Presence Of PDDA Research Articles

Polyvinyl acetate/reduced graphene oxide-poly (diallyl dimethylammonium chloride) composite coated wood surface reveals improved hydrophobicity

Wetting is a key problem in wood finishing because water causes deterioration and reduces the durability of wood. Herein, hydrophilic wood has been modified into a hydrophobic wood through simple surface coating using polyvinyl acetate (PVAc) / reduced graphene oxide (rGO)-poly (diallyl dimethylammonium chloride) (PDDA). The synthesized graphene oxide (GO) from graphene flakes is used for chemical modification with urotropin in presence of sodium borohydride. The hydrophobic property of PVAc has been increased by modified graphene oxide dispersed at the presence of PDDA in methanol. The synthesized polymer composite is used coating on the various wood surfaces (radial and cross-sectional). Synthesized materials are characterized by extensive characterization techniques. The water contact angle of wood surface coated with PVAc/rGO-PDDA shows 187.8 % better than uncoated wood and 20.7 % better than PVAc coated wood and 2.4 % better than commercial wood stain coated wood. This facile, low cost and eco-friendly approach could be used in a variety of applications.

EFFICIENT REMOVAL OF Cr(VI) BY POLYELECTROLYTE-ASSISTED ULTRAFILTRATION AND SUBSEQUENT ELECTROCHEMICAL REDUCTION TO Cr(III)

This work is focused on the removal of Cr(VI) ions from aqueous solution using water-soluble poly(diallyldimethylammonium chloride), PDDA, coupled to an ultrafiltration membrane of regenerated cellulose and subsequent electrochemical reduction of Cr(VI) to Cr(III). The removal of Cr(VI), using the washing mode, was studied as a function of pH, the molar ratio of polymer:Cr(VI), and the presence of interfering ions. The enrichment mode was used to determine the maximum retention capacity of the polymer, and the release of Cr(VI) and regeneration of the polymer were analysed by sorption-desorption process. Subsequently, the electroanalysis of Cr(VI) was conducted by linear sweep voltammetry and full electrolysis at controlled-potential in acidic media and in the presence of PDDA. The results show an efficient removal of Cr(VI) (95%, 30 mg/L in the feed) using PDDA at pH 9 and a polymer:Cr molar ratio of 20:1. The retention capacity of the polymer was decreased by the presence of sulphate anions. The maximum retention capacity of PDDA was 33 mg Cr/g polymer at pH 9. Using the sorption–desorption process, the results indicated that this water-soluble polymer can release Cr(VI) and be regenerated. Finally, the electrolysis of Cr(VI) to Cr(III) was performed successfully in the presence of PDDA.

Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

Abstract Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

Electrosynthesis of a Hybrid Film Consisting of Stacked Graphene and the Intercalated Manganese Oxide for Oxygen Evolution Reaction

1. Introduction Considering the fact that the energy from most renewable energy systems can be converted into electricity, the electrochemical water splitting may be an ideal process for producing hydrogen, a clean fuel. However, the slow kinetics of the oxygen evolution reaction (OER, 2H2O → 4H+ + O2 + 4e-) that occurs at the counter electrode necessitates a considerable overpotential, thus lowering the overall efficiency of water splitting. This has motivated the development of efficient catalysts for OER. In nature, a highly efficient oxygen evolving complex is involved within photosystem II, with a core structure containing only of non-precious elements, calcium and manganese (Mn4CaO5 cluster). Inspired by the exceptional efficiency of this biological system, many research groups have focused on manganese oxides and derivatives. However, the bulk structures of manganese oxides do not show high catalytic activity toward OER because the poor electrical conductivity (10-5 to 10-6 S cm-1) severely restricts the activity of catalytic systems involving electron transfer. Thus, we expected to overcome this drawback with the use of graphene (GR), a two-dimensional sp2 nanocarbon with high surface area, excellent electrical conductivity (107 to 108 S cm-1 for isolated single sheet), mechanical strength, and chemical stability. We report herein, a new electrochemical strategy to synthesize a thin film consisting of stacked GR sheets and manganese oxide.1The process involved the anodic formation of negatively charged Mn oxide nuclei on the electrode substrate, which triggered the assembly of cationic GR colloids to the negatively charged oxide for charge compensation, followed by the deposition of more Mn oxide onto the already deposited GR surface with excellent conductivity. The resulting thin film of GR-supported Mn oxide exhibited superior OER activity compared to pristine Mn oxide. 2. Experimental Graphene oxide (GO) was prepared from commercial graphite powder by a modified Hummers method. Cationic GR colloids were synthesized as described in the literature.2 In brief, an aqueous dispersion of GO was add to an aqueous solution of poly(diallydimethylammonium) (PDDA+). Then, NaBH4 was added, and the solution was refluxed for 24h at 100°C. The obtained GR colloids whose surfaces were modified with PDDA+ were washed thoroughly in water and centrifuged repeatedly to completely remove any other cationic species. MnOx/PDDA-GR+ film was prepared on an ITO electrode by anode electrolysis of a MnSO4 solution in the presence of PDDA+-modified GR colloids. The PDDA that had been attached to the GR surface was extracted by immersing the as-deposited film in an aqueous solution containing sodium polystyrene sulfonate (NaPSS). Characterization of the resulting films was made using XRD, TEM, and XPS. On the other hand, OER activity was studied in 0.1 M KOH. 3. Result and discussion Cross-sectional TEM images and XRD measurements of the as-deposited film suggested that the laminate structure consisting of GR sheets and MnOx was constructed (MnOx/PDDA-GR+ film) on the substrate. XPS spectra of the film immersed in a NaPSS-containing aqueous solution showed disappearance of the N 1s peak due to PDDA, while a new peak occurred in Na 1s region. This suggests that the PDDA cations attached to the GR surface was extracted into solution by PSS, and the resulting GR surface was neutralized by Na+ ions in solution. The thus-formed product corresponds to MnOx/GR. The catalytic activity of Mn oxide for OER in alkaline electrolyte was dramatically enhanced by hybridizing it with GR. Namely, the MnOx/GR film exhibited a onset potential (determined on the basis of the beginning of the linear portion in the corresponding Tafel plots) of 1.56 V vs. RHE, which was about 200 mV less positive than that of the counterpart without GR. In addition, the MnOx/GR film provided a Tafel slope of 58 mV per decade, being significantly smaller than most values reported for pure Mn oxides. The stability of the MnOx/GR catalyst was evaluated by chronopotentiometry with an applied anodic current density of 2.5 mA cm-2for 90,000 s. The potential increase remained within 0.11 V (1.748–1.856 V). Since GR has no catalytic activity for OER, the above-obtained results can be attributed to a synergistic effect of the catalytic activity of nano-sized Mn oxide deposits and the ability of GR to transfer electrons from the catalyst to the external circuit. References (1) M. Nakayama, Y. Fujii, K. Fujimoto, M. Yoshimoto, A. Kaide, T. Saeki, and H. Asada, RSC Adv., 6, 23377 (2016). (2) S. Wang, D. Yu, L. Dai, D.-W. Chang, and J.-B. Beak, ACS Nano, 5, 6202 (2011).

Ultrasensitive electrochemical sensor based on CdTe quantum dots-decorated poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite modified glassy carbon electrode for the determination of puerarin in biological samples

In the present study, a CdTe quantum dot (QD)-decorated poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (CdTe-PDDA-Gr) nanocomposite was synthesized via a simple one-step chemical reduction of exfoliated graphite oxides in the presence of PDDA and CdTe QDs. Characterization of as-prepared nanocomposite using transmission electron microscopy (TEM) and x-ray diffraction (XRD) clearly demonstrate the successful attachment of PDDA and CdTe QDs to the Gr sheets. The CdTe-PDDA-Gr showed an ultrafast electron transfer property and a strong absorption effect for puerarin and thus yields excellent electrocatalytic activity towards the oxidation of puerarin. Differential pulse voltammetry (DPV) was applied for the determination of puerarin, a good linear relationship of the oxidation peak current and the concentrations of puerarin in the range of 0.001 to 1.0μM was achieved. The detection limit was 0.6nM (SNR of 3) which was comparable with that of liquid chromatography-mass spectrometry (LC-MS). The proposed method was successfully applied for the determination of puerarin in human plasma and pharmaceutical injections with good recoveries.

Supersensitive electrochemical sensor for the fast determination of rutin in pharmaceuticals and biological samples based on poly(diallyldimethylammonium chloride)-functionalized graphene

In this work, poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-Gr) was prepared via in situ reduction of exfoliated graphite oxides in the presence of PDDA. The obtained nanostructure was used as a novel immobilization platform for the electrochemical sensor of rutin. PDDA-Gr has superior electrocatalytic activity for the redox of rutin due to its large surface, fast electron transfer character and strong adsorption effect on rutin. The electron transfer rate constant (ks) and the electroactive surface area were calculated as 1.59s−1 and 0.3324cm2 respectively. The saturating absorption capacity (Γ) value of rutin on modified electrode was calculated to be 2.23×10−9molcm−2. Applying differential pulse voltammetry (DPV), a good linear relationship of the reduction peak current and the concentrations of rutin in the range of 0.0004–1.0μM was achieved. The detection limit was 0.04nM (S/N of 3). Under the optimum conditions, the metabolite of rutin, quercetin can be effectively separated from rutin, which suggested the great potential of the proposed method for the practical application in pharmacokinetic and clinical analyses. The method was successfully applied to the fast determination of rutin in medicine tablets and human plasma with satisfactory recoveries.

Investigation of polyelectrolyte for electrochemical detection of uric acid in presence of ascorbic acid

Uric acid (UA) was detected in the presence of ascorbic acid (AA) at GC electrode by cyclic voltametry (CV) and differential pulse voltametry (DPV) in aqueous media of cationic polyelectrolyte (poly(diallyldimethylammonium chloride) (PDDA)). Both, UA and AA are anionic nature and electro-static attraction with cationic solution. This lowered their oxidation potentials and increased anodic current. In CV studies, the UA oxidation potential was decreased by 400mV in the presence of PDDA along with increase in peak current. Effect of PDDA and pH on Epa and Ipa were also studied. About 360mV difference in oxidation peak potentials was observed for AA and UA in PDDA media, which established a quick method for their simultaneous determination. The detection limit of UA in the presence of 200 folds AA was found as 1μM with correlation coefficient of 0.994 and sensitivity of 0.05μAμM−1. The proposed method has been also applied for determining the UA in human urine without any pretreatment, and found to be satisfactory.

Sonoelectrochemical fabrication of PDDA-RGO-PdPt nanocomposites as electrocatalyst for DAFCs

Sonoelectrochemical technique was successfully used to fabricate alloy–graphene nanocomposites. It not only provides a simple way to synthesize alloy nanoparticles, but also shows a general strategy for fabricating graphene-based nanostructures with anticipated properties. Pd was co-electrodeposited with Pt at different atomic ratios, and then was anchored with reduced graphene oxide (RGO) simultaneously in the presence of PDDA. The morphologies and structures of the as-prepared PDDA-RGO-PdPt nanocomposites were extensively investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The composition was evaluated by energy dispersive X-ray spectrometry (EDS) and inductively coupled plasma–atomic emission spectroscopy (ICP-AES). Raman spectra revealed the surface properties of graphene and its interaction with metallic nanoparticles. Cyclic voltammetric (CV) and chronoamperometric experiments further exhibited their catalytic activity and stability for the electro-oxidation of ethanol in alkaline media, which could be applied as promising electrocatalysts for direct alcohol fuel cells (DAFCs).

Synthesis of poly(diallyldimethylammonium chloride)-coated Fe 3O 4 nanoparticles for colorimetric sensing of glucose and selective extraction of thiol

We report a one-pot synthesis of poly(diallyldimethylammonium chloride)-coated Fe 3O 4 (PDDA-Fe 3O 4) nanoparticles (NPs) by the coprecipitation method. The formed PDDA-Fe 3O 4 NPs were characterized by powder X-ray diffraction and superconducting quantum interference device. The crystalline structure and superparamagnetic property of PDDA-Fe 3O 4 NPs were found to be similar to those of Fe 3O 4 NPs, indicating that the presence of PDDA does not affect the formation of Fe 3O 4 NPs. Moreover, glucose oxidase (GOx) and citrate-capped gold (Au) NPs, having negative charges, can be easily self-assembled at the surface of cationic PDDA-Fe 3O 4 NPs. Without the requirement of a peroxidise enzyme, the composites of PDDA-Fe 3O 4 NPs and GOx effectively catalyzes the H 2O 2-mediated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate acid) (ABTS) in the presence of glucose. This colorimetric method enables the analysis of glucose with a minimum detectable concentration that corresponds to 30 μM. We validate the applicability of this method by determining the concentration of glucose in serum samples. In another application, the composites of PDDA-Fe 3O 4 and Au NPs were shown to be capable of selectively enriching cysteine-containing peptides through the formation of Au–S bonds. The extracted peptides can be easily detected by matrix-assisted laser desorption/ionization-time of flight mass spectrometer. Both applications open up a new way for the synthesis of bifunctional NPs.

Stabilization of platinum nanoparticle electrocatalysts for oxygen reduction using poly(diallyldimethylammonium chloride)

A long-chain polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA), has been employed to stabilize platinum nanoparticles for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. Pt nanoparticles are synthesized by reducing H2PtCl6 with NaBH4 in the presence of PDDA and then deposited on a carbon support (PDDA-Pt/C). Transmission electron microscope images show that Pt nanoparticles of PDDA-Pt/C are uniformly dispersed on the carbon support with a mean size of about 2.2 nm (2.1 nm for commercial Etek-Pt/C). PDDA-Pt/C exhibits a higher activity towards oxygen reduction reaction (ORR) than Etek-Pt/C. The durability of PDDA-Pt/C is improved by a factor of 2 as compared with Etek-Pt/C. X-ray photoelectron spectroscopy characterization of PDDA-Pt/C reveals the interaction between Pt nanoparticles and PDDA, which increases Pt oxidation potential and prevents Pt nanoparticles from migrating/agglomerating on or detaching from carbon support. This provides a promising strategy to improve both the durability and activity of electrocatalysts for fuel cells.

Surface modification for the perfluorosulfonate proton-conducting electrolyte membrane

The positively charged ions of palladium particles are obtained by reducing the solution containing metallic ions in the presence of PDDA (poly-diallyldimethylammonium chloride) medium. The nascent palladium particles are dispersed evenly on the surface of the perfluorosulfonate proton-conducting electrolyte membrane and bonded firmly to the activation center of the membrane. The mechanical strength of membrane is greatly enhanced by surface modification. And the methanol diffusion coefficients of the modified membrane are decreased prominently by the deposition of palladium particles on the surface, which serves as a natural barrier for methanol crossing.

Controlled synthesis of PDDA stabilized Au–Pd bimetallic nanostructures and their activity in hydrogenation of acetylene

Pd hydrosol was synthesized by reducing PdCl2 solution with dissolved H2 in the presence of PDDA [poly(diallyldimethylammonium chloride)] as ionic stabilizer. O2 treatment resulted in the reappearance of ligand to metal charge transfer bands of PdCl 4 2− . Repeated oxidation and hydrogen treatments caused aggregation/agglomeration of the Pd particles yielding big spherical aggregates of 30–50 nm but still keeping the size of the 5–6 nm primary particles. Aggregation was attributed to the reduction of PdCl 4 2− anion having high local densities around Pd particles surrounded by PDDA polycation. Au–Pd bimetallic hydrosols were synthesized by reduction with 2-propanol and by pulse radiolysis technique in the presence of PDDA. Both reduction modes synthesize Au core–Pd shell structures. The mode of reduction was observed to affect the particle size and the thickness of the Au core and Pd shell. At the Au rich samples the differences in the optical spectra were attributed to different dispersions of the Au–Pd particles. Au–Pd bimetallic hydrosols were adsorbed on Aerosil 200 and the supported samples were tested in gas phase hydrogenation of acetylene.

Morphosynthesis of CaCO 3 at different reaction temperatures and the effects of PDDA, CTAB, and EDTA on the particle morphology and polymorph stability

Facile precipitation of CaCO 3 was performed using aqueous solutions of CaCl 2 with Na 2CO 3 over a wide range of mixing and aging temperatures. The precipitation process was then repeated in the presence of PDDA, CTAB, and EDTA at the mixing temperatures of 30 °C, 50 °C, 70 °C, and 90 °C. The presence of these additives was seen to greatly suppress the formation of aragonite. Among these additives, EDTA was the one that showed the most prominent effects on particle morphology of CaCO 3. The sequence of pH adjustment appeared to be a critical factor for the additive functionality.

Determination of serum albumin in the presence of poly(diallyldimethylammonium chloride) by resonance light scattering technique

By means of the resonance light scattering (RLS) technique, a new method was developed to determine the bovine serum albumin (BSA) and human serum albumin (HSA) by the interaction of serum albumin with poly(diallyldimethylammonium chloride) (PDDA). At Tris–NaOH buffer solution, the RLS intensity of serum albumin at the wavelength 320, 550 and 590 nm was obviously enhanced in the presence of PDDA. The influences of some experimental factors, including incubation time, addition sequence of reagents, pH value, concentration of PDDA and foreign substances, on the enhancement of the RLS intensity were examined. The optimum conditions of the experiment were selected. Under the selected experimental condition, the enhanced RLS intensities were directly proportional to the concentrations in the range of (0.0250–2.75) × 10 −6 mol/L for BSA and (0.0235–1.17) × 10 −6 mol/L for HSA. The detection limits (S/N = 3) were 8.40 × 10 −9 mol/L for BSA and 7.39 × 10 −9 mol/L for HSA. The synthetic samples were analysed and the results obtained were satisfactory.

A Direct Electrochemical Route to Construct a Polymer/Manganese Oxide Layered Structure

A layered nanocomposite with poly(diallyldimethylammonium), PDDA, intercalated between manganese oxide layers can be formed on a platinum electrode in a thin film form through a direct electrochemical route. The process involves a potentiostatic oxidation of aqueous Mn(2+) precursors in the presence of PDDA by applying a constant potential (+1.0 V vs Ag/AgCl).

Studies of the interaction between poly(diallyldimethyl ammonium chloride) and DNA by spectroscopic methods

Abstract The interaction of poly(diallyldimethyl ammonium chloride) (PDDA) with DNA has been studied by spectroscopic analysis of different kinds of nucleic acid probes, microscopic IR- and CD-spectroscopy. The two spectroscopic changes of ethidium bromide (EB) on its binding to DNA, namely red-shift of its maximum absorption wavelength ( ν max ) and enhancement of fluorescence intensity are utilized to study the interaction of PDDA with DNA. Reversion of ν max and decrease in fluorescence of DNA–EB system on addition of PDDA show the dissociation of DNA/EB complex and the formation of the DNA/PDDA complex. At the same time, the binding constant of EB and the number of binding sites per nucleotide decrease with increase in the concentrations of PDDA, indicating non-competitive inhibition of EB binding to DNA in the presence of PDDA. From the Scatchard analysis, we obtain the association constant of PDDA to DNA is 4.7×10 4 M −1 . Contrary to EB, the binding of PDDA with DNA can greatly enhance the fluorescence intensity of groove-binding probes, Hoechst 33258 and DAPI, which can also be used to investigate the formation of the DNA/PDDA complex. The fluorescence analysis shows that the interaction of DNA with PDDA may have effect on the conformation of secondary structure of DNA. IR-spectra show that PDDA interacts with DNA through both the phosphate groups and the bases of DNA and the formation of DNA/PDDA complex causes the change of the conformation of the DNA secondary structure, which is further proved by CD-spectra.