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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 [...]

Abstract In this article, systematic calculation of the radius of gyration ([R.sub.g]) of a block copolymer immersed in various solvents is presented. Using atomistically detailed, molecular dynamics computer simulations, we [...]

Polymeric biosurfactants were prepared by the transesterification reaction between rapeseed oil triacyl glycerides and carboxymethylcellulose (CMC). The reaction was performed in H₂O/N, N dimethylformamide (DMF) with potassium laurate as catalyst at various reaction conditions using microwave radiation as heating source. The structural features of the obtained water-soluble CMC derivatives were characterized Fourier-transform infrared (FT-IR) spectroscopy and their behavior in dilute aqueous solutions was investigated by surface activity measurements, viscometry and with a polarity probe, the Coomassie Brilliant Blue dye. All derivatives showed a very low esterification extent and moderate surface tension lowering effect. Nevertheless, they exhibited significant emulsifying efficiency comparable to that of the synthetic surfactant, Tween 20. They establish hydrophobic associations in bulk solution while adsorbing on the air/water interface. The presence of hydrophobic substituents in CMC molecules enhanced the hydrophobicity resulting in higher emulsion stability than produced by Tween 20. The results suggested that suitable polymeric biosurfactants applicable as emulsifying agents can be prepared from CMC under microwave heating at low microwave power and reaction times in the range of few minutes, what represents a great advantage in comparison with transesterification reactions lasting up to 6 h at conventional heating. POLYM. ENG. SCI.,, INTRODUCTION The increasing interest for biocompatible and biodegradable materials makes natural polymers like polysaccharides attractive raw materials for the preparation of biopolymeric surfactants, which have potential application in food and [...]

Adsorption and chromatographic properties of the mixed stationary phase poly-(1-trimethylsilyl-1-propyne)/ poly(1-phenyl-1-propyne) (PTMSP/PPP) composed as 97 : 3 by weight have been investigated by methods of low-temperature nitrogen adsorption and gas chromatography on packed columns. The resultant phase has uniform mesoporous structure. The chromatographic properties of the mixed phase are significantly different from the properties of the original porous polymers PTMSP and PPP. The adsorbent obtained by modifying Chromosorb P NAW with a mixture of polymers provides the selective separation of chlorosubstituted, saturated, and aromatic hydrocarbons. Keywords: gas chromatography, poly(1-trimethylsilyl-1-propyne), poly(1-phenyl-1-propyne), mixed stationary phase. DOI: 10.1134/S1061934811060219, Highly gas-permeable porous polymer poly(1-trimethylsilyl-1-propyne) (PTMSP) has become a subject of special interest of researches. This polymer was originally used as a material for membrane technology as then as a [...]

Terahertz spectroscopy has been presented as a new technique for analyzing the degree of dispersion of polymeric compounds. It is a contact-free and nondestructive technique that can also be used to monitor the filler content of compounds inline during the extrusion process as has already been presented elsewhere. The utilized terahertz frequency range bridges the infrared and the microwave region in the electromagnetic spectrum. Here, we present offline terahertz measurements and mechanical tests on injection molded specimens consisting of wood plastic composites with varying filler contents and different dispersion qualities. A clear linear relation between results of the terahertz measurements and mechanical tests has been found showing that terahertz spectroscopy is a powerful tool for analyzing polymeric compounding processes. POLYM. ENG. SCI., 51:109-116, 2011. [C] 2010 Society of Plastics Engineers, INTRODUCTION The use of filler materials and additives in the plastics industry has become indispensable. As additional substances incorporated into the base polymer matrix, they influence essential properties and potentially [...]

A fluorescent polymer sensor array (FPSA) was made from commercially available fluorescent polymers coated onto glass beads and was tested to assess the ability of the array to discriminate between different analytes in aqueous solution. The array was challenged with exposures to 17 different analytes, including the explosives trinitrotoluene (TNT), tetryl, and RDX, various explosive-related compounds (ERCs), and nonexplosive electron-withdrawing compounds (EWCs). The array exhibited a natural selectivity toward EWCs, while the non-electron-withdrawing explosive 1,3,5-trinitroperhydro-1,3, 5-triazine (RDX) produced no response. Response signatures were visualized by principal component analysis (PCA), and classified by linear discriminant analysis (LDA). RDX produced the same response signature as the sampled blanks and was classified accordingly. The array exhibited excellent discrimination toward all other compounds, with the exception of the isomers of nitrotoluene and amino-dinitrotoluene. Of particular note was the ability of the array to discriminate between the three isomers of dinitrobenzene. The natural selectivity of the FPSA toward EWCs, plus the ability of the FPSA to discriminate between different EWCs, could be used to design a sensor with a low false alarm rate and an excellent ability to discriminate between explosives and explosive-related compounds. 10.1021/ac102504t

The characteristic collision energy to obtain 50% fragmentation, expressed as the characteristic collision voltage (CCV), was used as a tool to discriminate different classes of polymers. The CCV value of different polymers was determined in a quadrupole ion trap mass spectrometer. Good linear correlation (0.980 < [R.sup.2] < 0.999) between the CCV values and precursor ion mass was found for all polymers studied. The position of the various linear trend lines varied among the various polymers, which allowed their grouping based on the respective CCV values. The collision energy necessary to drive fragmentation was decreasing in the order of polyethers > polymethacrylates > polyesters > polysaccharides. This suggests that polysaccharides fragment most easily (low CCVs), while polyethers require the highest collision energy among the polymers studied. The effect of end group on the CCV was also studied, showing a minor influence in most cases. In addition, the applicability of CCV as discriminator was studied for a mixture of (1) polylactic acid (PLA), (2) poly(tetramethylene glycol) (PTMEG), and (3) PLA-block-PTMEG-block-PLA block copolymer. Differences between the CCV values of four nominally isobaric polymers (of which two were copolymers and two were homopolymers) were observed. These results demonstrate that the insertion of a 'weak' link into a polymer chain significantly affects the energy required for fragmentation. 10.1021/ac101936v

The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid day-based material (H CM), montmorillonite (STx-1)--melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx-1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. '[he melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle. Abbreviations: DTA, differential thermal analysis; GHD, glutamine hybrid material naelanoidin fraction; GHS, glutamine hybrid material solid fraction; HCM, hybrid clay-based material; NMR, nuclear magnetic resonance; STx-1, sodium-montmorillonite; STXM, scanning transmission x-ray microscopy; THD, tyrosine hybrid material melanoidin fraction; THS, tyrosine hybrid material solid fraction; XPS, x-ray photoelectron spectroscopy. doi: 10.2136/sssaj2009.0454

Microtubules are slender (~25 nm diameter), filamentous polymers involved in cellular structure and organization. Individual microtubules have been visualized via fluorescence imaging of dye-labeled tubulin subunits and by video-enhanced, differential interference-contrast microscopy of unlabeled polymers using sensitive CCD cameras. We demonstrate the imaging of unstained microtubules using a microscope with conventional bright field optics in conjunction with a webcam-type camera and a light-emitting diode illuminator. The light scattered by microtubules is image-processed to remove the background, reduce noise, and enhance contrast. The setup is based on a commercial microscope with a minimal set of inexpensive components, suitable for implementation in a student laboratory. We show how this approach can be used in a demonstration motility assay, tracking the gliding motions of microtubules driven by the motor protein kinesin. [c] 2010 American Association of Physics Teachers. [DOI: 10.1119/1.3453264]

We describe the synthesis and characterization of metal-chelating polymers with a degree of polymerization of 67 and 79, high diethylenetriaminepentaacetic acid (DTPA) functionality, [M.sub.w]/[M.sub.n], [less than or equal to] 1.17, and a maleimide as an orthogonal functional group for conjugation to antibodies. The polymeric disulfide form of the [DP.sub.n] = 79 DTPA polymer was analyzed by thermogravimetric analysis to determine moisture and sodium-ion content and by isothermal titration calorimetry (ITC) to determine the [Gd.sup.3+] binding capacity. These results showed each chain binds 68 [+ or -] 7 [Gd.sup.3-] per chain. Secondary goat antimouse IgG was covalently labeled with the maleimide form of the DTPA polymer ([DP.sub.n] = 79) carrying [sup.159]Tb. Conventional ICPMS analysis of this conjugate showed each antibody carded an average of 161 [+ or -] 4 [sup.159]Tb atoms. This result was combined with the ITC result to show there are an average of 2.4 [+ or -] 0.3 polymer chains attached to each antibody. Eleven monoclonal primary antibodies were labeled with different lanthanide isotopes using the same labeling methodology. Single cell analysis of whole umbilical cord blood stained with a mixture of 11 metal-tagged antibodies was performed by mass cytometry. 10.1021/ac101901x

This paper explores the potential of sample-controlled thermal analysis (SCTA) in order to perform compositional analysis of multicomponent polymeric materials by means of thermogravimetric experiments. In SCTA experiments, the response of the sample to the temperature determines the evolution of the temperature by means of a feedback system; thus, what is controlled is not the temperature--time profile, as in conventional analysis, but rather the evolution of the reaction rate with time. The higher resolving power provided by the technique has been used for determining the composition of polymer blends composed of polyvinyl chloride (PVC) and different commercial plasticizers, a system where the individual components have very similar thermal stabilities, thereby rendering useless thermogravimetric experiments run under conventional conditions. Different SCTA procedures, such as constant rate thermal analysis (CRTA), which has received special attention, and high-resolution and stepwise isothermal analysis have been tested, and the results obtained have been compared with linear heating rate technique. It has been proven that CRTA can be used to effectively determine the exact composition of the blend. 10.1021/ac101651g

A challenging target in the noncovalent synthesis of nanostructured functional materials is the formation of uniform features that exhibit well-defined properties, e.g., precise control over the aggregate shape, size, and stability. In particular, for aqueous-based one-dimensional supramolecular polymers, this is a daunting task. Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing out attractive noncovalent forces within the hydrophobic core of the polymerizing building blocks with electrostatic repulsive interactions on the hydrophilic rim we managed to switch from elongated, rod-like assemblies to small and discrete objects. Intriguingly this rod-to-sphere transition is expressed in a loss of cooperativity in the temperature-dependent self-assembly mechanism. The aggregates were characterized using circular dichroism, UV and 1H-NMR spectroscopy, small angle X-ray scattering, and cryotransmission electron microscopy. In analogy to many systems found in biology, mechanistic details of the self-assembly pathways emphasize the importance of cooperativity as a key feature that dictates the physical properties of the produced supramolecular polymers. aqueous self-assembly | controlled architecture | supramolecular polymerization | dynamic materials doi/ 10.1073/pnas.1009592107

The water content was determined for five strongly basic anion-exchange resins (trimethyammonium type having different exchange capacities and cross-linking degrees by divinylbenzene) in definite anionic forms (ten singly, three doubly, one triply, and one quadruply charged) dried at 25[degrees]C and at a relative humidity of 50%. Incorporation of the results of the previous research on the conventional resins by X-ray absorption fine structure and diffraction methods indicated that the present method gave the number of intrinsic water molecules strongly interacting with an anion. The hydration numbers of weakly hydrating anions ([Cl.sup.-], [Br.sup.-], and Cl[O.sub.4.sup.-]) and a small anion ([F.sup.-]) were independent of the exchange capacity and slightly decreased with an increase in cross-linking, especially at 8%. The small and strongly hydrating ion [F.sup.-] kept the in-water hydration structure to form a water-separated ion pair in the resins, while the other weakly hydrating ions were appreciably dehydrated to form a contact ion pair. The hydration number of a strongly hydrating ion, [H.sub.2]P[O.sub.4.sup.-], appreciably decreased with increases in both the exchange capacity and cross-linking degree accompanied by intermolecular hydrogen bonding between the anions. This may be related to other characteristics of the [H.sub.2]P[O.sub.4.sup.-] form resin, such as a higher concentration required for quantitative exchange, a systematic change in infrared spectra on the degree of exchange, and facile thermal dehydration, giving [H.sub.2][P.sub.2][O.sub.7.sup.2-]. In contrast, multivalent anions were exchanged without dehydration, due to the larger space allowed for in the resins and the stronger interaction with water compared to those of monovalent anions. 10.1021/ac101707j

In recent years, matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a powerful tool for the study of synthetic polymers although its mechanism is still not understood in detail. Sample preparation plays the key role in obtaining reliable MALD1 mass spectra, in particular, the proper choice of matrix, cationization reagent, and solvent. There is still no general sample preparation protocol for MALDI analysis of synthetic polymers. For known synthetic polymers, such as polystyrenes and other frequently investigated polymers, application tables in review articles might be a guide for selecting a MALDI matrix, cationization reagent, and solvent. For unknown polymers (polymers which were not analyzed by MALDI-TOF MS before but whose structures are in part known from the manufacturing process and from NMR analysis as well), the selection of matrix and solvent is based upon the polarity-similarity principle. Chemometric methods provide a useful tool for the investigation of sample preparation because huge data sets can be evaluated in short time, that is, for extracting relevant information and for classification of samples, as well. Furthermore, chemometrics provide a suitable way for the selection of a proper matrix, cationization reagent, and solvent. In this paper, a prediction model is presented using the partial least-squares (PLS) regression. By applying the model, the suitability of appropriate (nontested) combinations (matrix, cationization reagent, solvent) can be predicted for a certain synthetic polymer based upon the investigation of a few combinations. This model may help find suitable combinations in a short dine and serve as a starting point for the investigation of unknown polymers. Results are exemplary presented for polystyrene PS2850. 10.1021/ac101526w

The construction of a trypsin column for rapid and efficient protein digestion in proteomics is described. Electrospun and alcohol-dispersed polymer nanofibers were used for the fabrication of highly stable trypsin coatings, which were prepared by a two-step process of covalent attachment and enzyme cress-linking. In a comparative study with the trypsin coatings on as-spun and nondispersed nanofibers, it has been observed that a simple step of alcohol dispersion improved not only the enzyme loading but also the performance of protein digestion. In-column digestion of enolase was successfully performed in less than 20 min. By applying the alcohol dispersion of polymer nanofibers, the bypass of samples was reduced by filling up the column with wen-dispersed nanofibers, and subsequently, interactions between the protein and the trypsin coatings were improved, yielding more complete and reproducible digestions. Regardless of alcohol dispersion or not, trypsin coatings showed better digestion performance and improved performance stability under recycled uses than covalently attached trypsin, in-solution digestion, and commercial trypsin beads. The combination of highly stable trypsin coatings and alcohol dispersion of polymer nanofibers has opened up a new potential to develop a trypsin column for online and automated protein digestion. 10.1021/ac101633e

Newly developed porous polymer monolithic capillary columns modified with gold nanoparticles coated with exchangeable functionalities allow easy switching of separation modes by a simple ligand exchange process. These columns are prepared from a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith through reaction of its epoxide moieties with cysteamine to 'afford a monolith rich in surface thiol groups. Gold nanoparticles prepared via in situ reduction of chloroauric acid within the column become attached to the surface of the pores of the monolith. Alternatively, a solution of colloidal gold nanoparticles can be pumped through the thiol modified column to achieve their attachment. While the first approach is faster, it affords a lower coverage of nanoparticles than the second method, while both methods preserve the excellent hydrodynamic properties that are typical of the monolithic columns. Functionalization of the surface of the bound gold nanoparticles is then carried out using low molecular weight thiol-containing surface ligands. The dynamic nature of the bond between gold and these surface ligands enables the replacement of one surface ligand by another through a simple solution exchange process. This novel approach expands the application range of monoliths as a single column can now he used in different separations modes. Applications of the columns with exchangeable chemistries are demonstrated with the capillary electrochromatographic separation of peptides and the nano-high-pressure liquid chromatography (HPLC) separation of proteins in both reversed phase and ion exchange modes. 10.1021/ac1015613

Chemiresistors are polymer-based sensors that transduce the sorption of a volatile organic compound into a resistance change. Like other polymer-based gas sensors that function through serption, chemiresistors can be selective for analytes on the basis of the affinity of the analyte for the polymer. However, a single sensor cannot, in and of itself, discriminate between analytes, since a small concentration of an analyte that has a high affinity for the polymer might give the same response as a high concentration of another analyte with a low affinity. In this paper we use a field-structured chemiresistor to demonstrate that its response kinetics can be used to discriminate between analytes, even between those that have identical chemical affinities for the polymer phase of the sensor. The response kinetics is shown to be independent of the analyte concentration, and thus the magnitude of the sensor response, but is found to vary inversely with the analyte's saturation vapor pressure. Saturation vapor pressures often vary greatly from analyte to analyte, so analysis of the response kinetics offers a powerful method for obtaining analyte discrimination from a single sensor. 10.1021/ac101259w

The moisture damage in polymer modified asphalts has been studied for decades, yet the effects of chemical functional groups on moisture sensitivity are not known. In this study, a nanoscale experiment is conducted to measure these effects in terms of adhesive/ cohesive forces using an atomic force microscopy (AFM). A base asphalt binder and two polymers such as styrene-butadiene (SB) and styrene-butadiene-styrene (SBS) modified asphalts are used to prepare an AFM sample on glass substrates. The AFM samples are conditioned under dry and wet conditions. In the AFM, these samples are probed by silicon nitrite (Si3N4), carboxyl (--COOH), methyl (--CH3), and hydroxyl (--OH) functionalized AFM tips and nanoscale pull-off or adhesion/cohesion forces between asphalt and tip molecules are measured. Based on the ratio of wet to dry adhesion/cohesion forces, it is shown that the polymer modification makes binders less susceptible to moisture damage. Among the four tips, the --COOH tip shows almost no difference in adhesion forces between wet and dry samples. Using--OH tips, it is shown that the cohesion in SBS modified wet asphalt samples is significantly higher than the cohesion in SB modified wet asphalt samples. The Si3N4 tip shows higher adhesion in SB modified wet samples than that in the SBS polymer modified wet samples. Based on the adhesion/cohesion force, 3% polymer is found to be the optimum for both SB and SBS polymers. In addition, this study determines the methodology for sample preparation and testing parameters for nanoscale AFM testing on asphalt binders. DOI: 10.1061/(ASCE)MT.1943-5533.0000072 CE Database subject headings: Microscopy; Moisture; Damage; Roughness; Polymer; Asphalts. Author keywords: Atomic force microscopy; Adhesion; Cohesion: Moisture damage; Roughness; Nanoscale; Polymer modified asphalts; Functionalized tips.

The life science and healthcare communities have been redefining the importance of ribonucleic acid (RNA) through the study of small molecule RNA (in RNAi/siRNA technologies), micro RNA (in cancer research and stem cell research), and mRNA (gene expression analysis for biologic drug targets). Research in this field increasingly requires efficient and high-throughput isolation techniques for RNA. Currently, several commercial kits are available for isolating RNA from cells. Although the quality and quantity of RNA yielded from these kits is sufficiently good for many purposes, limitations exist in terms of extraction efficiency from small cell populations and the ability to automate the extraction process. Traditionally, automating a process decreases the cost and personnel time while simultaneously increasing the throughput and reproducibility. As the RNA field matures, new methods for automating its extraction, especially from low cell numbers and in high throughput, are needed to achieve these improvements. The technology presented in this article is a step toward this goal. The method is based on a solid-phase extraction technology using a porous polymer monolith (PPM). A novel cell lysis approach and a larger binding surface throughout the PPM extraction column ensure a high yield from small starting samples, increasing sensitivity and reducing indirect costs in cell culture and sample storage. The method ensures a fast and simple procedure for RNA isolation from eukaryotic cells, with a high yield both in terms of quality and quantity. The technique is amenable to automation and streamlined workflow integration, with possible miniaturization of the sample handling process making it suitable for high-throughput applications. 10.1021/ac100063f

Supramolecular polymeric materials are of increasing interest for the use as drug delivery carriers. A thorough insight in the biocompatibility and the degradation of these materials in vivo are of fundamental importance to further their development and application in medical practice. Molecular imaging techniques are powerful tools that enable the elucidation of molecular distributions in and around such polymer implants. A supramolecular polymeric hydrogel was implanted under the renal capsule to study its biocompatibility with TOF-SIMS. This results in a molecular cartography of the polymer implant combined with the cellular signature of the implantation environment. In this experiment, molecular signals are observed from cells that are involved in the biological response to the implant, e.g., macrophages. These molecular signatures are compared with macrophage standards cultured in different polarization environments. On the basis of this comparison, information can be acquired on the various macrophage differentiations that are connected to different stages in the foreign body response. Mass spectrometric imaging techniques offer the opportunity to visualize different histological phenomena in a single experiment without the need for specific immunohistochemical markers. Cellular infiltration into the polymer is visualized, offering a clear view on both biological and polymer features in a single imaging experiment. 10.1021/ac100837n

A novel low-band-gap chromophore (5, 0.86 eV) having fluorene as a donor, benzobisihiadiazole (BBTD) as an acceptor, and pyrrole as a π-spacer was successfully designed and synthesized, to probe the effect of π-spacer on the band-gap level of the donor-π-acceptor-π-donor type of chromophores. Compared with the thiophene spacer analogue (in compound 3), the intramolecular hydrogen bonding between the pyrrole and the neighboring BBTD unit pushes the absorption maximum and fluorescence emission of chromophore 5 into the near-infrared spectral region with a red shift of 172 and 158 nm, respectively. The same red-shift phenomenon can also be realized by addition of Lewis acid (e.g., B[F.sub.3]) to the BBTD-containing chromophores with other spacers. Attempt of using low-band-gap chromophore 5 in bulk heterojunction (BHJ) solar cells was made, showing a non-optimized photovoltaic device with the power conversion efficiency of 0.01%. A precursor approach to introduction of the alkaline-labile BBTD acceptor into the polymer backbone has been demonstrated by successful synthesis of low-band-gap polymer P2. The same strategy can be in principle applied to the synthesis of a series of low-band-gap chromophores or polymers with strong acceptors. Key words: donor-π-acceptor-π-donor, chromophore, low band gap, bulk heterojunction (BHJ), precursor polymer. Afin de pouvoir etudier l'effet d'un espaceur π sur le niveau d'energie interbande des chromophores de type donneur-π-accepteur-π-donneur, on a developpe et synthetise un nouveau chromophore de basse energie interbande (5, 0,86 eV) comportant un fluorene comme donneur, un benzobisthiadiazole (BBTD) comme accepteur et un noyau pyrrole comme espaceur π. Par comparaison avec l'analogue comportant un espaceur thiophene (dans le compose 3), la liaison hydrogene intramoleculaire entre le pyrrole et l'unite adjacente BBTD deplace le maximum d'absorption et l'emission de fluorescence du chromophore 5 dans la region spectrale du proche infrarouge avec des deplacements vers le rouge de respectivement 172 et 158 nm. On peut observer le meme phenomene de deplacement vers le rouge par l'addition d'un acide de Lewis (tel le B[F.sub.3]) a des chromophores comportant du BBTD et d'autres espaceurs. On a essaye d'utiliser le chromophore 5 a faible energie interbande dans des cellules solaires a heterojonction globale (HJG); on a obtenu un dispositif non voltaique non optimise ayant une efficacite de conversion de pouvoir de 0,01 %. On a demontre l'applicabilite d'une autre approche a l'introduction de l'accepteur BBTD labile aux produits alcalins dans le squelette d'un polymere en effectuant avec succes la synthese du polymere P2 de faible energie interbande. En theorie, la meme strategie peut etre appliquee a la synthese d'une serie de chromophores ou de polymeres de faible energie interbande avec des accepteurs forts. Mots-cles: donneur-π-accepteur-π-donneur, chromophore, faible energie interbande, heterojonclion globale (HJG), polymere preeurseur., [Traduit par la Redaction] Introduction Research on low-band-gap organic materials (e.g.. chromophores and polymers), whose band-gap levels, defined as the difference between the highest occupied molecular orbital (HOMO) and the [...]

The polymeric composition of Titan's tholins--laboratory analogues of Titan's aerosols-is elucidated using high-resolution mass spectrometry. This complex organic matter is produced by plasma discharge in a gaseous nitrogen-methane mixture and analyzed with a hybrid linear trap/orbitrap mass-spectrometer. The highly structured mass spectra are treated with tools developed for petrolcomics (Kendrick and van Krevelen diagrams), with original adaptations for nitrogen-rich compounds. Our goal is to find the best chemical basis set to describe the compositional space that these polymers occupy, to shed light onto the chemical structure of tholins. We succeeded in assigning the molecules identified in the mass spectra of tholins to a small number of regularly distributed X-[([CH.sub.2).sub.2m][(HCN).sub.2] families, where the balanced copolymer (m = n) is determined to play a central role. Within each family, the polymer lengths n and m present Poisson-type distributions. We also identify the smallest species of a subset of families as linear and cyclic amino nitrile compounds of great astrobiological interest: biguanide, guanidin, acetamidine, aminoacetonitrile, and methylimidazole. 10.1021/ac902458q

Crystallinity of semicrystalline polymers such as aliphatic homopolymer poly(L-lactic acid) (PLLA) affects their degradation and physical properties. In this paper, the effects of laser irradiation using the third harmonic of a Nd:YAG laser on the crystallinity, long-range order, and short-range conformations at the surface of PLLA films are investigated. The factors affecting the transformation are also studied. Detailed characterization of the effect of laser treatment is accomplished using microscopy, X-ray diffraction, and infrared spectroscopy. The cooling rates in the process and the spatial and temporal temperature profiles are numerically examined. The simulation results in conjunction with melting and crystallization kinetics of PLLA are used to understand the effect on sample crystallinity. The effects of laser fluence and annealing conditions on the crystallinity of the processed films are examined. Since degradation profiles depend on crystallinity, laser processing can potentially be used to achieve a modified spatially controlled polymer surface with promising applications such as controlled drug delivery. [DOI: 10.1115/1.3039519]

Monolithic poly(butyl methacrylate-co-ethylene dimethacrylate) columns have been prepared in capillaries ranging in inner diameter from 5 to 75 [micro]m using thermally initiated free-radical polymerization of a mixture of butyl methacrylate, ethylene dimethacrylate, and porogens at different temperatures. Scanning electron microscopy and the measurement of hydrodynamic properties reveal that the downward scalability of the monolithic columns is greatly affected by the confinement effect of the capillary wall resulting from the decreased volume-to-surface ratio as the capillary diameter is decreased. The downscaling process is affected most by the polymerization temperature, the diffusion of the propagating radicals, and the density of coverage of polymerizable groups on the inner walls of the capillary. Optimization of all these factors enables the preparation of monolithic structures in capillaries with inner diameters as low as 5 [micro]m while retaining the desirable properties of monoliths prepared in much larger capillaries. Under these conditions, formation of undesired dense polymer layers attached to the capillary wall was minimized. The chromatographic performance of 10, 25, and 50 [micro]m capillaries evaluated in the reversed phase gradient separation of three proteins showed no change in elution times at identical flow velocities and gradient times, while peak elution width was the smallest with the narrowest capillary.

Problem statement: This study showed the results of an experimental investigation on the strengthening of corrosion damaged reinforced concrete beams with unidirectional cloth glass fiber reinforced polymer (UDCGFRP) laminates. Approach: All the beam specimens 150x250x3000 mm were cast and tested for the present investigation. One beam specimen was neither corroded nor strengthened to serve as a reference. Two beams were corroded to serve as a corroded control. A reinforcement mass loss of approximately 10 and 25% were used to define medium and severe degrees of corrosion. The remaining two beams corroded and strengthened with GFRP. Results: The test parameters included first crack load, first crack deflection, yield load, yield deflection, service load, service deflection, ultimate load and ultimate deflection. Based on the results it was found that GFRP Laminates had beneficial effects even at the corrosion-damaged stage. Conclusion/Recommendations: The UDCGFRP laminated beams showed distinct enhancement in ultimate strength and ductility by 72.37 and 49.49% respectively. Key words: Corrosion, reinforced concrete, strengthening, UDCGFRP laminates, INTRODUCTION The problem of deterioration of concrete structures due to corrosion of steel reinforcement has received worldwide attention. Even though current codes of practice provide recommendations and precautions to avoid [...]

Laser photoablation of poly(ethylene terephthalate) (PET), a flexible dielectric organic polymer, was used to design an acoustic miniaturized DNA biosensor. The microchip device includes a 100-[micro]m-thick PET layer, with two microband electrodes patterned in photoablated microchannels on one side and a depressed photoablated disk decorated by gold sputtered layer on the other side. Upon application of an electric signal between the two electrodes, an electroacoustic resonance phenomenon at ~30 MHz was established through the microelectrodes/PET/ gold layer interface. The electroacoustic resonance response was fitted with a series RLC motional arm in parallel with a static Co arm of a Buttlerworth-Van Dyke equivalent circuit: admittance spectra recorded after successive cycles of DNA hybridization on the gold surface showed reproducible changes on R, L, and C parameters. The same hybridizations runs were performed concomitantly on a 27-MHz (9 MHz, third overtone) quartz crystal microbalance in order to validate the PET device developed for bioanalysis applications. The electroacoustic PET device, ~100 times smaller than a microbalance quartz crystal, is interesting for the large-scale integration of acoustic sensors in biochips.