Synthesis and Polymerization of N-(2,4,5-trichlorophenyl) Acrylamide Monomer and its Thermal and Antimicrobial Properties

N-(2,4,5-trichlorophenyl) acrylamide (CPAM) new monomer was synthesized by condensing acrylic acid and 2, 4, 5-tri chloro aniline using dicyclohexyl carbodiimide as a coupling agent. The CPAM monomer was characterized by ¹HNMR, FT-IR, and mass spectroscopy. Further, the CPAM monomer was homopolymerized by solution technique in toluene using azobisisobutyronitrile (AIBN) as an initiator. The CPAM monomer and its homopolymer were employed to screen an antimicrobial activity against E. coli, S. aureus, M. luteus, and B. subtilis microorganisms, which are representative of Gram-positive and Gram-negative bacteria using ciprofloxacin and Sulphametoxazol as standards. The results showed that the CPAM monomer has good antimicrobial activity, comparable with its homopolymer. Also, the CPAM homopolymer was investigated for its thermal stability by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).     

Electroinduced dispersion polymerization of acrylonitrile in the presence of poly(acrylic acid) and catalytic amount of CE(IV)

Electroinduced dispersion polymerization of acrylonitrile initiated by Ce(IV) was performed in an electrolytic cell in the presence of poly(acrylic acid) (PAA). Micron‐size polyacrylonitrile (PAN) particles were stabilized with PAA by electrostatic interaction or by a PAA–Ce(III)–PAN ternary complex formation. A PAA–PAN stable polymer was formed in the cathodic compartment, and the reduced initiator was reoxidized in the anode, thus allowing for the continuation of the process. A possible mechanism of polymerization is suggested. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 723–728, 2002; DOI 10.1002/app.10076     

Polymerization of acrylonitrile initiated by Ce(IV)-sucrose redox system: A kinetic study

The polymerization of acrylonitrile (M), initiated by the free radicals formed in situ in the Ce (IV)-sucrose redox system, was studied in aqueous sulfuric acid medium under nitrogen atmosphere in the temperature range of 30–60°C. The rate of polymerization is proportional to [M]^1.0, [R]^0.76, [Ce(IV)]^0.8, and [H⁺]^−0.46. The rate of Ceric ion disappearance and the rate of polymerization R_p have been measured. The effects of some water–miscible organic solvents, surfactants, ionic strength, and complexing agents on the rate of polymerization were investigated. The temperature-dependence of the rate was studied and the activation parameters were computed using the Arrhenius and Eyring plots. A mechanism consistent with the experimental data, involving Ce(IV)-sucrose complex formation, which generates free radicals, is suggested. The chain termination step of the polymerization reaction was determined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synergistic Enhancement and Separation of Zirconium(IV) and Hafnium(IV) with 3-Phenyl-4-Benzoyl-5-Isoxazolone in the Presence of Crown Ethers

Abstract

3-Phenyl-4-benzoyl-5-isoxazolone (HPBI) was synthesized and examined with regard to the synergistic solvent extraction behavior of zirconium(IV) and hafnium(IV) in the presence of various crown ethers (CEs), namely, 18-crown-6 (18C6), dicylohexano-18-crown-6 (DC18C6) and benzo-15-crown-5 (B15C5) from hydrochloric acid solutions. The results demonstrated that zirconium(IV) and hafnium(IV) were synergistically extracted into chloroform with mixtures of HPBI and CEs as ZrO(PBI)₂ · CE and HfO(PBI)₂ · CE, respectively. The complexation strength follows the order DC18C6 >18C6 > B15C5. The addition of CEs not only enhances the extraction efficiency of zirconium(IV) and hafnium(IV) but also significantly, especially in the presence of B15C5, improves the selectivity (Zr/Hf = 4.73) between these metal ions as compared to HPBI alone (Zr/Hf = 2.09). On the other hand, selectivity has been moderately decreased by the addition of 18C6 or DC18C6 to the metal-chelate system.     

Influence of cerium (IV) ions on the mechanism of organosilane polymerization and on the improvement of its barrier properties

In this work, the effect of cerium (IV) ammonium nitrate (CAN) addition on the polymerization of bis-[triethoxysilyl]ethane (BTSE) film applied on carbon steel was studied. The electrochemical characterization of the films was carried out in 0.1 mol L⁻¹ NaCl solution by open-circuit potential measurements, anodic and cathodic polarization curves and electrochemical impedance spectroscopy (EIS). Morphological and chemical characterization were performed by atomic force microscopy (AFM), contact angle measurements, infrared-spectroscopy, nuclear magnetic resonance and thermogravimetric analysis. The results have clearly shown the improvement on the protective properties of the Ce⁴⁺ modified film as a consequence of the formation of a more uniform and densely reticulated silane film. A mechanism is proposed to explain the accelerating role of Ce⁴⁺ ions on the cross-linking of the silane layer.     

Synergistic effects of cerium(IV) phosphate with intumescent flame retardant in styrene butadiene rubber

Abstract

Cerium(IV) phosphate [CeP(IV)] was synthesised by hydrothermal synthesis and used as a synergistic agent on the flame retardancy of styrene butadiene rubber (SBR)/intumescent flame retardant (IFR) system. The IFR system mainly consisted of ammonium polyphosphate and pentaerythritol. Limiting oxygen index, UL-94 test, thermogravimetric analysis, cone calorimeter, scanning electron microscopy and microscale combustion calorimeter were used to evaluate the synergistic effects of CeP(IV). The addition of CeP(IV) to SBR/IFR composites leads to the improvement in UL-94 values of the SBR/IFR/CeP(IV) composites, and the peak of heat release rate decreases with increasing CeP(IV) content. SEM was used to analyse the morphological structure of the residue chars formed from the SBR/IFR systems with and without CeP(IV). A possible mechanism for catalysing carbonisation was discussed. The experimental results indicated that there existed a synergistic effect between CeP(IV) and IFR for the flame retardancy of SBR.     

Interpretation of the chain structures of PMMAs, PANs and PAAms obtained by using Ce(IV) and KMnO4 in combination with NTA and DTPA as initiator systems by FTIR spectroscopic analysis

Polyacrylamides (PAAms), polyacrylonitriles (PANs) and poly(methyl methacrylate)s (PMMAs) were synthesized by using Ce(NH₄)₂(NO₃)₆, Ce(SO₄)₂·4H₂O and KMnO₄ in combination with nitrilotriacetic acid (NTA) and diethylenetriamine pentaacetic acid (DTPA), which have strong chelating properties, as redox initiators. Polymerizations were carried out in the aqueous acidic solutions at 25°C and 55°C in the presence of air. The chain structures of the resulting products were studied by Fourier-transform infrared (FTIR) spectroscopic measurements. From the comparison of the spectroscopic results with gravimetric and viscometric data it was concluded that both the differences between the solubility behaviour in aqueous solutions of MMA, AN, AAm and their polymers, and catalyst–activator–monomer combinations were important parameters effecting the polymerization mechanisms, conversions and the structures of the polymers. The FTIR and viscosity results indicated that PAAms obtained in our experimental conditions formed crosslinked structures with sulphated complexes of Ce(III) and MnSO₄ produced by the redox reactions between catalysts (MnO₄⁻ and Ce(IV)), NTA and AAm. Further, it was observed that PAN chains were terminated by hydrated and sulphated complexes of Ce(III) while the termination of PMMA radicals took place by primary radicals because PMMAs were formed by emulsion polymerization kinetics.     

Note: Zr(IV)-Immobilized Resin Prepared by Surface Template Polymerization for Fluoride Ion Removal

Abstract

A novel adsorbent Zr(IV)-immobilized resin was prepared to remove fluoride ions from tap water and industrial wastewater. In order to enhance both the kinetics and efficiency, large pathways were formed in the resin for fluoride ion adsorption and the Zr(IV)-phosphate complexes were immobilized on the polymer surface by surface-template polymerization. The Zr(IV)-immobilized resin had a fluoride adsorption capacity of 0.30 mmol/g. The morphology of the Zr(IV)-immobilized resin was evaluated by measuring the specific surface area, pore volume, and pore size distribution. The resin possessed large amounts of large macropores with diameters around 300 nm. The molecular structure at the fluoride adsorption sites was investigated by measuring the amounts of phosphorus, zirconium, and fluoride ion in the resin, and developing a model complex using computational chemistry. On the polymer surface, a fluoride ion/Zr(IV)/dioleyl phosphoric acid complex with an ideal F:Zr:P mole ratio of 3:1:3 could be formed.     

有氧环境的氧化还原/乙烯基自缩合法制备超支化聚丙烯酰胺

采用了有氧条件下的乙烯基自缩合(SCVP)法制备了超支化的聚丙烯酰胺,并对SCVP反应机理及聚合物结构进行了讨论。结果表明:在有氧条件下合成超支化聚丙烯酰胺时,增加引发剂的用量能够提高聚丙烯酰胺的支化度;延长反应时间能够提高聚合物的分子量,提高支化度;增加单体用量,升高温度能够促使转化率及分子量提高,但会降低支化度;当氧化剂用量较大时,聚合物体现出超支化结构特征。     

Cerium(IV)oxide modification by inclusion of a hetero-atom: A strategy for producing efficient and robust nano-catalysts for methanol carboxylation

Cerium(IV) oxide has been reported to catalyse the direct carboxylation of methanol to dimethylcarbonate, DMC. Nevertheless, the life of commercially available catalysts is quite short as after the first cycle the activity decreases and after a few cycles goes to zero. Noteworthy, no reports are in the literature about the stability of catalysts and their life. We have investigated the behaviour of catalysts and their de-activation using either surface techniques, such as XPS, or structural techniques, such as XRD. The reduction of Ce(IV) to Ce(III) and surface modification seem to be responsible for de-activation of the oxide. The results of a detailed study correlating the size and structure of particles to the activity of the catalysts are reported in this paper. In particular, pure commercial CeO₂ is compared, using High Throughput Experiments (HTE), with CeO₂ synthesised in our laboratory and with the latter loaded with Al or Fe at various concentrations. The hetero-metals have a different effect on the stabilization of the Ce-catalyst and on its activity. Al-loaded CeO₂ affords the most interesting results in terms of lifetime and activity. Therefore, the correlation of the structural properties of CeO₂ loaded with Al at a concentration variable between 3 and 40% to the activity in catalysis is discussed in detail. XPS and XRD data have been used for the characterization of the catalyst before and after a catalytic run. Pure synthesised CeO₂ and CeO₂ loaded with Al are able to maintain their activity for several cycles (apparent TON of several tens) or three days of operation without any treatment after recovery, with a much better performance than the commercial catalysts that, conversely, loose their activity after a few cycles. The size of the particles determines the activity of the catalyst and we show that particles having a size 15–60 nm are the most active, while particles sized micrometers are much less active.     

Polymerization kinetics of methylmethacrylate by oxidation: Reduction system using cerium(IV)/lactic acid in aqueous medium

The kinetics of polymerization of methylmethacrylate initiated by cerium(IV)–lactic acid redox system was studied in an aqueous medium in the temperature range of 25–50°C. The rate of polymerization (R_p) and the rate of cerium(IV) disappearance have been measured. The effects of some water‐miscible organic solvents, cationic, anionic, nonionic surfactants, and complexing agents on the rate of polymerization were investigated. The temperature dependence of the rate was studied, and the activation parameters were computed using the Arrhenius and Eyring plots. The effects of inorganic and organic solvents on polymerization were also investigated. All of them depressed both the initial rate and limiting conversion. A mechanism consistent with the experimental data, involving cerium(IV)–lactic acid complex formation, which generates free radicals, is suggested. The chain termination step of the polymerization reaction is by mutual interaction of the growing macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3498–3505, 2007     

Polymerization of acrylonitrile initiated by cerium (IV)‐oxalic acid redox system: A kinetic study

The kinetics of aqueous polymerization of Acrylonitrile initiated by the Cerium (IV)‐Oxalic acid redox system in Sulfuric acid medium has studied under nitrogen atmosphere in the temperature range of 25–50°C. The rate of polymerization (R_p) and the disappearance of Cerium (IV) have been measured. The water‐miscible organic solvents and inorganic salts were depressed both the rate and the conversion. The effects of ionic strength, effects of surfactant have been investigated. The temperature dependence of the rate was studied and the activation parameters were computed using Arrhenius and Eyring plots. A mechanism consistent with the experimental data, involving Ce(IV)–Oxalic acid complexation that generates free radical was suggested. The chain termination step of the polymerization reaction was determined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

On the retention of n-butylamine by crystalline and fibrous cerium(IV) phosphate

The retention of n-butylamine dissolved in cyclohexane on both crystalline and fibrous cerium(IV) hydrogen phosphate has been studied. The products involved were characterized by thermogravimetry, derivative thermogravimetry, differential scanning calorimetry, IR spectroscopy and X-ray diffraction. The experimental results obtained reveal that the adsorption of n-butylamine from cyclohexane solutions results in a net increase in the lattice space of the crystalline variety of the phosphate. Integral enthalpies and entropies, isosteric heats and differential entropies of retention were calculated from the adsorption isotherms run at 10, 15, 20, 25 and 30°C. The results show that variation of the different thermodynamic parameters with the degree of coverage for the two types of phosphate to be rather different.     

Selective Extraction and Separation of Ce (IV) and Th (IV) from RE(III) in Sulfate Medium using Di(2-ethylhexyl)-N-heptylaminomethylphosphonate

The extraction and separation of Ce(IV) and Th(IV) from trivalent rare earths (RE, including scandium) in sulfate medium using di(2-ethylhexyl)-N-heptylaminomethylphosphonate (DEHAMP, L) were studied. The effects of H₂SO₄ concentration, extractant concentration, and temperature on the metal extraction were investigated systematically. It was found that the extraction of metal ions by DEHAMP decreases in the following order: Ce(IV) > Th(IV) > Sc(III) > other RE(III). A possible extraction mechanism was proposed and the extracted complexes as Ce(SO₄)₂·2L and Th(HSO₄)₂SO₄·L were determined by the slope analysis method. Thermodynamic parameters (ΔH, ΔG, and ΔS) were calculated. The extraction reactions of Ce(IV) and Th(IV) were each exothermic processes. The loaded Ce(IV) and Th(IV) can be stripped efficiently by 3% H₂O₂ and 4 mol/L HCl, respectively. The extraction capacity of 0.63 mol/L DEHAMP is 30.0 g/L CeO₂ and 24.4 g/L ThO₂, respectively. Furthermore, a solvent extraction process to selectively extract and recover cerium and thorium from bastnaesite leaching was proposed, by which the purities of cerium and thorium products reached 97.2% and 96.5% with a yield of 85.4% and 98.8%, respectively.     

Electrochemical study of cerium(IV) in the presence of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetate (DTPA) ligands

The electrochemical behaviour of the complexation of cerium(IV) with EDTA and DTPA was studied using both cyclic voltammetry (CV) and rotating disc electrode (RDE). The Ce(IV)–DTPA complex at various scan rates gave a linear correlation between the peak potential (E _p ) and square root of scan rate, showing that the kinetics of the overall process was controlled by mass transport. However, when the EDTA ligand was added to the Ce(IV) there was no specific change to the potential peak, i.e. the Ce(IV)–EDTA complex has the same redox potential as the Ce(IV)/(III) couple. Kinetic parameters such as potential, limiting current, diffusion coefficients, transfer coefficient and rate constants were studied. The results from RDE experiments confirmed that the parameters measured by CV are similar under hydrodynamic conditions and can be used to determine the kinetic parameters of the redox couples. The use of DTPA as a ligand for complexation of Ce(IV) gaves more favourable results compared to the Ce–(EDTA) complex reported previously. The results of kinetic studies of Ce(IV)–DTPA complex shows promise as an electrolyte for redox flow battery.     

Synthesis and Characterization of in situ Polyethylene and Polypropylene Nanocomposites: Gas Phase Polymerization by Nanosilica Supported <Emphasis Type="Italic">bis</Emphasis> (Cyclopentadienyl) Zirconium (IV) Dichloride Catalyst System

In the present work, in situ polyethylene and polypropylene nanocomposites have been successfully synthesized by gas phase polymerization of ethylene and propylene in presence of surface treated nanofillers with nanosilica-supported-bis (cyclopentadienyl) zirconium (IV) dichloride as a coordination catalyst. The nanofillers used are Cloisite-20A and nanosilica, respectively. These were pre-treated with MAO (Methylaluminoxane) to inhibit their deactivating action on the catalyst because of the presence of either acidic or basic groups on their surfaces; in this way MAO acts as a co-catalyst for the polymerization reactions being discussed. Two in situ Polyethylene (PE) i.e., CFPE and SFPE (Cloisite-20A filled polyethylene and nanosilica filled polyethylene) and two in situ polypropylene (PP) i.e., CFPP and SFPP (Cloisite-20A filled polypropylene and nanosilica filled polypropylene) nanocomposites have been prepared by gas-phase polymerization. The in situ polyethylene and polypropylene nanocomposites were characterized using Fourier transform infrared Spectroscope (FTIR), Thermogravimetric analyzer (TGA), Differential Scanning Calorimeter (DSC) and Scanning electron microscope (SEM). By our approach, it has been observed that the nanofillers are completely encapsulated by a thin layer of polymer chains.     

快速测定磷酸(氢)钙中磷含量

本方法适合于pH4．2时水溶性的磷酸盐中磷含量的测定、磷酸（氢）钙中磷含量的测定。     

A novel solvent-impregnated resin containing 3-hydroxy-2-naphthoic acid for stepwise extraction of Th(IV) and U(VI) over other coexistence ions

A new solvent-impregnated resin (SIR) was constructed using Amberlite XAD-2 and 3-hydroxy-2-naphthoic acid (3H2NA). The SIR was applied for stepwise extraction of Th(IV) and U(VI) from the coexistence ions dissolved in aqueous media at pHs of 3.0 and 7.0, respectively. The U(VI) and Th(IV) ions adsorbed on the minicolumn were consecutively eluted with 0.5 M and 4 M HCl solutions. They were then measured by Arsenazo III at their maximum absorption wavelengths. The characteristic parameters for the successful separation of these ions from the aqueous media were investigated. The SIR showed excellent reproducibility during the 800 subsequent extraction cycles.     

N,N′-Methylenebisacrylamide polymerization initiated by Ce(IV)—Malic acid redox system—A kinetic study

Free-radical-initiated linear cyclopolymerization of a symmetrical non-conjugated divinyl monomer, viz. N,N'-methylenebisacrylamide, was carried out using cerium sulphate as initiator and malic acid as activator, in an inert atmosphere at 25 ± 0.1°C. A gel-free polymer was formed under the experimental conditions. The order with respect to malic acid and monomer was found to be 1 and 2, respectively. The rate of polymerization was found to be inversely proportional to the concentration of Ce(IV). The overall energy of activation was found to be 25.5 kJ mol^?1. An intramolecular cyclization prior to propagation is proposed in formulating a suitable mechanism to explain the kinetic results.