Anionic Polyelectrolyte Research Articles

A bio-based adhesive composed of polyelectrolyte complexes of lignosulfonate and cationic polyelectrolytes

Polyelectrolyte complexes composed of lignosulfonate and cationic polyelectrolytes were used as bio-based adhesives. Sodium lignosulfonate (L-SO3Na), a wood-derived anionic polyelectrolyte, was combined with three different cationic polyelectrolytes and the adhesive strength of the resulting complexes was evaluated on various substrates. Higher adhesive strength was observed with polar substrates (stainless steel, aluminum, and wood) compared to a nonpolar substrate (polypropylene). Complexes L-SO3Na/poly(allylamine) and L-SO3Na/ε-poly-l-lysine exhibited higher adhesive strength than the other polyelectrolyte complexes on aluminum and a commercial polyvinyl acetate adhesive on wood. In addition, our adhesives do not require any additional chemical reagents, such as organic solvents, crosslinkers, or condensation agents. The L-SO3Na/ε-poly-l-lysine complex is a strong and completely biodegradable adhesive. This study demonstrates the use of lignosulfonate in the development of low-toxicity, sustainable, and biodegradable adhesives with excellent adhesive strength.

Effect of adsorbed polyelectrolytes on the interactions and elasticity of charged surfactant bilayers

We present studies on the structure of complexes of the cationic, bilayer-forming surfactant, didodecyldimethylammonium bromide (DDAB), and the anionic polyelectrolyte sodium polyacrylate (PAANa). In the presence of uncomplexed polyelectrolyte in the coexisting aqueous solution, these complexes are found to exhibit a swelling transition followed by a deswelling transition on increasing the salt concentration. Lamellar structures with low periodicities occur at both low and high salt concentrations, which are stabilized by polymer bridging and van der Waals attraction, respectively. The swollen complex found at intermediate salt concentrations forms the sponge phase. Our results reveal that polyelectrolyte adsorption on bilayers has a profound effect on inter-bilayer interactions. The polymer-induced interaction changes from being attractive to repulsive as the surface coverage increases on increasing the salt concentration. Our results also confirm that polymer adsorption alters the elastic moduli of the bilayer, in agreement with earlier theoretical predictions.

Molecular aggregates of pyronin dyes with polyelectrolyte polystyrene sulfonate (PSS) in aqueous solution

Aggregation of the cationic dyes pyronin B (PyB) and pyronin Y (PyY) in aqueous solution containing anionic polyelectrolyte polystyrene sulfonate (PSS) has been studied by using steady-state and time-resolved fluorescence and UV–vis absorption spectroscopy techniques. Although H-aggregates of these pyronin dyes have been previously observed in colloidal suspension, this is the first report of their J-aggregates obtained as a function of dye concentration by using constant concentration of PSS in solution. The best dye concentrations for the J-aggregates were determined as 2.4 × 10−5 M and 1.2 × 10-4 M for PyB and PyY, respectively. Moreover, aggregation equilibrium constants (KD) and thermodynamic functions were determined as a function of temperature for H-type aggregation. By employing the exciton theory, angle (α) between the molecular transition dipole moments and the long aggregate axis, and the intermolecular distance (R) were also calculated for each dye aggregates. In addition, the fluorescence lifetime values were determined from fluorescence decay measurements for the monomer and aggregated species of pyronin compounds in polyelectrolyte aqueous solution.

Formation of Chitosan/Sodium Phytate/Nano-Fe3O4 Magnetic Coatings on Wood Surfaces via Layer-by-Layer Self-Assembly

Magnetic wood would have potential uses in electromagnetic shielding and electromagnetic wave absorption. In this paper, magnetic coatings on a wood surface were synthesized using a layer-by-layer self-assembly method. As the cationic polyelectrolyte carrier, natural macromolecular chitosan was pre-immobilized on a wood surface first, followed by the alternate adsorption of anionic polyelectrolyte sodium phytate and positively-charged Fe3O4 nanoparticles. The concentration of pH-controlled chitosan solution, sodium phytate solution, and Fe3O4 nanoparticle suspension, soaking time, and the number of alternating sedimentary layers varied. The morphology and crystal structure of the Fe3O4 modified wood samples were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The magnetic hysteresis loops showed that the modified wood had magnetic properties which were improved as the number of assembled layers increased.

Substrate-independent polymer coating with stimuli-responsive dexamethasone release for on-demand fibrosis inhibition.

Tissue fibrosis caused by implantation of tissue engineering scaffolds is an urgent problem in clinical research. In this work, a substrate-independent coating with on-demand release of an antifibrotic drug has been fabricated to effectively address this issue. This coating was formed through a substrate-independent layer-by-layer (LBL) technique via a cationic polyelectrolyte (poly-diallyldimethylammonium, PDDA) and an anionic polyelectrolyte (poly-styrenesulfonate, PSS), where parts of PSS and PDDA were physically replaced by carboxyl functionalized polyethylene glycol grafted onto antifibrotic drug dexamethasone (DEX-PEG-COOH). Considering the easy generation of local inflammation after implantation, an ester bond was designed between PEG-COOH and DEX. Therefore, the overexpressed esterase under inflammatory conditions hydrolyzes the ester bond and thereby releases DEX from the film to inhibit fibrosis occurring in the tissue repair process. The in vivo capacity of this coating to restrain tissue fibrosis was investigated by a skin defect model using porous polycaprolactone (PCL) scaffolds as substrates. The experimental results showed that the fibrosis-related proteins (Col-I, TGF-β and fibronectin) and the infiltration of myofibroblasts (α-SMA) of skin tissues in the coated PCL scaffold group were significantly lower than those in the blank control group and pure PCL scaffold group. Moreover, the histological evaluations showed that the coating group could significantly decrease the deposition of collagen and meanwhile promote the partial regeneration of skin appendages. These results successfully demonstrate that the universal coating prepared with a simple protocol would be an effective strategy to address the fibrosis issues during tissue engineering.

Response of metal-coordination-based polyelectrolyte complex micelles to added ligands and metals.

Polyelectrolyte complex based micelles have attracted significant attention due to their potential regarding bio-applications. Although the morphology and functions have been studied extensively, dynamic properties, particularly component exchange with other surrounding molecules, have remained elusive to date. Here, we show how micelles based on metal-ligand coordination complex coacervate-core micelles (M-C3Ms) respond to addition of extra ligand and metal ions. The micelles are prepared from a polycationic-neutral diblock copolymer and an anionic coordination polyelectrolyte, which is obtained by coordination between metal ions (lanthanides Ln3+ and Zn2+) and a bis-ligand (LEO) containing two dipicolinic acid (DPA) groups connected by a tetra-ethylene oxide spacer (4EO). Our findings show that the bis-ligand LEO is essential for the growth of coordination polymers and consequently the formation of micelles, leading to equilibrium structures with the same micellar composition and structure independent of the order of mixing. In other words, adding single DPA has no effect on the formed M-C3Ms. As for metal exchange, we find that added Zn2+ can replace some of the Ln3+ from Ln-C3Ms, leading to a hybrid coordination structure with both Ln3+ and Zn2+. We find that component exchange occurs in these coordination polyelectrolyte micelles, but it is more favorable in the direction of replacing the weak binding components with strong ones. Hence, the designed M-C3Ms based on the strong binding components, such as Ln-C3Ms, shall be relatively stable in biological surroundings, paving the way for the application of such particles as bio-imaging probes.

Magnetic methacrylated gelatin-g-polyelectrolyte for methylene blue sorption.

The presence of organic dyes in wastewater is a problem of growing interest due to its effect on the environment and human health. The aim of this work was to obtain magnetic hydrogels of methacrylated gelatin-g-polyelectrolyte to be used for the removal of methylene blue (MB) used as a model contaminant dye. Grafted gelatins with two degrees of functionalization (48% and 76%) were obtained and subsequently crosslinked using 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and sodium 4-vinylbenzenesulfonate (SSNa) monomers. Magnetic nanoparticles were formed by an in situ precipitation method to easily remove the hydrogel from the adsorption medium. Our data show that the hydrogel with a low degree of methacrylation displayed a high degree of swelling and decreased stiffness due to its less connected polymer network. MB adsorption experiments showed that neither the low degree of methacrylation nor the presence of the aromatic group in the PSSNa polyelectrolyte generated an increase in the adsorption capacity of the hydrogel. However, a significant increase in the adsorption capacity was observed when dry hydrogels were combined compared to that of previously swollen hydrogel. The experimental data were non-linearly fitted to the pseudo-first and pseudo-second order models and in both cases, the highest qe values were obtained for the GelMA-HF/PAMPS and GelMA-LF/PAMPS hydrogels. The Freundlich isotherm model was the one with the best correlation with the data (r2 > 0.9700). Higher kf values were obtained for the GelMA-HF/PAMPS and GelMA-LF/PAMPS hydrogels at 20 °C. The results obtained from this study demonstrated that magnetic polyelectrolyte-grafted gelatins are an efficient option for the removal of contaminant dyes from aqueous solutions.

Effects of polyelectrolytes on the hardness of borax decahydrate crystals

The hardness of borax decahydrate crystals was measured using cationic polyelectrolytes of FO4115, FO4400 and FO4990 with anionic polyelectrolytes of AN923, AN930 and AN999 as an additive. The measurements were carried out in the indentation load range of 10 g to 30 g. It was determined that the Vickers hardness (H V ) decreased with increasing applied load, showing that the borax decahydrate crystals exhibited an indentation size effect. Vickers microhardness measurements revealed that pure borax decahydrate crystals had a brittle structure, yet the crystals obtained in additive media were categorized as a soft material. The proportional specimen resistance model was applied to determine the load-independent microhardness. The crystal hardness of borax decahydrate was found to change depending on the type and concentration of polyelectrolyte used. In addition to the mechanical properties, the thermal and physical characteristics of borax decahydrate crystals were investigated by thermogravimetric and Fourier transform infrared spectroscopy analysis. The characterization results confirmed that the polyelectrolytes were adsorbed on the crystal’s surface.

Hardness and Indentation Fracture Toughness of Slip Cast Alumina and Alumina-Zirconia Ceramics.

Alumina (Al2O3) and zirconia (ZrO2) have good overall properties and thus are widely used oxide technical ceramics. The biggest drawback of Al2O3 is its low fracture toughness. In contrast, ZrO2 is relatively tough, but is also much more expensive. In order to improve the alumina toughness, composite ceramics are being developed. Slip casting technology has economic advantages over the conventional hot isostatic pressure technology, but problems may arise when preparing stable highly-concentrated suspensions (slip) for filling the mold. The purpose of this study is to prepare aqueous suspensions using 70 wt. % α-Al2O3, with 0, 1, 5 and 10 wt. % of added t-ZrO2. Suspensions were electrosterically stabilized using the ammonium salt of polymethylacrylic acid, an alkali-free anionic polyelectrolyte dispersant. Also, magnesium oxide in form of magnesium aluminate spinel (MgAl2O4) was used to inhibit the abnormal alumina grain growth during the sintering process. Minimum viscosities were used as stability estimators, where an increase in ZrO2 content required adding more dispersant. After sintering, the Vickers indentation test was used to determine the hardness and the indentation fracture toughness from the measurement of the crack length. Also, the brittleness index (Bi, μm−1/2) was calculated from values of Vickers hardness and the Vickers indentation fracture toughness. It was found that with increasing ZrO2 content the fracture toughness increased, while the hardness as well as the brittleness index decreased. Zirconia loading reduces the crystallite sizes of alumina, as confirmed by the X-ray diffraction analysis. SEM/EDS analysis showed that ZrO2 grains are distributed in the Al2O3 matrix, forming some agglomerates of ZrO2 and some pores, with ZrO2 having a smaller grain size than Al2O3.

Enhancement of flocculation and shear resistivity of bentonite suspension using a hybrid system of organic coagulants and anionic polyelectrolytes

In this study, the influence of the hybrid coagulation-flocculation system on the flocculation and shear resistivity of bentonite suspension has been investigated. Two short-chained coagulants, polyamine and polyDADMAC, accompanied with low and high Molecular Weight (Mw) long-chained anionic Polyacrylamide (PAM) flocculants have been used to enhance the size and mechanical properties of the produced flocs. Four characterization techniques were used as evaluation criteria of degree of flocculation including turbidity, zeta potential (ζ), floc size analysis and rheology. Optimum dosages between 5 and 10 mg/L were obtained for flocculants and between 20 and 30 mg/L for coagulants in hybrid systems. Compared to single systems, hybrid systems performed exceptionally well. Removal efficiency of 99% was achieved using hybrid systems producing water with turbidity as low as 1.05 NTU. Although differences were insignificant in the treatment quality, significant improvement was achieved in floc size and rheological behavior. Hybrid systems were able to produce large flocs of more than 400 µm, five times bigger than flocs from the single cationic coagulant systems. Most importantly, rheological testing of produced slurries revealed the remarkable advancement achieved by hybrid systems. Hybrid systems were able to increase the elastic modulus (G′) by more than ten times resulting from the compacted flocs present in the system. Furthermore, resistivity toward shear and oscillations were improved. Ultimately, hybrid systems have surpassed the single cationic systems by achieving slightly better treatment besides producing larger, denser and more resistive flocs. Generally, polyDADMAC performed better than polyamine in hybrid systems. The combination of polyDADMAC with high Mw PAM gave the best separation as well as the largest flocs, while the combination with low Mw PAM resulted in the best rheological properties.

Controlling Self-Assembly with Light and Temperature.

Complexes between the anionic polyelectrolyte sodium polyacrylate (PA) and an oppositely charged divalent azobenzene dye are prepared in aqueous solution. Depending on the ratio between dye and polyelectrolyte stable aggregates with a well-defined spherical shape are observed. Upon exposure of these complexes to UV light, the trans → cis transition of the azobenzene is excited resulting in a better solubility of the dye and a dissolution of the complexes. The PA chains reassemble into well-defined aggregates when the dye is allowed to relax back into the trans isomer. Varying the temperature during this reformation step has a direct influence on the final size of the aggregates rendering temperature in an efficient way to easily change the size of the self-assemblies. Application of time-resolved small-angle neutron scattering (SANS) to study the structure formation reveals that the cis → trans isomerization is the rate-limiting step followed by a nucleation and growth process.

Layer‐by‐layer self‐assembly of multifunctional enzymatic UF membranes

ABSTRACTIn order to eliminate membrane fouling and to ensure enzymatic hydrolysis of urea, multifunctional biocatalytic membranes were prepared by using urease (URE) and trypsin (TRY) enzymes on the sulfonated polysulfone (SPSf) ultrafiltration membrane via layer‐by‐layer (LbL) self‐assembly method. The membrane architecture consisted of multilayer assembly with TRY and URE enzymes as the outer layer and inner sandwiched layer, respectively. Polyethyleneimine (PEI) and alginate (ALG) were used as cationic and anionic polyelectrolytes. Sulfonation and PEI deposition were successfully accomplished as confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy analysis, contact angle measurements, staining with toluidine blue and Congo red dyes and dead‐end filtration experiments. A characteristic value of SPSf membrane with a high water permeability (1000 L/m2.h.bar) and 95% bovine serum albumin (BSA) rejection was observed. In static conditions, URE activities of SPSf2‐PEI‐URE membrane were not affected by BSA fouling, while TRY immobilizations with increased concentrations (SPSf2‐PEI‐URE‐PEI‐ALG‐TRY) significantly lowered the activity of URE. In dynamic conditions, each deposited layer exhibited individual resistance to flow that can be considered as irreversible fouling and caused 90% of flux decline for the SPSf2‐PEI‐URE‐PEI‐ALG‐TRY membrane assembly. The recovery of the initial flux for the multilayered membrane at the end of six fouling and washing cycles was observed 85%. Moreover, at the end of 5 cycles, 78% of the URE initial activity of the multilayered membrane was preserved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48750.

Formation of carboxymethylchitosan/gemini surfactant adsorption layers at the air/water interface: Effects of association in the bulk

The surface properties of mixed solutions containing an anionic polyelectrolyte, carboxymethylchitosan (CMCH), and a cationic gemini surfactant, 1,2-bis(dodecyldimethlyammonio)hexane dibromide (C12C6C12), were studied by measuring the surface tension and the dynamic surface elasticity. The association behaviors in the solutions were also measured by fluorescence probe technique. The results showed that the adsorption layer transformed from pure elastic 2D layer to visco-elastic 3D layer with increase in surfactant concentration. The microparticles in the 3D layer were adsorbed from the adjacent bulk to the surface but not formed directly in the surface layer as it was sometimes assumed in other polyelectrolyte/surfactant systems. The stress relaxation mechanism were supposed to be the mass exchange between the unstructured thinner film surrounding the microparticles and the adjacent bulk during the surface compression or expansion. These surface properties of CMCH/C12C6C12 solutions were influenced strongly by the association in the bulk solution.

Purification of real car wash wastewater with complex coagulation/flocculation methods using polyaluminum chloride, polyelectrolyte, clay mineral and cationic surfactant.

In the present study, real car wash wastewater was purified by different coagulation/flocculation methods. As coagulant, polyaluminum chloride ('BOPAC'), conventional iron(III) chloride, iron(III) sulfate, and aluminum(III) chloride were used, while as flocculant non-ionic and anionic polyelectrolytes were investigated. The effects of added clay mineral (Na-bentonite) and cationic surfactant (hexadecyltrimethyl ammonium bromide - 'HTABr') were also investigated. The use of BOPAC was significantly more effective than conventional coagulants. Extra addition of clay mineral was also beneficial in relation to both the sediment volume and sedimentation speed, while polyelectrolyte addition enhanced further the sedimentation. Moreover, the simultaneous addition of HTABr significantly enhanced the color removal efficiency due to the successful in-situ generation of organophilic bentonite. In summary, the application of 100 mg L-1 Na-bentonite with 20 mg L-1 Al3+ (from BOPAC) and 0.5 mg L-1 anionic polyelectrolyte resulted in the efficient reduction of the turbidity (4-6 NTU), the COD (158 mg L-1) and the extractable oil content (4 mg L-1) with efficiencies of 98%, 59%, and 85%, respectively. By applying organophilic bentonite in high concentration (500 mg L-1) with identical concentrations of BOPAC and anionic polyelectrolyte, significant color removal (5 times lower absorbance at λ = 400 nm) and 27% lower sediment volume were achieved.

Viscoelastic Solutions of Wormlike Micelles of a Cationic Surfactant and a Stiff-Chain Anionic Polyelectrolyte

The phase behavior and rheological properties of the mixtures of wormlike micelles of the cationic surfactant erucyl-bis(hydroxyethyl) methyl ammonium chloride and oppositely charged stiff-chain polyelectrolyte xanthan are studied. It is shown that, in the presence of an excess of a low molecular weight salt, which suppresses complex formation between the surfactant and the polymer, mixing allows a synergistic increase in the elastic modulus of the system to be achieved, which may be due to the formation of entanglements between polymer chains and wormlike micelles.

Counterion-binding and related phenomena in sodium alginate-sodium chloride-water ternary systems: A conductometric study

Counterion-binding and related phenomena in aqueous solution of the naturally-occurring anionic polyelectrolyte sodium alginate have been explored in absence as well as in presence of sodium chloride using electrical conductivity as the probe. In particular, the variations of the counterion-binding behavior as functions of polyelectrolyte concentration, added electrolyte concentration, and temperature were investigated. A phenomenological treatment of the data which considered the additivity of salt and polyelectrolyte conductivities taking into account the Debye-Hückel interactions using Manning's theoretical expressions for self-diffusion was performed. The results indicated a marked departure from additivity. The data were, therefore, analyzed on the basis of the de Gennes scaling model for the configuration of a polyion chain in semidilute solutions. Counterion-dissociation reached its maximum in absence of the added salt, whereas counterion-binding reached its maximum in presence of the highest amount of the added salt. In moderately saline media, however, counterion-binding was initially found to increase with polyelectrolyte concentration which then gradually leveled off indicating confinement of counterions within the domains of polyion chains at higher polyelectrolyte concentrations. Results indicated the existence of alginate ions as flexible chains in aqueous solutions. A subtle balance of the influences of the effective monomer charge and the effective monomer size played a pivotal role the polyion mobility. Possible conformational changes of the polyion chains caused by dilution led to changes in hydrodynamic resistance in the investigated solutions. The results also provided important insight as to the influence of the alterations of the hydration behavior of the counterions and the relative permittivity of the media on counterion-binding in the investigated systems.

Modular Layer‐by‐Layer Assembly of Polyelectrolytes, Nanoparticles, and Molecular Catalysts into Solar‐to‐Chemical Energy Conversion Devices

AbstractThe design and fabrication of solar‐to‐chemical energy conversion devices are enabled through interweaving multiple components with various morphologies and unique functions using a versatile layer‐by‐layer assembly method. Cationic and anionic polyelectrolytes are used as an electrostatic adhesive to assemble the following functional materials: plasmonic Ag nanoparticles for improved light harvesting, upconversion nanoparticles for utilization of near‐infrared light, and polyoxometalate water oxidation catalysts for enhanced catalytic activity. Polyelectrolytes also have an additional function of passivating the surface recombination centers of the underlying photoelectrode. These functional components are precisely assembled on a model photoanode (e.g., Fe2O3 and BiVO4) in a desired order and various combinations without degradation of their intrinsic properties. As a result, the performance of water oxidation photoanodes is synergistically enhanced. This study can enable the design and fabrication of novel solar‐to‐chemical energy conversion devices.

Insights into the Rheological Behavior of Aqueous Dispersions of Synthetic Saponite: Effects of Saponite Composition and Sodium Polyacrylate

Synthetic saponite (Sap) easily delaminates in water to form a transparent sol and hydrogel with excellent rheological performance and is thus widely used in paints, cosmetics, and nanomaterials. The thixotropic property of Sap hydrogels is heavily dependent on the nature of Sap and the external electrolyte and polyelectrolyte; yet, details on the relationship between rheological behaviors of saponite hydrogels and Sap composition and polyelectrolyte remain unclear. In this work, thixotropic rheological behaviors of a series of synthetic Sap hydrogels, with and without added sodium polyacrylate polyelectrolyte (NaPA), were investigated. The Sap samples, with a Si/Al molar ratio from 5 to 25, were successfully synthesized using hydrothermal methods and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The rheological performances of aqueous Sap dispersions and particle sizes and ζ-potentials of Sap were measured. The results showed that the crystallinity of the Sap increased with an increasing Si/Al molar ratio. All Sap samples, with the exception of the Sap with a Si/Al molar ratio of 5, dispersed well in water (3 wt %) to form hydrogels. The rheological behaviors of the hydrogels were related to the chemical composition and the layer charge of the Sap. The Sap with a Si/Al molar ratio of 25 had higher viscosity due to improved delamination. The addition of the NaPA, an anionic polyelectrolyte, into the hydrogels decreased the viscosity and altered the thixotropic properties such that the hydrogel becomes a sol. The addition of NaPA facilitated the dispersion and delamination of Sap, because under the electric field of negatively charged Sap particles in the hydrogel, the anionic NaPA was instantaneously polarized and thereby entered the hydration layer of the Sap particles.

Layer-by-layer Multilayered Film Formation on Gradient Polyelectrolyte Brush Prepared by Bipolar Electrochemistry

Polyelectrolyte multilayer formation on a gradient polymer brush was investigated for the first time. The gradient anionic polyelectrolyte brush was synthesized by combining bipolar electrochemistr...

Lead Dioxide Based Oxide-Surfactant Composites

Great attention is paid to various electrochemical methods of coatings synthesizing in connection with the simplicity of their implementation, low cost equipment and the ability to control the composition and properties of the materials obtained by changing the electrolysis regimes and the composition of electrolytes [1, 2]. Composite materials based on lead dioxide, containing surfactants are of considerable interest for research, since while maintaining the basic properties of PbO2, the composition, physico-chemical properties, and electrocatalytic activity of such materials can vary widely. At the same time, there is a lack of information [4, 5] regarding the effect of surfactants on the regularities of electrodeposition of materials based on lead dioxide, especially the physico-chemical properties of the oxides obtained and their electrocatalytic activity. In this connection, herein, we report the regularities of synthesizing, the effect of deposition conditions on the composition, physico-chemical properties of composite PbO2-sodium laureth sulfate (SLES) materials obtained from nitrate electrolytes. The addition of surfactants has a significant impact on the kinetics of lead dioxide electrodeposition, without changing the mechanism of the process. In this way, at low anodic polarizations second electron transfer stage is rate determining, whereas at high anodic polarizations such stage is diffusion transport of the lead ions to the electrode surface. The presence of sodium laureth sulfate in the deposition electrolyte leads to a slight inhibition of the deposition of lead dioxide. The content of the additive in lead dioxide is determined mainly by its adsorption on the oxide. An increase in the adsorption of additive due to an increase in its concentration in the solution and an increase in electrostatic attraction (an increase in the anodic current density and the acid content in the deposition electrolyte) leads to the enrichment of the composite material with organic substance. Anionic surfactants, SLES in particular, are included in the growing lead dioxide. The content of organic substance in the oxide can vary from 3.4 to 12.5 w.%, forming a surfactant-oxide composite coating. The changing in deposition conditions (temperature, pH and anodic current density) allows one to control the content of surfactant in the resulting oxide. Based on the data obtained, a colloidal-electrochemical mechanism for the formation of composites was proposed, according to which the process proceeds in several stages: the formation of colloidal oxide particles in the near-electrode zone; adsorption of anionic polyelectrolyte on colloidal particles; electrophoretic delivery of oxide particles with adsorbed surfactant to the electrode surface; sedimentation and crystallization of the composite at the interface. The surface morphology and chemical composition of obtained materials were investigated by SEM, EDAX, phase composition and texture was determined by X-Ray powder diffraction. The morphology and structure of composite materials differs significantly from lead dioxide. With an increase in the additive content in the composite, there is a transition from large-grained deposits to materials with submicron and nano-sized crystals. The electocatalytic activity of the materials involved was investigated in respect to oxygen evolution reaction and the oxidation of 4-chlorophenol. The calculated value of Tafel slope is 229 on nonmodified PbO2, while on 10.2 wt.% SLES-PbO2 it is 178 mV/dec. Slope decreasing in the case of PbO2-SLES denotes the increasing of lead dioxide infilling degree by oxygen-containing radicals, which are directly involved in the electrochemical stages of oxygen evolution. The most likely, surfactants on the electrode surface play the role of mediators in the process of oxygen evolution and inhibit the surface blocking by sulfate ions on such materials. The processes of electrooxidation of 4-chlorophenol on lead dioxide and PbO2-based composite materials proceed qualitatively in the same way and differ only in the rate. Thus, lead dioxide based surfactant-oxide composite coatings are of great interest because of high electrocatalytic activity in respect to oxygen transfer reactions. References R. Vargas, C. Borras, D. Mendez, J. Mostany, B.R. Scharifker, J. Solid State Electrochem. 20, 875 (2016).M. Krishna, E. J. Fraser, R. G. A. Wills, F. C. Walsh, J. Energy Storage, 15, 69 (2018).X. Li, H. Xu, W. Yan, J. Alloy Compd., 718, 386 (2017).A. B. Velichenko, T. V. Luk'yanenko, N. V. Nikolenko, R. Amadelli, F. I. Danilov, Russ. J. Electrochem., 43, 118 (2007).