Synthesis and characterization of hybrid organic–inorganic materials based on sulphonated polyamideimide and silica

The preparation of hybrid organic–inorganic membrane materials based on a sulphonated polyamideimide resin and silica filler has been studied. The method allows the sol–gel process to proceed in the presence of a high molecular weight polyamideimide, resulting in well dispersed silica nanoparticles (<50 nm) within the polymer matrix with chemical bonding between the organic and inorganic phases. Tetraethoxysilane (TEOS) was used as the silica precursor and the organosilicate networks were bonded to the polymer matrix via a coupling agent aminopropyltriethoxysilane (APTrEOS). The structure and properties of these hybrid materials were characterized via a range of techniques including FTIR, TGA, DSC, SEM and contact angle analysis. It was found that the compatibility between organic and inorganic phases has been greatly enhanced by the incorporation of APTrEOS. The thermal stability and hydrophilic properties of hybrid materials have also been significantly improved.     

Synthesis and properties of novel donor–acceptor copolymers based on thiophene and squaraine moieties

Two novel donor–acceptor copolymers were synthesized by Sonogashira cross-coupling of alkyl/alkoxy thiophene and dibromo-substituted squaraine moieties. The structures and properties of these polymers were characterized using FT–IR, NMR, UV–Vis, gel permeation chromatography, and cyclic voltammetry. Both copolymers are readily soluble in common organic solvents. The polymer films exhibit broad absorption in the wavelength range from 300 to 1000 nm with the maximum peaks over 750 nm. Electrochemical studies reveal that the band gaps of the polymers range from 1.05 to 1.36 eV. Compared to the alkyl thiophene, the alkoxy thiophene units can effectively lower the band gap and result in significant red-shift absorption spectrum of the resulted polymer. The strong overlap of the solar spectrum and the extremely low band gaps of the polymers suggest that they may be promising candidates for solar cells.     

Synthesis and characterization of homo- and heterometallic metal–organic frameworks based on 1,2,4,5-benzenetetracarboxylate ligand

Two new three-dimensional metal–organic frameworks, [H₂N(CH₃)₂]₂[Zn(btec)]·DMF (1, H₄btec = 1,2,4,5-benzenetetracarboxylate acid) and [H₂N(CH₃)₂][ZnLi(btec)]·DMF (2), have been solvothermally synthesized and structurally characterized by single crystal X-ray diffraction. Compound 1 based on μ₄-btec features an anionic homometallic framework with 4-connected pts topology. Compound 2 is a heterometallic organic framework with rare (4, 4, 8)-connected network topology, which can be considered as constitute of a Li-btec (pts) net and a Zn-btec net. Moreover, the luminescent properties of two compounds are investigated in the solid state at room temperature.     

Synthesis and photoluminescent properties of four novel trinuclear europium complexes based on two tris-β-diketones ligands

Four novel trinuclear europium complexes with two tris-β-diketones ligands have been synthesized, and the chemical structures of ligands and complexes were characterized by FT-IR, UV-vis, ¹H NMR, ¹³C NMR, XRD, ESI-MS, and element analysis. The potoluminescent properties of trinuclear complexes in solid and THF solution were investigated. All trinuclear complexes exhibited strong relative luminescent intensity and long luminescent lifetime. Meanwhile, the results of lifetime decay curves indicated that only one chemical environment existed around the europium ion. The intrinsic luminescent quantum yields (Φ_LN) and experimental intensity parameters of trinuclear complexes were obtained based on the emission spectra and luminescent lifetime of ⁵D₀ excited state for europium ion. All trinuclear europium complexes exhibited relative high intrinsic luminescent yield and intensity parameters. Especially, due to the contribution of addition two europium lumophors in trinuclear europium complexes, the trinuclear complexes containing TTA exhibited much longer lifetime and higher intrinsic quantum yield than mononuclear europium complex Eu(TTA)₃phen.     

Synthesis and characterization of conducting polymer composites based on polyaniline–polyethylene glycol–zinc sulfide system

Hybrid semiconducting polymer composites containing polyaniline, polyethylene glycol and zinc sulfide have been prepared in various combinations by in-situ polymerization of aniline using ammonium per disulfate in acidic medium. A biomimetic approach of controlled precipitation has been used. A mechanism of formation of these hybrid materials has been suggested in which polyethylene glycol works as a medium for diffusion-limited growth of various components during their precipitation. These materials have been characterized by a variety of spectroscopic techniques, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and alternating current impedance spectroscopy. Equivalent circuits for different contributions from grain, grain boundary and electrode for different systems have been determined with the help of complex non-linear least square analysis software. The microstructure-property correlation have been discussed along with the possible conduction mechanisms from the temperature dependence of conductivity as variable-dimension variable-range hopping for different compositions of single, double and triple composite materials.     

Synthesis and characterization of composites based on polyaniline and styrene–divinylbenzene copolymer using benzoyl peroxide as oxidant agent

This work presents a method to prepare composites based on polyaniline (Pani) and styrene–divinylbenzene copolymers (SD) by in situ polymerization of aniline using benzoyl peroxide as oxidant agent. The composites were obtained from copolymers with two degrees of porosities which have higher and lower surface areas. Emeraldine Pani was prepared using hydrochloric acid as dopant. One cycle or four cycles of aniline polymerization were performed. The copolymers and their respective composites characterizations were performed by infrared spectroscopy, thermogravimetric analysis, physical nitrogen adsorption–desorption measurements, morphology analysis, elemental analysis and determination of Brönsted acid sites. The Pani was distributed overall porous SD copolymer producing composites with high surface area. Then, they were evaluated as catalysts for esterification reaction of a fat acid. It was found that that composites prepared with four cycles of in situ polymerization presented best catalytic activity than one cycle composites.     

Synthesis,structure and magnetic property of a Gd–Mn coordination polymer based on 2,3,5-pyrazinetricarboxylate

A new three-dimensional lanthanide–manganese metal–organic framework [Gd₂Mn₃(PZTC)₄(H₂O)₁₂]·5H₂O (PZTC = 2,3,5-Pyrazinetricarboxylate) has been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, and X-ray diffraction. Single-crystal X-ray diffraction shows that Gd^3 + and Mn^2 + ions are linked together to form a porous 3D Gd–Mn MOF by the alternative arrangement of two kinds of PZTC^3 − ligands. Taking the Gd, Mn and PZTC as node, the Schläfli symbol of the topology can be expressed as {4;8²}₂{4²;6}₂{4²;8⁴}₂{4³;6;8⁴;10²}₂{8}. Magnetic study indicates the magnetic coupling between two Mn^2 + ions through double monatomic carboxylate–oxo bridges is weak antiferromagnetic, while that between Gd^3 + and Mn^2 + ions through the carboxylate group in syn–anti-bridging mode is negligible.     

Mass transfer characterization for hydrocarbon liquid–particle collision based on sensitive tracing of fluorescent probe

The heat and mass transfer characteristics during the collision process of hydrocarbon droplets and polyethylene particles in a liquid-containing gas–solid polyethylene fluidized bed reactor significantly affect the product quality. In this work, the mass transfer process of single-component hydrocarbon and bi-component hydrocarbon liquid films on the polyethylene particle surface were quantitatively characterized by a newly developed experimental approach, based on a novel synthesized hydrocarbon liquid soluble fluorescent probe for sensitive tracing of hydrocarbon liquid diffusion. It was found that the boiling point and surface tension of the liquid as well as the surface temperature of the particle are the key factors affecting the mass transfer properties of the liquid film. Marangoni convection was observed and characterized on the particle surface. The critical time for the onset of Marangoni flow is between 4 and 8 s.     

Synthesis of secondary amine-based fluorescent porous organic polymers via Friedel–Crafts polymerization reaction for adsorbing and fluorescent sensing iodine

We present the preparation and characterization of a novel class of secondary amine-based porous organic polymers (POPs: TDPA and TTPBTA), and their iodine adsorption, fluorescence sensing properties for the first time. Two secondary amine-based POPs were synthetized by Friedel−Crafts polymerization reaction catalyzed via methylsulfonic acid with yields of 22.51 and 54.44%. The thermal stability of resulting POPs run up to above 268 and 568°C, and their BET specific surface areas are 56.5 and 2.49 m² g⁻¹, respectively. Their iodine adsorption and fluorescent sensing properties are comparable to that of triphenylamine (TPA)-based (tertiary amine) POPs. The resulting POPs display excellent sorption abilities to iodine molecules with the iodine adsorption capacity of about 3.93 and 1.64 g g⁻¹. Adsorbed iodine is easily desorbed by heating or washing with organic solvents, which make them reusable. They can also adsorb iodine from cyclohexane solution. Moreover, the POPs possess excellent fluorescent sensing property for I₂ with Ksv of 1.85 × 10⁴ and 6.56 × 10⁴ L mol⁻¹, as well as the limits of detection (LODs) of 1.62 × 10⁻¹¹ and 6.86 × 10⁻¹² mol L⁻¹. The performance of adsorbing and fluorescence sensing iodine can be explained by electron transfer mechanism.     

Ignition of droplets of coal–water–oil mixtures based on coke and semicoke

To permit expansion of the resource base and utilize industrial waste, coal–water–oil fuels may be prepared on the basis of coke and semicoke, as well as common petroleum derivatives (fuel oil and spent compressor, turbine, and transformer oils). The minimal oxidant temperature corresponding to stable ignition of coal–water–oil slurries is established. Typical variation in fuel temperature in the course of reaction is determined, as well as the delay time of ignition and the total combustion time for individual droplets of such fuel suspensions. For droplets of initial size 0.5–1.5 mm, the influence of the various factors (droplet size, oxidant temperature, and concentration of the components) on the threshold (minimum) temperature and inertia of ignition is studied. It is shown that stable ignition of coke and semicoke in such fuel is possible at moderate oxidant temperatures: 700–1000 K.     

Porous membrane based on chitosan–SiO2 for coin cell proton battery

Porous chitosan–SiO₂ membranes were prepared by ultrasonic mixing solution-cast and porogen removal method at different SiO₂ weight ratios. To remove SiO₂ from chitosan membranes, NaOH solution was used to dissolve SiO₂. Porous chitosan:SiO₂ membrane with the weight ratio 1:2 produced optimum average pore size (8.5 μm) with an amorphous structure and the highest water uptake (257.1%). Further soaking of this membrane in NH₄CH₃COO electrolyte solution for two days produced the highest conductivity (3.6×10⁻³ S cm⁻¹) and optimum breakdown voltage (1.8 V). Fabrication of coin cell proton battery displayed an open circuit potential of 1.5 V for 7 days, maximum power density (6.7 mW cm⁻²) and small current resistance (0.03 Ω). The specific discharge capacities obtained from discharge profile of 39.7 mA h g⁻¹ (0.5 mA) and 43.8 mA h g⁻¹ (1.0 mA) increased as the discharge currents were increased. These results showed that a porous chitosan–SiO₂ membrane is suitable membrane for the proton batteries.     

Synthesis and characteristics of fly ash and bottom ash based geopolymers–A comparative study

The research was carried out to develop geopolymers mortars and concrete from fly ash and bottom ash and compare the characteristics deriving from either of these products. The mortars were produced by mixing the ashes with sodium silicate and sodium hydroxide as activator solution. After curing and drying, the bulk density, apparent density and porosity, of geopolymer samples were evaluated. The microstructure, phase composition and thermal behavior of geopolymer samples were characterized by scanning electron microscopy, XRD and TGA-DTA analysis respectively. FTIR analysis revealed higher degree of reaction in bottom ash based geopolymer. Mechanical characterization shows, geopolymer processed from fly ash having a compressive strength 61.4 MPa and Young's modulus of 2.9 GPa, whereas bottom ash geopolymer shows a compressive strength up to 55.2 MPa and Young's modulus of 2.8 GPa. The mechanical characterization depicts that bottom ash geopolymers are almost equally viable as fly ash geopolymer. Thermal conductivity analysis reveals that fly ash geopolymer shows lower thermal conductivity of 0.58 W/mK compared to bottom ash geopolymer 0.85 W/mK.     

Synthesis,structure and unprecedented self-assembly strategy of two six-membered Zn–organic macrocycles

Two novel cyclohexane-like metallamacrocycles [ZnCH₃COO(L)]₆·solvent (1) and [Zn(HNO₃)(L)]₆·solvent (2) (HL = 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine) have been synthesized under hydrothermal conditions and characterized by IR spectra, single crystal X-ray diffraction, PXRD analysis, thermogravimetric analysis. The X-ray single crystal diffraction indicates that the self-assembly of the metallamacrocycle generates a fused-ring network that is further assembled into a 3D structure with 1D suprachannels. In particular, a designed self-assembly strategy has been applied to achieving six-membered Zn–organic metallamacrocycles unprecedentedly.     

Novel nanocomposites based on reactive organoclay of l-tyrosine and amine end-capped poly(amide–imide): Synthesis and characterization

In the present study, a series of nanocomposite materials were successfully prepared using a poly(amide–imide) (PAI) matrix and novel reactive organoclay as a reinforcing agent. The organoclay was synthesized from Cloisite Na⁺ and protonated form of l-tyrosine amino acid via ion-exchange reaction. It was confirmed by Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetry analysis techniques. An optically active PAI was synthesized via solution polycondensation reaction of N,N′-(pyromellitoyl)-bis-phenylalanine diacid chloride and 4,4′-diaminodiphenylether. Then it was end-capped with amine end groups near the completion of the reaction to interact chemically with organoclay. Organoclay/PAI nanocomposite films containing different amounts of organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The nanostructures and properties of the organoclay/PAI hybrids were investigated using different techniques. Thermogravimetry analysis results indicated that the addition of organoclay into the PAI matrix increased the thermal decomposition temperatures of the resulting hybrid materials. The presence of amino acids as a biodegradable segment in both novel organoclay and optically active PAI, made the resulting nanostructure materials susceptible for biodegradation.     

Polyaniline Coating on Iron–Synthesis and Characterization

Protective coating has been used widely for metal corrosion control. Polyaniline (PANi) films can be electrosynthesized by oxidation of aniline on a metal surface from an aqueous acid medium. In this study, an iron surface was coated by polyaniline thin film. While iron easily oxidizes in acid solutions, the electropolymerization reactions were carried out in dilute acidic media. Rust, fats, etc. on the surface of iron were removed by alkali-ethanol solution, dichloroethylene, and, finally, hydrochloride (HCl) solution (10%), respectively. Coating was carried out in different potential (1.0, 1.5, and 2.5 V). To observe the effect of elemental contents of iron samples, spectral analysis also was taken before electropolymerization. Especially, effects of chromium and nickel elements were investigated. Physical resistance of the coating was examined by “band test.” Dissolving and defective coatings were also tested in acidic solutions and common organic solvents. In addition, to observe the morphology of coating, photos of samples were taken by scanning electron microscope (SEM) and metal microscope (MM).     

Alternating copolymers based on 1-methylpyrrole and thiophene – synthesis and electrochemical studies

The synthesis and electrochemical polymerisation behaviour of a series of monomers containing 1-methylpyrrole and thiophene is reported. These monomers provide copolymers of well defined monomer sequence in the backbone. Received: 30 October 1997/Revised version: 26 November 1997/Accepted: 27 November 1997     

Preparation and anti-evaporation properties of organic–inorganic superabsorbent based on Tragacanth gum and clay

In this study, the application of superabsorbent resin (SAP) in inhibiting the soil moisture evaporation (or slowing down the water outflow) was studied. The clay-SAP composites were fabricated by grafting of poly (acrylic acid-N-hydroxymethyl acrylamide/clay) (GT-g-P [AA-co-NHA]/clay) on Tragacanth gum (GT), using solution polymerization. The structure, morphology and stability of the clay-SAP composites were investigated by Fourier transform infrared, scanning electron microscope and TGA. The maximum swelling ratio of Attapulgite (3%)-, Kaolin (3%)- and Montmorillonite (3%)-SAP composite in deionized water reached 1180, 819 and 525 g/g respectively, and the maximum swelling ratio in tap water reached up to 206, 192 and 170 g/g respectively. Meanwhile, the maximum swelling ratio in 0.9% NaCl solution was 95, 82 and 62 g/g respectively. The water retention of clay-SAP composites was also analyzed as a function of temperature. In addition, by simulating the desertification area, the effect of the APT (3%)-SAP composite on the anti-evaporation performance was studied. The obtained results revealed that the water retention of APT (3%)-SAP composite was 36% at 45°C for 12 h. Under natural conditions, the evaporation rate of the anti-evaporation material was inversely proportional to the amount of APT (3%)-SAP composite added.     

Preparation and properties of ferrimagnetic glass–ceramic foams based on pyrite slag

By employing a melt-sintering method, we prepared a new type of ferrimagnetic glass–ceramic foam (FGCF) using ferrimagnetic glass–ceramic and foaming agent SrCO₃. The ferrimagnetic glass–ceramics were fabricated based on pyrite slag by a melt-quenching method. The effects of foaming agent content, sintering temperature and time on microstructure, magnetic properties, microwave absorption performance, compressive strength, and thermal conductivity of the as-obtained FGCF were analyzed. This foaming process at 1100°C for 40 min with 3-wt% SrCO₃ provided an FGCF with a bulk density of .693 g/cm³, a porosity of 63.60%, a specific saturation magnetic moment of 5.2 A m²/kg, a compressive strength of 2.61 MPa, a thermal conductivity of .241 W/(m K), and the calculated reflection loss of −12.1 dB for a layer thickness of 9 mm.