Electrokinetic Properties Research Articles

Formation of Bilayer Thin-Film Electrolyte on Cathode Substrate by Electrophoretic Deposition

Potentialities of the method of bilayer thin-film electrolyte electrophoretic deposition onto cathodic substrate are analyzed. Ce0.8Sm0.2O1.9–δ (SDC) nanopowder and BaCe0.89Gd0.1Cu0.01O3–δ BCGCuO) micropowder are prepared by the methods of laser evaporation–condensation and pyrolysis, respectively. The effect of ultrasonic treatment on the SDC and BCGCuO particle distribution in suspensions and their electrokinetic properties are studied. The using of the ultrasonic treatment combined with centrifugation allowed obtaining an aggregative-stable suspension of the BaCe0.89Gd0.1Cu0.01O3–δ micron particles in the isopropanol–acetylacetone mixed medium (70/30 v/v) that is characterized by high zeta potential. Ce0.8Sm0.2O1.9–δ and BaCe0.89Gd0.1Cu0.01O3–δ thin films are obtained at the La2NiO4 +δ cathode substrate using electrophoretic deposition; microstructure and electric properties of the prepared thin-film structures are studied. The conductivity and electric properties of the bilayer electrolyte were found to be determined by the Ce0.8Sm0.2O1.9–δ film properties. Despite the sintering high temperature, the grain structure of the BaCe0.89Gd0.1Cu0.01O3–δ film is underdeveloped; this is determined by the micron powder properties.

The Study and Exposure of Laws of Distribution Protein Substances in Uroliths

The characterization of urinary stones mineral and organic composition in Omsk region and Saint-Petersburg (Russia) was studied. It was established that nature and amount of amino acids and trace elements in composition of phosphate, oxalate and urate urinary stones are different. For studying processes of formation of the main mineral phase of urinary stones on the model systems powders of calcium oxalate monohydrate and hydroxyapatite with molar Ca/P ration 1.57 –1.67 were synthesized. The determination of electro kinetic properties and particle size of synthesized powders were made. The effects of amino acids (glutamic acid, glycine and lysine) on the process of formation of calcium oxalate monohydrate and hydroxyapatite were investigated. It was shown that amino acids inhibited growth and aggregation of calcium oxalate monohydrate and hydroxyapatite particles and preferential adsorb on to their crystal surface.

Effect of fullerene content on the thermal, microstructure, and electrokinetic properties of fullerene/poly(vinyl pyrrolidone) nanofluids and nanocomposites

In this study I report the thermal stability, microstructures, dynamic light scattering (DLS) and electro-kinetic effect in the fullerene (C60):poly(vinyl pyrrolidone) PVP nanofluids (NFs) and nanocomposite films. An improvement in the degradation temperature of C60:PVP nanocomposite reported here is ascribed to free radical scavenging ability of C60. An analysis of DLS data in terms of polydispersity index (PDI) reveals a well dispersed structure of C60 assemblies with PVP in liquid medium. The typical electro-kinetic parameters such as zetapotential (ξ) and surface conductivity (σsc) in a NF evaluates the magnitude of electrostatic repulsion between C60 particles and such measurement tender a way to boost stability of C60 nanoparticles in presence of PVP molecules in a particular carrier. Microstructures in various films were found to vary with increasing in the C60 content and decreasing in the relative PVP content in the nanocomposites. Highest thermal degradation temperature (∼ 422 °C) was observed for the sample consisting of 13.9 μM C60 owing to uniform distribution of C60 in the PVP matrix with a low PDI (0.272).

Predicting the electrokinetic properties of the crude oil/brine interface for enhanced oil recovery in low salinity water flooding

The low-salinity waterflooding (LSWF) technique during enhanced oil recovery has received increasing attention over the last decade. Several studies have attempted to understand the effects of LSWF through both experiments and modelling, but their results are inconsistent due to a lack of understanding of the crude oil/brine and brine/rock interfaces. In this paper, the crude oil/brine interface was studied by developing a triple-layer surface complexation model. The carboxyl groups (–COOH) were attributed to the surface charge and electrical triple-layer development of the crude oil in LSWF. The zeta potentials of the emulsion at various pH levels and the calcium and magnesium concentrations were measured to examine the interface. These data were then directly fitted to the simulated zeta potentials to determine the surface site density of –COOH and the associated equilibrium constants for the dissociation and adsorption of calcium and magnesium. The –COOH site density was determined by fitting the pH-independent zeta potential, while the equilibrium constant values were estimated from the variations in the zeta potential with the changes in pH and the concentrations of calcium and magnesium. The determined surface complexation parameters were validated by comparing the experimental zeta potential data from different ionic solutions. The developed surface complexation model was used along with the estimated parameters to predict the interface of crude oil in seawater, formation water, and their dilutions. The simulated zeta potential results agreed well with the experimental data, demonstrating that the model is applicable to understand the crude oil/brine interface in LSWF. Finally, the importance of the prediction of the surface and zeta potentials in the evaluation of the interface and the estimation of electrostatic forces, and thus the wettability alteration, was discussed.

340 Convection-Enhanced Delivery of Macromolecules to the Brain Using Electrokinetic Transport

Electrokinetic transport in brain tissue represents the movement of molecules due to an applied electric field and the interplay between the electrophoretic and electroosmotic velocities that are developed. This dissertation provides a framework for understanding electrokinetic transport and how it may be utilized for short-distance ejections, relevant to capillary iontophoresis, and long-distance infusions, for the clinical management of malignant brain tumors as a novel convection-enhanced drug delivery system.In particular, electrokinetic transport was first analyzed in a series of poly(acrylamide-co-acrylic acid) hydrogels that demonstrated varying electroosmotic velocities. Moreover, a hydrogel was synthesized to mimic the electrokinetic properties of organotypic hippocampal slice cultures (OHSC), as a surrogate for brain tissue. Short- and long-distance capillary infusions of molecules into the hydrogels and OHSC provided a framework to understand the relevant phenomena, such as the effect of varying the capillary tip size, applied electrical current, ζ-potential of the capillary or the outside matrix, infusion time, tortuosity, and properties of the solute (including molecular weight and electrophoretic mobility). Control of the directional transport of molecules was also demonstrated over a distance of several hundred micrometers to millimeters. Finally, electrokinetic infusions were conducted in vivo in the adult rat brain, with results compared to those of pressure-driven infusions.The experiments and results described in this dissertation provide a foundation for further development, by presenting a methodical means to increase the ejection profile and attain clinically relevant penetration distances while minimizing adverse effects to the brain tissue, including from the electric field itself. The rate of electrokinetic transport is greater than the rate of diffusion, and therefore it represents a novel form of convection-enhanced drug delivery system.

The mechanism of anionic polyacrylamide adsorption on the montmorillonite surface in the presence of Cr(VI) ions

The anionic polyacrylamide AN PAM (with various contents of carboxyl groups) adsorption mechanism on the montmorillonite surface was examined. The effect of hazardous chromium(VI) ions addition was studied. The anionic polyacrylamide is a popular soil flocculant, commonly used to prevent erosion of arable soils. On the other hand, polymeric macromolecules can increase the accumulation of various toxic substances, such as heavy metal ions (among others Cr(VI) ions) in soil minerals. For this purpose the adsorption properties of soil mineral – montmorillonite in relation to mixed system containing AN PAM and Cr(VI) ions was investigated. The impact of solution pH, order of individual adsorbates addition, chromium(VI) ions concentration and anionic groups content in the polymeric macromolecules were determined. The montmorillonite was characterized using the low-temperature nitrogen adsorption/desorption method, XRF, FTIR and SEM techniques. In turn, the adsorption and electrokinetic properties of examined montmorillonite – AN PAM - Cr(VI) systems were examined by means of spectrophotometry, potentiometric titration and microelectrophoresis methods.

Zeta potential determination with a microchannel fabricated in solidified solvents

This paper proposes a simple and versatile method for the determination of the zeta potential of a channel wall and discusses the values measured for the surface of frozen solvents, which are not only of scientific interest but also of potential use for microfluidic platforms. The zeta potential of the solid surface is an important parameter for discussing its electrokinetic properties, the distribution and reaction of ions in an electric double layer, and the fluidic behavior in the space surrounded by the surface. While the zeta potential of colloidal matters can be determined from their electrophoretic mobility, it is often difficult to determine that of a bulk material. In this paper, the zeta potential of a microchannel fabricated in a frozen solvent is determined by measuring the apparent mobility of microparticles as the probe. The electrophoretic mobility of the microparticles has been measured in advance using microchip electrophoresis under various conditions. This approach allows us to determine the zeta potential of water-ice and frozen cyclohexane. We discuss the pH dependence of the zeta potential of ice and also effects of the NaCl concentration on that of ice and frozen cyclohexane.

Electrophoretic deposition and microstructure development of Si3N4/polyetheretherketone coatings on titanium alloy

Nanocomposite Si3N4/PEEK coatings were deposited on the model Ti-13Nb-13Zr titanium alloy by cathodic electrophoretic deposition. The use of different dispersion media and surfactants, the cationic polyelectrolytes polyethylenimine and chitosan, added to the suspensions has been studied. Understanding of the deposition mechanism process was obtained by monitoring the suspension properties, concentration of coating components, pH and zeta potential as well as investigation of interaction between solid particles in the suspension by electron microscopy. Based on the electrokinetic properties of suspensions and observations of the as-deposited coating morphology, the electrophoretic co-deposition of amorphous Si3N4 nanoparticles and PEEK micro-particles parameters, constant voltage and deposition time, were elaborated. It was found that the coating, 120 μm thick, deposited from the suspension containing a low amount of Si3N4 stabilized by chitosan under a constant voltage of 15 V during 90 s and with a constant distance between electrodes of 10 mm, was homogeneous. The coating structure and morphology changed as a result of post-deposition heat treatment from amorphous with a granular morphology into a semi-crystalline continuous and solid matrix. The separate Si3N4 nanoparticles and their agglomerates were relatively homogeneously distributed within the PEEK matrix. The coatings deposited from the suspension containing chitosan exhibited higher scratch resistance than the coatings deposited from the suspension stabilizing by polyethylenimine. The results demonstrate that electrophoretic deposition is a useful method to deposit homogeneous composite Si3N4/PEEK coatings well-adhered to the titanium alloy substrate, which could potentially improve both the bioactive and bio-tribological properties of titanium alloys used in biomedical applications.

Gold Nanoparticle Layers on Polystyrene Microspheres of Controlled Structure and Electrokinetic Properties.

Formation of positively charged gold nanoparticle layers on polystyrene microparticles (PSMs600) was studied using the electrokinetic and the concentration depletion methods based on atomic force microscopy (AFM) and scanning electron microscopy (SEM) imaging. Primarily, the dependence of electrophoretic mobility of microparticles on the gold nanoparticle concentration in the suspension was measured. These results were quantitatively interpreted in terms of the three-dimensional electrokinetic model. This allowed to derive a formula for calculating the coverage of nanoparticles under in situ conditions whose validity was confirmed by direct SEM imaging of deposited gold nanoparticles (AuNPs). Additionally, the maximum coverage of gold nanoparticles for various ionic strengths was determined using a concentration depletion method based on AFM imaging of residual particles deposited on the silica substrate. The maximum coverage increased with ionic strength attaining a value of 0.35 for the ionic strength of 3 × 10-3 M. This effect was attributed to the decreasing range of lateral electrostatic interactions among deposited particles. The electrokinetic properties of the gold nanoparticle layers were also evaluated in pH cycling experiments that confirmed their stability. Beyond significance to basic science, the new data acquired in this work confirm the feasibility of preparing gold nanoparticle layers on polymer microparticles characterized by a controlled structure, coverage, and electrokinetic properties.

Regulation of clay particles charge for design of protective electrokinetic barriers

Coupled electrokinetic protective reactive barriers (PRB) are considered as a perspective technology for the treatment of contaminated groundwater. Design of PRB is directly connected with a problem of barrier material choice. Clays can be considered as an appropriate material due to high adsorptive properties and relative cheapness. The barrier internals are formed by clay surface charge properties. We revealed that acidic and alkaline treatment of clay is an effective way to affect its protective properties so that clay can be used to treat various pollutants. Surface charge and electrokinetic properties of clays were characterized by point of zero charge (p.z.c.), point of zero net proton charge (p.z.n.p.c.) and ζ-potential at different pH. Suspensions of 3 main clay types were studied by microelectrophoresis and potentiometric titration methods. At pH > p.z.n.p.c. clayey barrier adsorbs predominantly cationic toxicants and at pH < p.z.c. – anionic ones. The barrier is seemed to be the least effective in pH range between p.z.c. and p.z.n.p.c. Given the physicochemical and electrokinetic parameters, the most efficient clays for barrier design are Cambrian illite and all montmorillonite clays.

Stability, adsorption and electrokinetic properties of the chitosan/silica system

The aim of this paper was to analyze stability, adsorption and the electrokinetic properties of suspensions containing chitosan and silica. Chitosan (Ch), the second most abundant natural polysaccharide, biodegradable and relatively cheap can be very good alternative for artificial polymers used in the stabilization of metal oxide suspensions. The results obtained from spectrophotometric and turbidimetric stability measurements proved that the higher concentrations of chitosan the more stabile the silica suspensions. The mechanism of the stabilization is the electrosteric one because the studied polymer not only adsorb on the silica surface but also possesses amino groups creating additional charge barrier preventing from flocculation. The adsorption of chitosan increases also with the increase of pH of the solution. However, the protonation of this polymer is the highest in pH = 5–6.3 and as the consequence in the above mentioned pH stabilization of the silica suspensions is the best. There is no significant influence of chitosan molecular weight on stability of studied suspensions when concentration of the polymer is relatively low (60 ppm–120 ppm). However, for higher concentrations of chitosan (200 ppm–800 ppm) stability increases with the increase of its molecular weight as well as the adsorption of this polymer on the silica surface. The additional information about stability and the structure of the adsorption layer was obtained from the zeta potential measurements. The presented results can find practical applications connected with functionalized materials especially in medicine, pharmacy, cosmetics and agriculture.

Formation, properties and stability of silver nanoparticle monolayers at PDADMAC modified polystyrene microparticles

A facile self-assembly procedure was developed for the preparation of silver nanoparticle shells at polystyrene microparticles (PSMPs) modified by poly(diallyldimethylammonium chloride) (PDADMAC). Initially, physicochemical properties of microparticles, silver particles and (PDADMAC) were determined for various ionic strength and pHs. Then, PDADAMAC adsorption on the PSMPs was studied in situ via electrokinetic measurements. The influence of polyelectrolyte bulk concentration on electrokinetic properties of PDADMAC-coated microparticles for different ionic strength was investigated. The coverage of PDADMAC monolayer was estimated applying an electrokinetic model. The stability of PDADMAC-modified microparticles under controlled conditions of pH and ionic strength was also evaluated. It was confirmed that under acidic conditions (pH 4–5.6) the microparticles were stable for at least two weeks. The modified microparticles were used as substrate for silver nanoparticle immobilization carried out under a diffusion controlled self-assembly process. The coverage of nanoparticles was precisely determined using electrophoretic mobility measurements, the concentration depletion method involving atomic force microscopy and via direct scanning electron microscopy imaging of particles. A large stability of the silver particle monolayers was confirmed. These monolayers of well-defined coverage and acid-base properties can be used for controlled delivery of silver nanoparticles.

Investigation of the interaction mechanism of depressants in the reverse cationic flotation of complex iron ores

Iron ore mineral processing techniques are constantly challenged with the emergence of complex gangue minerals such as amphiboles, pyroxenes and others. Magnetic separation technique that achieves good results for some richer iron ores cannot guarantee the same results for such complex ores. The flotation route allows upgrading the concentrate grade but is also challenged because of the depression of Fe–Mg–Al-bearing silicates due to the presence of metal ions on the mineral surface, which can form strong chemical complexes with starch molecules used as depressant of iron oxides. The adsorption mechanism of the principal depressants used in oxide ore flotation was investigated on chamosite (chlorite group), diopside (pyroxene group) and epidote. Since the adsorption of reagents is related to the mineral surface charge in physical adsorption systems, the electrokinetic properties of these minerals were also investigated to develop a common approach for complex iron ores processing by flotation when the gangue is presented by complex Fe-Mg-Al bearing silicates.

Rheological behavior and electrokinetic properties of pectin extracted from pumpkin (Cucurbita maxima) pulp and peel using hydrochloric acid solution

The aim of this study is to investigate the chemical composition, hydrodynamic, rheological, and electrokinetic properties of pectin extracted from pulp and peel of pumpkin “Cucurbita maxima” by hydrochloric acid solution at pH 1.8. Chemical analysis of the extracted pectin showed an abundance of galacturonic acid which represents the totality of the uronic acid. Its content in the pulp and peel pectin extracts was 52.91 ± 0.02 g/100 g and 55.14 ± 0.10 g/100 g of dried samples, respectively. The results for intrinsic viscosity [η] ranged from 5.13 ± 0.04 to 5.65 ± 0.08 dl/g and for molecular weight from 234.64 ± 2.33 to 267.40 ± 5.39 kDa. These macromolecules are semi-flexible chain biopolymers with flexibility values of 0.07 ± 0.00. The parameter measurement of the pectin such as hydrodynamic radius (Rh) ranged from 32.39 ± 0.19 to 34.93 ± 0.40 nm, the relaxation time (tr) from 2.77 ± 0.02 × 10−7 to 11.26 ± 0.00 × 10−7 ms, and the diffusivity coefficient (D) from 2.17 ± 0.00 to 8.73 ± 0.00 cm2/s. The rheological behavior was suitably represented by the Bingham and Herschel–Bulkley models for all concentrations. The electrokinetic behavior of pectins allows control of electrostatic interactions. The calculated Zp of the system constituted by pumpkin pectin and citric acid/sodium citrate buffer ranged from − 28.10 ± 0.20 to + 0.35 ± 0.65 mV.

Impact of interfacial Al- and Si-active sites on the electrokinetic properties, surfactant adsorption and floatability of diaspore and kaolinite minerals

The active sites of mineral surfaces play an important role in many industrial processes, such as mineral flotation and dewatering. This paper was aimed to investigate the effect of Al- and Si-active sites on the mineral crystal faces exposed to water on the electrokinetic properties, surfactant adsorption, and floatability of diaspore and kaolinite, which are, respectively, the valuable and gangue minerals in the processing of diasporic bauxite ores. Specifically, the acid treatment was used to change the physicochemical properties of diaspore and kaolinite minerals for their selective flotation. Microelectrophoresis method was used to determine the zeta (surface) potential of diaspore and kaolinite particles before and after the acid treatment as a function of pH. The change in the surface potential was analyzed applying the theory on the electrical double layers at the solid-solution interface. The proton donor–acceptor reactions occurring simultaneously on amphoteric alumina or/and silica sites of diaspore and kaolinite were considered. The mass balances were applied to link the surface active sites with the minerals charge and potential. Comparing the modeling with the experimental data revealed the significant decrease in the Al-active sites and increase in the Si-active sites by the acid treatment. Single mineral flotation and surfactant adsorption tests of diaspore and kaolinite before and after the acid treatment were carried out using sodium hexametaphosphate (HMP) and dodecylamine hydrochloride (DAH) as a depressant and a collector, respectively. After the acid treatment, the adsorption density of depressant on both diaspore and kaolinite decreased due to the reduced density of Al-active sites on the minerals surfaces. The changes of collector adsorption capacity and floatability of diaspore were very small while those of kaolinite were significantly increased. These changes were caused by decreasing the density of Al-active sites (covered by HMP and thereby preventing DAH adsorption) on both diaspore and kaolinite and increasing the density of Si-active sites of kaolinite (not covered by HMP and thereby facilitating DAH adsorption). The results clearly indicated that the acid treatment was shown to be conducive to changing the active Al- and Si-sites on diaspore and kaolinite and thereby improving their flotation separation.

Electrokinetic transport properties of deoxynucleotide monophosphates (dNMPs) through thermoplastic nanochannels

The electrokinetic behavior of molecules in nanochannels (<100 nm in length) have generated interest due to the unique transport properties observed that are not seen in microscale channels. These nanoscale dependent transport properties include transverse electromigration arising from partial electrical double layer overlap, enhanced solute/wall interactions due to the small channel diameter, and field-dependent intermittent motion produced by surface roughness. In this study, the electrokinetic transport properties of deoxynucleotide monophosphates (dNMPs) were investigated, including the effects of electric field strength, surface effects, and composition of the carrier electrolyte (ionic concentration and pH). The dNMPs were labeled with a fluorescent reporter (ATTO 532) to allow tracking of the electrokinetic transport of the dNMPs through a thermoplastic nanochannel fabricated via nanoimprinting (110 nm × 110 nm, width × depth, and 100 μm in length). We discovered that the transport properties in plastic nanochannels of the dye-labeled dNMPs produced differences in their apparent mobilities that were not seen using microscale columns. We built histograms for each dNMP from their apparent mobilities under different operating conditions and fit the histograms to Gaussian functions from which the separation resolution could be deduced as a metric to gage the ability to identify the molecule based on their apparent mobility. We found that the resolution ranged from 0.73 to 2.13 at pH = 8.3. Changing the carrier electrolyte pH > 10 significantly improved separation resolution (0.80–4.84) and reduced the standard deviation in the Gaussian fit to the apparent mobilities. At low buffer concentrations, decreases in separation resolution and increased standard deviations in Gaussian fits to the apparent mobilities of dNMPs were observed due to the increased thickness of the electric double layer leading to a partial parabolic flow profile. The results secured for the dNMPs in thermoplastic nanochannels revealed a high identification efficiency (>99%) in most cases for the dNMPs due to differences in their apparent mobilities when using nanochannels, which could not be achieved using microscale columns.

Janus Droplets and Droplets with Multiple Heterogeneous Surface Strips Generated with Nanoparticles under Applied Electric Field

A novel method of fabricating Janus droplets and droplets with heterogeneous strips is presented in this article. These droplets were made by covering the surfaces of oil droplets with different nanoparticles under an electric field in a microfluidic chip. The microfluidic chip was used to control the delivery of nanoparticles, and the electric field was employed to assemble the nanoparticles adhering on the droplet. By controlling the delivery of nanoparticles in the microfluidic chip under the electric field, different nanoparticles accumulate on the droplet surface and the desired Janus droplets and droplets with heterogeneous strips can be formed. Because of the presence of charged nanoparticles on droplets’ surfaces, the Janus droplets and droplets with heterogeneous strips have unique electrokinetic properties. The electro-osmotic flow fields around Janus droplets and droplets with heterogeneous strips in different pH solutions were visualized, and the electrokinetic velocities of these droplets in ...

Study of electrokinetic and magnetic properties of ZrNi1-xRhxSn semiconductive solid solution

The features of electrokinetic, energy state and magnetic characteristics of ZrNi1-xRhxSn semiconductive solid solution were investigated in the ranges: T = 80-400 K, x = 0-0.10. It was shown that substitution of Ni atoms (3d84s2) by Rh atoms (4d85s1) in the structure of ZrNiSn compound generated the structural defects with acceptor nature, and holes became the main charge carriers in the ZrNi1-xRhxSn at low temperature. Based on analysis of the motion rate of the Fermi level ΔεF/Δх in ZrNi1-xRhxSn to the valence band and change of sign of thermopower coefficient from positive to negative it was suggested that the structural defects of acceptor and donor natures were generated simultaneously (donor-acceptor pairs), and deep donor band ɛD2 was formed.

Protein-Based Nanoparticle Preparation via Nanoprecipitation Method.

Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been dedicated to the preparation of protein- based nanoparticles. Then, the aim of this work was to report on the preparation of bovine serum albumin (BSA)-based nanoparticles using a well-defined nanoprecipitation process. Special attention has been dedicated to a systematic study in order to understand separately the effect of each operating parameter of the method (such as protein concentration, solvent/non-solvent volume ratio, non-solvent injection rate, ionic strength of the buffer solution, pH, and cross-linking) on the colloidal properties of the obtained nanoparticles. In addition, the mixing processes (batch or drop-wise) were also investigated. Using a well-defined formulation, submicron protein-based nanoparticles have been obtained. All prepared particles have been characterized in terms of size, size distribution, morphology, and electrokinetic properties. In addition, the stability of nanoparticles was investigated using Ultraviolet (UV) scan and electrophoresis, and the optimal conditions for preparing BSA nanoparticles by the nanoprecipitation method were concluded.

Impact of formulation excipients on the thermal, mechanical, and electrokinetic properties of hydroxypropyl methylcellulose acetate succinate (HPMCAS)

Hydroxypropyl methylcellulose acetate succinate (HPMCAS) has been widely used in amorphous solid dispersions and as an enteric coating polymer. Under aqueous coating conditions and at elevated coating temperatures, HPMCAS particles tend to aggregate and clog the spray-nozzle, hence interrupting the coating process. This research focused on how plasticizers and surfactants, excipients used for aqueous coating, affect the properties and stability of HPMCAS. This information would be useful in identifying suitable excipients for developing a stable HPMCAS aqueous enteric coating formulation. Triethyl citrate was found to be the most compatible plasticizer with HPMCAS, and displayed suitable thermal and mechanical properties. PEG 4000, the co-plasticizer, provided dispersion stability by yielding a dispersible sediment without aggregation at the elevated processing temperatures. Zeta potential measurements indicated sodium lauryl sulfate (SLS) could be used as a potential stabilizing agent at concentrations above its critical micelle concentration (CMC). This study facilitated the understanding of the HPMCAS aggregation mechanism, in addition to identifying suitable stabilizing agents. These stabilizing excipients could potentially be used to develop a stable aqueous coating formulation that does not exhibit polymer aggregation and nozzle clogging during the coating process.