of excipients on drug apparent solubility was assessed with the use of pharmacopoeia (compendial) and biorelevant media. Presence of HPMC affected drug solubility according to the physicochemical properties of studied compounds. The possible combined effects of polymer adsorption (drug shielding effect) or the formation of a polymeric viscous layer around drug particles may have retarded drug dissolution leading to reduced apparent solubility of highly soluble and/or highly ionized compounds and were pronounced mainly at early time points. Increase in the apparent solubility of poorly soluble low ionized drugs containing a neutral amine group was observed which may relate to enhanced drug solubilization or reduced drug precipitation. The use of multivariate data analysis confirmed the importance of drug physicochemical properties on the impact of excipients on drug apparent solubility and revealed that changes in HPMC material properties or amount may not be critical for oral drug performance when HPMC is used as a binder. The construction of a roadmap combining drug, excipient, and medium characteristics allowed the identification of the cases where HPMC presence may present risks in oral drug performance and bioavailability.

Effects of polymer adsorption on the effective viscosity in microchannel flows: phenomenological slip layer model from molecular simulations

Molecular simulations (Dissipative Particle Dynamics - DPD) were used to quantify the effect of polymer adsorption on the effective shear viscosity of a semi-dilute polymer solution in microchannel Poseuille flow. It is well known that polymer depletion layers develop adjacent to solid walls due to hydrodynamic forces, causing an apparent wall slip and reduced effective viscosity (increased total flow rate). We found that depletion layers also developed in the presence of hydrodynamically rough adsorbed layers on the wall. Polymer-polymer (steric) repulsion between flowing and adsorbed polymer expanded the depletion layer compared to no-adsorption cases, and the effective viscosity was reduced further. Desorption occurred for higher shear rates, reducing the repulsion effect and shrinking the depletion layers. A phenomenological algebraic model for the depletion layer thickness, including a shear modified adsorption isotherm, was developed based on the simulation data. The depletion layer model can be used together with the effective viscosity model we developed earlier.

Evaluation of the near fracture face formation damage caused by the spontaneously imbibed fracturing fluid in unconventional gas reservoirs

In the present study, spontaneous imbibition experiments, steady-state permeability measurements, and numerical simulation were integrated to quantify the changes in the effective water permeability, capillary pressure, and water relative permeability curves due to the polymer adsorption of the spontaneously imbibed fracturing fluid. The effect of the nonionic surfactant and core bedding plane on the fluid spontaneous imbibition volumes were also investigated.The researchers considered the impact of the spontaneous imbibition of a friction reducer fluid in tight sand and shale core samples. Three comparative systematic spontaneous imbibition experiments were conducted for each of the core samples using brine, anionic friction reducer fluid, and brine again. The core sample water permeability before and after the imbibition experiment was measured using a constant rate steady-state permeability apparatus.The polymer adsorption from the spontaneously imbibed fracturing fluid significantly reduced the brine spontaneous imbibition volumes in tight sand samples and in shale samples, though to a lesser degree. Moreover, the effective water permeability was decreased because of the polymer adsorption effect. Therefore, the polymer adsorption during hydraulic fracturing reduces the fluid leak-off into the formation and also the fluid flowback.The nonionic surfactant increased the fluid spontaneous imbibition volumes in both tight sand and shale samples. Thus, adding a nonionic surfactant to the friction reducer pad fluid during hydraulic fracturing leads to enhance both of the fluid leak-off and fluid flowback. The results also showed that the effect of polymer adsorption on the imbibition rates is less when the rock-fluid contact surface is parallel to the bedding plane.The imbibition potentials and imbibition capillary pressure curves were calculated before and after polymer adsorption. The polymer adsorption led to a slight increase in the capillary pressure; moreover, the tight sand samples had higher capillary pressure than the shale samples. The imbibition water relative permeability curves were calculated using ECLIPSE commercial simulator. The polymer adsorption significantly reduces the water relative permeability curves for tight sand samples and in less degree for shale samples.

Dewetting Kinetics of Thin Polymer Films with Different Architectures: Effect of Polymer Adsorption

We have investigated the influence of the adsorption process on the dewetting behavior of the linear polystyrene film (LPS), the 3-arm star polystyrene film (3SPS) and the ring polystyrene film (RPS) on the silanized Si substrate. Results show that the adsorption process greatly influences the dewetting behavior of the thin polymer films. On the silanized Si substrate, the 3SPS chains exhibit stronger adsorption compared with the LPS chains and RPS chains; as a result, the wetting layer forms more easily. For LPS films, with the decrease of annealing temperature, the kinetics of polymer film changes from exponential behavior to slip dewetting. As a comparison, the stability of 3SPS and RPS films switches from slip dewetting to unusual dewetting kinetic behavior. The adsorbed nanodroplets on the solid substrate play an important role in the dewetting kinetics by reducing the driving force of dewetting and increase the resistant force of dewetting. Additionally, Brownian dynamics (BD) simulation shows that the absolute values of adsorption energy (e) gradually increase from linear polymer (−0.3896) to ring polymer (−0.4033) and to star polymer (−0.4264), which is consistent with the results of our adsorption experiments.

Effects of Polymer Adsorption and Desorption on Polymer Flooding in Waterflooded Reservoir

Polymer Flooding is one of the most well-known methods in Enhanced Oil Recovery (EOR) technology, resulting in favorable conditions for displacement mechanism to lower residual oil in the reservoir. Polymers can lower mobility ratio by increasing the viscosity of injected water, hereby increasing volumetric sweep efficiency. Moreover, polymer adsorption onto the rock surface can help decrease reservoir permeability contrast. Due to absolute permeability reduction, the effective permeability to water is also reduced. Once the polymer is adsorbed onto the rock surface, polymer molecules can be desorbed with a chaser. This study is performed to further evaluate the effects of the adsorption and desorption process of polymer solutions to yield benefits on the oil recovery mechanism. A reservoir model is constructed by the reservoir simulation program called STAR® from Computer Modeling Group (CMG). Various polymer concentrations, starting times of polymer flooding process and polymer injection rates were evaluated with selected degrees of polymer desorption including 0, 50 and 100%. According to the results, polymer desorption lowers polymer consumption, especially at low concentrations. Polymer desorption causes polymer re-employment that is previously adsorbed onto rock surface, resulting in an increase of sweep efficiency in the further period of polymer flooding process. Furthermore, the results show that waterflooding followed by earlier polymer flooding can increase the oil recovery factor whereas the higher injection rate also enhances the recovery. Polymer concentration has relationship with polymer consumption due to the two main benefits described above. Therefore, polymer slug size should be optimized based on polymer concentration.

An Investigation of Polymer Adsorption in Porous Media Using Pore Network Modelling

Polymer injection in hydrocarbon reservoirs has been of great interest in petroleum engineering as an enhanced oil recovery method. In order to have a reliable injection plan, an accurate estimation of polymer behaviour is required to control the fluid flow in porous media. However, it is difficult to calculate the flow properties of polymer solutions—known as non-Newtonian fluids—in porous media, due to variable viscosity at different shear rates. Adsorption of polymer molecules onto the rock surface decreases the available cross-sectional area of polymer solution, therefore at a constant rate, the shear rate increases. As a result, it is important to investigate how polymer adsorption can affect the polymer solution flow behaviour in porous media. Moreover, prior to any polymer injection plan, the amount of adsorbed polymer should be calculated, due to the high cost of polymers. In the present study, pore network modelling was used to investigate the effect of polymer adsorption on flow behaviour of polymer solutions in porous media. To achieve this goal, a simple pore was constructed to adequately represent the real structure of the porous medium. It was then validated by simulation of Newtonian fluid flow in the network and comparison of the calculated flow properties with the experimental data. After validation, the pore network was used for simulation of non-Newtonian fluid flow in porous media. The experimental apparent viscosity of non-Newtonian fluid was used for verification of the procedure and the developed network. The apparent viscosity of non-Newtonian was calculated successfully using macroscopic properties of the rock sample and measured bulk properties of non-Newtonian fluid. The effect of polymer adsorption on calculation of non-Newtonian fluid apparent viscosity was then investigated. It was shown that the polymer adsorption process plays an important role in calculation of polymer solution apparent viscosity. The results reveal that polymer adsorption cannot be neglected, especially in near well-bore areas where the adsorption is high. Finally, the effect of wettability in calculating the total amount of adsorbed polymer volume was studied. The results suggest that neglecting the rock’s wettability can result in an overestimation or underestimation of the amount of adsorbed polymer.

Probing effects of polymer adsorption in colloidal particle suspensions by light scattering as relevant for the aquatic environment: An overview

Modification of particle surfaces by adsorption of polymers is a process that governs particle behavior in aqueous environmental systems. The present article briefly reviews the current understanding of the adsorption mechanisms and the properties of the resulting layers, and it discusses two environmentally relevant cases of particle modification by polymers. In particular, the discussion focuses on the usefulness of methods based on light scattering to probe such adsorbed layers together with the resulting properties of the particle suspensions, and it highlights advantages and disadvantages of these techniques. Measurement of the electrophoretic mobility allows to follow the development of the adsorption layer and to characterize the charge of the modified particles. At saturation, the surface charge is governed by the charge of the adsorbed film. Dynamic light scattering provides information on the film thickness and on the behavior of the modified suspensions. The charge and the structure of the adsorbed layer influence the stability of the particles, as well as the applicability of the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). This fundamental knowledge is presented in the light of environmental systems and its significance for applied systems is underlined. In particular, the article discusses two examples of environmental processes involving adsorption of polymers, namely, the modification of particles by natural adsorption of humic substances and the tailoring of surface properties of iron-based particles used to remediate contaminated aquifers.

Investigation of Isotherm Polymer Adsorption in Porous Media

The injection of chemical solutions plays an important role in increasing the recovery factor of mature fields. Chemical flooding is considered as an attractive alternative to conventional waterflooding; it can improve the area sweep efficiency not only at the macroscale but also in the microscale by control mobility of displaced fluid. Adsorption of polymer in reservoir rock is an extremely important parameter for chemical flooding. Adsorption represents a loss of chemical agent from solution and, consequently, a net reduction in the surfactant–polymer slug. Therefore, the efficiency of polymer flooding is significantly diminished both technically and economically. However, numerical simulation of multicomponent adsorption is still limited and adsorption processes in a polymer–rock system have not yet been well developed, especially for highly heterogeneous reservoirs. In this article, adsorption was modeled by the Langmuir isotherm theory. The simulation results indicated that polymer adsorption strongly depends on polymer concentration, shear rate, pH, salt concentration, and reservoir heterogeneity. Effective control of such parameters can reduce the effect of polymer adsorption to minimize chemical loss and improve the economic efficiency of chemical flooding processes.

Effect of Polymer Adsorption on Permeability Reduction in Enhanced Oil Recovery

In order to reduce the permeability to water or brine, there is a possibility of polymer injection into the reservoir. In the present work, special focus has been paid in polymer [partially hydrolyzed polyacrylamide (PHPA)] injection as a part of chemical method. Tests were conducted in the laboratory at the ambient temperature to examine the reduction in permeability to water or brine in the well-prepared sand packed after the polymer injection. The experiments were performed to study the effect of polymer adsorption on permeability reduction by analyzing residual resistance factor values with different concentrations of polymer solutions. The rheological behavior of the polymer has also been examined. The experimental results also indicate that the adsorption behavior of polymer is strongly affected by salinity, solution pH, and polymer concentration. To investigate the effect of polymer adsorption and mobility control on additional oil recovery, polymer flooding experiments were conducted with different polymer concentrations. It has been obtained that with the increase in polymer concentrations, oil recovery increases.

The effect of polymer adsorption on the wetting properties of partially hydrophobized magnetite

Upon reverse flotation of iron ore, the surface of the iron ore concentrate may become partially hydrophobized due to adsorption of flotation collector, which is facilitated by the calcium ions present in the process water. Hydrophobic areas on the concentrate surface may introduce problems in subsequent pelletization of the concentrate. A possible way to restore the wettability of the surface could be by modifying the surface with a hydrophilic polymer. The effect of hydrophilic polymers of different types, viz. cationic, anionic, and non-ionic, on the wettability of the magnetite surface after adsorption of a surfactant was investigated. Although all the polymers could adsorb on magnetite at pH 8.5, the contact angle measurements revealed that only anionic ammonium polyacrylate could decrease the contact angle of synthetic magnetite after surfactant adsorption to a level close to that of as-synthesized magnetite. Such effect was probably achieved due to shielding of the hydrophobic surfactant chains from the aqueous phase by hydrophilic polyacrylate molecules. The fact that polyacrylate adsorption on magnetite occurred via calcium ions makes polyacrylate suitable for application in calcium-rich process water. The results presented in this work illustrate that ammonium polyacrylate could be successfully used to improve the wettability of magnetite after adsorption of surfactants.

Effects of Polymer Adsorption on the Oil Recovery during Polymer Flooding Processes

The influence of water-soluble polymer adsorption on the flow behavior and oil recovery was investigated. This article presents results from an extensive numerical simulation performed for a two-well model in a five-spot pattern operating under polymer flood followed by waterflood. For different systems of adsorption parameters, slug sizes, and reservoir properties performances were compared in terms of cumulative recovery and water–oil ratio (WOR) at the production well. Properties of polymers and reservoir rocks such as adsorption parameters and vertical permeability heterogeneity are shown to impact the predicted recovery. Improvement in oil recovery and reduction in WOR was obtained for smaller values of adsorption parameters. Polymer flood in reservoirs with a severe permeability contrast between horizontal strata leads to lower volumetric sweep efficiency and displacement efficiency. The size of the polymer bank also affects the predicted recovery.

Polymer Adsorption Effects on Colloidal Stabilities of Ceria Particles and Chemical Mechanical Polishing of Silicone Oxide Films by Ceria Particles

Characterization of ceria particles in the presence of poly(vinyl pyrrolidone) (PVP) was performed by the measurements of adsorbed amounts of PVP, average sizes, ζ potentials, and back scattering intensities of the ceria particles as functions of PVP molecular weight and PVP concentration. In particular, the measurements of the hydrodynamic average diameters, ζ potentials, and back scattering intensities of the ceria particles have been carried out for the re-dispersed ceria particles, whose particles were washed by the dispersion medium to remove the free PVP chains and then they were dispersed again in the corresponding dispersion medium after adsorption of PVP on the ceria particles and sedimentation of the ceria particles. PVP adsorption on the ceria surfaces enhanced the stability of ceria particles by the steric stabilization of the thicker adsorbed layer of PVP for the larger molecular weight of PVP. Moreover, the chemical mechanical polishing (CMP) of SiO2 films deposited on Si wafers has been performed by the ceria slurries without and with PVP. Removal rates of the deposited SiO2 films were increased with an increase in the adsorbed amount of PVP and their magnitudes were larger than that in the absence of PVP.

The effect of adsorption kinetics on film formation of silica/PVA suspension

Particle/binder/solvent systems are widely used in many applications and have long been studied. Understanding and controlling polymer adsorption in these complex material systems are important to achieve successful final performance. In this study, the effect of polymer adsorption on film formation and the relation between the microstructures of the suspension and film have been investigated by measuring the amount of polymer adsorption and the stress development during drying. In terms of mixing (or dispersion) time ( t m ), the adsorption amount ( Γ PVA), characteristic stress ( σ ch ) and dried film density ( ρ) showed a similar behavior in the form of 1 - e t m / τ with a single characteristic time τ = 45 h, which implies that the drying process is determined by this single time constant. The porous and non-uniform microstructure of the dried film at short t m became close-packed and uniform with longer t m . The polymer adsorption was found to play a key role in film formation as it introduces steric repulsion in suspension and suppresses the flocculation during solvent evaporation. It was also pointed out that enough mixing time for the saturated polymer adsorption is critical to acquire the consolidated and uniform film microstructure.

Effect of polymer adsorption on cellulose nanofibril water binding capacity and aggregation

Polymer adsorption on cellulose nanofibrils and the effect on nanofibril water binding capacity were studied using cellulose nanofibril films together with quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The experiments were performed in the immersed state, and special attention was paid to the effect of polymer properties on the water content and viscoelastic properties of the polymer/fibril layer. The dry mass of the adsorbed polymers was determined using SPR. The type of the adsorbed polymer strongly affected the water content and viscoelastic properties of the nanofibril film. The adsorption of a highly charged flocculating polymer, PDADMAC, caused dehydration of the film, which was also detected as nanofibril film stiffening. The adsorption of xyloglucan introduced a dispersing effect to the nanofibril film, which was detected as a loosening and softening of the nanofibril/polymer layer. A dispersing effect was also achieved with carboxymethyl cellulose (CMC), but CMC did not adsorb irreversibly on the nanofibril surfaces. In addition to the nanofibril film studies, the effect of polymer adsorption on cellulose nanofibril suspension aggregation was demonstrated using confocal laser scanning microscopy (CLSM). Xyloglucan was shown to open the nanofibril aggregate structures and act as a dispersing agent, whereas the other polymers studied did not have as significant an effect on aggregation.

Gas/Water Flow in Porous Media in the Presence of Adsorbed Polymer: Experimental Study on Non-Darcy Effects

Summary The objective of this paper is to report some experimental investigations on the effect of polymer adsorption on gas/water flow in non-Darcy regimes in homogeneous porous media, in contrast to previously available analyses focused mainly on the Darcy regime. Our investigation concentrates on gas flow either at low mean pressure, when Klinkenberg effects (or gas slippage) must be considered, or at high flow rates, when inertial effects are significant. The experimental study reported here consists of water and nitrogen injections into various silicon carbide model granular packs having different permeabilities. Experiments are carried out at different water saturations before and after polymer adsorption over flow regimes ranging from slip flow to inertial flow. In good agreement with previous works, in the Darcy regime, we observe an increase in irreducible water saturation and a strong reduction in the relative permeability to water, while the relative permeability to gas is slightly affected. At low mean pressure in the gas phase, the magnitude of the Klinkenberg effect is found to increase with water saturation in the absence of polymer, whereas for the same water saturation, the presence of an adsorbed polymer layer reduces this effect. In the inertial regime, a reduction of inertial effects is observed when gas is injected after polymer adsorption, taking into account water-saturation and permeability modifications. Experimental data are discussed according to hypotheses put forth to explain these effects. Consequences for practical use are also put under prospect.

Effect of polymer adsorption on the water structure at the quartz/water interface studied by optical sum frequency generation

The effect of polymers weakly adsorbed on a quartz surface on the structure of the interfacial water molecules was investigated by optical sum frequency (SF) spectroscopy. As polymers, poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and two types of tri-block copolymer of Pluronic L64 and 17R-4 were used. SF intensity spectra of OH stretching mode of water molecules at the interface between a quartz substrate and aqueous solutions of the polymers were measured. The total SF intensity of the interfacial water of the L64 aqueous solution was smaller than those of other solutions. This result indicates that the L64 aqueous solution has smaller number of oriented interfacial water molecules. It is suggested that the rapid motion of hydrophilic parts of the adsorbed L64 disturbs the average orientation of the interfacial water molecules. On the other hand, the SF intensity from the interfacial water molecules of aqueous solutions with high ion strength did not depend on the species of the polymers in the solutions. The latter result suggests that the hydration of ions determines the structure of the interfacial water molecules.