Bipyridine copper functionalized polymer resins as support materials for the aerobic oxidation of alcohols

Here, we report the first polymer resin supported Cu(I)/bipyridine/N ‐oxyl catalyst systems for the aerobic oxidation of alcohols at room temperature with ambient air. We chose polystyrene‐poly(ethylene glycol) copolymer (TentaGel®) and Merrifield resin as support materials because of their different swelling properties in polar and nonpolar solvents. The bromo functionalized TentaGel resin TG1 or Merrifield resin MR1 were functionalized with 4,4′‐dimethoxy‐2,2′‐bipyridine (^MeObpy) to give the ligand modified polymer resin TG2/MR2 that was loaded with Cu^I(Br) to give the final Cu^I(Br)/bipyridine support TG3/MR3. These resins were characterized by Fourier transform infrared, SEM, SEM energy dispersive X‐ray spectroscopy and elemental analysis. Catalytic activity and recyclability of TG3 was investigated in acetonitrile and cyclohexane and displayed high activities in acetonitrile but also high metal leaching. In cyclohexane as solvent leaching was reduced to 1% ? 2%, and catalytic activity was still at 75% after the fifth run. MR3 was consequently tested in cyclohexane and toluene. In both solvents low metal leaching was observed with higher activity in toluene as solvent, showing still over 90% conversion after the seventh run with 9‐azabicyclo[3.3.1]nonane N ‐oxyl (ABNO) and 80% with 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl (TEMPO). © 2016 Society of Chemical Industry     

Dispersivity of modified ZnO and characterization of polyurethane/ZnO composites

The properties of inorganic nanoparticles/polymer composites depend on the dispersivity of nanoparticles in a polymer matrix. The effect of surface modification on the dispersivity of ZnO nanoparticles in a polyurethane (PU) resin matrix was investigated. The nanocomposites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis, and X‐ray diffraction. The scanning electron micrographs show that ZnO nanoparticles (CDI–SA–APS–ZnO), which were modified by aminopropyltriethoxysilane (APS) and activated stearic acid (SA) by N,N′‐carbonyldiimidazole (CDI), can be homogeneously dispersed and had been encapsulated in the PU phase. The interfacial compatibility between ZnO nanoparticles and PU matrix was significantly improved by hydrophobically modifying ZnO nanoparticles with APS and SA. The tensile strength and elongation at break of PU/CDI–SA–APS–ZnO nanocomposites increased by 82 and 64% respectively, compared with the pure PU material. The thermal stability and ultraviolet‐shielding properties were also improved by incorporating ZnO nanoparticles into the PU matrix. POLYM. COMPOS., 35:237–244, 2014. © 2013 Society of Plastics Engineers     

Self‐crosslinkable lignin/epoxidized natural rubber composites

Self‐crosslinkable lignin/epoxidized natural rubber composites (SLEs) were prepared through a high‐temperature dynamic heat treatment procedure followed by a postcuring process. Because of the ring‐opening reaction between lignin and epoxidized natural rubber (ENR), lignin as a crosslinker and reinforcing filler was uniformly dispersed into the ENR matrix and was highly compatible with the polymer matrix; this was confirmed by scanning electron microscopy. The curing behavior, mechanical properties, and dynamic mechanical properties of the SLEs were studied. The results show that the crosslinking degree, glass‐transition temperature, modulus, and tensile properties of the SLEs substantially increased with the addition of lignin. A physical model was used to verify the strong interactions between lignin and ENR. Stress–strain curves and X‐ray diffraction suggested that the reinforcement effect on the SLEs mainly originated from lignin itself rather than from strain‐induced crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41166.     

Palladium Nanoparticles Immobilized on Nano‐Silica Triazine Dendritic Polymer (Pdnp‐nSTDP): An Efficient and Reusable Catalyst for Suzuki–Miyaura Cross‐Coupling and Heck Reactions

A new catalyst based on palladium nanoparticles immobilized on nano‐silica triazine dendritic polymer (Pd_np‐nSTDP) was synthesized and characterized by FT‐IR spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X‐ray, transmission electron microscopy and elemental analysis. The size of the palladium nanoparticles was determined to be 3.1±0.5 nm. This catalytic system showed high activity in the Suzuki–Miyaura cross‐coupling of aryl iodides, bromides and chlorides with arylboronic acids and also in the Heck reaction of these aryl halides with styrenes. These reactions were best performed in a dimethylformamide (DMF)/water mixture (1:3) in the presence of only 0.006 mol% and 0.01 mol% of the catalyst, respectively, under conventional conditions and microwave irradiation to afford the desired coupling products in high yields. The Pd_np‐nSTDP was also used as an efficient catalyst for the preparation of a series of star‐ and banana‐shaped compounds with a benzene, pyridine, pyrimidine or 1,3,5‐triazine unit as the central core. Moreover, the catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity.     

Initiation of surface graft polymerization by ceric ions on polymer microspheres

The surface graft polymerization of acrylamide on poly(styrene‐co‐acrylonitrile) copolymer microspheres by the initiation of ceric ions was studied. The grafting was verified by IR spectra and X‐ray photoelectron spectroscopy measurements. The resultant microspheres with surface‐grafted polymer chains were employed in the preparation of polymer‐microsphere‐supported palladium composite particles. The composite particles were then studied by transmission electron microscopy and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 936–940, 2003     

Vertically aligned carbon nanotube‐based composite: Elaboration and monitoring of the nanotubes alignment

We present the different elaboration steps of a composite formed of carbon nanotubes (CNT) carpet embedded in an epoxy polymer. Detailed characterization at each step of the elaboration process is performed. The good alignment of CNT in as‐grown carpets is kept all along the elaboration process of the composite, as it is measured at both macro and microscopic scales by X‐ray scattering. We also ensured by X‐ray fluorescence measurements that the iron‐based catalyst particles used for the synthesis were removed from the carpet after a high temperature post‐annealing treatment. These measurements give valuable information for further applications involving unidirectional nanotube composites and membranes, where CNT alignment is a key parameter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39730.     

Synthesis and analytical application of a chelating resin based on a crosslinked styrene/maleic acid copolymer for the extraction of trace‐metal ions

A new chelating polymer sorbent was synthesized through the copolymerization of styrene and maleic anhydride in the presence of divinyl benzene as the crosslinking agent, followed by hydrolysis. This polymeric resin, bearing O donor groups, had the advantage of being stable in basic and saline media, unlike its linear analogue. This newly developed chelating matrix has a high resin capacity for metal ions such as Cr, Fe, Ni, Cu, and Pb. Various physicochemical parameters, such as the pH, volume, and flow rate, and the interference effect on metal uptake were studied. The sorption capacities of the crosslinked resin for Cr(III), Fe(III), Ni(II), Cu(II), and Pb(II) were 10.2, 14.3, 14.2, 15.4, and 8.8 mg/g, respectively. A high recovery of 98% was obtained for all the metal ions with 2N HCl as the eluting agent. The chelating resin was characterized by swelling studies, Fourier transform infrared, elemental analysis, X‐ray studies, and thermal analysis. The Langmuir and Freundlich adsorption isotherms were used to validate the metal‐uptake data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1771–1779, 2004     

Thermo mechanical properties of organically modified halloysite nanotubes/cyclic olefin copolymer composite

This report deals with the development of unmodified and modified halloysite nanotube (HNT) based cyclic olefin copolymer (COC) composites. Maleic anhydride grafted polyethylene (MA‐g‐PE) has been used as a compatibilizer. Exfoliation of organically modified HNTs (mHNTs) and dispersion of it in polymer matrix was observed by X‐ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy analysis, respectively. Augmented dynamic mechanical and thermal properties of the composites were provided by incorporating mHNTs into the pure matrix. In this work, we have proposed that the modification of HNTs enhanced the dispersion and strong interfacial interaction which led to better performance of the composites where MA‐g‐PE acts as a bridging tool between polar clays and nonpolar COC. POLYM. COMPOS., 36:955–960, 2015. © 2014 Society of Plastics Engineers     

Mechanical and damping properties of epoxy/liquid rubber intercalating organic montmorillonite integration nanocomposites

Two different kinds of micro‐nanoconstrained damping structure units (M‐NCDSUs) were prepared by carboxyl‐terminated butadiene acrylonitrile copolymer and epoxy‐terminated butadiene acrylonitrile copolymer liquid rubbers intercalating organic montmorillonite, respectively. The prepared M‐NCDSUs were then blended with epoxy resin to obtain damping structure integration nanocomposites. The X‐ray diffraction and transmission electron microscope measurements applied for the obtained samples confirmed the good formation of M‐NCDSUs in the epoxy network. The tensile strength decreased slightly with the addition of M‐NCDSUs, whereas the damping properties measured by dynamic mechanical analysis showed a remarkable increase. Besides, the cured epoxy resin exhibited a two‐phase morphology where the spherical rubber phase dispersed uniformly in the epoxy matrix. The nanocomposites containing M‐NCDSUs showed superior comprehensive properties compared with that without the functional units. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39797.     

Acid‐Free Nickel Catalyst for Stereo‐ and Regioselective Hydrophosphorylation of Alkynes: Synthetic Procedure and Combined Experimental and Theoretical Mechanistic Study

The nickel catalyst prepared in situ from nickel bis(acetylacetonate) [Ni(acac)₂] precursor and bis(diphenylphosphino)ethane (DPPE) ligand has shown excellent performance in the hydrophosphorylation of alkynes. Markovnikov‐type regioselective addition to terminal alkynes and stereoselective addition to internal alkynes were carried out with high selectivity without an acidic co‐catalyst (in contrast to the palladium/acid catalytic system). Various H‐phosphonates and alkynes reacted smoothly in the developed catalytic system with up to 99% yield. The mechanisms of catalyst activation and C P bond formation were revealed by experimental (NMR, ESI‐MS, X‐ray) and theoretical (density functional calculations) studies. Two different pathways of the alkyne insertion in the coordination sphere of the metal are reported for the first time.     

Polymer/metal interpenetrating phase composites prepared via γ‐ray initiated in‐situ emulsion polymerization

The poly(methylmethacrylate)/metal and poly(butylacrylate‐co‐styrene)/metal interpenetrating phase composites (IPCs) were prepared via γ‐ray irradiation in‐situ bulk and emulsion polymerization, respectively. The monomers were first introduced into open‐cell aluminum foam and aluminum alloy foam and were in‐situ polymerized by γ‐ray irradiation at room temperature. The characterization and compressive test results showed that this method expands the variety of the polymer component resulting in a useful range of physical properties of the IPCs, such as density and porosity. The PMMA/metal IPC has a high polymer filling ratio, modulus and exhibits a similar compressive behavior to that of PMMA. On the other hand, the P(BA‐co‐St)/metal IPC has a relatively low polymer filling ratio and its compressive behavior is similar to that of metal foam matrix, but it has wider plastic plateau than the component metal foams, like the case of metal foam filled with rubber. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Single‐stage Treatment in Selective Hydrogenation of Acetylene over CDS Type of Pd‐Ag/Al2O3 Catalyst

The (computer designed shape) CDS type of Pd‐Ag/Al₂O₃ catalyst in single‐stage reactor provides superior catalytic activity and selectivity of ethylene in comparison with those of existed two‐stage reactors packed with G‐58B catalyst under industrial operating conditions. In this research, the contents of palladium and silver of catalysts were analyzed by inductive coupling plasma (ICP). The X‐ray photoelectron spectroscopy (XPS) showed that Pd‐Ag alloy has been formed. Higher yield of ethylene may be interpreted by both geometric and electronic effect induced from silver metal. By means of Pyrolysis/GC/MS analysis of used catalysts, the components of carbonaceous deposits were found to be n‐alkenes, including n‐C8 ～ n‐C16 or n‐C18, which may result from oligomerization of acetylene.     

Regioselective Heck Reaction of N‐Vinylphthalimide: A General Strategy for the Synthesis of (E)‐N‐Styrylphthalimides and Phenethylamines

The arylation of N‐vinylphthalimide takes place at the β‐position with aryl iodides, bromides and chlorides using palladium acetate [Pd(OAc)₂] or phenone oxime‐derived palladacycles as catalysts under phosphine‐free conditions. The reaction is succesfully carried out in organic solvents, such as DMF, in the presence of an organic base, such as dicyclohexylmethylamine, and with TBAB as additive at 120 °C under conventional or microwave heating. (E)‐N‐Styrylphthalimides are mainly obtained using a rather low palladium loading (0.05–1 mol%). Similar catalytic efficiency is observed using a Kaiser oxime resin‐derived palladacycle, which allows reuse of the polymeric complex for three cycles. The high regioselectivity observed supports that these palladacycles work as a source of Pd(0) species operating mainly through a neutral mechanism. The syntheses of 2‐thienylphenethylamine and mescaline have been performed by subsequent hydrogenation with Wilkinson’s catalyst and hydrazinolysis.     

Efficient Palladium‐Catalyzed Double Arylation of Phosphonoalkynes and Diarylalkynes in Water: Use of a Dinuclear Palladium(I) Catalyst

A novel use of the dinuclear palladium(I) catalyst [(OCH₂CMe₂CH₂O)P‐S‐Pd(PPh₃)]₂ in aqueous medium for the double arylation of phosphonoalkynes as well as diarylalkynes is reported. This double arylation requires both the iodoarene and arylboronic acid along with the catalyst. The structures of some key products have been proven by X‐ray crystallography.     

Crystallization behavior of ultrahigh‐molecular‐weight polyethylene/polyhedral oligomeric silsesquioxane nanocomposites prepared by ethylene in situ polymerization

A [3‐t‐Bu‐2‐O? C₆H₃CH?N(C₆F₅)]₂TiCl₂ catalyst (bis(phenoxyimine)titanium dichloride complex – FI catalyst) was immobilized on disilanolisobutyl polyhedral oligomeric silsesquioxane (OH‐POSS) to prepare ultrahigh molecular‐weight polyethylene (UHMWPE)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites during ethylene in situ polymerization. The dispersion state of POSS in the UHMWPE matrix was characterized by X‐ray diffraction measurements and transmission electron microscopy. It was shown that the OH‐POSS achieved uniformed dispersion in the UHMWPE matrix, although its polarity was unmatched. The isothermal and nonisothermal crystallization behavior of the nanocomposites was investigated by means of differential scanning calorimetry. The crystallization rate of the nanocomposites was enhanced because of the incorporation of POSS during the isothermal crystallization. POSS acted as a nucleus for the initial nucleation and the subsequent growth of the crystallites. For nonisothermal studies, POSS showed an increase in the crystallinity. The crystallization rate of the nanocomposites decreased because the presence of POSS hindered the crystal growth. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40847.     

Mechanical,electrical, and dielectric properties of polyvinylidene fluoride/short carbon fiber composites with low‐electrical percolation threshold

In this investigation, polyvinylidene fluoride (PVDF)/short carbon fiber (SCF) composites have been prepared by solution casting technique to enhance electrical and dielectric properties with very low‐electrical percolation threshold (0.5 phr SCF). The effect of SCF content on mechanical, thermal and morphological properties of the composites have also been investigated. The mechanical properties of the composites are found to reduce compared to neat PVDF due to poor polymer–filler interaction which can be concluded from FESEM micrographs showing poor bonding between PVDF and SCF. The PVDF/SCF composites exhibit either positive temperature coefficient effect of resistivity or negative temperature coefficient effect of resistivity depending on the loading of SCF in the polymer matrix. The change in conductivity during heating–cooling cycle for these composites shows electrical hysteresis along with electrical set. The melting point of the composites marginally increases with the increase in fiber loading in PVDF matrix as evidenced from DSC thermograms. X‐ray diffraction analysis reveals the crystallinity of PVDF decreases with the increase in SCF loading in matrix polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39866.     

Suzuki Coupling Reactions in Pure Water Catalyzed by Supported Palladium – Relevance of the Surface Polarity of the Support

Heterogeneous (supported) palladium catalysts like palladium on carbon and a variety of metal oxides have been shown to be highly active for Suzuki coupling reactions in neat water under mild reaction conditions (T=65 °C). It has been demonstrated for the first time that hydrophobic effects of the catalyst surface play an important role for the catalyst activity in water. Catalysts possessing hydrophobic surfaces (e.g., palladium on carbon) show higher activity for Suzuki coupling reactions in water than their hydrophilic counterparts (palladium on metal oxides). Tuning of the surface polarity of metal oxide supports (by silylation) results in higher activity under these conditions. Stronger alkaline conditions (three‐fold excess of base) compensate the effect of hydrophobic supports and result in high activity of the catalysts also with hydrophilic supports. The addition of tetrabutylammonium bromide to generate, activate and stabilize the catalytic species (dissolved palladium complexes) is necessary for the conversion of more demanding substrates. The reaction is considered to be homogeneous taking place near the catalyst surface inside a droplet or layer of the reactant.     

EVA nanocomposites based on South African Koppies clay

South African Koppies bentonite was organomodified with single‐tail and double‐tail alkyl ammonium cationic surfactants with the latter intercalated both below and above the clay cationic exchange capacity. Corresponding poly(ethylene‐co‐vinylacetate) nanocomposites were prepared by twin‐screw melt compounding. Transmission electron microscopy indicated the presence of mixed nano‐sized and micron‐sized clay morphologies. X‐ray diffraction studies revealed that the crystallinity of the particles improved and that the d‐spacing values increased on incorporating the clays in the polymer matrix. It is postulated that, rather than indicating polymer co‐intercalation, this is caused by further intercalation of either excess surfactants or surfactant residues that were released by shear delamination of the clays during compounding. Improved mechanical properties were realized especially when using the clay containing the longer double‐tail surfactant intercalated at levels in excess of the cation exchange capacity of the clay. The nanocomposites showed improved tensile modulus and elongation‐at‐break values at the expense of a reduction in impact strength, whereas tensile strength was about the same as for the neat polymer. J. VINYL ADDIT. TECHNOL., 20:143–151, 2014. © 2014 Society of Plastics Engineers     

Effect of pressure on the structure and electrical conductivity of cardanol–furfural–polyaniline blends

Pressure‐sensitive polymers that simultaneously present reasonable electrical conducting properties, useful thermosetting behavior, and softness are hard to develop. To combine these properties into a single material, a cardanol‐based phenolic resin was prepared and blended in situ with polyaniline (PAni). The final polymer blend was composed of a soft solid material that could not be dissolved in ordinary solvents. Samples were characterized through X‐ray scattering, Fourier transform infrared (FTIR) spectroscopy, and electrical conductivity and pressure sensitivity measurements. FTIR results indicate that the insertion of PAni into the blends did not change the chemical nature of the resin. According to wide‐angle X‐ray scattering results, PAni was dispersed homogeneously in the final polymer samples; this improved the sensitivity of the electrical conductivity to pressure variations, as confirmed through electromechanical tests. Pressure sensitivity and electromechanical analyses indicated that the produced blends could be used as pressure‐sensing materials. Among the tested materials, the blends containing 5 wt % PAni·H₂SO₄ presented the largest compression sensitivity values. Finally, it was shown for the first time through XRD analyses under pressure that PAni chains were considerably disturbed by compressive stresses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Triphase catalysis: Hydroxylation of cyclo‐octane by NaOCl catalyzed by coordinatively bound manganese(III) porphyrin to nitrogen‐based polymer supports

The anionic manganese (III) porphyrin was immobilized onto crosslinked poly(benzylpicoline‐co‐styrene) resin through coordinate linkage. The immobilized metalloporphyrin was employed as a heterogeneous catalyst for the hydroxylation of cyclo‐octane by NaOCl. The observed reaction rates depend on experimental parameters such as stirring speed, substrate amount, temperature, and catalyst amount. The influence of different polymer‐based axial ligands, particle size, and percent crosslinking of the polymer support was also discussed. The imidazole‐based polymer supports show higher rate constant values than the pyridine‐based supports. The catalyst shows significant decrease in catalytic activity on recycling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 104–111, 2000