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The present study article aims to clarify the effect of colloidal polystyrene (PS) latexes with a broad particle size distribution on film formation kinetics of multi-walled carbon nanotube (MWCNT)-added polymer nanocomposites by considering theoretical film formation models. Experimentally, light transmitted from nanocomposite films, each having different weight fractions of MWCNT, was recorded at different annealing temperatures via UV-Visible spectrophotometry. Optical data set was then theoretically elaborated by taking into account void closure and Prager-Tirrell models. Activation energies of viscous flow ([DELTA]H) and backbone motion for reptating PS chains ([DELTA][E.sub.B]), minimum film formation ([T.sub.0]) and healing (T h) temperatures were then computed from optical data. Experimental results revealed that [DELTA]H required for void closure phenomenon remained unaffected by both nanofiller and size distribution of latexes. On the other hand, it was found that [DELTA][E.sub.B] for backbone motion promoted upon the addition of nanofillers into latex particles. Our experimental findings suggested that film formation from MWCNT-added latex films with a broad particle size distribution mainly originates from void closure mechanism since [DELTA]H for viscous flow suppresses [DELTA][E.sub.B] acquired for backbone motion of repeating PS chains to a great extent. Highlights * A broad size distribution effect of PS on film formation was investigated. * Voids closure and Prager-Tirrell models were applied to spectroscopic data. * Activation energy of viscous flow is unaffected by size distribution of PS. * Latex film formation with varying size distribution stems from void closure. KEYWORDS film formation, interdiffusion, light transmission, particle size distribution, void closure, 1 | INTRODUCTION Understanding film formation mechanisms of colloidal latex particles plays a pivotal role in fabrication of new-generation nanomaterials with improved features that can be potentially integrated into film [...]

The solubility of boehmite nanoparticles was determined experimentally for 20 different solvents using Hansen solubility parameter method (HSP). The algorithm given by Gharagheizi was optimized using MATLAB. The solubility was found as, [delta] = 33.08 [MPa.sup.1/2] with, [[delta].sub.D] = 16.50 [MPa.sup.1/2], [[delta].sub.D] = 15.54 [MPa.sup.1/2], and [[delta].sub.H] = 24.09 [MPa.sup.1/2]. Flory-Huggin's theory was used to model the quarternary system of a blend polymeric membrane. The thermodynamic equations were solved and optimized using MATLAB and ternary phase diagrams were obtained for different filler compositions. Thermodynamic enhancement and kinetic hindrance parameters were obtained to predict the membrane morphologies. The porosity of the membrane was increased with the addition of nanoparticles. Contact angle of the membrane was decreased from 84.45[degrees] to 50.2[degrees]. KEYWORDS Boehmite, Flory-Huggin's theory, Hansen solubility parameter, phase inversion, Polyvinylidene fluoride, ternary phase diagram, 1 | INTRODUCTION Membrane-based filtration is rapidly expanding due to its ease of scale-up, and it can be coupled with other processes such as adsorption to treat groundwater and industrial [...]

In the saline soil environment of western China, salts can corrode ordinary cement concrete seriously, and the durability of concrete structure deteriorates gradually until it fails. This impedes the application of ordinary Portland cement concrete in this area. Aiming at the problem of the short service life of concrete in the harsh environment of western China, this study examines the performance of nano-CaC[O.sub.3] modified concrete in a sulfate environment. The durability of the concrete was evaluated by the apparent phenomena on the relative quality evaluation parameter, the relative dynamic elastic modulus evaluation parameter, and the comprehensive damage evaluation parameter. The microstructure of corroded products was investigated using scanning electron microscopy to reveal the deterioration mechanism. The results show that the addition of 1% nano-CaC[O.sub.3] can enhance the resistance of concrete to sulfate corrosion, and the service life of concrete structures will increase significantly. Key words: cement concrete, sulfate erosion, nano-modified concrete, resistance, durability. Dans le sol salin de l'ouest de la Chine, les sels peuvent serieusement corroder le beton de ciment ordinaire, et la durabilite d'une structure en beton se deteriore progressivement jusqu'a la defaillance. Cela entrave l'application du beton de ciment Portland ordinaire dans cette zone. Dans le but de trouver une solution au probleme de la courte duree de vie du beton dans l'environnement hostile de l'ouest de la Chine, cette etude examine la performance du beton modifie par nanoCaC[O.sub.3] dans un environnement sulfate. La durabilite du beton a ete evaluee par les phenomenes apparents du parametre d'evaluation de la qualite relative, du parametre d'evaluation du module elastique relatif et du parametre d'evaluation des dommages. La microstructure des produits corrodes a ete etudiee par microscopie electronique a balayage pour reveler le mecanisme de deterioration. Le resultat montre que l'ajout de 1 % de nano-CaC[O.sub.3] peut ameliorer la resistance du beton a la corrosion au sulfate, et la duree de vie des structures en beton augmentera considerablement. [Traduit par la Redaction] Mots-cles : beton de ciment, erosion par les sulfates, beton modifie par nanoparticules, resistance, durabilite., Introduction An important engineering property of concrete is its durability which significantly influences the service life of concrete structures (Qiao et al. 2012; Shah et al. 2016; Zhou et al. [...]

Defects, both native and extrinsic, critically determine functional properties of metal oxides. Gallium oxide has recently gained significant attention for its promise in microelectronics, owing to the unique combination of conductivity and high breakdown voltage, and solid-state lighting, owing to the strong photoluminescence in the visible spectral region. These properties are associated with the presence of native defects that can form both donor and acceptor states in [Ga.sub.2][O.sub.3]. Recently, [Ga.sub.2][O.sub.3] nanocrystal synthesis in solution and optical glasses has been developed, allowing for a range of new applications in photonics, lighting, and photocatalysis. This review focuses on the structure and properties of [Ga.sub.2][O.sub.3] nanocrystals with a particular emphasis on the electronic structure and interaction of defects in reduced dimensions and their role in the observed photoluminescence properties. In addition to native defects, the effect of selected external impurities, including lanthanide and aliovalent dopants, and alloying on the emission properties of [Ga.sub.2][O.sub.3] nanocrystals are also discussed. Key words: gallium oxide, nanocrystals, defects and dopants, photoluminescence, lanthanides. Les defauts, qu'ils soient intrinseques ou extrinseques, determinent dans une large mesure les proprietes fonctionnelles des oxydes metalliques. L'oxyde de gallium a recemment suscite l'attention par ses applications prometteuses en microelectronique, grace a une combinaison unique de conductivite et de tension de claquage elevee, et dans l'eclairage a semi-conducteurs, grace a sa forte photoluminescence dans la region spectrale visible. Ces proprietes sont associees a la presence de defauts intrinseques qui peuvent former des etats donneurs et accepteurs dans le [Ga.sub.2][O.sub.3]. Recemment, une synthese de nanocristaux de [Ga.sub.2][O.sub.3] en solution et en verres optiques a ete mise au point, donnant lieu a toute une gamme de nouvelles applications dans les domaines de la photonique, de l'eclairage et de la photocatalyse. Cette revue de la litterature porte sur la structure et les proprietes des nanocristaux de [Ga.sub.2][O.sub.3], en particulier sur la structure electronique de ces materiaux et sur l'interaction des defauts a echelle reduite ainsi que leurs effets sur les proprietes de photoluminescence observees. En plus des defauts intrinseques, nous abordons aussi l'effet de certaines impuretes d'origine externe, notamment des lanthanides et des dopants aliovalents, ainsi que celui des alliages sur les proprietes d'emission des nanocristaux de [Ga.sub.2][O.sub.3]. [Traduit par la Redaction] Mots-cles : oxyde de gallium, nanocristaux, defauts et dopants, photoluminescence, lanthanides., Introduction Transparent metal oxides exhibit a range of unique functional properties and are indispensable for many technological applications. (1-3] This richness of properties arises from their complex crystal and electronic [...]

Mechanical interlocking of molecules (catenation) is a nontrivial challenge in modern synthetic chemistry and materials science.sup.1,2. One strategy to achieve catenation is the design of pre-annular molecules that are capable of both efficient cyclization and of pre-organizing another precursor to engage in subsequent interlocking.sup.3-9. This task is particularly difficult when the annular target is composed of a large ensemble of molecules, that is, when it is a supramolecular assembly. However, the construction of such unprecedented assemblies would enable the visualization of nontrivial nanotopologies through microscopy techniques, which would not only satisfy academic curiosity but also pave the way to the development of materials with nanotopology-derived properties. Here we report the synthesis of such a nanotopology using fibrous supramolecular assemblies with intrinsic curvature. Using a solvent-mixing strategy, we kinetically organized a molecule that can elongate into toroids with a radius of about 13 nanometres. Atomic force microscopy on the resulting nanoscale toroids revealed a high percentage of catenation, which is sufficient to yield 'nanolympiadane'.sup.10, a nanoscale catenane composed of five interlocked toroids. Spectroscopic and theoretical studies suggested that this unusually high degree of catenation stems from the secondary nucleation of the precursor molecules around the toroids. By modifying the self-assembly protocol to promote ring closure and secondary nucleation, a maximum catenation number of 22 was confirmed by atomic force microscopy. Nanoscale toroids with a high percentage of poly-catenation and radii of up to about 13 nm are kinetically organized using fibrous supramolecular assemblies with intrinsic curvature and a solvent-mixing strategy., Author(s): Sougata Datta [sup.1] , Yasuki Kato [sup.2] , Seiya Higashiharaguchi [sup.2] , Keisuke Aratsu [sup.2] , Atsushi Isobe [sup.2] , Takuho Saito [sup.2] , Deepak D. Prabhu [sup.1] , [...]

ABSTRACT. Fourier transform infrared spectroscopy (FTIR) was used to investigate the interactions between [C.sub.60] and [C.sub.70] molecules (nanoparticles in solutions) and dimethylacetamide, dimethylformamide, and acetamide using toluene as a solvent. [...]

The degradation behavior of poly(lactic-co-glycoiic acid) (PLGA) is important for its application as a biomaterial. In this work, the influence of nano-hydroxyapatite (nano-HA) on the degradation behavior of PLGA matrix was studied. PLGA-based in situ forming system containing nano-HA was prepared using the immersion precipitation method and the polymer hydrolysis was investigated in a phosphate buffer (pH 7.4) at 37[degrees]C. The pH values in the testing medium were evaluated to quantify the degradation process. Gel permeation chromatography and scanning electron microscopy techniques were employed to monitor changing of the weight-average molecular weight ([M.sub.W]) and the body structures of PLGA matrices, respectively. To model the [M.sub.W] changes, a first-order degradation model was employed. The formed PLGA matrices had different porosities that effected water penetration into the matrices following the hydrolysis process. The obtained degradation rate constant using a mathematical model for PLGA matrices with different nano-HA content was about from 2.5 to 4.5 times lower than neat PLGA matrix., INTRODUCTION Recently, biodegradable polymers have drawn a great attention for their wide application in new fields of medicine, including scaffolds for tissue engineering, medical devices and pharmaceuticals [1-4]. One of [...]

The kinetics of catalyzed by dibutyltin dilaurate reaction of polyurethane foam synthesis infused with 1 wt% of fillers was studied in dependence of Type 1D (nanosized [multiwall carbon nanotubes] or macrosized [carbon fibers]) or 2D (thermoexpanded graphite) carbonaceous fillers by IR spectroscopy and optical microscopy. It is shown that the foaming reaction has two stages: the first stage being a first-order reaction, and the second stage a second-order reaction. The mean diameter of the bubbles and the bubble size distribution has been determined during the process of foaming. It is shown that the presence of 2D fillers leads to a decrease in the mean diameter of the bubbles., INTRODUCTION Cellular materials such as foams have excellent application prospects in civil, aerospace and mechanical engineering. As a type of lightweight material, polyurethane (PU) foams have good heat insulation and [...]

To circumvent the complicated natural peroxidases, palladium nanoparticles embedded in melamine cyanurate (MCA-Pd NPs) were synthesized. MCA-Pd NPs catalyzed the oxidation of [ABTS.sup.2-] by [H.sub.2][O.sub.2], and the solution turned green, which could be quantified via a typical absorption peak at 420 nm. MCA-Pd NPs had high peroxidase-like activity in a wider pH range than that of natural peroxidases. MCA-Pd NPs were used to develop a colorimetric sensor for [H.sub.2][O.sub.2] over the pH range of 7.0 to 11.0, which had same linear range, and their linear regression equations had similar slopes. Moreover, MCA-Pd NPs were applied to establish the biosensor for glucose by using glucose oxidase (GOx); it had a linear range of 5.0-120 [micro]mol/L, with a linear regression equation of A = 0.04926 + 0.00536C (C: [micro]mol/L, R = 0.9960) and a detection limit of 0.3 [micro]mol/L (3[sigma]/slope). When we applied it to detect glucose level in human blood, satisfactory results were obtained. Key words: peroxidase-like activity, MCA-Pd NPs, [ABTS.sup.2-], [H.sub.2][O.sub.2], glucose. Afin d'éviter l'emploi compliqué des peroxydases naturelles, nous avons synthétisé des nanoparticules de palladium incorporées dans du cyanurate de mélamine (NP de Pd-CM). Nous avons observé que ces nanoparticules étaient capables de catalyser l'oxydation de l'[ABTS.sup.2-] par le [H.sub.2][O.sub.2], et que cette réaction était visible par le changement de couleur de la solution qui passe au vert et quantifiable au moyen d'un pic d'absorption typique à 420 nm. Les NP de Pd-CM ont révélé une activité enzymomimétique élévée analogue à celle des peroxydases dans un intervalle de pH plus étendu que celui dans lequel sont actives les peroxydases naturelles. Nous les avons utilisées pour mettre au point un capteur colorimétrique pour le [H.sub.2][O.sub.2] dans l'intervalle de pH allant de 7,0 à 11,0. Les NP de Pd-CM et les peroxydases naturelles présentaient des domaines linéaires identiques et les pentes de leurs équations de régression linéaire étaient comparables. En outre, nous avons utilisé les NP de Pd-CM comme biocapteur de glucose en présence de glucose oxydase (GOx). Leur domaine linéaire était de 5,0 à 120 [micro]mol/L, leur équation de régression linéaire se décrivait comme A = 0,04926 + 0,00536 C (C: [micro]mol/L, R = 0,9960) et leur limite de détection était de 0,3 [micro]mol/L (3 a/pente). Lorsque nous avons appliqué les NP de Pd-CM à la détection du taux de glucose dans le sang humain, nous avons obtenu des résultats satisfaisants. [Traduit par la Rédaction] Mots-clés : enzymomimétisme des peroxydases, NP de Pd-CM, [ABTS.sup.2-], [H.sub.2][O.sub.2], glucose., Introduction Natural peroxidases, including horseradish peroxidase, are significant components in different fields of medicine, biotechnology, and environmental chemistry owing to their good catalytic activity and high substrate specificity under mild [...]

The current work presents a new approach to achieve high quality dispersion of surfactant-free nanoclay tactoid particles in sub-micron thin films despite the absence of organic modifier. Natural Montmorillonite particles, [Na.sup.+] Cloisite, were dispersed in thin films of polycaprolactone (PCL) through a flow coating technique assisted by ultrasonication. Wide-angle X-ray scattering (WAXS), grazing-incidence wide-angle X-ray scattering (GI-WAXS), and transmission electron microscopy (TEM) were used to confirm the level of natural clay dispersion down to the level of tactoids (sub-micron scale stacks of clay sheets). These characterization techniques were carried out in conjunction with an analysis of nanomechanical properties via strain-induced buckling instability for modulus measurements (SIEBIMM), a high-throughput technique to characterize thin film mechanical properties. The buckling patterns indicate that the natural clay tactoids separate buckling-enhancing (high-modulus) crystalline regions and interconnect buckling-suppressing amorphous (low-modulus) regions. Due to the tactoid length scale, the glass transition behavior of the composites as characterized by broadband dielectric relaxation spectroscopy was unmodified by the clay. Likewise, the glass transition temperature, [T.sub.g], and fragility (slope of relaxation time behavior approaching [T.sub.g]), remain unaffected, indicating that these dispersed tactoids do not induce pronounced confinement effects on dynamics. POLYM. ENG. SCI., 58:1285-1295, 2018., INTRODUCTION Polymer/clay nanocomposites (PCN) have been widely investigated in recent decades towards preparation methods and determining the associated improvements in a broad range of applications [1]. Common strategies to obtain [...]

Thiolate-protected Ag nanoparticles (NPs) exhibit interesting physical and chemical properties which may lead to various sensing, diagnostic, and therapeutic applications. Further, understanding structure-property relationships of Ag NPs is of great interest to optimize their application. Herein, we used TEM, UV-vis, and a series of synchrotron X-ray spectroscopy techniques to probe the local structure and chemical bonding properties of thiolate-stabilized Ag NPs. Compared with other Ag nanostructures prepared under slightly modified conditions, the Ag NPs were found to have pronounced structural changes, which led to immensely different optical properties. Notably, the NPs were also found to have similar surface structure to recently elucidated Ag nanoclusters prepared with different thiolates. These findings suggest that the NP structure and optical properties can be sensitively tailored by controlling the synthetic conditions. The multi-element, multi-core excitation approach (i.e., Ag K-, Ag [L.sub.3]-, and S K-edges) employed in the X-ray absorption spectroscopy measurements was also demonstrated as an effective tool to uncover the NP structure from both the metal core and the ligand shell perspectives. Key words: silver nanoparticles, X-ray absorption spectroscopy, local structure, bonding. Des nanoparticules (NP) d'Ag protegees par des thiolates presentent proprietes physiques et chimiques interessantes en vue d'applications de detection et d'applications diagnostiques et therapeutiques. Il est egalement d'un grand interet de comprendre les relations structure-proprietes des NP d'Ag si l'on veut pouvoir optimiser leurs applications. Dans le present article, nous avons employe la MET, la spectroscopic UV-vis et une serie de techniques de spectroscopic des rayons X synchrotron pour etudier la structure locale et les proprietes chimiques de liaison des NP d'Ag stabilisees par des thiolates. En comparant ces NP d'Ag avec d'autres nanostructures d'Ag preparees en conditions legerement modifiees, nous avons decouvert que les premieres presentaient des changements structuraux marques, lesquels ont donne lieu a des proprietes optiques extremement differentes. Notons par ailleurs que ces NP ont revele une structure de surface semblable aux nanoagregats d'Ag prepares avec differents thiolates qui ont ete recemment decouverts. Ces observations laissent supposer que la structure des NP et leurs proprietes optiques peuvent etre finement reglees par modification des conditions de synthese. Nous avons egalement demontre que l'approche d'excitation de plusieurs elements et de plusieurs centres (c.-a-d. le seuil K de l'Ag, le seuil [L.sub.3]- de l'Ag et le seuil K du S) employee dans les mesures spectroscopiques d'absorption des rayons X etait un outil efficace pour reveler la structure de NP tant du point de vue du centre metallique que de celui de la couche de ligands. [Traduit par la Redaction] Mots-cles : nanoparticules d'argent, spectroscopic d'absorption des rayons X, structure locale, liaison., Introduction Metal nanoparticles (NPs) are of great interest due to their unique properties and potential uses in various applications such as biosensing, nanoelectronics, and catalysis. (1-7) Notably, NPs with thiol [...]

3-(4'-Amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid, was synthesized and used to construct a modified-graphene oxide nano sheets paste electrode. The electro-oxidation of isoproterenol at the surface of the modified electrode was studied using cyclic voltammetry, chronoamperometry, and square wave voltammetry. Under the optimized conditions, the square wave voltammetric peak currents of isoproterenol increased linearly with isoproterenol concentrations in the range of 2.5 x [10.sup.-8] to 2.0 x [10.sup.-5] M and detection limit of 12 nM was obtained for isoproterenol. Finally this modified electrode was used for determination of isoproterenol in some real samples. Keywords: isoproterenol, graphene oxide nano sheets, chemically modified electrodes, carbon paste electrode, Isoprenaline (INN) or isoproterenol (4-[1hydroxy-2-(isopropylamino)ethyl] benzene-1,2-diol) is a catecholamine medication. It is a non-selective beta-adrenergic agonist structurally similar to adrenaline (epinephrine). The isopropyl amino group in isoproterenol makes it selective [...]

Viscoelastic phase separation (VPS) is a fundamental physical phenomenon that creates percolated network structure in dynamically asymmetric mixtures. The object of this study was to investigate the effect of rod shape nanoparticies with different surface chemistries on VPS in the polystyrene/poly(vinyl methyl ether), PS/PVME, blend. For this purpose, hydrophilic (CNWs) and hydrophobic (M-CNWs) cellulose nanowhiskers (CNWs) were prepared to be used as nanorods. Rheological measurments were employed to investigate the effect of nanowhiskers on phase separation temperature, kinetics of phase separation, and dynamic asymmetry. The evolution of morphology during the phase separation at a fixed quench depth was assessed using polarized optical microscopy. The nanowhiskers were effective in decreasing the correlation length, which slowed down the phase separation. CNWs self-assembled into the PVME-rich phase during the phase separation, which led to a decrease in the dynamic asymmetry and beyond a critical volume fraction of CNWs, the VPS mechanism changed to spinodal decomposition (SD). However, in the presence of M-CNW, the localization of M-CNWs into the PS-rich phase enhanced the dynamic asymmetry and at 2 vol% M-CNWs, the induced PS-rich network by VPS was arrested. The linear and non-linear viscoelastic behavior of the samples were Studied as well. POLYM. ENG. SCI., 58:920-942, 2018. [C] 2017 Society of Plastics Engineers, INTRODUCTION Phase separation in polymer blends is of scientific and practical interest as different mechanisms of phase separation yield different morphologies which are related to various functions associated with electrical, [...]

Poly(methy methacrylate) (PMMA)-Si[O.sub.2] nanoparticles were prepared via differential microemulsion polymerization. The effects of silica loading, surfactant concentration, and initiator concentration on monomer conversion, particle size, particle size distribution, grafting efficiency, [...]

Two anions (dodecylbenzenesulfonate anion and stearate anion) are employed to synthesize intercalated layered double hydroxides (LDH) by co-precipitation method. Then the intercalated LDHs are incorporated in the casting solutions of [...]

Nanocomposites of organic nano-montmorillonite (nano-OMMT)-filled immiscible polyamide 6 (PA6)/polystyrene (PS) blends were prepared by three different processing methods. Masterbatch M1 of OMMT/PA6 and masterbatch M2 of OMMT/PS were prepared as [...]

A new chiral sorbent based on mercaptosilica modified by gold nanoparticles, then treated by [beta]-mercaptopropionic acid and macrocyclic antibiotic vancomycin, was obtained. The enantioseparation of isomeric [beta]-blockers (nadolol, atenolol, metoprolol, alprenolol, oxprenolol, and pindolol) by HPLC was studied on the synthesized sorbent. The effect of the composition of the mobile phase (nature and concentration of the organic solvent, concentration and pH of the buffer solution) on retention times of [beta]-blocker enantiomers, selectivity of separation, and resolution of chromatographic peaks were studied. The best separation was achieved for pindolol and metoprolol. The procedure was used to determine the pindolol enantiomers in the preparation 'Visken,' and metoprolol in the 'Vazocardin' preparation. Keywords: [beta]-blockers, enantiomers, high-performance liquid chromatography, macrocyclic antibiotic, vancomycin, gold nanoparticles DOI: 10.1134/S1061934818020028, Current trends in the development of the pharmaceutical industry indicate a growing need in obtaining optically pure dosage forms. Many synthetic drugs occur as of two or more spatial isomers. [...]

A simple and effective strategy for designing a fluorescent probe for bromate was described in this work. Organosilane modified carbon dots were prepared by pyrolysis of citric acid in N-([beta]-aminoethyl)-[gamma]-aminopropyl methyldimethoxysilane solvent at 230 [degrees]C and further doped onto silica nanoparticles by a silylation reaction. The fluorescence of carbon dot doped silica nanoparticles was quenched by bromate in acidic medium. By utilizing this property, the nanoparticle could be used as a sensor to detect bromate. The parameters affecting the performance of the sensor probe such as types of acid medium, acid concentration, reaction temperature, and time were investigated and optimized. The detection limit of the sensor was found to be 1.1 ng [mL.sup.-1], with a linear range from 8 to 400 ng [mL.sup.-1] and relative standard deviation of 2.0% (150 ng [mL.sup.-1], n = 9). The method was successfully applied to the determination of bromate in drinking water samples, and the recoveries were in the range of 96.3%-103.7%. Key words: carbon dots, bromate, silica nanoparticles, drinking water sample. Dans le cadre des presents travaux, nous avons decrit une strategie simple et efficace pour la conception d'une sonde fluorescente capable de detecter le bromate. Nous avons prepare par pyrolyse de l'acide citrique dans le N-([beta]-aminoethyl)-[gamma]-aminopropylmethyldimethoxysilane comme solvant a 230 [degrees]C des points quantiques de carbone modifies par des organosilanes, que nous avons utilises pour doper des nanoparticules de silice par reaction de silylation. L'extinction de la fluorescence des nanoparticules de silice dopees par les points quantiques de carbone s'est produite en presence du bromate en milieu acide. En exploitant cette propriete, il est possible d'utiliser cette nanoparticule comme capteur pour detecter le bromate. Nous avons etudie et optimise les parametres qui influent sur la performance de la sonde de detection, tels que le milieu acide, la concentration de l'acide ainsi que la temperature et le temps de reaction. Le capteur a revele une limite de detection de 1,1 ng [mL.sup.-1] dans un intervalle lineaire de8a 400 ng [mL.sup.-1], avec un ecart-type de 2,0 % (150 ng [mL.sup.-1], n = 9). En appliquant cette methode, nous avons reussi a doser le bromate dans des echantillons d'eau potable avec des taux de recuperation variant de 96,3 a 103,7 %. [Traduit par la Redaction] Mots-cles : points quantiques de carbone, bromate, nanoparticules de silice, echantillon d'eau potable., Introduction Ozone is a strong oxidizing agent that can oxidize organic and inorganic substances in water (1,2) and is commonly used as a disinfectant. Ozone reacts with bromide to produce [...]

This study examines the selective dispersion of nano-Si02 in polystyrene (PS) and polyamide 6 (PA6) blends. With the coupling assistance of 3-methacryloylpropyl trimethoxysilane (MPS), nano-Si[O.sub.2] surfaces are grafted with PS chains of different molecular weights (Si[O.sub.2]-MPS-PS) or reactive random copolymer of styrene (St) and 3-isopropenyl-[alpha],[alpha]'-dimethylbenzene isocyanate (TMI) to produce Si[O.sub.2]-MPSP-(St-co-TMI). The isocyanate groups of the reactive copolymer can react with the terminal group of the PA6 to form a graft copolymer, which helps in controlling the location of nano-Si[O.sub.2] between the PS and PA6 phases. Field-emission scanning electron microscopy imaging combined with the rheological method was used to investigate the location and dispersion of nano-Si[O.sub.2], as well as the morphology of the PS/PA6 blends, at low nano-Si[O.sub.2] loading. Compared with pristine Si[O.sub.2], the modified Si[O.sub.2] with different chain lengths adjusted the PA6 phase with refined size and narrow size distribution because of the strong interaction with both phases. The Si[O.sub.2]-MPS-PS with appropriate length is the most effective. The use of nano-Si[O.sub.2] along with the reactive compatibilizer provides synergistic effects for improving the compatibilization of PS/PA6 blends., INTRODUCTION Polymer blends with two or more components have gained commercial attention, owing to their superior compositive performance with respect to virgin polymeric materials. However, unfavorable interfacial conditions sometimes render [...]

Abstract: Large-scale Si[O.sub.2] hollow nanoparticles were synthesized by a sol-gel method. The composition, morphology, and chemical bonding information of Si[O.sub.2] hollow nanoparticles were studied by X-ray absorption near edge structure [...]

Abstract: Poly and mono sulfonamide ligands were successfully used for the stabilization of palladium nanoparticles. The prepared nano catalysts that appeared to be heterogeneous and novel were characterized with various [...]