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Separation and Purification Technology (13835866) 354
Janus membranes have asymmetric wettability on each side. This contrasting structure gives them an internal driving force for spontaneous fluid transport (caused by Laplace pressure). The objective of this research is to attain the maximum Laplace pressure for electrospun PVDF/PAN Janus membranes by adjusting the fiber diameter and, consequently, the pore size and contact angle in each layer of the membrane. To achieve this goal, the Taguchi method was employed, and the parameters of the electrospinning process were modified to determine the optimal conditions for obtaining the smallest and largest fiber diameters for PAN and PVDF polymers. Accordingly, four distinct types of Janus membranes with different morphologies in each layer were synthesized. SEM analysis was employed to characterize the structural and morphological properties of the fibers in each layer. Additionally, the contact angle (CA) was measured to assess the hydrophilicity of each layer and determine the droplet penetration rate across the membrane. According to the results, the maximum Laplace pressure (205.60 kPa calculated by the analysis of SEM images and 197.4 kPa calculated by the bubble point test) and highest droplet penetration rate (0.83 µL/s) were attributed to the Janus membrane with the lowest pore size in the hydrophilic layer (0.65 µm) and the highest pore size in the hydrophobic layer (3.44 µm). The performance of the optimized membrane was evaluated with respect to unidirectional water transport and water–oil mixture separation. The results showed a rectification ratio of 3.92, a permeate flux of 7.9 × 104 L·m−2·h−1·bar−1, and a separation efficiency of 96.8 %. Finally, it was demonstrated that the Laplace pressure of the optimal Janus membrane in this study is 2.66 times superior to that of the best similar one in previous studies. The appropriate and allowable range for pore size and contact angle, necessary to attain a satisfactory Laplace pressure (exceeding 100 kPa), has been explored, determined, and recommended for future researchers to foster inspiration in the field of Janus membranes. © 2024 Elsevier B.V.
Desalination and Water Treatment (19443994) 286pp. 16-28
An interpenetrating polymer network (IPN) membrane and its modified form with NaA zeolite were prepared using polyvinyl alcohol/polyacrylic acid and were used in desalination of saline solutions by pervaporation and reverse osmosis. The prepared membranes were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, tensile and swelling test. The effective parameters in the membrane preparation were investigated and optimized through experimental design. Then, Salt rejection and solution flux were selected as the criteria for the membrane performances. The pervaporation results showed that the flux increases with the feed temperature going up and the membrane thickness decrease. However, better rejection was achieved at less feed temperature and more membrane thickness. At the optimized conditions, flux 7.1 kg/h·m2 and rejection 99% were obtained by net IPN membrane while, these parameters were changed to 11.2 kg/h·m2 and up to 95% by IPN/NaA membrane. Reverse osmosis experiments revealed that as the pressure on the membrane increases, the amount of flux goes up, while it requires less pressure and more cross-linked membrane for having higher rejection (flux 16.2 kg/h·m2 and rejection 90%). According to the obtained results, it was found that this composite membrane has a high ability in desalination with appropriate rejection and fluxes. © 2023 Desalination Publications. All rights reserved.
Desalination and Water Treatment (19443994) 307pp. 18-29
Composite membranes consisting of PVA/PAA as interpenetrating polymer networks (IPN), along with various MOFs (MIL-101-Cr, Cu-BTC, UiO-66-NH2) or graphene oxide (GO), were synthesized using a sequential method. These membranes were designed for use in the pervaporation desali-nation of NaCl and MgCl2 salts. The membranes were characterized using swelling, contact angle, FTIR, tensile, and SEM tests, and the optimal preparation parameters were determined using an experiment design method. Subsequently, the optimal membranes were employed in the pervapo-ration desalination process, with salt rejection and fluxes serving as the pervaporation responses. The results showed that as the temperature of the feed increased, the water flux also increased. However, as the feed solution temperature and concentration increased, the salt rejection decreased. Under optimal conditions, the IPN/MIL-101-Cr membrane provided 15.19 and 14.59 kg/m2·h flux and 99.24% and 99.37% rejection for sodium and magnesium ions, respectively, while the GO/IPN membrane provided 13.65 and 12.98 kg/m2·h flux and 98.97% and 99.10% rejection for sodium and magnesium ions, respectively. These composite membranes also exhibited excellent performance in salt mixtures. Based on the experimental design results, preliminary evaluation tests, and comparison with other membranes, it can be concluded that the IPN/MIL-101-Cr composite membrane is highly effective for pervaporation desalination and has potential for industrial-scale applications. © 2023 Elsevier Inc.
High Performance Polymers (09540083) 34(4)pp. 377-387
New poly(amic-acid)s sorbents, bearing bipyridine chelating groups, were synthesized by reaction of benzophenonetetracarboxylic dianhydride (BTDA) with different percentages of 4,6-bis(4-aminophenyl)-2,2′-bipyridine (BAPB), and 1,4-phenylene diamine (PPD) and were characterized by FTIR and 1HNMR spectroscopies. Because of the imidization of these poly(amic-acid)s after about 10% weight loss, their thermal stability was raised to about 500°C. The glass transition temperatures of these polymers were in the range of 154–166°C. The sorption of Ni(II) by these sorbents from the aqueous solutions was investigated by varying different parameters such as the contact time, pH, and sorbent dosage. Results indicated that the optimum efficiencies of these sorbents toward Ni(II) were at 25°C, at pH = 4 and after about 75 min. According to the Langmuir equation, the maximum uptake capacity (qm) of PAA30/70 as a best sorbent for nickel was 14.66 mg.g−1. The modeling results confirmed the pseudo-second-order sorption for the metal ion. The morphology of these sorbents before and after sorption of Ni(II) was investigated using Scanning Electron Microscopy and the results confirmed the porous structure of these sorbents. (Figure presented.) © The Author(s) 2022.
Journal of the Turkish Chemical Society, Section A: Chemistry (21490120) (3)
In this study, zirconium phosphate was synthesized and modified with KH570 linker. It was then used to prepare several nanocomposites with different percent with poly (methyl methacrylate-co-N-2-methyl-4-nitro-phenylmaleimide) (Poly (MMA-co-MI)). The synthesized compounds were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM). The particles size and structure determining showed nanoparticle are sheet and about 9-20 nm. Thermal stability of these compounds were evaluated by thermogravimetric analysis (TGA). The results showed adding nanoparticles to copolymer increased starting weight lost about 20oC and finishing weight lost about 90oC. The results of differential scanning calorimetry (DSC), showed that adding nanoparticles decreased the glass transition temperatures (Tg) of the copolymer. The transparency of these nanocomposites were examined by ultraviolet–visible (UV–Vis) spectroscopy. The results showed the best transparency refer to nanocomposites 0.5 to 1% of nanoparticles. © 2022, Turkish Chemical Society. All rights reserved.
The Arabian Journal For Science And Engineering (2193567X) (6)
In this study, a new series of thermally stable polyamides and copolyamides are prepared through reaction of oxazolopyridine functional diamine, 2-(3,5-diaminophenyl) oxazolo [4,5-b] pyridine with four commercial dicarboxylic acids: pyridine 2,6-dicarboxylic acid, pyridine 2,5-dicarboxylic acid, 4,4′-dicarboxylic acid diphenyl sulfone and 4,4′-dicarboxylic acid diphenyl ether. The synthesized polymers were characterized by FT-IR and 1HNMR spectroscopy. The physical properties of the polymers including solubility and viscosity were studied. The results displayed good solubility, viscosity and high thermal stability. Their viscosities and glass transition temperatures are in the range of 0.66–0.73 and 170–200 °C, respectively. Thermal stabilities for 10% weight loss temperature are higher than 445–500 °C. © 2020, King Fahd University of Petroleum & Minerals.
Soft Materials (15394468) 17(1)pp. 41-56
Cross-linked polyvinyl alcohol/polyvinyl pyrrolidone/zeolite fibers were prepared in the presence of potassium peroxodisulphate (K 2 S 2 O 8 ) under the curing process by the electrospinning technique. The narrowest nanofibers of PVA/PVP (50:50) were prepared under optimum experimental conditions of 2.5 × 10 −4 mol of K 2 S 2 O 8 , an applied voltage of 22 KV, the distance of 15 cm and the feed rate of 0.2 mL/h. The progress of the cross-linking was examined by immersion of the prepared nanofibers in water and following the swelling degrees. By raising the K 2 S 2 O 8 amount and curing time, the cross-linking density was increased. X-ray diffraction (XRD) demonstrated that the crystallinity of the nanofibers was decreased by the increase of K 2 S 2 O 8 and the lowest crystallinity was observed for PVA/PVP (70:30). The contact angle of nanofibers was decreased from 72° to 34 by increasing PVP ratio from 30 to 70. The morphology of the nanofibers before and after immersion in the simulated body fluid (SBF) was studied using electron scanning microscopy (SEM) and PVA/PVP (70:30) showed the highest changes in the morphology while the lowest one was observed for PVA/PVP (50:50). Moreover, the cross-linked PVA/ PVP with the ratio of 50:50 had the narrowest diameter of 200 ± 100 nm, and by addition of about 0.5% zeolite, it was even reduced more to 150 ± 50 nm. The cross-linked nanofibers (50:50) with 0.5 wt% and 1.5 wt% zeolite nanoparticles showed the tensile modules of 416.26 and 703.52 MPa, respectively, while in the absence of zeolite, it was209.25 MPa. Fibroblast L929 cells were cultured on the cross-linked PVA/PVP/zeolite (50:50:0.5) nanofiber, and the cell proliferation and growth was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Fibroblasts grew on the surface of scaffold showed good morphology and proliferation after seven days and the absorption amount was increased from 0.075 to 0.78. © 2018, © 2018 Taylor & Francis Group, LLC.
Polymer Science - Series B (15600904) (2)
The paper presents the synthesis of a series of polyesters containing nitro-substituted phenyl azothiazole, azobenzothiazole and azobenzene chromophores and their characterization by 1H NMR, FTIR and UV–Vis spectroscopy. Also the solubility, glass transition temperatures, thermal stability of the synthesized polyesters as well as the surface morphology of thin films of the polyesters were studied. © 2018, Pleiades Publishing, Ltd.
Journal of Electroanalytical Chemistry (15726657)
In this paper, simple strategies for the modification of glassy carbon electrode (GCE) with iron-4″(phenyl)-2, 2″:6″, 2“-terpyridine complex (Fe-PTPY) and Fe-PTPY covalently bonded to ordered mesoporous carbon (OMC) are described. The Fe-PTPY/OMC modified GCE (Fe-PTPY/OMC/GCE) was prepared in a three steps strategy. In the first step, OMC modified GCE was prepared by simple casting. Then, PTPY ligand was attached directly to the electrode surface through electrochemical reduction of 4'(4aminophenyl)-2, 2':6', 2“-terpyridine (APTPY) diazonium salt. The modification was completed by iron attachment to the electrode surface through complex formation reaction with surface PTPY groups. The Fe-PTPY modified GCE (Fe-PTPY/GCE) was prepared in similar manner by omitting the first step of the above strategy. The reactions progress and the electrochemical behavior of the modified electrodes were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The modified electrodes showed good electrocatalytic activity for reduction of H2O2. Using hydrodynamic amperometry, under optimum conditions, calibration plots for H2O2 were linear in the ranges of 0.15–0.4 and 0.4–5.0 mM with slopes of 0.2743 and 0.2112 μA/mM on Fe-PTPY/GCE and 0.01–0.1 and 0.1–13.0 mM with slopes of 4.91 and 0.91 μA/mM on Fe-PTPY/OMC/GCE, respectively. © 2017 Elsevier B.V.
Chemical Engineering and Processing - Process Intensification (02552701) 118pp. 47-53
Mixed matrix membranes were prepared by uniformly dispersing of zeolite particles in a polyvinyl alcohol matrix. After membrane characterization, the ability of the prepared membranes was examined toward pervaporation dehydration of binary and ternary mixtures of acetone, isopropanol and water because of their industrial importance. The effect of different parameters on the membrane performance was investigated and the best conditions were obtained. The results showed that, NaA zeolite particles significantly improved the separation performance of the membranes. The selectivity was increased with an increase of zeolite loading up to 5% wt. The best results were obtained for dehydration of isopropyl alcohol where the separation factor was calculated as 1881. Based on the findings of the research, the incorporation of NaA zeolites into the polymer matrix can be very effective for dehydration of acetone and isopropanol. The results show that the prepared membrane can be a good candidate for removal of water in acetone production from isopropyl alcohol. © 2017 Elsevier B.V.
Polymer Bulletin (14362449) 72(11)pp. 2979-2990
A new copolymer was synthesized via reaction of new pyridine-containing dibromo compound, 2,6-bis(4-bromophenyl)-4-(naphthalen-1-yl) pyridine, with thiophene-based diboronic ester via Suzuki cross-coupling reactions. 2,6-Bis(4-bromophenyl)-4-(naphthalen-1-yl) pyridine was synthesized starting from condensation reactions of 4-bromoacetophenone and 1-naphthaldehyde. The synthesized monomer and polymer were characterized by FT-IR and NMR spectroscopy. The physical properties of the polymer, including solubility and viscosity were studied, and the results showed good solubility and chain growth for polymer. Maximum absorption peak for polymer was 388 nm. The optical band gap energy of the polymers was determined by absorption onset and found to be 2.38 eV for polymer. © 2015, Springer-Verlag Berlin Heidelberg.
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry (15205738) (4)
In this research, poly(vinyl butyral) (PVB)/single wall carbon nanotubes (SWCNT) composites were prepared via solution blending method. Dispersion degree of SWCNT in the composites was characterized by Scanning Electron Microscopy (SEM) and mechanical properties were measured with tensile testing. Thermal degradation of composites was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). SEM analysis confirmed good dispersion of the nanotubes in the PVB. The tensile tests showed significant increases in mechanical properties such as exceptional improvement in tensile strength, Young's modulus and flexibility for the composites compared to PVB at low SWCNT content.The TGA curves indicated that adding SWCNT improved the thermal stability of the PVB significantly and the degradation of the polymer matrix shifted to the higher temperatures. For the sample containing 0.6 wt%, an increase of 171% in modulus and a 258.4% enhancement of tensile strength were achieved. Also, elongation at break increased 28.7% at this loading. In fact, intrinsic properties of nanotubes caused enhancement of strength and flexibility simultaneously. Also, for this composite, Tonset and Tmax enhanced remarkably and weight loss reduced greatly and residue at 600°C increased to high values. These results are promising for application of the PVB in industry. © 2014 Copyright Taylor & Francis Group, LLC.
Journal of Applied Polymer Science (00218995) (13)
In this study, to investigate the effect of functionalized carbon nanotubes on the thermal and mechanical properties of the poly(vinyl butyral) (PVB) resin, PVB/functionalized single-walled carbon nanotube (f-SWCNT) composites were fabricated by a solution casting method. The functionalized nanotubes were prepared by acid treatment. The formation of oxygen-containing functional groups on the surface of the nanotubes was confirmed by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy (SEM) measurements. SEM analysis also showed that the nanotubes were dispersed well in the PVB matrix. The thermal stability of the composites were investigated with thermogravimetric analysis, and the results show better stability for PVB in the presence of a very low content of the f-SWCNTs. The prepared composites exhibited a significant increase in the temperature of degradation at 50 wt % loss and also in the onset temperature and decomposition temperature at the maximum rate of weight loss of butyral degradation. A significant enhancement in the mechanical properties was also achieved for these prepared composites. Copyright © 2014 Wiley Periodicals, Inc.
Designed Monomers and Polymers (15685551) 17(5)pp. 401-415
Two new copolymers, P1 and P2, composed of 4[4-(alkoxy)phenyl]-2, 6-bis(4-bromophenyl)pyridine and bithiophene units, have been synthesized via Suzuki cross-coupling reactions. 4[4-(alkoxy)phenyl]-2, 6-bis(4-bromophenyl)pyridines were synthesized starting from condensation reaction of 4-bromoacetophenone and 4-hydroxy benzaldehyde, and subsequent alkoxylation of hydroxyl groups. All of the polymers and intermediates were characterized using FTIR and NMR spectroscopies. The synthesized polymers exhibit good solubility in common organic solvents. The maximum absorption peak for P1 and P2 was 430 and 420 nm, respectively. The optical band gap energy of the polymers was determined by absorption onset and found to be 2.17 eV for P1 and 2.13 eV for P2. © 2013 Taylor & Francis.
Journal of Applied Polymer Science (10974628) (1)
Reversible addition-fragmentation chain transfer (RAFT) polymerization was performed in the presence of a new RAFT agent based on bisphenol A and modified clays and successfully prepared polystyrene/MMT nanocomposite. The structure of RAFT agent was investigated by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy ( 1H NMR). The polymer had well-defined molecular weight and narrow polydispersity obtained by gel permeation chromatography (GPC). The morphology of polystyrene/MMT nanocomposite was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and was found to be exfoliated. Thermal stability of pure polystyrene and polystyrene/MMT synthesized via RAFT polymerization was also investigated and showed better thermal stability for nanocomposite. Copyright © 2012 Wiley Periodicals, Inc.
Journal of Polymer Research (10229760) (10)
Poly (vinylbutyral) (PVB) was synthesized by condensation of poly (vinylalcohol) (PVA) with butyraldehyde. Nanocomposites of PVB with graphene (0.1 to 0.6 wt%) were prepared via solution blending. The structure and properties of prepared compounds were characterized by FT-IR, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile strength tester (TST). The prepared nanocomposites showed considerable thermal and mechanical properties than PVB and showed good toughness and flexibility. © 2012 Springer Science+Business Media B.V.
Designed Monomers and Polymers (15685551) (3)
A new thermally-stable second-order nonlinear optical polyimide with side-chain second-order nonlinear optical (NLO) chromophore was synthesized. First a diamine functionalized azo chromophore (9) was synthesized and then polymerized by reaction with 4,4′-hexafluro isopropylidene-diphthalic anhydride. The synthesized polymer had a glass transition temperature of 215°C. The corona poling process of the NLO-substituted polyimide was also studied in detail by measuring the second harmonic generation (SHG) from the polymer films. The second harmonic measurement indicate long-term stability of the dipole orientation (>500 h at 150°C) for this polyimide. © 2012 Koninklijke Brill NV, Leiden.
International Journal Of Polymer Science (16879422)
Polystyrene, PS, was grafted from poly(vinyl alcohol), PVA, backbone by reversible addition-fragmentation chain transfer (RAFT) polymerization. The hydroxyl groups of the PVA were converted into aromatic dithioester RAFT agent and polymerization began in the presence of this agent. The structure of compounds was confirmed by FT-IR and 1 HNMR spectroscopy. The graft copolymer was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Grafted polystyrene chains were cleaved from the PVA backbone by acidic hydrolysis of the PVA-g-PS, and its polydispersity index, PDI, was determined by gel permeation chromatography (GPC) showing narrow molecular weight distribution. Copyright © 2011 Gholam Ali Koohmareh et al.
International Journal Of Polymer Science (16879422)
The effects of titanate as a coupling agent and some particulate nanoscale particles such as TiO2, CaCO3, and ZnO on thermal and mechanical properties of emulsion polyvinylchloride (E-PVC) were investigated by thermogravimetric analysis (TGA), and mechanical tests. In this research, it was found that, in the presence of nanoparticles of CaCO3, TiO, and ZnO, the peak temperature of dehydrochlorination of E-PVC was shifted to higher temperatures, and the rate of mass loss was decreased. Also results of differential scanning calorimetry showed that the addition of nanoparticle of CaCO3, TiO2, and ZnO led to an increase in glass transition temperature. The impact strength, elastic modulus and toughness of the samples were enhanced after addition of 0-10 part of filer in hundred parts of resin (phr) nano-CaCO3, nano-TiO2, and nano-ZnO due to improvement of compatibility of the polymer and the nano-particles. Also UV and thermal stability of the samples were enhanced by means of the nanoparticles. It was found that, in the presence of titanate as coupling agent, content of additives that could be used in the composite of PVC shifts to higher amounts. Copyright © 2011 Morteza Hajian et al.
Designed Monomers and Polymers (15685551) (5)
A new series of polyamides and co-polyamides were synthesized via reaction of a newly synthesized bipyridine containing diamine, 4,6-bis(4-aminophenyl)-2, 2′-bipyridine, with commercial diacides. The synthesized polymers were characterized by FT-IR and 1H-NMR spectroscopy. The physical properties of the polymers including solubility and viscosity were studied and the results showed acceptable solubility and good chain growth for the polymers. Thermal stability of these polymers was also studied by thermogravimetric analysis (TGA). The polymers start to lose weight because of thermal degradation at about 350° C. From differential scanning calorimetry (DSC), the polymers showed a T g between 160 and 180° C. The morphology of these polymers was also investigated by X-ray diffraction (XRD) and the results showed good crystallinity. © 2011 Koninklijke Brill NV, Leiden.
Journal of Polymer Research (10229760) (5)
A new series of polyimides and copolyimides were synthesized via reaction of new bipyridine containing diamine, 4, 6-bis(4-aminophenyl)-2, 2′-bipyridine, with commercial dianhydrides. 4, 6-bis(4-aminophenyl)-2, 2′-bipyridine was synthesized starting from condensation reactions of 4-nitro acetophenone, 4-nitrobenzadehyde and pyridacyl pyridinium iodide (Kronke salt) and reduction of the desired dinitro compound. The synthesized monomer and polymers were characterized by FT-IR, NMR and CHN elemental analysis. The physical properties of the polymers, including solubility and viscosity were studied, and the results showed acceptable solubility and good chain growth for polymers. Thermal stability of these polymers was also studied by Thermo Gravimetric Analysis (TGA). The polymers start to lose weight because of thermal degradation at about 300 °C. From Differential Scanning Calorimetry (DSC), the polymers were showed Tg between 190 and 230 °C. The morphology of these polymers was also investigated by X-ray Diffraction (XRD), and the results showed only broad reflections originated from their low crystallinities. © 2010 Springer Science+Business Media B.V.
Journal of Applied Polymer Science (10974628) (6)
Polyvinyl butyral (PVB) was prepared by condensation reaction of butyral with polyvinyl alcohol (PVA) in aqueous phase containing an acid as a catalyst and an emulsifying agent. Properties of the polymer were a function of the relative amounts of the three randomly distributed units of acetal, acetate and vinyl alcohol groups, and the molecular weight. In this work, some effective factors in synthesis of PVB have been investigated by Taguchi method. The percent of the acetalization has been determined according to the ASTM D1396, and the polymer was characterized by IR, TG, and DTG techniques. © 2009 Wiley Periodicals, Inc.
Designed Monomers and Polymers (15685551) (2)
A new supramolecular polymer with isocyanate end-groups was synthesized by polymerization of coordination-type monomer (1), with excess bis(4-isocyanatophenyl)methane (MDI). This polymer was then end capped with terpyridine which can be more polymerized in treating with metal ions. The synthesized monomer and polymer were characterized with FT-IR, 1H-NMR and CHNS analysis. The physical properties of the polymer, including viscosity and solubility, were also examined. The coordination behavior of polymer was investigated by using Fe(II) and monitored by UV-Vis spectroscopy and viscometery to show the increasing in the length of the polymer backbone by addition of metal ions. © 2010 Koninklijke Brill NV, Leiden.
Journal of Applied Polymer Science (10974628) (1)
A maleimide functionalized terpyridine, 4′(4- maleimidophenyl)-2, 2′ : 6′, 2″-terpyridine, was synthesized and copolymerized with styrene via radical polymerization. The synthesized monomer was characterized by CHN elemental analysis, FT-IR, 1H NMR, and Mass spectrometry. The structure of polymer was also confirmed by FT-IR and UV-Vis spectroscopy. The resulting polymer was soluble in chloroform and polar aprotic solvents, and showed an inherent viscosity of 1.5 dL/g in N, N-dimethyl formamide at 25°C. The polymer solution in CHCl3/methanol showed a metal-ligand charge-transfer band of 586 nm upon addition of Fe(II) ion, exhibiting that coordination between terpyridine units and Fe(II) had occurred. The thermal stability of polymer before and after complexation with Fe(II) was examined by thermogravimetric analysis. For polymer before complexation, the weight loss started at 180°C whereas for complexed polymer it started at 260°C, which demonstrates good thermal stability of complexed polymer. © 2009 Wiley Periodicals, Inc.
Designed Monomers and Polymers (15685551) (6)
A new series of organo-soluble polyimides was synthesized by polycondensation of new a dianhydride, 4-(4-t-butyl-phenyl)-2,6-bis(3,4-phenyl dicarboxylic acid anhydride)pyridine (BPPDA) with available aromatic diamines via the conventional two-step method. The structures of the synthesized monomer and polymers were confirmed by FT-IR, NMR and elemental analysis. Thermal and solubility properties of resulting polymers were evaluated. The investigations showed that the polymers had high molecular weights and excellent thermal stability, as well as good solubility in common organic solvents. © 2007 VSP.
Designed Monomers and Polymers (15685551) (2)
A series of thermally stable poly(ether-imide)s (PEI1-16) bearing bulky aryl pendant groups were synthesized by nitro-displacement condensation of a new series of dinitrobisimide monomers, namely 4-aryl-2,6-bis[4-(3-nitrophtharimido)phenyl]pyridines (DNBI1-4), with commercially available aromatic diols (DO1-4). These dinitrobisimides were prepared from the reaction of 4-aryl-2,6-bis(4- aminophenyl)pyridines (DA1-4) and 3-nitrophthalic anhydride in N,N-dimethyl acetamide. A model compound was synthesized by reaction of DNBI1 with phenol in the presence of potassium carbonate in dimethyl formamide and the resulting bis(ether-imide) derivative was obtained in high yield. These polymers were characterized by FT-IR, 1H-NMR and elemental analysis, and their physical properties, including solution viscosity, solubility properties and thermal stabilities, were studied. The synthesized PEIs show excellent thermal stability and solubility in polar aprotic solvents.
Designed Monomers and Polymers (15685551) (3)
A series of new pyridine-containing diisocyanates bearing bulky aryl groups, 4-aryl-2,6-bis(4-isocyanatophenyl)pyridines (DIG1-3), was successfully synthesized by Weinstock modification of the Curtius rearrangement of the corresponding diacids, 4-aryl-2,6-bis(4-carboxyphenyl)pyridines (DA 1-3). These diisocyanates were fully characterized by FT-IR and NMR spectroscopy and were employed to synthesize a series of new polyureas by polycondensation with various aromatic diamines. The best synthetic approach was achieved by synthesis of a model compound via reaction of DIC1 with aniline in N-methyl 2-pyrrolidone (NMP) and in the presence of a catalytic amount of dibuthyltin dilurate (DBTDL). The synthesized polymers were characterized by 1H-NMR, FT-IR and elemental analysis, and physical properties, including solubility behavior, viscosity and thermal properties, were also studied. All polymers have an inherent viscosity in the range of 0.4-0.6 g/dl in DMSO at 30°C, which shows that these polymers have a high molecular weight.
European Polymer Journal (00143057) (8)
A new class of aromatic polyesters containing pyridine heterocyclic rings (PE1-15) was prepared via reactions of 4-aryl-2,6-bis(4- chlorocarbonyl phenyl) pyridines (DAC1-3) and commercial diols by high temperature solution polymerization method in o-dichlorobenzene and catalytic amount of triethylamine hydrochloride. The optimum condition of polymerization was obtained via study of a model compound prepared from reaction of 4-phenyl-2,6-bis(4-chlorocarbonylphenyl) pyridine (DAC1) and phenol. All polymers were characterized by FTIR and 1H-NMR spectroscopies, and their physical properties including solution viscosity, solubility properties, thermal stability and thermal behavior were studied. The prepared polyesters showed excellent thermal stability and good solubility in polar aprotic solvents. © 2004 Elsevier Ltd. All rights reserved.
Synthetic Communications (00397911) (1)
Aluminum trifluromethanesulfonate [Al(OTf)3] is a highly efficient and chemoselective catalyst for the thioacetalization of carbonyl compounds.
Phosphorus, Sulfur and Silicon and Related Elements (10426507)
2,3-Dichloro-5,6-dicyanobenzoquinone (DDQ) catalyses the addition of thiocyante ion to epoxides to afford β-hydroxy thiocyanates in high yields and regioselectivity.
