Polymerization Of Benzene Research Articles

Bioactive Polymers for Biohybrid Artificial Pancreas

To address the solution for some of the obstacles, such as low insulin secretion, limited lifespan and aggregation of transplanted islets, encountered in developing a biohybrid artificial pancreas (BAP), polymeric materials including a reversible polymeric extracellular matrix (ECM), crystallized glucagon-like peptide-1, and oxygen carrying polymers, were prepared and their potential utilities in designing a compact and rechargeable BAP were investigated. For a synthetic, reversible ECM, high molecular weight N-isopropylacrylamide copolymer with a small amount of acrylic acid (2mole%) was synthesized by conventional radical polymerization in benzene, and its aqueous solution above a critical polymer concentration displayed a sol-gel transition temperature near physiological temperature (33–35°C) without noticeable hysteresis. The physicochemical properties of the gel with islet compatibility proved that the synthetic ECM is an appropriate matrix which can make a BAP rechargeable. Glucagon-like peptide-1 (GLP-1,7-37) is known to have a strong stimulatory effect on insulin secretion, particularly at high glucose concentrations. When zinc-crystallized GLP-1 was entrapped along with islets in a hollow fiber macrocapsule device, insulin secretion was enhanced at a high glucose concentration (300mg/dl) with a >85% increase in insulin secretion after an induction period. The cross-linked hemoglobin with difunctional PEO (Hb-C) was prepared to increase the high molecular weight of Hb. This prevents diffusional loss when enclosed in an immunoprotecting membrane. The Hb-C, entrapped in microcapsules, enhanced insulin secretion and improved the viability of microencapsulated islets by promoting oxygen supply to islets. The introduction of the synthetic ECM, crystallized GLP-1, and Hb-C into a BAP may provide a basis for designing a compact and rechargeable BAP (macrocapsule).

Electrochemical polymerization of benzene in the presence of Ag+, Pb2+ and Cu+ ions

Poly(p-phenylene) (PPP) films were synthesized by using benzene and fluorosulphonic acid (FSO3H) as a strong acid containing Ag+, Pb2+ and Cu+ ions in methylene chloride (CH2Cl2) solution. Addition of Ag+ or Pb2+ ions into the polymerization medium improved the PPP films formation, but Cu+ ion did not have an effect on polymerization. PPP films were characterized by cyclic voltammetry, IR and TGA. Dry conductivities were measured by using four probe technique.

Conjugation of Arg-Gly-Asp sequence into thermo-reversible gel as an extracellular matrix for 3T3-L1 fibroblast cell culture

High molecular weight N-isopropylacrylamide copolymers with small amounts of acrylic acid (typically 2–5 mol% in feed) were synthesized by free radical polymerization in benzene and then conjugated with adhesion molecules of Gly-Arg-Gly-Asp-Ser (GRGDS) peptides. Aqueous polymer solutions (5, 6, 8 and 10% w/v) in culture medium (pH 7.4, ionic strength; 0.15 M) with 3T3-L1 fibroblast cells were mixed and poured in Millicells, which supported the gel formation without a significant gel induction time at 36 °C (gelation temperature). The initially formed gel was translucent and became more opaque as the temperature increased. The interaction between fibroblast cells and an artificial matrix of GRGDS containing p(NiPAAm-co-AAc) copolymer gel resulted in effective cell attachment, proliferation and growth. This study supported that specific attachment is the result of the interaction between the integrin families on the fibroblast and the RGD sequence on the p(NiPAAm-co-AAc) copolymer gel.

Low potential electrochemical polymerization of benzene in a composite electrolyte of boron trifluoride diethyl etherate and trifluoroacetic acid

Abstract The electropolymerization of benzene on a Pt electrode was investigated in a composite electrolyte of boron trifluoride diethyl etherate and trifluoroacetic acid with a volume ratio of 2:1. The oxidation potential of the monomer in this medium was measured to be about 1.5 V (vs. SCE) instead of 2.0 V found in liquid SO 2 at a low temperature. The polyphenylene films synthesized by this technique are homogenous and flexible and can easily be cut into any shape such as fibres, circles and triangles. In particular, the film had a linear chain structure with a degree of polymerization of about 20 according to its FTIR spectrum.

Solid state structural aspects of electrochemically prepared poly ( p -phenylene) thin films - crystalline order and spherulite morphology

The electrochemical polymerization of benzene via the microemulsion approach yields highly crystalline and anisotropic “spherulitic” polyparaphenylene (PPP) thin films. The crystalline order and the origin of spherulite morphology are discussed.

Sonochemical polymerization of benzene derivatives: the site of the reaction

Sonochemical polymerization of benzene and halogen-substituted benzenes has been studied. The difference of absorption spectra of polymerization products can be explained qualitatively using bond energies of the primary products. The relative rate constant of the polymerization reaction is apparently proportional to the inverse of the vapour pressure of the liquids. Using this relation, we analysed the relative rate constant of the polymerization in benzene/chrolobenzene mixtures. From this, we conclude that sonochemical polymerization proceeds in the vapour phase of a bubble.

Polymerization of n-Butyl Acrylate by Atom Transfer Radical Polymerization. Remarkable Effect of Ethylene Carbonate and Other Solvents

Atom transfer radical polymerization (ATRP) of n-butyl acrylate with the homogeneous catalyst, CuIBr/4,4‘-di(5-nonyl)-2,2‘-bipyridine (dNbpy), in benzene, afforded well-defined poly(n-butyl acrylate) with predetermined molecular weights and low polydispersities, Mw/Mn = 1.1. The number-average molecular weight, Mn (measured by GPC and MALDI-TOFMS), was close to the theoretical molecular weight, predetermined by DPn = Δ[M]/[I]0. A similar polymerization in benzene using 2,2‘-bipyridine (bpy) as ligand instead of dNbpy displayed poor control, yielding a polymer whose molecular weight was higher than the theoretical value and demonstrating high polydispersity (Mw/Mn = 2.4). Several solvents were subsequently employed for the polymerizations with the CuIBr/bpy catalyst system. Good control of molecular weight and polydispersity were achieved using ethylene carbonate, and in this system the observed rate of polymerization was even faster than in bulk. The rate of polymerization with the CuIBr/bpy catalyst in e...

Determination of the sequence distribution and stereoregularity of ethyl ?-benzoyloxymethylacrylate?methyl methacrylate copolymers by means of proton and carbon-13 NMR

Proton and Carbon-13 NMR spectra of ethyl α-benzoyloxymethylacrylate (E)–methyl methacrylate (M) copolymers were analyzed in terms of sequence distribution and stereoregularity of monomer units. The copolymers were prepared by free radical polymerization in benzene at 50°C. The methoxy region of the M proton signal resonance was found to be sensitive to the copolymer composition for M-centred sequences. The carbon-13 NMR spectra of the EM copolymers, in particular the carbonyl signal resonances of carbomethoxy and carboethoxy groups, are discussed in terms of M- and E-centred configurational sequences. The experimental values were in excellent agreement with those calculated taken into account the terminal copolymerization model and Bernoullian distribution of stereoregularity with the statistical parameters determined from reactivity ratios rE = 0.32 and rM = 1.34 and the coisotacticity parameters σMM = 0.22, σEE = 0.70, and σME = σEM = σ = 0.30. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3483–3493, 1997

Determination of the sequence distribution and stereoregularity of ethyl α‐benzoyloxymethylacrylate—methyl methacrylate copolymers by means of proton and carbon‐13 NMR

Proton and Carbon-13 NMR spectra of ethyl α-benzoyloxymethylacrylate (E)–methyl methacrylate (M) copolymers were analyzed in terms of sequence distribution and stereoregularity of monomer units. The copolymers were prepared by free radical polymerization in benzene at 50°C. The methoxy region of the M proton signal resonance was found to be sensitive to the copolymer composition for M-centred sequences. The carbon-13 NMR spectra of the EM copolymers, in particular the carbonyl signal resonances of carbomethoxy and carboethoxy groups, are discussed in terms of M- and E-centred configurational sequences. The experimental values were in excellent agreement with those calculated taken into account the terminal copolymerization model and Bernoullian distribution of stereoregularity with the statistical parameters determined from reactivity ratios rE = 0.32 and rM = 1.34 and the coisotacticity parameters σMM = 0.22, σEE = 0.70, and σME = σEM = σ = 0.30. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3483–3493, 1997

High-quality poly( p-phenylene) film prepared by electrochemical polymerization of benzene at a stainless steel electrode

Poly( p-phenylene) (PPP) film has been electrochemically deposited onto a stainless steel electrode surface by direct oxidation of benzene in BF 3diethyl ether solution at an applied potential of 1.7 V (vs Ag AgCl ). The morphology, conductivity and the mechanical property of the film were studied. As-grown PPP film has a conductivity of 2.7 S cm −1. It has a high modulus of 1.2 × 10 10 dyne cm −2 and a large tensile strength of 550–650 kg cm −2. Furthermore, this film was flexible and could be easily cut into any shapes, such as fibres, circles, squares and triangles.

XPS depth profiles and optical properties of plasma polymer multilayers with embedded metal particles

XPS depth profile of plasma polymer thin films with various embedded metal particles (gold, silver, copper and indium) were used to determine the vertical distribution of the metal particle in the plasma polymer film and to investigate the chemical composition of the films. For plasma polymer gold composite films deposited by simultaneous plasma polymerization of perfluoropropane and gold sputtering, a very homogeneous depth profile of the embedded gold particle was found. Otherwise, multilayer systems consisting of a plasma polymer metal composite film between a bottom and a top plasma polymer film were deposited by plasma polymerization of benzene or styrene and simultaneous or alternating evaporation of gold, silver, copper or indium. The XPS depth profiles demonstrate that the multilayer systems were not destroyed by thermal annealing up to 480 K or by appropriate laser annealing. Except for multilayers with embedded indium particles, oxygen was only adsorbed at the surface and not detected after some monolayers were etched. The optical properties of multilayer systems with embedded gold or silver particles change substantially after thermal annealing. The spectral position of the plasma resonance absorption of the metal particle shifts to higher wave numbers. Based on XPS depth profiles it was demonstrated, that these changes in the optical spectra are only a result of metal particle reshapening and coalescence.

A kinetic study of the formation of polystyrene stars using 1,2-bis(trichlorosilyl)ethane

The kinetics of formation of a chlorosilane-linked polystyrene six-arm star is reported. The precursor arm material (Mn = 88,000) was made using anionic polymerization in benzene. Prior to addition to the 1,2-bis(trichlorosilyl) ethane linking agent, the anions were endcapped with about five units of isoprene. Size exclusion chromatography using multiangle laser light scattering and viscosity detectors was utilized for characterization. This technique has allowed the molecular weights, radii of gyration, and intrinsic viscosities to be measured for star components in aliquots taken from the reactor at various times. It was found that four-arm star is formed within 30 min after the addition of the chlorosilane linking agent. There is a linear relationship between the logarithm of molecular weight of the star samples and logarithm of time of the reaction after the formation of the four-arm star. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 587–594, 1997

Polymers from multifunctional isocyanates, 12. Alternating copolymers from isocyanatoalkenes and electron deficient 1,2‐disubstituted alkenes

AbstractThe free radical copolymerization of the electron rich monomers vinyl isocyanate, isopropenyl isocyanate, trans‐1‐propenyl isocyanate, and trans‐β‐styryl isocyanate with maleic anhydride has been investigated. The copolymerization behaviour of different electron deficient monomers like maleic anhydride, citraconic anhydride, N‐phenylmaleimide and fumaronitrile with isopropenyl isocyanate or vinyl isocyanate has also been studied. Polymerization in benzene is accompanied by precipitation of polymer, while the polymerization proceeds in solution in 2‐butanone. Alternating copolymers were obtained in all cases. The alternating behaviour is favoured by the very low tendency of all monomers except maleimides to undergo homopolymerization. From the reaction with maleic anhydride the reactivity of electron donating monomers was found to be vinyl isocyanate ≈ isopropenyl isocyanate ≫ β‐styryl isocyanate ≈ ≫ 1‐propenyl isocyanate, while the reactivity of electron accepting monomers with isopropenyl isocyanate was: maleic anydride > N‐phenylmaleimide > fumaronitrile.

Polymerization of Benzene and Aniline on Cu(II)-Exchanged Hectorite Clay Films: A Scanning Force Microscope Study

AbstractThe technique of scanning force microscopy (SFM) was used to study the nanometer-scale structure of Cu(II)-exchanged hectorite thin films. Supporting data were also obtained from Electron Spin Resonance (ESR) and X-ray diffraction (XRD) techniques. The surfaces studied included pure Cu(II)-exchanged hectorite, Cu(II)-exchanged hectorite exposed to benzene and Cu(II)-exchanged hectorite exposed to aniline. SFM images of the unexposed Cu(II)-exchanged hectorite surface revealed a smooth surface composed of interlocking platelets. The lateral dimension of these platelets ranged from a few nm to about 1 μm. After exposure to refluxing benzene, the SFM showed that the platelets underwent vertical shifts in position. This is believed to have occurred from intercalated benzene that polymerized in the interlayer region. No SFM evidence was obtained for benzene polymerization on the surface of the hectorite. Hectorite films exposed to aniline at room temperature revealed a post-polymerization structure on the hectorite surface consisting of small polymer bundles. The diameter of these bundles was measured to be 300–3000 Å, similar to the structure seen on electropolymerized polyaniline films. Aniline polymerized on the surface of hectorite films at 180 °C revealed a structure similar to undoped n-methyl-pyrrolidinone (NMP) cast polyaniline films. In this case, the polymer bundles are only 300 Å in dimension on average. XRD and ESR data also indicated interlayer aniline polymerization in Cu(II) exchanged hectorite. Mechanistic considerations affecting these polymerization reactions are presented.

ChemInform Abstract: Structure and Growth Mechanisms of Polyphenylene Films Formed on Platinum by Anodic Polymerization of Benzene and Biphenyl in Various Electrolytic Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Scanning force microscopy and polymerization studies on cast thin films of hectorite and montmorillonite

Thin films of the smectite clays Na+ exchanged montmorillonite, Ca2+ exchanged montmorillonite, Na2+ and Cu2+ exchanged hectorite, Cu2+ exchanged sintered hectorite, and Cu2+ and Na2+ exchanged hectorite exposed to benzene, aniline, and thiophene were studied using the techniques of scanning force microscopy (SFM), electron spin resonance (ESR), and x-ray diffraction. The microstructure of the two montmorillonite clays was markedly different, with the Ca-montmorillonite exhibiting a sturdy, close packed array of crystallites of average dimension 0.4 μm. The Na-montmorillonite clays consisted of smaller (0.1 μm), more poorly defined crystallites with an overall cauliflowerlike appearance. The pure Na-hectorite and Cu-hectorite clays exhibited large flat regions composed on interlocking platelets. Heat sintering as well as exposure to benzene resulted in measurable shifts in the platelets perpendicular to the surface for the Cu-hectorite. It is proposed that in the sintered case these shifts are due to interlayer water loss accompanied by Cu reactions, while in the benzene case interlayer benzene polymerization causes inhomogeneous vertical expansion of the clay. Exposure of Cu-hectorite films to both aniline and thiophene results in large-scale polymerization of these monomers. The microstructure of both of these polymers is similar to that observed in electrochemically prepared films on Pt substrates. Na-hectorite samples did not exhibit surface polymerization upon thiophene, aniline, or benzene exposure.

Synthesis and Polymerization of a Nonionic Surfactant: Poly(Ethylene Oxide) Macromonomer

Abstract A polymerizable nonionic surfactant macromonomer, ω-methoxy poly(ethylene oxide)nundecyl-α-methacrylate (n = 40) has been synthesized from poly(ethylene glycol) methyl ether, 11-bromoundecanol, and methacryloyl chloride. The critical micelle concentration of the macro-monomer is 6.6 × 10−5 mol/L at 25°C. The kinetics of its polymerization in aqueous medium follows conventional solution polymerization, i.e., first and half order with respect to the concentrations of the macro-monomer and K2S2O8, respectively. The rate of its polymerization in water was extremely rapid (within 30 minutes) as compared to its solution polymerization in benzene (days). The activation energies for the macromonomer polymerization were 57 kJ/mol in water but 179 kJ/mol in benzene. The aqueous system produced polymers with a number-average degree of polymerization (DPn) ranging from about 130 to 160, but it was much lower (DPn ≐ 7) for the benzene system. The possible micellar polymerization mechanism for the macromonomer...

Reactions of Polynuclear Aromatic Hydrocarbons on Soil

The interactions of anthracene with three soils and montmorillonite clay were studied as a function of time and moisture content. Selected experiments also used phenanthrene and pyrene. The soils contained a range of organic matter, from 0.6 to 4.4%, and all had a high clay content. Anthracene was loaded onto the soils by dissolving in methylene chloride and then soaking the soil from 30 min to 17 d. After removing the methylene chloride, the soil was extracted to see how much contaminant was recoverable. Up to 100% of anthracene and pyrene were not extractable from the soil, and up to 25% of the phenanthrene was not extractable. Experiments with [14C]anthracene and analysis of extracts by UV, TLC, and GC/MS showed that anthracene was oligomerized to higher molecular weight aromatic products. The lowest member of the series, bianthracene, was detected by GC/MS. This reaction was consistent with prior studies of benzene polymerization on clays that were substituted by ion exchange with transition metals. Addition of water inhibited the reactions, and a kinetic model based on competitive inhibition between water and anthracene for access to active sites was consistent with the data. The reacted anthracene was not available to an active bacterial culture for degradation. These results suggest that analysis of air-dried or oven-dried soil samples may be subject to error and that thermal desorption processes for treating soil may cause polymerization on the soil surface.

Comonomer sequence determination of vinyl acetate-glycidyl methacrylate copolymers by NMR spectroscopy

(Vinyl acetate)/(glycidyl methacrylate) (V/G) copolymers were prepared by free radical solution polymerization in benzene. Copolymer composition was determined by 1H-NMR spectroscopy. Comonomer reactivity ratios were calculated by Kelen-Tudos (KT) and error-in-variables (EVM) methods. The values reactivity ratios calculated by these methods are rV = 0.03 ± 0.01; rG = 38.9 ± 6.20 (KT) and rV = 0.03 ± 0.002; rG = 39.5 ± 1.97 (EVM). The microstructure of V/G copolymers in terms of the distribution of V and G centered was obtained from 13C{1H}-NMR spectra using the carbonyl carbon resonance signals of V as well as G units. © 1996 John Wiley & Sons, Inc.

High Temperature Pyrolysis ofO-Terphenyl: Evidence for Kinetic Control in the Benzene Polymerization Pathway and Importance of Arene Aggregation/ Condensation Reactions in the Formation of Polycyclic Aromatic Hydrocarbons

Abstract The pyrolysis of o-terphenyl was effected in a drop tube furnace at 5 temperatures between 1248–1352 K, a range over which a significant change in product composition occurs. the use of atmospheric pressure chemical ionization mass spectrometry with a heated nebulizer interface permitted product characterization up to a molecular mass of 900 u. Least-condensed benzene polymers dominate the product spectrum at the lower temperatures. A shift to more condensed PAH, many of which are total resonant sextet (TRS) compounds, is seen at the higher temperatures, in agreement with previously established theory. However, the low abundance of the TRS compounds, the absence of a rate-limiting critical species, and the high abundance of o-terphenyl dimers, together suggest that the product suite is not at equilibrium but is instead kinetically determined. the abundance of several ring-rupture products, such as benz[a]anthracene, cyclopent[hi]acephenanthrylene and chrysene is also indicative of a kineti-cally-...