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Four siiicon-containing acrylacetylene resins were synthesized by polycondensation of Grignard reagent of m-diethynylbenzene with methylethyldichlorosilane, dimethyldichlorosilane, methylphenyldichlorosilane, and diphenyldichlorosilane, respectively. The structures of the resins were verified by nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The solubility, crystallinity, and rheological character of the resins were characterized. The curing behavior was traced by differential scanning calorimetry (DSC) and FTIR analyses. The effect of the side groups on the silicon atom on the properties was investigated. The results show that the resins with asymmetrical side groups display better processability (wide processing window) as compared with those with symmetrical side groups. The resin with side phenyl groups shows higher flexural strength but lower thermal stability as compared with those without side phenyl groups. Meanwhile, the side phenyl groups also enhance the temperature at which secondary relaxation occurs. KEYWORDS effect of side groups, high-performance resins, siiicon-containing arylacetylene resin, structure-properties relationships, 1 | INTRODUCTION Siiicon-containing arylacetylene resins are a kind of highperformance polymers with excellent heat resistance and low dielectric constant, which has already shown highly potential applications as ceramic precursors, [...]

The solvothermal synthesis and characterization of a three-dimensional, interpenetrated uranyl dicyanoaurate coordination polymer, [K.sub.2][(U[O.sub.2]).sub.2][(U[O.sub.2]).sub.2][(Au[(CN).sub.2]).sub.2][(O).sub.2][(N[O.sub.3]).sub.4], from U[O.sub.2][(N[O.sub.3]).sub.2]*6[H.sub.2]O and KAu[(CN).sub.2] is described. The structure contains a three-dimensional (3D) lattice of planar tetranuclear uranyl-oxo-nitrate clusters connected by dicyanoaurate linkers, with the rotation of the clusters providing the increased dimensionality. The material undergoes a reversible single-crystal to single-crystal transformation on exposure to water vapour, which is taken up in the channels of the 3D system. A second uranyl dicyanoaurate coordination polymer of the form [U[O.sub.2][(DMSO).sub.3]([H.sub.2]O)(Au[(CN).sub.2])][Au[(CN).sub.2]] was structurally characterized as a linear chain of dicyanoaurate units connected by gold-gold bonds with pendant uranyl-water-DMSO adducts that are hydrogen bonded into a two-dimensional sheet. Both materials exhibit emission arising from both the uranyl moiety and the gold(I) centre and represent the first multidimensional uranyl-dicyanoaurate coordination polymers. Key words: coordination polymer, aurophilic interactions, uranyl, cyanide, emission. Nous decrivons la synthese solvothermale d'un polymere de coordination tridimensionnel interpenetre forme de dicyanoaurate d'uranyle, le [K.sub.2][(U[O.sub.2]).sub.2][(U[O.sub.2]).sub.2][(Au[(CN).sub.2]).sub.2][(O).sub.2][(N[O.sub.3]).sub.4], a partir de U[O.sub.2][(N[O.sub.3]).sub.2]*6[H.sub.2]O et de KAu[(CN).sub.2], et nous presentons la caracterisation de ce polymere. La structure se compose d'un reseau tridimensionnel d'agregats tetranucleaires planaires formes d'unites d'uranyl-oxo-nitrate reliees par des espaceurs dicyanoaurate, dans lequel la rotation des agregats constitue une dimension supplementaire. Cette substance subit une transformation monocristal a monocristal reversible sous l'effet de la vapeur d'eau, qui s'introduit dans les canaux du systeme tridimensionnel. Nous avons caracterise un second polymere de coordination a base de dicyanoaurate d'uranyle de formule [U[O.sub.2][(DMSO).sub.3]([H.sub.2]O)(Au[(CN).sub.2])][Au[(CN).sub.2]] se presentant sous la forme d'une chaine lineaire d'unites de dicyanoaurate reliees par des liaisons Au-Au, a laquelle sont attaches des adduits d'uranyleau-DMSO maintenus par des liaisons hydrogene et disposes en pendentifs dans un feuillet bidimensionnel. Les deux substances presentent des proprietes d'emission provenant des motifs uranyle et des centres Au(I) et constituent les premiers polymeres de coordination multidimensionnels a base de dicyanoaurate d'uranyle. [Traduit par la Redaction] Mots-cles: polymere de coordination, interactions aurophiles, uranyle, cyanure, emission., Introduction The creation of coordination polymers through self-assembly allows for the design and generation of functional materials. The modular construction of coordination polymers from linking units, metal centres, and ancillary [...]

In this work, synthesis, characterization, and antioxidant activities of two Schiff base monomers (1 and 2) and their corresponding oxidation products (3 and 4) were reported. The monomers were prepared by condensation of 8-amino-2-naphthol with 2,4-dihydroxybenzaldehyde and 3,4-dihydroxybenzaldehyde, and then, they were oxidized to in alkaline medium by NaOCl to obtain the corresponding oxidation products. The compounds 1-4 were characterized by various spectral techniques. The analysis results indicated that the oxidation products had a chain structure consisting of randomly ordered phenylene and oxyphenylene units. In vitro antioxidant activities of 1-4 were evaluated against a ABTS cation radical and a DPPH free radical and compared with standard natural antioxidants, vitamin C (ascorbic acid), and vitamin E ([alpha]-tocopherol). The ferric reducing antioxidant power and ferrous-ion chelating activities of 1-4 were also determined. Key words: oxidative polymerization, Schiff base, phenol, antioxidant activity. Dans le cadre des presents travaux, nous decrivons la synthese, la caracterisation et l'activite antioxydante de deux bases de Schiff employees comme monomeres (1 et 2) et de leurs produits d'oxydation respectifs (3 et 4). Nous avons prepare les monomeres par condensation du 8-amino-2-naphtol avec le 2,4-dihydroxybenzaldehyde et le 3,4-dihydroxybenzaldehye, puis nous les avons soumis a une oxydation par le NaOCl en milieu alcalin pour obtenir les produits d'oxydation correspondants. Nous avons caracterise les composes 1 a 4 a l'aide de diverses techniques spectrales. Les resultats de l'analyse indiquent que les produits d'oxydation presentent une structure en chaine composee d'unites de phenylene et d'oxyphenylene ordonnees de maniere aleatoire. Nous avons evalue l'activite antioxydante in vitro des composes 1 a 4 a l'egard du radical cationique ABTS et du radical libre DPPH, et nous l'avons comparee a celle d'antioxydants naturels, a savoir la vitamine C (acide ascorbique) et la vitamine E ([alpha]-tocopherol). Nous avons egalement soumis les composes 1 a 4 au test de capacite de reduction des ions ferriques et au test de capacite chelatrice des ions ferreux. [Traduit par la Redaction] Mots-cles : polymerisation oxydante, base de Schiff, phenol, activite antioxydante., Introduction The polymers we use in our daily life are often exposed to various oxidative stresses. This leads to deterioration in their physical and mechanical properties and shortens their shelf [...]

During phase transition, the physical as well as chemical properties of polymers change dramatically. While the viscoelastic properties can usually be characterized with a rheometer, no chemical information is obtained [...]

The effect of dicumyl peroxide (DCPO) concentration on the polymerization kinetics of a polysilazane system has been investigated through DSC analyses. DCPO acts as polymerization initiator by activating the polyaddition of vinyl groups. The overall heat of reaction is found to be a linear function of the DCPO concentration above 1.5 wt%, due to the addition of the heat of fully initiated polymerization and the heat of DCPO decomposition. Below 1.5 wt% of DCPO, the polymerisation of polysilazane is not fully initiated and only part of the reaction occurs. The resulting overall heat of reaction is therefore lower than that provided by the linear law valid for higher concentrations. A two-reaction kinetic model built on this interpretation leads to a satisfactory representation of the DSC analyses performed for each DCPO concentration between 0.1 and 20 wt%. POLYM. ENG. SCI., 58:859-869, 2018. [C] 2017 Society of Plastics Engineers, INTRODUCTION Discovered in 1885 [1], polyorganosilazanes encompass a wide variety of silicon carbo-nitrides precursors utilized since the 1950s to prepare ceramic materials [2, 3] from a single component [4]. Processed [...]

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, [...]

A free-radical inverse emulsion polymerization formulation has been developed for preparation of acrylamide (AAm)/sodium 2-acrylamido-2-methylpropanesulfonate (AMPSNa)/N-vinylpyrrolidone (VP) terpolymers. An aqueous solution of a blend of monomers is emulsified in ndecane using Tween 85 (Tw85). Ammonium persulfate (APS) and dicumyl peroxide (DCP) were used as initiators for water and oil phases, respectively. The reactions were catalyzed by temperature and by a redox pair; the former is achieved at 60[degrees]C and the latter by adding tetramethyle-thylenediamine (TEMED) and sodium bisulphite (BisNa) to activate the initiator in water and oil phase, respectively. The emulsion type, stability, conversion, and rate of polymerization were analyzed. The obtained terpolymer was characterized by elemental analysis, infrared spectroscopy (FTIR), [sup.13]C nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheology. Thermal catalyzed emulsion polymerization initiated with DCP showed the best performance as viscosity control agent and as polymeric precursor for in situ gel forming, for water mobility control and flow diversification, respectively. Both application for enhanced oil recovery purposes in harsh oil reservoir conditions are presented., INTRODUCTION Polyacrylamide (PAAm) and their heteropolymers are of great importance, because of their good thickening capability, flocculation, and rheological behavior [1], Polymers based on acrylamide (AAm) and their derivatives are [...]

In this work, a compatibilizer (UHMWPE-g-GO) with large specific surface was prepared from graphene oxide (GO) and ultra-high molecular weight polyethylene (UHMWPE). First, GO was modified by 2, 3-epoxypropyltrimethylammonium chloride (GTA), subsequently grafted with UHMWPE. UHMWPE-g-GO was used to compatibilize the immiscible monomer casting (MC) nylon/UHMWPE blends. With the addition of very low content of UHMWPE-g-GO, the compatibility of UHMWPE and the matrix (MC nylon) was remarkably improved without visible agglomerates, which was proved by photographs, scanning electron microscope, dynamic thermomechanical analysis, and contact angle measurement. Therefore, thermal stability, mechanical and tribological properties were obviously increased. A dramatic increment of 94.1% in the impact strength and a decrement of 39.4% in the coefficient friction were observed in the presence of UHMWPE-g-GO in the immiscible polymer blends. The approach used in this work was an efficient strategy for immiscible polymer blends with ultra-high molecular weight., INTRODUCTION In the past few decades, polymer blends have attracted considerable scientific and industrial interest because they play an important role in the modern polymer industry not only for the [...]

In this study, P(NIPAAm-MAm)/A, which is a new smart polymer on which the temperature sensitivity of Nisopropyl acrylamide monomer and pH sensitivities of methacrylic acid (MA) and itaconic acid (IA) monomers unite, were prepared by free radical polymerization. The influence of crosslinkers on the properties of polymer and adsorption was studied using two different crosslinkers. These new environmentally multistimuli responsive hydrogels were characterized by FTIR, TG, and DSC. In order to determine the swelling behaviors of polymers, the equilibrium swelling studies were carried out at different temperatures and pHs. With the aim of studying the usability of the prepared polymers in the adsorption of nicotine and its pharmaceutical derivatives, the effects of temperature, pH, and adsorbent mass on adsorption equilibrium were Studied., INTRODUCTION Nicotine is an alkaloid present in several plants, but its major source is tobacco, used for cigarette manufacture. Nicotine is a highly toxic compound: 40-60 mg can be a [...]