Copolymerization of methyl α-(chloromethy1)acrylate with styrene accompanied by addition-fragmentation chain transfer

Summary Copolymerization of methyl α-(chloromethy1)acrylate (MCMA, M₁) as homo-polymerizable addition-fragmentation chain transfer (AFCT) agent with styrene (St, M₂) was investigated. The monomer reactivity ratios were r ₁ = 0.12 and r ₂ = 0.18 at 60° C indicating high alternating tendency. The copolymers bearing the 2-carbomethoxy-2-propenyl (CH₂=C(C0₂Me)CH₂-) ω-end group formed by AFCT were submitted for ¹H-NMR structural analysis. The M _n, of copolymer and contribution of AFCT as end forming reactions decreased and increased with increasing MCMA content in comonomer, respectively. The propenyl end groups bound to the St and MCMA units were separately detected. Furthermore, it was concluded that the MCMA-St copolymerization involves not only AFCT but also chlorine abstraction by the poly(St) radical. Received: 21 October 2002/Accepted: 19 November 2002 Correspondence to Bunichiro Yamada     

Hydrophobically modified polyglycidol – the control of lower critical solution temperature

Summary Polymers of glycidol (2,3-epoxypropanol-1) of different molar masses (between 2˙10⁴ and 2˙10⁵) and chain topology (linear and comb-like) were synthesised and used to obtain a series of temperature responsive water-soluble poly(glycidol-co-glycidol acetate)s. The degree of the substitution of the hydroxyl groups with the acetate groups influences the solution behaviour of the obtained copolymers, the cloud point may be controlled between +4°C and +lOO°C. Received: 24 September 2002/Revised version: 2 November 2002/ Accepted: 2 November 2002 Correspondence to Andrzej Dworak     

Thermal stability of additivated isotactic polypropylene

Summary Isotactic polypropylene stabilised with fullerene [C60], its adduct with methyl levopimarate, carbon black, p-t-butylcalix[4]arene, p-t-butylcalix[6]arene, Irganox 1076 or Topanol OC was investigated by means of oxygen uptake method under isothermal (165^°C) and isobaric (normal pressure) conditions. Oxidation investigations were performed in air as degradation environment. Additive concentration was 0.25 % (w/w). Kinetic parameters, oxidation induction and oxidation rate are compared with similar characteristics of additive-free i-PP. Effect of γ-irradiation on thermal oxidation is also presented. Three γ-exposure doses (50, 100 and 150 kGy) were selected. The influence of radiation treatment on the efficiency of studied compounds and some mechanistic aspects are also presented. Received: 5 June 2002/Revised version: 10 August 2002/ Accepted: 12 September 2002 Correspondence to Traian Zaharescu     

Synthesis and optical properties of the [2.2]paracyclophane-containing π-conjugated polymer with a diacetylene unit

Summary Novel through-spaceπ-conjugated polymer based on poly(p-henyleneethynylene)/poly(p-phenylenebutadiynylene) hybrids containing a [2.2]paracyclophane unit in the main chain was synthesized by copper-catalyzed alkyne coupling reaction. The structure of the polymer was supported by ¹H NMR and IR spectra. The obtained polymer was soluble in common organic solvents such as THF, CH₂C1₂, CHC1₃ and toluene. The number-average of molecular weight of the polymer was estimated to be 63000 by GPC. The polymer emitted a bluish green light in solution and in the solid state. Received:24 September 2002/Revised version: 19 November 2002/Accepted: 19 November 2002 Correspondence to Yoshiki Chujo     

Electrode heat balances of electrochemical cells: application to NaCl electrolysis

This paper deals with a method of estimating single electrode heat balances during the electrolysis of molten NaCl-ZnCl₂ in a cell using a-alumina diaphragm. By measuring the thermoelectric power of the thermogalvanic cells: (T) Na/-alumina/NaCl-ZnCl₂/-alumina/Na(T+dT) and (T) C,Cl₂/NaCl-ZnCl₂/Cl₂,C(T+dT) the single electrode Peltier heat for sodium deposition and for chlorine evolution at 370° C were estimated to be –0.026±0.001 JC^–1 and+0.614±0.096 J C^–1, respectively.     

Synthesis and ionic conductivity of comb-like polysiloxanes with Pendant oligo(oxyethy1ene) side chains and quaternary ammoniurn groups

Summary A series of novel comb-like polysiloxanes with oligo(oxyethy1ene) side chains and quaternary ammonium groups, has been synthesized by hydrosilylation of poly(methylhydrosi1oxane) with poly(ethy1ene glycol) allyl methyl ether and N,N-dimethylallylamine, followed by quaternization with methyl iodide. The glass transition temperature of these solvent-free electrolytes was measured and found to be dependent on the content of quaternary ammonium side groups anchored to the polysiloxane backbone. The influence of quaternary ammonium group content and temperature on the ionic conductivity has been investigated. A maximum conductivity of 1.57 × 10⁻⁵ S cm⁻¹ at 25 °C was achieved for a poiysiloxane containing 30 % quaternary ammonium side groups. The temperature dependence of the ionic conductivity shows the “Vogel-Tammann-Fulcher” (VTF) behavior. The values of the VTF Parameters were calculated. Rcceived: 24 June 2002/Revised version: 19 August 2002/ Accepted: 22 August 2002 Correspondence to Shibi Fang     

Study of the influence of the reaction parameters on the composition of the metallocene‐catalyzed ethylene copolymers using temperature rising elution fractionation and 13C nuclear magnetic resonance

Polyethylene copolymers prepared using the metallocene catalyst rac‐Et[Ind]₂ZrCl₂ were fractionated by preparative Temperature Rising Elution Fractionation (p‐TREF) and characterized by ¹³C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) to study the heterogeneity caused by experimental conditions. Two ethylene–1‐hexene copolymers with different 1‐hexene content and an ethylene–1‐octene copolymer all obtained using low (1.6 bar) ethylene pressure were compared with two ethylene–1‐hexene copolymers with different 1‐hexene content obtained at high ethylene pressure (7.0 bar). Samples obtained at low ethylene pressure and with low 1‐hexene concentration in the reactor presented narrow distributions in composition. Samples prepared with high comonomer concentration in the reactor or with high ethylene pressure showed an heterogeneous composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 155–163, 2002; DOI 10.1002/app.10284     

Novel hole-transporting carbazole main chain oligomer and its model glass-forming compound

Summary The oligomer containing 9-[2-(9H-carbazo1-9-yl)cyclobutyl]-9H-carbazole moiety in the main chain and its model compound were synthesized by Wittig reaction. Both compounds form glasses with glass transition temperatures of 254°C and 135°C respectively. The optical and photoelectrical properlies of the compounds were studied. The hole drift mobilities observed in the film of the oligoiner by the time of flight technique were in the range of 2·10⁻⁶ – 7·10⁻⁶ cm²/(V·s) at an applied electric field ranging from 5·8.10⁴ to 2·7.10⁵ V/cm. Rcceivcd: 3 April 2002/Revised version: 16 July 2002/ Accepted: 5 August 2002 Correspondence to Juozas V. Grazulevicius e-mail: juogra@ctf.ktu.lt. Tel/Fax: +37 07 456525     

Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Ir<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> electrodes

The generation of active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L⁻¹) and a low current density (5 mA cm⁻²) it was possible to produce up to 60 mg L⁻¹ of active chlorine on a Ti/Sn_0.99Ir_0.01O₂ anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm⁻² and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 × 10⁻⁴ mol L⁻¹. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.     

Study of the polymerization of 1-octadecene with different rnetallocene catalysts

Summary 1-Octadecene (C18) was polymerized by using different metallocene catalysts. The rac-Et(Ind)₂ZrC1₂/MAO (I) and rac-Me₂Si(Ind)₂ZrC1₂/MAO (III) presented the highest activity as compared with ra-Et(2-Me-Ind)₂ZrCl₂/MAO (II) and Ph₂C(Flu)(Cp)ZrC1₂/MAO (IV) catalysts. Catalyst IV produced polymers with highest molecular weights. The microstructure of the polymers was determined by ¹³C-NMR spectroscopy. Catalyst systems I, II and III produced isotactic polymers while catalyst IV produced polymers with mainly syndiotactic structures but with large amount of stereoregular error. Received: 21 June 2002/Revised version: 4 November 2002/ Accepted: 4 November 2002     

High-temperature chlorine corrosion of technical carbons Part II. Anodic corrosion in chloride melt

Medium (200 to 400°C) to high (600 to 800°C) temperature corrosion of technical carbons (Acheson graphites) have been investigated in alkali chloride melts at chlorine evolving anodes. At low temperature in chloride melts containing free Lewis acid (AlCl₃) no chlorine is evolved — even at high current densities — because chlorine, together with aluminium chloride, instantaneously form intercalation compounds with graphite and, as a consequence, the carbon desintegrates very rapidly. At 200°C carbon is consumed anodically in a C/Cl of molar ratio 70/1. With increasing temperature Scheson graphites become more stable so that at 700°C short term destruction cannot be observed in melts which contain free Lewis acid. Chlorine corrosion of carbon electrodes in purified basic alkali chloride melts, which are free of oxygen carriers and, in particular, free of water at temperatures between 600 and 800°C in basic chloride melts, is an electrochemical reaction proceeding at low current densities slower than anticipated from thermodynamic data for carbon chlorination equilibria. The anodic carbon corrosion reaction has an activation energy of only 50 kJ mol^–1 and its rate increases with increasing anode potential, or anodic current densities (rate: exp (i)). At a technical current density of 0.4 A cm^–2 at 700°C the corrosion rate is estimated to be of the order of centimeters per year, rendering carbon anodes dimensionally unstable. Most important is to note that apart from CCl₄, chlorinated carbon compounds (olefins and arenes) are generated as side-products which are noxious and ecologically dangerous and must not be released from processes which use carbon anodes for chlorine evolution from salt melts.This paper is dedicated to Professor Dr Fritz Beck on the occasion of his 60th birthday.     

Mechanical Activation of Perovskite-Type Oxides for Catalytic Combustion

The effect of grinding on the catalytic properties of La_0.8Sr_0.2MnO_3± powders prepared via a ceramic or sol–gel process was studied with respect to the carbon black combustion temperature (T ^C). For the ceramic process, a milling time of 5 h led to a decrease of 77°C in the T ^C (from 615 to 538°C) in relation with increasing BET surface area. Regarding the sol–gel process, the T ^C decreased from 535 to 505°C after 1 h of grinding. Nevertheless, upon further milling (10 h), the benefit of the grinding effect disappeared due to a continuous decrease in the BET surface area. Finally, grinding (when well controlled) enabled one to obtain ceramic powders showing performances as good as sol–gel materials (T ^C540°C).     

Formation of chlorite and chlorate from chlorine dioxide with Han river water

This study was designed to elucidate the behavior of chlorine dioxide in drinking water systems. Furthermore, the factors that influence the formation of chlorite, chlorate in terms of reaction time, concentration of chlorine dioxide, pH, temperature and UV irradiation were experimentally reviewed. At 20 ‡C, pH 7, 70–80% of chlorine dioxide injected was converted to chlorite and 0–10% of that was transformed into chlorate within 120 min with 2.91 mg/L of DOC. The amount of chlorite formed also increased when pH and temperature increased. As DOC content increased, the residual chlorine dioxide decreased but the amount of chlorite and chlorate were increased. These experiments revealed that chlorate was a dominant by-product under UV irradiation. The models that were obtained by the regression analysis for the formation of chlorite and chlorate from chlorine dioxide with Han River water are as follows: Chlorite (mg/L)=10^-2.20[ClO₂]^0.45[pH]^0.90[temp]^0.27[TOC]^1.04[time]^0.20, Chlorate (mg/L)=10^-2.61[ClO₂]^1.27[pH]^-0.50[temp]^1.28 [TOC]^0.31[time]^0.12     

Synthesis and Properties of Novel Poly(p-phenylenevinylene)s Containing a Tricarbonyl(arene)chromium Unit in the Main Chain

Summary Novel π-conjugated polymers based on poly(p-phenylenevinylene)s (PPVs) containing a tricarbonyl(arene)chromium unit in the main chain were synthesized by Horner-Wadsworth-Emmons olefination. The structures of the polymers were supported by ^lH NMR and IR spectra. The polymers obtained were soluble in common solvents such as THF, CH₂Cl₂, CHCl₃ and toluene. The molecular weights of the polymers were determined by GPC. Their thermal, optical, and electrochemical properties were investigated in detail. Received: 18 November 2002/Revised version: 10 February 2003/ Accepted: 11 February 2003 Correspondence to Yoshiki Chujo     

Radical copolymerization of potassium 4-vinyl biphenyl-sulfonylimide and oligo(oxyethylene) methacrylates. Thermal behavior and single-ion conductivity of the copolymer electrolytes formed

Summary Radical copolymerization of potassium 4-vinyl biphenylsulfonylimide (K-4VPSI) and a series of oligo(oxyethylene) methacrylates (EO)_nMA (n=3, 9 and 22) has been carried out in aqueous medium. Free radical copolymerization reactivity ratios were determined. They indicate a statistical copolymerization for n=9 and a tendency to alternation for n=22. When n≥9, significant single ion conductivity values are obtained at lower salt concentrations, where the mobility of the polyelectrolytes is highest. The K-4VPSI / (EO)₉MA copolymers present a domain of salt content where a leveling of conductivity is observed, due to aggregation. Received: 20 June 2002/Revised version: 4 November 2002/ Accepted: 4 November 2002 RID="*" ID="*" Present address : ATOFINA Chemicals, 900 First Avenue, King of Piussia, PA 19406, USA Correspondence to Léonard C. Reibel     

Synthesis, characterization and thermal behavior of Poly(methyl-n-octadecyl itaconate) a comb-like polymer with crystallizable side chain

The radical polymerization of methyl n-octadecyl itaconate initiated with AIBN, produces poly(methyl n-octadecyl itaconate) with a yield of 47% and a molecular weight of about 10⁵ g/mol. ¹³C-NMR studies point out that this polymer is mainly syndiotactic. The combined studies of DSC and solid state ¹³C CP/MAS NMR indicate that the polymer side chains are able to crystallize in a paraffinic phase, presumably in an hexagonal form which melts at 44°C with a ΔH of 4.8Kcal/mol. Received: 12 September 2001/Revised version: 3 January 2002/Accepted: 10 January 2002     

Formation of monodisperse polyacrylamide particles by radiation‐induced dispersion polymerization. I. Synthesis and polymerization kinetics

Highly monodisperse polyacrylamide (PAM) microparticles were directly prepared by radiation‐induced dispersion polymerization at room temperature in an aqueous alcohol media using poly(N‐vinylpyrrolidone) (PVP) as a steric stabilizer. Monomer conversion was studied dilatometrically and polymer molecular weight was determined viscometrically. The gel effect was found evidently from the polymerization kinetics curves. The influence of the dose rate, monomer concentration, stabilizer content, medium polarity, polymerization temperature on the polymerization rate, and the molecular weight of the polymer was examined. The polymerization rate (Rp) can be represented by Rp ∝ D^0.15[M]^0.86[S]^0.47[A/W]^0.64 and the molecular weight of the polymer can be represented by M_w ∝ D^?0.19 [M]^1.71[S]^0.43[A/W]^0.14 at a definite experimental variation range. The overall activation energy for the rate of polymerization is 10.57 kJ/mol (20–35°C). Based on these experimental results, the polymerization mechanisms were discussed primarily. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2567–2573, 2002     

Polyphosphonates obtained by vapor-liquid interfacial polycondensation

Summary A series of polyphosphonates were synthesized by base promoted liquid-vapor interfacial polycondensation of various alkyl (aryl) phosphonic dichlorides (methylphosphonic dichloride (MPD), cyclohexylphosphonic dichloride (CPD) and phenylphosphonic dichloride (PPD)) with different bisphenols (hydroquinone (HQ), bisphenol A (BA), 4,4′ - biphenol (BP), 1,5-naphtalenediol (ND) and 4,4′ - sulfonyldiphenol (SD)). The polyphosphonates were characterized by infrared (IR) and proton magnetic resonance (¹H-NMR) spectroscopy. Yields in the range of 20–80% and Mn of ∼ 8500–35000 were obtained. DSC measurements show Tg in the range 95°–148°C. These polymers are soluble in solvents such as N,N-dimethylformamide, tetrahydrofuran and chloroform. Polyphosphonates were stable up 240°–300°C in air atmosphere. Received: 11 March 2002 / Revised version: 29 May 2002 / Accepted: 12 June 2002