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Using a simple one-pot method, the reduction of liquid terminated-carboxyl fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

This study evaluates the dehydrofluorination of fluoroelastomer (poly(VDF-co-HFP) copolymer) which was dissolved by organic solvent and reacted with different concentrations of KOH and different amount of phase transfer catalyst (PTC) at 20–60 °C.The structures, sequence types and contents of double bonds of samples were analyzed and investigated by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy(ATR-FTIR), 1H nuclear magnetic resonance (NMR), 19F NMR spectroscopy and chemical titration method. The results revealed that dehydrofluorination of the studied fluoroelastromers could be carried out at room temperature in alkaline environments, wherein the temperature and alkali concentration were the great factors. And the dehydrofluorination of poly(VDF-co-HFP) copolymer conformed mainly to Zaitsev's rule and partially to Hofmann's rule. The double bonds (–C=C–) would generate in five positions of molecular chains and contents could be controlled. With increase of alkali concentration or reaction temperature, there would be dehydrofluorination accompanied with oxidation reaction whereby some –C=C– converted to hydroxyl groups. Finally, the mechanism of reaction was also deduced.

This study evaluates the dehydrofluorination mechanism, structure and thermal stability of pure fluoroelastomer which was dissolved by organic solvent and reacted with different concentrations of KOH at 20 ∼ 60 °C. The sequence types and contents of double bonds and other oxygen-containing groups of samples were analyzed and investigated by Attenuated total reflectance/Fourier transform infrared (ATR-FTIR), 1H nuclear magnetic resonance (NMR), 19F-NMR spectroscopy and chemical titration method; thermal decomposition temperatures of samples were analyzed by thermogravimetric analysis (TGA). The results revealed that dehydrofluorination of fluoroelastomer would accompain with oxidation reaction whereby some double bonds conforming to Hofmann’s rule had been converted to hydroxyl groups, wherein the temperature and alkali concentration were the important factors. The double bonds generated in seven positions of molecular chains, sequence types were mainly conformed to Hofmann’s rule and Zaitsev’s rule supplemented. With the increase of reaction temperature and concentration of KOH, the thermal stability of fluoroelastomer decreased obviously since hydroxyl groups had a greater effect on it. Finally, the mechanism of reaction was also deduced.

Using a simple one-pot method, the reduction of liquid terminated-carboxyl fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH

Dark-field microscopy is a widely used tool for measuring the optical resonance of plasmonic nanostructures. However, current numerical methods for simulating the dark-field scattering spectra were carried out with plane wave illumination either at normal incidence or at an oblique angle from one direction. In actual experiments, light is focused onto the sample through an annular ring within a range of glancing angles. In this paper, we present a theoretical model capable of accurately simulating the dark-field light source with an annular ring. Simulations correctly reproduce a counterintuitive blue shift in the scattering spectra from gold nanodisks with a diameter beyond 140 nm. We believe that our proposed simulation method can be potentially applied as a general tool capable of simulating the dark-field scattering spectra of plasmonic nanostructures as well as other dielectric nanostructures with sizes beyond the quasi-static limit.

Localized surface plasmon resonance (LSPR) on gold nanoparticles and nanostructures shows its capability to modulate the spontaneous emission rate for photoluminescence. However, beyond the quasi-static limit with oblique incidence conditions, probing a retardation-based plasmonic resonant state excited by the horizontal incident wave-vector component has not been reported yet in the plasmon-mediated photoluminescence of gold nanostructures. In this paper, we investigated the photoluminescence of individual and coupled gold nanodisks with increasing size, and the peaks in the size-dependent photoluminescence spectra are shown to originate from the preferential excitation of vertical (LSPR) and horizontal (retardation-based) plasmonic resonant states. We have also proposed a three-step model to well describe the contribution of vertical and horizontal plasmonic resonant states in the photoluminescence of gold nanodisks. Our study makes a new contribution to the understanding of photoluminescence from gold ...

The thermal properties of chlorosulfonated polyethylene (CSM), which was prepared via gas–solid phase method, were studied in this article. The thermal curves were completely tested by differential thermal analysis, thermogravimetry, and differential thermogravimetry. The results showed that CSM 3550 and CSM 3570 prepared by gas–solid phase method had more excellent thermal properties (high initial/final temperature of degradation) than those via solution method, due to the uniform chlorine distribution of them in macromolecular chain. The differential scanning calorimetry curves showed that the transitions of CSM 3550 and CSM 3570 from glassy to the elastic state were also higher than those via solution method. Particularly, CSM 3570 was amorphous and no clear melting peak was observed during the melting process.

The oil-wetting behavior in water and water-wetting behavior in oil on superhydrophobic/superoleophilic surface and superhydrophobic/superoleophobic surface have been investigated. Two superhydrophobic surfaces both present an oil contact angle of about 0° in water, but show a water contact angle around 180° in oil. When two superhydrophobic surfaces are immersed in water, both of them retain a layer of air on the surface. The oil can crowd out the air and seep into the grooves on superhydrophobic/superoleophilic surface when oil droplet drips on the surface, but it will not occur on superhydrophobic/superoleophobic surface because of surface superoleophobicity. In oil, the rough grooves of superhydrophobic/superoleophilic surface fill with oil, but the superhydrophobic/superoleophobic surface keeps a layer of air on its grooves. The air layer makes the rough surface forming a continuous liquid/air interface in liquid. When the other liquid droplet drips on the surface, it will be a contact with liquid/air interface which accord with liquid spreading happening at liquid/air interface in air. And the situation and the shape of the other liquid droplet on the surface were also as same as it at liquid/air interface in air.

The morphology and thermal properties of Allylisobutyl Polyhedral Oligomeric Silsesquioxane (POSS)/Polybutadiene (PB) nanocomposites prepared through anionic polymerization technique were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of XRD, SEM and TEM showed that the aggregation of POSS in PB matrix occurred obviously, forming crystalline domains and the size of POSS particles increased with increasing POSS content. The DSC and TGA results indicated that the glass transition temperature (Tg) of the nanocomposites was significantly increased and the maximum degradation temperature (Tdmax) of nanocomposites was slightly increased compared with pure PB, implying an increase in thermal stability.

Trichlorosilanes nanostructures have been fabricated on glass substrates through a fast and facile liquid phase method and the impact of alkyl length on surface nanostructures and the corresponding wettability have been studied. With the increase of alkyl chain length, the prepared surfaces showed different surface geometries on shape, size and quantity, as well as the corresponding wettability. The competition between the decrease of the reactivity caused by the raise of the steric effect and the increase of the alkyl hydrophobicity with the variation of alkyl length is considered to be responsible for these behaviors.

Polybutadiene (PB)/Allylisobutyl Polyhedral Oligomeric Silsesquioxane (A-POSS) nanocomposites have been prepared by using A-POSS and butadiene (Bd) as comonomers, n-BuLi as initiator, cyclohexane as solvent, ethyltetrahydrofurfuryl ether as structure modifier through the anionic polymerization technique. The reaction conditions, the kind and content of the modifier and POSS, etc. affecting the copolymerization process and the microstructure of the nanocomposites were also investigated. The results showed that POSS incorporation obviously decreased the rate of polymerization and the molecular weight of the copolymers, increased polydispersity index of the copolymers. The reaction conditions (the reaction time and reaction temperature) had little effect on copolymerization. However, the addition of the modifier could increase the rate of polymerization significantly. In particular, the POSS incorporation resulted in dramatically increasing the content of 1,2-units in PB. POSS and the modifier had the excellent cooperative effect modifying the microstructure of the PB. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

When the superamphiphobic meshes are immersed in water, the rough structures on steel wires are filled with air. The nanostructured superamphiphobic surfaces were prepared on the stainless-steel mesh. By adjusting the mesh size of the surface, the continuity of trapped air layer on the superamphiphobic surface underwater could be controlled. Then the underwater oil-wetting behavior on the prepared superamphiphobic mesh was investigated. The oil droplet spread out on the superamphiphobic surface without mesh and exhibited an oil contact angle of about 0° under water. But the oil contact angle formed on the superamphiphobic mesh surfaces and extended with increasing mesh size. We thought the discontinuity of trapped air layer on the surface and the entry of water into interval between the steel wires should be responsible for these behaviors.

In order to recycle alkali chemicals from wheat straw alkaline pulping waste liquor effectively, an environmentally friendly route was developed to remove silicate containing in the green liquor of wheat straw pulping. In this route, silica (SiO2) microspheres were synthesized from wheat straw green liquor (WSGL) using carbon dioxide (CO2) as the precipitating reagent and anhydrous ethanol as the dispersant at different stirring rates. The resulting SiO2 microspheres with narrow size distribution had an amorphous structure with a diameter of about 190 nm under the optimal synthesis conditions with a pH value of 8.6, a stirring rate of 100 r min−1, and an ethanol addition amount of 60 ml. In this optimized route, the SiO2 removal rate (SRT) of WSGL was more than 99%. Except CO2, all the chemical reagents used in the designed process had been validly used. The SiO2 microspheres obtained from WSGL could be used as reinforcing agents to strengthen the mechanical properties of natural rubber.

Catalytic Sommelet-Hauser rearrangement is reported. The Rh(II)-catalyzed reaction of aryldiazoacetates with ethyl benzylthioacetate affords Sommelet-Hauser rearrangement products in good to excellent yields. This reaction provides a reliable and efficient way to introduce a substituent to the ortho position of arylacetates.

In this paper silane coupling agents A151, A171, A174 and A187 were used to modify the surface of nanosilica (Si0 2 ) and polybutadiene (PB)/Si0 2 nanocomposites (NC) had been prepared by in situ anionic polymerization. The morphology and chemical constitution of NC were characterized by Transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR); Thermogravimetric analysis (TGA) was used to investigate the thermal properties of NC; the molecular weight and molecular weight distribution of NC were characterized by gel permeation chromatography (GPC). The effect of different SiO 2 and silane coupling agents on the molecular weight and distribution of PB, microstructure and properties were studied. The results showed that the hydrophobicity of SiO 2 was increased after the surface modification by silane coupling agents and can disperse in PB matrix uniformly. The thermal stability of NC also increased.

Hydrophobic organic montmorillonite (OMMT) which exists as stable dispersions in cyclohexane has been prepared by the combined modification of quaternary ammonium salts and coupling agents, and polybutadiene (PB)/OMMT nanocomposites (NCs) were successfully synthesized by in situ living anionic polymerization. The results showed that the interlayer spacing of OMMT increased dramatically on increasing the length of the long alkyl chain of C12, C16, C18 and C22 in n-alkyltrimethylammonium ions and the number of long alkyl chains of 1C16, 2C16 and 3C16 in hexadecylmethylammonium ions. The interlayer spacings reached 4.9 and 5.07 nm, respectively, when C22 and 3C16 were used. The dispersion of MMT intercalated by quaternary ammonium salts was improved significantly after surface modification by different coupling agents, and the OMMTs could be disperses stably in cyclohexane for at least 72 h. In addition, the coupling agents did not change the inherent intercalation structure of OMMT. The results from a kinetic study and 1H NMR analysis indicated that the incorporation of OMMT had little influence on the living polymerization and PB microstructure (proportions of 1,2- and 1,4-units) when the OMMT content was below 3 wt%. However, the OMMT modified by different coupling agents had some influence on the molecular weight distribution. The results from transmission electron microscopy and X-ray diffraction revealed that exfoliated structures of clay were obtained for all NCs. Furthermore, the results of differential scanning calorimetry and thermogravimetric analysis indicated that Tg and Tdc of NCs were increased compared to those of PB. Copyright © 2006 Society of Chemical Industry

Styrene and butadiene block copolymers (SBS) end functionalized with amino group at the initiating chain ends were synthesized using hexamethyleneimine alkenyl lithium (N-Li) as initiator, tetrahydrofuran (THF) as polar modifier, and cyclohexane as solvent. By attaching a few number of butadiene molecules to N-lithium hexamethyleneimine, a new N-Li initiator that can effectively initiate the polymerization of SBS was obtained. 1H NMR spectrums of the N-Li initiator terminated by ethanol, end functionalized polystyrene, and SBS block copolymer proved the structure of N-Li and its ability to initiate the polymerization of styrene and SBS block copolymer. Kinetics studies suggested that the polymerization rate of styrene in the first block reached the maximum when the ratio of THF/Li was increased to 5, while further increase of the ratio of THF/Li could not improve the polymerization rate. The molecular weight distribution (MWD) of SBS initiated by N-Li varied with the ratio of THF/Li. The vinyl content of polybutadiene block increased by improving the ratio of THF/Li, while the content of cis-1,4 and trans-1,4 structures decreased. The vinyl content of end functionalized SBS was somewhat higher than that of SBS initiated by classical n-butyllithium when other condition was the same. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 81–88, 2006

Polybutadiene (PB)/Montmorillonite nanocomposites (NCs) were prepared by in situ polymerization through the anionic polymerization technique. The effects of treating method of organophilic MMT (OMMT), the type of OMMT, and the solvent used in polymerization were studied. The structure and properties of NCs were characterized using X-ray Diffraction (XRD), transmission electron micrograph (TEM), H-NMR spectrum, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The consumption of BuLi was varied with different treating methods. The molecular weight distribution of PB added with OMMT (DK1) was wide, and the molecular weight distribution became narrow when OMMT-DK1B and DK4 were added. OMMT did not disperse stably in cyclohexane, but could form a homogeneous solution in toluene and xylene. XRD and TEM showed that exfoliated NCs were obtained by in situ polymerization through the anionic polymerization technique. From the H-NMR spectrum of PB and PB/OMMT NCs, it could be seen that the content of 1, 2 units of PB increased ∼100%, while 1, 4 units decreased when 6.2 wt % of OMMT was added. The results of DSC and DMA indicated that Tg and Tdc were increased when compared with those of PB. Both storage modulus and loss modulus were increased with the addition of OMMT, and tan δ was decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3615–3621, 2006

End amino, carboxylic acid, and hydroxyl functionalized styrene–butadiene–styrene (SBS) triblock copolymers were prepared with 1,5-diazabicyclo[3.1.0]hexane, carbon dioxide, and epoxy ethane as capping agents, respectively. The effects of the end polar groups on the morphology and dynamic mechanical properties were investigated. Transmission electron microscopy images suggested that the group at the end of the polystyrene (PS) segment made the morphology of the PS domains disordered and incompact. Dynamic mechanical results showed that the storage and loss modulus increased after SBS was end-functionalized. End amino and carboxylic acid groups improved the compatibility and storage stability of SBS-modified asphalt. However, the effect of the end-hydroxyl group on the improvement of the storage stability of SBS-modified asphalt was not obvious. The differential scanning calorimetry analysis of SBS-modified asphalt further showed that the compatibility and storage stability of SBS-modified asphalt were improved by the attachment of amino or carboxylic acid groups through the anionic polymerization method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 8–16, 2007

Polybutadiene (PB), polyisoprene (PI), and styrene–butadiene rubber/organic montmorillonite (OMMT) nanocomposites (NCs) were prepared by in situ anionic intercalation polymerization. The intercalation structure, chemical constitution, and morphology of the rubber/OMMT NCs were characterized with X-ray diffraction, H NMR spectroscopy, and transmission electron microscopy; the thermal and dynamic mechanical properties of the rubber/OMMT NCs were characterized with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The mechanical properties of PB/OMMT NC were also tested. The results showed that a certain extent of exfoliated rubber/OMMT could be prepared by anionic in situ intercalation polymerization. The incorporation of OMMT obviously changed the microstructure content of PB and PI: the concentrations of the 1,2-unit, 3,4-unit, and trans-1,4-unit increased dramatically with an increasing concentration of OMMT, and the concentration of the cis-1,4 structure decreased. The addition of OMMT-DK1B and OMMT-DK4 had little effect on the molecular weight and molecular weight distribution, but the addition of OMMT-DK1 reduced the molecular weight of rubber, and the molecular weight distribution became broad. The glass-transition temperature, weight-loss temperature, storage modulus, and loss modulus of the NCs evidently increased, but tan δ decreased. OMMT apparently enhanced the rubber matrix; for example, the breaking strength and hardness of PB/OMMT NC crosslinked rubber increased greatly, but the tear strength and permanent deformation did not change much. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1344–1353, 2005

A new synthetic route to anti-α,β-dihydroxy esters has been developed. The new method consists of three steps starting from an aldehyde: the nucleophilic condensation with ethyl diazoacetate, oxidation with dimethyldioxirane, and stereoselective reduction with NaBH 4 .

Star-shaped and linear block thermoplastic poly(styrene-b-butadiene) copolymer (SBS)/organophilic montmorillonite clays (OMMT) were prepared by a solution approach. The intercalation spacing in the nanocomposites and the degree of dispersion of nanocomposites were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The mechanical properties, dynamic mechanical properties, and thermal stability of these nanocomposites were determined. Results showed that SBS chains were well intercalated into the clay galleries and an intercalated nanocomposite was obtained. The mechanical strength of nanocomposites with the star-shaped SBS/OMMT were significantly increased. The addition of OMMT also gave an increase of the elongation, the dynamic storage modulus, the dynamic loss modulus, and the thermal stability of nanocomposites. The increase of the elongation of nanocomposites indicates that SBS has retained good elasticity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3430–3434, 2004

The Rh2(OAc)4-catalyzed reaction of methyl aryldiazoacetates with thioacetic S-acid gives exclusively the S−H insertion products in high yields, while the corresponding reaction mediated by BF3·OEt2 gives O-esters. The mechanism of the reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003

SBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular-weight-distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003

In this work, we investigate the one-photon photoluminescence from a system consisting of an Ag nanowire on an Au film with a ∼6 nm dielectric spacer that supports a localized resonance known as the gap plasmon mode. Although the Ag nanowire and Au film exhibit weak photoluminescence on their own, the combined system produces an enhanced PL emission. Our analysis reveals that the strong PL emission in this system was due to the enhanced laser absorption in, and PL emission from Au, with the Ag nanowire acting as an efficient antenna. The PL due to the gap mode is sensitive to the polarization of the laser excitation with respect to the nanowire orientation, and shows a clear dipolar emission profile. PL emission wavelengths were found to depend only on the nanowire width, and independent of its length. These observations were supported by simulation results indicating that gap plasmons are excited by light polarized transverse to the nanowire length. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore)

[14661-69-9] C9H10ClN2O3S (MW 261.73) InChI = 1S/C9H9ClN2O3S/c1-7-2-4-8(5-3-7)16(14,15)12-11-6-9(10)13/h2-6,12H,1H3 InChIKey = HQXCAVDYGRHYMF-UHFFFAOYSA-N InChI = 1/C9H9ClN2O3S/c1-7-2-4-8(5-3-7)16(14,15)12-11-6-9(10)13/h2-6,12H,1H3 InChIKey = HQXCAVDYGRHYMF-UHFFFAOYAK (synthesis of α-diazo esters and amides2) Physical Data: mp 103–110 °C (dec). Solubility: sol methylene chloride, chloroform, THF, and warm benzene. Preparative Method: not commercially available; however, it can be prepared readily by the reaction of p-Toluenesulfonylhydrazide 1 and Glyoxylic Acid.2 Handling, Storage, and Precautions: anhydrous conditions are required; it is advisable to prepare the reagent freshly prior to use.

The Doyle–Kirmse reaction, namely the [2,3]-sigmatropic rearrangement of sulfonium ylides generated from transition metal carbenoids and sulfides has been, for the first time, carried out in water.

CuSO4 was found to be an efficient catalyst for the diazo decomposition of β-hydroxy α-diazoesters in water. 1,2-H shift occurred efficiently to give β-keto esters in high yields. No O–H bond insertion products were identified.

The addition products of Ti(IV)-enolate derived from β-keto α-diazo carbonyl compound to ketones or α,β-unsaturated compounds were subjected to Rh 2 (OAc) 4 -catalyzed and photo-induced diazo decomposition. The Rh 2 (OAc) 4 -catalyzed reaction afforded intramolecular O–H insertion products, while the photo-induced reaction gave Wolff rearrangement/intramolecular nucleophilic addition products. The transformations represent new approaches to tetrahydrofuran and γ-butyrolactone derivatives.

A new synthetic route to anti-α,β-dihydroxy esters has been developed. The new method consists of three steps starting from an aldehyde: the nucleophilic condensation with ethyl diazoacetate, oxidation with dimethyldioxirane, and stereoselective reduction with NaBH 4 .

The interesting oil-wetting behavior to a superamphiphobic surface in water has been investigated. We demonstrated that the trapped air can tune the underwater wettability of the surface, changing from superoleophilic to superoleophobic. The trapped air in the grooves of the superamphiphobic surface can cause the significant change of the three-phase contact line (TCL).

A facile method to fabricate nano-architecture organosilane surfaces with tunable geometry is presented. By changing the water content of the reaction system, surface geometries with controlled shape, size and quantity are obtained. The corresponding wettability variation can vary from hydrophobic to superhydrophobic with the surface topography evolution.