Synthesis and characterization of water soluble poly(N‐acetyl)iminoethylene and poly(ethyleneimine) by ion‐exchanged clay montmorillonite

The cationic polymerization of 2‐méthyl‐2‐oxazoline was carried out at 0°C in acetonitrile using an acid‐exchanged montmorillonite as acid solid ecocatalyst (Maghnite‐H⁺). The effect of the amount of catalyst, solvent, and times of polymerization on yield and viscosity of polymer was studied. A typical reaction product (PMOX) was analyzed by infrared and nuclear magnetic resonance spectroscopy as well as by gel‐permeation chromatography and MALDI‐TOF MS. The polymers presented similar spectrometric results and narrow molecular weight distribution. The poly(N‐acetyl)iminoethylene was hydrolyzed in acid medium obtaining a linear poly(ethyleneimine). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3741–3750, 2006     

Ring‐opening bulk polymerization of five‐ and six‐membered cyclic phosphonates using maghnite,a nontoxic proton exchanged montmorillonite clay

A new method of preparation of poly(alkylene H‐phosphonate)s by ring‐opening bulk polymerization of the five‐ and six‐membered cyclic phosphonates monomers using the nontoxic Maghnite‐H⁺ as the initiator is described. Cyclic phosphonate monomers have been first synthesized. In particular, a new one‐step synthesis of 2‐hydro‐2‐oxo‐1,3,2‐dioxaphospholane is reported with a yield of 70%. The efficiency of the montmorillonite sheet silicate clay which exchanged with protons, called Maghnite‐H⁺, as cationic initiator has been proved and the resulting biomimetic poly(alkylene H‐phosphonate)s have been characterized. The Maghnite‐H⁺ regenerated after one turn‐over has showed to be still efficient as initiator for the ring‐opening polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of perfluorohexyl‐terminated poly(ethylene oxide) using maghnite‐h as clay catalyst

Activated monomer cationic ring‐opening polymerization of ethylene oxide initiated with 1H,1H,2H, 2H‐perfluorooctan‐1‐ol, using acid exchanged montmorillonite clay called Maghnite‐H⁺ (Mag‐H⁺) as an effective catalyst, was carried out to obtain the corresponding homopolymers with narrow polydispersity ratios. The molecular weights of the obtained polymers could be controlled with the feed ratio of the monomer and initiator. The effect of amount of catalyst and time on the polymerization yield and viscosity of the polymers were studied. The structure was confirmed by ¹H‐NMR and MALDI‐TOF‐MS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One‐step synthesis of bis‐macromonomers of poly(1,3‐dioxolane) catalyzed by Maghnite‐H+

Telechelic poly(1,3‐dioxolane) (PDXL) bis‐macromonomers bearing methyl methacrylate end groups were prepared by cationic ring‐opening polymerization of 1,3‐dioxolane (DXL), in the presence of methacrylic anhydride, catalyzed by Maghnite‐H⁺ (Mag‐H⁺), in bulk and in solution. Maghnite is a montmorillonite sheet silicate clay, which exchanged with protons to produce Mag‐H⁺. The influence of the amount of Mag‐H⁺, monomer (DXL), and methacrylic anhydride on monomer conversion was studied. The polymerization yield and the molecular weight of α,ω‐bis‐unsaturated PDXLs prepared depend on the amount of Mag‐H⁺ used and the reaction time. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Maghnite‐H+ as a cationic catalyst in the synthesis of poly(1,3‐dioxolane) and α,ω‐methacryloyloxy‐poly(1,3‐dioxolane)

The polymerization of 1,3‐dioxolane catalyzed by Maghnite‐H^+; (Mag‐H⁺), a montmorillonite sheet silicate clay exchanged with protons, was investigated. The cationic ring‐opening polymerization of 1,3‐dioxolane was initiated by Mag‐H⁺ at different temperatures (20, 30, 50, and 70°C) in bulk and in a solvent (dichloromethane). The effects of the amount of Mag‐H⁺ and the temperature were studied. The polymerization rate and the average molecular weights increased with an increase in the temperature and the proportion of the catalyst. These results indicated the cationic nature of the polymerization and suggested that the polymerization was initiated by proton addition to the monomer from Mag‐H⁺. Moreover, we used a simple method, in one step in bulk and in solution at room temperature (20°C), to prepare a telechelic bismacromonomer: α,ω‐bisunsaturated poly(1,3‐dioxolane). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 78–82, 2006     

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H+

Copolymers (polyoxymethylene) were prepared by cationic copolymerization of 1,3,5‐trioxane (TOX) with 1,3‐dioxolane (DOX) in the presence of Maghnite‐H⁺ (Mag‐H⁺) in solution. Maghnite is a Montmorillonite sheet silicate clay, with exchanged protons to produce Mag‐H⁺. Various techniques, including ¹H‐NMR, ¹³C‐NMR, FT‐IR spectroscopy, and Ubbelohde viscometer were used to elucidate structural characteristics properties of the resulting copolymers. The influence of the amount of catalyst, of dioxolane (DOX), temperature, solvent, and time of copolymerization on yield and on intrinsic viscosity of copolymers was studied. The yield of copolymerization depends on the amount of Mag‐H⁺ used and the reaction time. We also propose mechanisms involved in the synthesis of copolymer (polyoxymethylene). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Structural and photooxidation studies of poly(styrene oxide) prepared with Maghnite‐H+ as cationic catalyst

The nature of irregularities and end‐groups in poly(styrene oxide) samples prepared using Maghnite‐H⁺ as a cationic catalyst were studied by ¹H‐ and ¹³C‐NMR at 200 MHz. Head‐to‐head (H‐H) and tail‐to‐tail (T‐T) irregularities are detected in all the samples studied. Secondary hydroxyl terminal groups are identified in polymers prepared with Maghnite‐H⁺. Poly(styrene oxide) was found to undergo chain scission by aging at 25°C. It was confirmed that oxidation of this type of polymers results from the important sensitivity of the polyether soft segment to oxidative degradation. For this reason, the scissions due to the oxidation of the material lead to notable quantities of low molecular weight photoproducts. Among the various structures produced by the oxidative degradation process, benzoate and secondary hydroxyl groups are identified by MALDI‐TOF‐MS. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of Cyclic Polyesters of Poly(Oxybutylene Oxymaleoyl)

In the present work cyclic oligomers of poly(oxybutylene oxymaleoyl) were prepared successfully and cleanly from the polycondensation of the tetrahydrofuran with maleïc anhydride using the Maghnite-H⁺ (Mag-H) as catalyst. Maghnite is a montmorillonite sheet silicate clay exchanged with protons to produce Maghnite-H⁺ (M. Belbachir, U.S. Patent 066969.0101–2001). The effects of reaction temperature, amount of Maghnite-H⁺ and reaction time on the yield and the molecular weight are investigated. The results indicate that the polymerization yield increases with increasing the proportion of catalyst.     

Cationic polymerization of ethylene oxide with Maghnite‐H as a clay catalyst in the presence of ethylene glycol

The activated‐monomer cationic ring‐opening polymerization of ethylene oxide, initiated with ethylene glycol and using an acid‐exchanged montmorillonite clay called Maghnite‐H⁺ as an effective catalyst, was carried out to obtain the corresponding homopolymers with narrow polydispersity ratios. The molecular weights of the obtained polymers were controlled with the feed ratio of the monomer to the initiator. The effects of the amount of the catalyst and time on the polymerization yield and viscosity of the polymers were studied. The structure was confirmed with proton nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Maghnite‐H+, a solid catalyst for the cationic polymerization of α‐methylstyrene

The polymerization of α‐methylstyrene (AMS) catalyzed by Maghnite‐H⁺ (Mag‐H) was investigated. Mag‐H is a montmorillonite sheet silicate clay, exchanged with protons. It was found that the cationic polymerization of AMS is initiated by Mag‐H at ambient temperature in bulk and in solution. The effect of the amount of Mag‐H, the temperature, and the solvent was studied. The polymerization rate increased with increase in the temperature and the proportion of catalyst, and it was larger in nonpolar solvents. These results indicated the cationic nature of the polymerization. It may be suggested that the polymerization is initiated by proton addition to monomer from Mag‐H. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ring‐opening polymerization of styrene oxide with Maghnite‐H+ as ecocatalyst

The polymerization of styrene oxide was carried out at 20°C in chloroform with an acid‐exchanged montmorillonite as acid solid ecocatalyst (Mag‐H⁺). The effect of the amount of catalyst, solvent, and concentration of monomer on yield and molecular weight of polymer was studied. A typical reaction product (PSTO) was analyzed by infrared and nuclear magnetic resonance spectroscopy, as well as by gel‐permeation chromatography and MALDI‐TOFMS. The mechanism of the polymerization appears to be cationic. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1681–1687, 2006     

Lewis acid mediated polymerization of poly(dimethylsiloxane) polymers: Investigating reaction kinetics using both NMR spectroscopy and cyclic voltammetry

Bulk condensation polymerization of (dimethylmethoxy)‐m‐carborane and (dichlorodimethyl)silane occurs in the presence of an M^x+Cl_x Lewis acid catalyst. In the literature, FeCl₃ is commonly used as the catalyst of choice but little is known about the activation energy and entropy of this polymerization. By monitoring using ¹H‐NMR the reaction of a methoxy‐terminated poly(dimethylsiloxane) and (dichlorodimethyl)silane the rate determining step in the FeCl₃ catalyzed system is determined. The activation energy was calculated to be +43.6 kJ mol^?1 and the entropy of the reaction was also calculated. The calculated large entropy of reaction indicates that the transition step is highly ordered. The formation of the electrophile intermediate species in the first step of the reaction has also been investigated using cyclic voltammetry. To the cyclic voltammetry data Randles‐Sevcik fits have been applied to the oxidation peaks to determine the diffusion coefficients for the oxidation of Fe²⁺ to Fe³⁺. Also, the initial prediction of a reversible reaction Step 1 was shown to be incorrect as the normalized reduction peak maxima increase with scan rate, indicative of an electron transfer‐chemical reaction mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and Characterization of Estolide Esters Containing Epoxy and Cyclic Carbonate Groups

The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by ¹H and ¹³C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm^?1 and δ 82 ppm in the FTIR and ¹³C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.     

Synthesis of sulfonated rubber ionomers by the ring‐opening reaction of epoxidized styrene–butadiene rubber,their characterization,and their properties

A novel method for the synthesis of the sulfonate ionomer of styrene‐co‐butadiene rubber (SBR) was developed. SBR was first epoxidized by performic acid formed from hydrogen peroxide and formic acid in situ in solution, and this was followed by a ring‐opening reaction with an aqueous solution of NaHSO₃. The optimum conditions for the epoxidation of SBR in the presence of a phase‐transfer catalyst and for the ring‐opening reaction of epoxidized SBR with an aqueous solution of NaHSO₃ were studied. During the epoxidation of SBR, a phase‐transfer catalyst, such as poly(ethylene glycol), could enhance the conversion of double bonds to epoxy groups. During the ring‐opening reaction, both the phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of the epoxy groups to ionic groups. The addition of Na₂SO₃ to the reaction mixture was important to obtain 100% conversion. The products were characterized with Fourier transform infrared spectrophotometry, ¹H‐NMR spectroscopy, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). DSC showed that the sodium sulfonate SBR ionomer possessed a dissociation temperature of ionic domains at 110°C, which appeared as black spots under TEM, after the sodium ions of the ionomer were substituted by lead ions. Some properties of the sodium ionomer, such as the water absorbency, oil absorbency, and dilute solution behavior, were studied. With increasing ionic groups, the water absorbency of the ionomer increased, whereas the oil absorbency decreased. The dilute solution viscosity of the ionomer increased abruptly with increasing ionic group content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3090–3096, 2006     

Environmentally friendly liquid phase oxidation: enhanced selectivity in the aerial oxidation of alkyl aromatics,epoxidations and the Baeyer–Villiger oxidation using novel silica supported transition metal ions

Active transition metal species (Co, Cu, Cr, Ni or Mn) supported on a chemically modified silica gel are used as heterogeneous catalysts in a range of liquid phase oxidation reactions: alkyl aromatic side chain oxidations, epoxidations of alkenes and Baeyer–Villiger oxidations of linear ketones to esters and cyclic ketones to lactones. The catalyst employs metal centres bound to the silica surface via a hydrophobic spacer chain and is thus chemically robust and has a relatively high loading for a supported reagent (c 0.4 mmol g⁻¹). The Cr version of the catalyst promotes the oxidation of ethylbenzene to acetophenone in a solvent‐free system at a rate of 5.5% h⁻¹ (>370 turnover h⁻¹). It is also active for the oxidation of p‐chlorotoluene and p‐xylene to p‐chlorobenzoic acid and p‐toluic acid respectively. Cyclohexene is converted to its oxide at room temperature at a rate of c 28% h⁻¹ (c 12 turnover h⁻¹) using either the Ni or Cu versions of the catalyst. The room temperature Baeyer–Villiger oxidation of cyclohexanone is achieved at a rate of 44% h⁻¹ (49 turnover h⁻¹) using the Ni‐containing catalyst. The same material also promotes the Baeyer–Villiger oxidation of linear aliphatic ketones and aromatic side chains. All the above systems use either air or molecular oxygen as the oxidant rather than peroxides or peracids. © 1999 Society of Chemical Industry     

Synthesis and characterization of copolyarylates using tin octoate as a catalyst

A series of copolyarylates of bisphenol A (BPA) with varying ratios of diphenyl terephthalate (DPT) and diphenyl isophthalate (DPI) were prepared by melt polymerization at a temperature ranging from 200 to 290°C under reduced pressure in the presence of tin octoate catalyst. Tin octoate catalyst has been extensively used for the preparation of biodegradable polymers namely, poly(lactic acid), poly(glycolic acid), and poly(lactide‐glycolide) copolyesters. However, there are no reports on the preparation of copolyesters by melt polymerization using tin octoate catalyst. The effect of tin octoate catalyst was studied on the preparation of BPA/DPT/DPI copolyarylates. The copolyarylates were characterized by infrared and ¹H NMR spectroscopy, solution viscosity, thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction. The solution viscosities of copolyarylates were varied from 0.43 to 0.56 dL/g and the glass transition temperature (T_g) of copolyarylates was varied from 155 to 222°C by varying the ratio of DPT and DPI. Most of the copolyarylates were found to be soluble in commonly used organic solvents and had film‐forming properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 70–77, 2006     

Electropolymerization kinetics of o‐aminophenol and characterization of the obtained polymer films

Poly(ortho‐aminophenol) has been synthesized electrochemically from a previously deoxygenated acid medium. The initial rate of electropolymerization reaction on platinum electrode is small and the rate law is: Rate = k₂ [D]^0.50[HCl]^1.125[M]^1.29. The apparent activation energy (E_a) was found to be 68.63 kJ mol^?1. The polymer films obtained have been characterized by cyclic voltammetry, X‐ray diffraction, elemental analysis, TGA, scanning electron microscopy, ¹H NMR, UV–visible, and IR spectroscopy. The mechanism of the electrochemical polymerization reaction has been discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3093–3109, 2006     

Use of trifluoromethanesulfonic acid as catalyst for the cyclization of polyisoprene

In this study, trifluoromethanesulfonic acid was employed as catalyst for the cyclization of polyisoprene. From ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography investigations, cyclization was confirmed, and the molecular structure variation of polyisoprene during cyclization reaction was determined. With the comparison to that catalyzed by other strong acids (methanesulfonic acid), polyisoprene was cyclized with much higher efficiency, using trifluoromethanesulfonic acid as catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3666–3669, 2006     

Preparation of high‐molecular‐weight poly(L‐lactic acid)‐based polymers through direct condensation polymerization in bulk state

Poly(L ‐lactic acid‐co‐succinic acid‐co‐1,4‐butanediol) (PLASB) was synthesized by a direct condensation copolymerization of L ‐lactic acid, succinic acid (SA), and 1,4‐butanediol (BD) in bulk state using titanium(IV) butoxide (TNBT) as a catalyst. Weight average molecular weight (M_w) of PLASB increased from 3.5 × 10⁴ to 2.1 × 10⁵ as the content of SA and BD went up from 0.01 to 0.5 mol/100 mol of L ‐lactic acid (LA). PLASB having M_w in the range from 1.8 × 10⁵ to 2.1 × 10⁵ showed tensile properties comparable to those of commercially available poly(L ‐lactic acid) (PLLA). In sharp contrast, homopolymerization of LA in bulk state produced PLLA with M_w as low as 4.1 × 10⁴, and it was too brittle to prepare specimens for the tensile tests. M_w of PLASB synthesized by using titanium(IV)‐2‐ethyl(hexoxide), indium acetate, indium hydroxide, antimony acetate, antimony trioxide, dibutyl tin oxide, and stannous‐2‐ethyl 1‐hexanoate was compared with that of PLASB obtained by TNBT. Ethylene glycol oligomers with different chain length were added to LA/SA in place of BD to investigate effect of chain length of ethylene glycol oligomers on the M_w of the resulting copolymers. Biodegradability of PLASB was analyzed by using the modified Sturm test. Toxicity of PLASB was evaluated by counting viable cell number of mouse fibroblast cells that had been in contact with PLASB discs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 466–472, 2006     

Electrochemical Deposition of Highly Dispersed Palladium Nanoparticles on Nafion‐Graphene Film in Presence of Ferrous Ions for Ethanol Electrooxidation

An efficient method was developed to produce highly dispersed Pd nano particles (NPs), supported on Nafion‐graphene film by electrochemical deposition at constant potential in presence of ferrous ions. The Fe²⁺ ions govern the size, shape and morphology of Pd NPs. The as‐prepared catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). It was obeserved from TEM that the mean diameter of electrodeposited Pd NPs was 6.4 ± 1.3 nm with narrow diameter range from 4 to 10 nm. The electrocatalytic performance of the Pd NPs deposited on Nafion‐graphene (Nf‐G) catalyst was studied by cyclic voltametry (CV) and chronoamperometric measurements. The highly dispersed Pd NPs on Nf‐G film were obtained in presence of Fe²⁺ ions. This alters electrochemical active surface area and hence catalytic activity of Pd NPs. The prepared Pd/Nf‐G catalyst exhibit highest tolerance to the intermediate poisoning species (ratio I_f/I_b = 2.2). The as‐obtained catalyst shows an efficient electrocatalytic activity and good stability for ethanol oxidation in alkaline medium.