Recent advances in the preparation of functionalized polysulfones

This review summarizes the studies related to chemical functionalization of polysulfones used in many different applications such as membranes with special functions, nanocomposites, biofilm formation, fuel cells etc. reported in recent years from the literature since 2000. Various strategies have been applied for the functionalization of polysulfones. One strategy is to add desired functionality into starting monomers in the solution containing the main components of commercial polysulfones, the aromatic dihalide sulfone and bisphenol monomers, or to functionalize the related monomers before the condensation. Another approach is to form difunctional polysulfone oligomers. Then, functional groups can be utilized to react with monomers or other polymers to obtain functional polymers or block copolymers. The most applied method is post‐modification of commercially available polysulfones by incorporation of functional groups to their aromatic groups and their use in the formation of graft polymers or polysulfone‐based networks. © 2013 Society of Chemical Industry     

Electrorheological properties of kaolinite,polyindole, and polyindole/kaolinite composite suspensions

In this study, polyindole (PIN) and polyindole/kaolinite (PIN/KAO) composite were synthesized by free radical polymerization using FeCl₃ as an initiator. Average particle sizes (d₅₀) of PIN and PIN/KAO composite were determined by dynamic light scattering (DLS) as 7.2 and 6.2 μm, respectively. The samples were characterized by FTIR, elemental analysis, DSC/TGA and SEM measurements. Suspensions of KAO, PIN, and PIN/KAO composite were prepared in silicone oil (SO) and the sedimentation stabilities were determined. Electrorheological (ER) properties of these suspensions were studied as a function of dispersed phase concentration, shear rate, shear stress, and temperature; and yield stresses and excess shear stresses determined. Further, dielectric properties of KAO, PIN, and PIN/KAO composite were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis, characterization, and cyclopolymerization of a functional non-symmetric divinyl monomer

A non-symmetric divinyl monomer with terminal carboxylic acid functionality was readily synthesized from the reaction of ethyl α-hydroxymethylacrylate (EHMA) with maleic anhydride. The new monomer (EHMA-MA) was homopolymerized in both bulk and ethyl acetate using AIBN as an initiator to give cyclopolymers. The synthesis of the monomer and cyclopolymers were followed by ¹³C NMR, ¹H NMR, and FTIR. ¹H NMR was also utilized to obtain the degree of cyclization of the polymers, which were found to be 95% or higher in all cases. The molecular weights of the cyclopolymers were around 40-60,000 g/mol as estimated by SEC. The cyclopolymers were thermally stable up to 150 °C. Although the cyclopolymers obtained were not water-soluble; they were soluble in aqueous 1 M NaOH solution. In addition to the carboxylic acid functionality present, the cyclopolymers also had an ethyl ester and a lactone moiety. These functional groups were reacted with hexylamine to obtain a polymer with imide and amide moieties.     

Desulphiting dried apricots by exposure to hot air flow

Sulphited dried apricots were exposed to hot air flows at 40, 50 and 60 °C and the removal of SO₂ was investigated as their moisture content fell from an initial value of 193.2 g kg^?1 to a final value of 80–90 g kg^?1. A first‐order kinetic model was found for the removal of SO₂ between 40 and 60 °C. Temperature quotients (Q₁₀) for the removal of SO₂ were 2.84 between 40 and 50 °C and 4.93 between 50 and 60 °C; the activation energy (E_a) was 114.40 kJ mol^?1 between 40 and 60 °C. Analysis of the kinetic data also suggested a first‐order reaction for non‐enzymatic browning, with Q₁₀ values of 2.34 between 40 and 50 °C and 5.36 between 50 and 60 °C and an E_a value of 109.36 kJ mol^?1 between 40 and 60 °C. Exposure of dried apricots to a 60 °C air flow resulted in a rate constant for brown pigment formation that was 12 and 5 times higher than those at 40 and 50 °C respectively. © 2002 Society of Chemical Industry     

Laser Treatment of Sintered Silicon Carbide Surface for Enhanced Hydrophobicity

In this study, laser treatment of sintered SiC surfaces is carried out to enhance the surface hydrophobicity. Morphological and metallurgical changes of the treated surfaces are evaluated using optical and scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction (XRD). Microhardness and fracture toughness are measured using indentation tests. The residual stresses present are determined using the XRD technique. The wetting characteristics of the treated surfaces are assessed through contact angle measurements. It is found that the laser-treated surfaces consist of fine grooves and pillars and that the resulting surface roughness enhances the surface hydrophobicity. The fracture toughness of the treated surface is reduced possibly because of the microhardness increase at the surface. The residual stress formed in the surface region is on the order of 1.8 GPa, and it is compressive.     

Synthesis and electrochemical,in situ spectroelectrochemical,electrical and gas sensing properties of ball-type homo- and hetero-dinuclear phthalocyanines with four [1a,8b-dihydronaphtho[b]naphthofuro[3,2-d]furan-7,10-diyl] bridges

The new mono-nuclear Fe^II 2 and ball-type homo-dinuclear Fe^II–Fe^II 3 phthalocyanines have been synthesized from the corresponding 4,4′-(1a,8b-dihydronaphtho[b]naphthofuro[3,2-d]-furan-7,10-diyl)bis(oxy)diphthalonitrile 1 while ball-type hetero-dinuclear Fe^II–Co^II phthalocyanine 4 was synthesized from 2. The compounds have been characterized by elemental analysis, UV–vis, IR and MALDI-TOF-mass spectroscopies. The redox behaviours of the complexes were identified by controlled-potential coulometry, cyclic voltammetry and differential pulse voltammetry measurements on Pt in dimethylsulfoxide containing tetrabutylammonium perchlorate. The assignments of the redox processes and the understanding of the interactions between the metal phthalocyanine units in 3 and 4 were achieved by the combined evaluation of the voltammetric and in situ spectroelectrochemical outcomes. Complex 3 showed ring-based mixed-valence behaviour as a result of the considerable interaction between the phthalocyanine rings. On the other hand, the interactions between the two metal phthalocyanine units of 4 were found to be much weaker than those in 3. The potential application of molecular organic semiconductors needs the control adjustment of conductivity. Ac and dc conductivity measurements were performed with the applied external electric filed. At high frequency, the conduction follows the universal power law and conduction mechanism can be explained by classical hopping barriers mechanism for the system.     

The combined effects of boron and oil heat treatment on beech and Scots pine wood properties. Part 1: Boron leaching,thermogravimetric analysis,and chemical composition

The aim of the study was to screen any possible synergistic effect available with combination of plant oils and boron compounds to decrease boron leaching and improve thermal degradation of wood by means of dual treatment. In order to reduce the leachability of boron compounds, sapwood of beech and Scots pine samples were treated with oils to create a hydrophobic layer on the wood cells that may prevent water uptake. Increase (%) of boron retained in double-treated samples after leaching was approximately 20% compared to boron-treated samples without oil. The most promising results on boron leaching obtained in the case of using waste and sunflower oil. Thermogravimetric residues were increased by the higher loading of boron compounds in double-treated samples. Spectra of FTIR-Photoacoustic spectrometer showed some deformation of lignin and cellulose followed by degradation of hemicelluloses of treated wood samples due to heat effect at 160 °C.     

Synthesis and electrochemical,electrochromic and electrical properties of novel s-triazine bridged trinuclear Zn(II), Cu(II) and Lu(III) and a tris double-decker Lu(III) phthalocyanines

The new s-triazine-bridged trinuclear Zn(II) and Cu(II) phthalocyanines have been synthesized from the reaction of corresponding anhydrous metal salts, Zn(OAc)₂ and CuCl with 4,5-bis(hexylthio)-phthalonitrile and 2,4,6-tris(2-thiophthalonitrile)-s-triazine. The tris phthalonitrile derivative of s-triazine was prepared from the reaction of 4-nitrophthalonitrile and thiocyanuric acid in dry dimethylformamide as solvent using K₂CO₃ as the base. The same route was applied to prepare the trinuclear Lu(III) phthalocyanine analogue. The conversion of tris phthalonitrile into its isoindoline derivative was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives and 4,5-bis(hexylhthio)-1,2-diiminoisoindoline, with lutetium (III) acetate in dimethylformamide gave trinuclear Lu(III) phthalocyanine. The reaction of this complex with octakis-hexylthio phthalocyanine led to the isolation of tris double-decker Lu(III) phthalocyanine. The structures of the target compounds were confirmed by elemental analysis, UV–vis, IR and MALDI-TOF mass spectroscopies. The d.c. and a.c. conductivities of the phthalocyanine compounds were measured as a function of temperature. The small value of pre-exponential factor suggested the conduction by localized states in the band tails and by localized states near the Fermi level. The temperature dependence of the frequency exponent showed that the conduction in these compounds is due to hopping of charge carriers. The tris double-decker phthalocyanine complex showed well-defined electrochromic behaviour with green-blue and blue-purple colour transitions.     

Electrochemical conversion of phenolic wastewater on carbon electrodes in the presence of NaCl

The electrochemical conversion of highly concentrated synthetic phenolic wastewater was studied on carbon electrodes in a batch electrochemical reactor. The effects of reaction temperature, electrolyte concentration, current density and initial phenol concentration on phenol conversion were elucidated. The wastewater was synthetically prepared and used in reactions carried out generally at 25 °C with an initial phenol concentration of 3500 mg dm^?3. Although current density increased, phenol conversion% and initial phenol conversion rate did not increase correspondingly above 35 °C and an electrolyte concentration of 90 g dm^?3. As the voltage values applied were increased, the increasing current density resulted in fast phenol conversion. Kinetic investigations denoted that overall phenol destruction kinetics was of zero order with an activation energy of 10.9 kJ mol^?1. Under appropriate conditions, phenol was completely converted within 15 min for an initial phenol concentration of 98 mg dm^?3 while 8 h was required to gain 95% conversion using 4698 mg dm^?3. Solid polymeric materials were produced at initial phenol concentrations above 500 mg dm^?3 using the appropriate current density. In the reaction medium, only mono‐, di‐ and tri‐substituted chlorophenols were formed and 100% of all species were either oxidised or contributed to the formation of a polymeric structure. Almost all of the phenol loaded to the reactor was converted into non‐passivating polymeric products, denoting a safe and easy method for the separation of phenol. © 2001 Society of Chemical Industry     

Palladium-Catalyzed Suzuki–Miyaura Reaction Using Saturated N-Heterocarbene Ligands

Recent studies have pointed to the heptamethylbenzenium cation as a prominent intermediate in the methanol to hydrocarbons (MTH) reaction. The reactions of the heptamethylbenzenium cation in a H-beta zeolite was studied at 300 °C by feeding its corresponding base (WHSV = 0.4 h^?1). The reactant was converted completely into aliphatic products, polymethylbenzenes and coke under the employed conditions. The results testify that the proposed reaction intermediate yields the same product spectrum as methanol. The composition of the material retained in the catalyst micropores after 15 min of reaction was determined by dissolving the catalyst in 15% HF. Polymethylated benzenes (predominantly pentamethylbenzene), dihydro-trimethylnaphthalenes, and hexamethylnaphthalene were the major components. The results also support the idea that the lowest naphthalene derivative is formed from the heptamethylbenzenium cation by a molecular rearrangement. Hence, the heptamethylbenzenium cation is inherently linked to both product formation and catalyst deactivation in the MTH reaction.