Grafting of polypropylene and its potential use as metal ion adsorption resin

Polypropylene (PP) was modified by radical grafting of acrylic acid (AA) in the melt by using dicumyl peroxide (DCP) as initiator. To reach a high grafting degree (GD) without substantially modifying PP‐chain structure, a few runs were carried out by employing butyl 3‐(2‐furanyl)propenoate (BFA), which is a coagent able to preserve the molecular weight (MW) of PP macromolecules in the presence of radical grafting reagents. All the samples were extracted with selective solvents to remove unreacted chemicals and free poly(acrylic acid) (PAA), and the GD was accurately determined by using the FTIR methodology. The GD ranged from 1.51 to 4.67 mol %. High‐temperature size permeation chromatography analysis was used to evaluate MW behavior, confirming the control exerted by the presence of BFA on the degradation reactions. DSC, TGA, and SEM analyses were performed to analyze the chemical modification effects on the polymer products' thermal and morphological properties. Finally, selected samples, with a particle size distribution in the range 100–850 μm, were tested as metal ion adsorption resins. Al(III), Cr(III), Zn(II), Cd(II), Pb(II), and Hg(II) were studied, and the highest adsorption efficiency values (in percentage) were obtained for Al(III) (15–20%) and Hg(II) (25–30%). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies of poly(8‐hydroxy‐4‐azoquinolinephenol‐formaldehyde) and its metal complexes

Poly(8‐hydroxy‐4‐azoquinolinephenol‐formaldehyde) resin (8H4AQPF) was prepared by condensing 8‐hydroxy 4‐azoquinoline phenol with formaldehyde (1 : 1 mol ratio) in the presence of oxalic acid. Polychelates were obtained when the DMF solution of poly(8H4AQPF) containing a few drops of ammonia was treated with the aqueous solution of Cu(II) and Ni(II) ions. The polymeric resin and polymer–metal complexes were characterized with elemental analysis and spectral studies. The elemental analysis of the polymer–metal complexes suggested that the metal‐to‐ligand ratio was 1 : 2. The IR spectral data of the polychelates indicated that the metals were coordinated through the nitrogen and oxygen of the phenolic ? OH group. Diffuse reflectance spectra, electron paramagnetic resonance, and magnetic moment studies revealed that the polymer–metal complexes of the Cu(II) complexes were square planar and those of the Ni(II) complexes were octahedral. X‐ray diffraction studies revealed that the polymer metal complexes were crystalline. The thermal properties of the polymer and polymer–metal complexes were also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1506–1510, 2006     

Grafting of polyelectrolytes onto polyacrylamide by reactive processing

Low‐molecular‐weight high‐charge‐density cationic poly diallydimethyl ammonium chloride (polyDADMAC) was grafted onto nonionic polyacrylamide (PAM) using organic peroxide initiators in the molten state carried out in a batch mixer. The graft copolymer can be used as a high performance flocculant. Glycerol was selected as a plasticizer. The grafting reaction was characterized in terms of composition, temperature, degree of grafting, and grafting efficiency. It was found that free radicals on polymer chains were induced by the decomposition of the initiator. Grafting was produced by free radical recombination termination. The degree of grafting increases with an increase of the polyDADMAC/PAM feed ratio. However, the grafting efficiency was lower than 10 wt % in this highly viscous polymer melt system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1412–1416, 1999     

Crosslinked poly(glycidyl methacrylate)‐based resin for removal of mercury from aqueous solutions

Glycidyl methacrylate–based resin crosslinked beads with acetamide functions were demonstrated to be efficient in the removal of mercury. Beaded polymer supports were prepared by suspension polymerization of glycidyl methacrylate (0.9 mol) and ethylene glycol dimethacrylate (0.1 mol). The resulting copolymer beads were modified through epoxy functions in two steps: (1) by treatment with excess dibutyl amine and (2) by subsequent reaction with chloroacetamide. The resulting polymer resin, which had a chloroacetamide content of 2.5 mmol/g, was effective in extracting mercury from aqueous solutions. The mercury sorption capacity was around 2.2 mmol/g in nonbuffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), and Fe(III) ions also were extractable in low quantities (0.2–0.8 mmol/g). The sorbed mercury could be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 348–352, 2006     

Grafting biodegradable polyesters onto cellulose

To increase the compatibility between cellulose fibers and polyester matrix an original method for grafting hydrophobic oligoesters onto cellulose was proposed. Two kinds of cellulose substrates were employed as cellulose films and microcrystalline cellulose powder. Different oligoesters containing reactive end groups based on poly(DL ‐lactic acid) PDL‐LA, poly(ε‐caprolactone) PCL and poly(3‐hydroxyalkanoate)s PHA were first prepared and characterized by size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). The carboxylic end groups of the polyesters were activated using thionyl chloride (SOCl₂) to increase the esterification reaction with the hydroxyl groups of the cellulose. The esterification was realized in a heterogenous medium without any catalyst by deposition of chloride oligoesters in solution (2–100 g L⁻¹) onto cellulose film at different temperatures (25–105°C) during 1–12 h. The successful grafting on the various substrates was confirmed on the basis of FTIR spectroscopy, contact angle measurement, X‐ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). In particular, it is shown that a small quantity of grafted oligoesters led to a significant increase of the hydrophobic character of the cellulose with a contact angle near 130°. The increase of hydrophobicity of cellulose is independent of the nature and length of grafting oligoesters. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Grafting of branched polymers onto nano-sized silica surface: Postgrafting of polymers with pendant isocyanate groups of polymer chain grafted onto nano-sized silica surface

To control the surface wettability of nano-sized silica surface, the postgrafting of hydrophilic and hydrophobic polymers to grafted polymer chains on the surface was investigated. Polymers having blocked isocyanate groups were successfully grafted onto nano-sized silica surface by the graft copolymerization of methyl methacrylate (MMA) with 2-(O-[1′-methylpropylideneamino]caboxyamino)ethyl methacrylate (MOIB) initiated by azo groups previously introduced onto the surface. The blocked isocyanate groups of poly(MMA-co-MOIB)-grafted silica were stable in a desiccator, but isocyanate groups were readily regenerated by heating at 150 °C. The hydrophilic polymers, such as poly(ethylene glycol) (PEG) and poly(ethyleneimine) (PEI), were postgrafted onto the poly(MMA-co-MOIB)-grafted silica by the reaction of functional groups of PEG and PEI with pendant isocyanate groups of poly(MMA-co-MOI)-grafted silica to give branched polymer-grafted silica. The percentage of grafting increased with increasing molecular weight of PEG, but the number of postgrafted chain decreased, because of steric hindrance. The hydrophobic polymers, such as poly(dimethylsiloxane) were also postgrafted onto poly(MMA-co-MOI)-grafted silica. It was found that the grafting of hydrophobic polymer and the postgrafting of hydrophilic polymer branches readily controls the wettability of silica surface to water.     

Influence of untreated and novel electron‐beam‐modified surface‐coated silica filler on the thermorheological properties of ethylene–octene copolymer

We developed surface‐modified silica fillers by coating these with an acrylate monomer, trimethylolpropane triacrylate, or a silane coupling agent, triethoxyvinyl silane, followed by electron‐beam irradiation at room temperature. These were incorporated in an ethylene–octene copolymer rubber. Thermorheological studies of the unvulcanized ethylene–octene copolymer and its untreated and modified silica‐filled composites were done with a shear dynamic oscillating rheometer. Modification of the silica filler, especially via the silanization process followed by electron beam treatment, significantly reduced filler–filler networking as revealed from the log–log plots of storage modulus and complex shear viscosity, and its real component. The rheological complexity of the compositions was analyzed from a double logarithmic plot of the storage modulus and loss modulus. The results obtained from the master curves constructed on the basis of the time–temperature superposition principle and the activation energy calculated from the Arrhenius equation for the flow of above these compounds further supported these findings. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2453–2459, 2003     

Synthesis and metal ion adsorption studies of chelating resins derived from macroporous glycidyl methacrylate‐divinylbenzene copolymer beads anchored schiff bases

Two novel chelating resins are prepared by anchoring diethylenetriamine bis‐ and mono‐furaldehyde Schiff bases onto the macroporous GMA‐DVB copolymer beads and utilized for the adsorption towards Cu(II), Co(II), Ni(II), and Zn(II). FTIR spectra show that Schiff base groups have been successfully introduced into the polymer matrix and the chelating resins can form complexes with the metal ions. The chelating resins show a higher adsorption capacity toward Cu(II). The conductivity method can be used for determining the adsorption kinetics of the resins towards metal ions. The results show that the adsorption rates towards Cu(II) are much higher than those towards other ions and pseudo second‐order and intraparticle diffusion models can be applied to treat the adsorption amount‐time data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fe(II) adsorption onto natural polymers derived from low‐grade lignites

In comparison with conventional chemical treatment methods for Fe(II) ions, adsorption and ion exchange are considered more easily applicable and economical, depending on the material used. Polymeric materials are the examples used in these commonly applied removal processes. In this study, the adsorption of Fe(II) ions from aqueous solutions onto two different natural polymers, insoluble humic acids (IHAs) extracted from low‐grade lignites from Beysehir and Ermenek (in the central Anatolia region, Konya, Turkey), was investigated. The IHAs were synthesized through a series of acid–base reactions, and the obtained precipitates were chemically stable and had about 40% humic matter together with functional carboxyl and hydroxyl groups. The effects of the time and initial metal concentration on the effectiveness of the IHAs for Fe(II) adsorption were determined through batch experiments; the adsorption isotherms and capacities were calculated. The IHAs were effective, with capacities of 59 mg/g for the Beysehir IHA and 57 mg/g for the Ermenek IHA, for Fe removal under neutral pH conditions. The adsorption followed mainly a Freundlich isotherm for both IHAs, and the calculated adsorption rates were 0.86 for the Beysehir IHA and 0.81 for the Ermenek IHA. This indicated that the effectiveness of the Beysehir IHA was slightly higher than that of the Ermenek IHA. The results confirmed the real possibility of the practical application of IHAs for the separation of Fe(II) in aqueous systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Chemical modification of controlled‐pore silica with N‐propylsalicylaldimine

Two controlled‐pore silica phases were prepared with a sol–gel precursor from a sodium silicate solution. N‐Propylsalicylaldimine was immobilized on these silica species to be used as chelating ion exchangers (IE11 and IE2). The monomer phase was also prepared for comparison. The N‐propylsalicylaldimine moiety was detected by Fourier transform infrared and ultraviolet in both the ion exchangers and the monomer phases. 1H‐NMR and mass spectrometry of the monomer also confirmed the structure. The capacity (C) of the ion exchangers was dependent on the porosity of the ion exchanger (C_IE11 = 0.36 mmol of Cu/g and C_IE2 = 0.026 mmol of Cu/g). The uptake behavior of IE11 toward some metal ions was studied, and log distribution coefficient (k_d) was within the range of 2.19–5.16. Also, thermogravimetric and differential thermogravimetric analysis data were used to study the kinetics of the thermal decomposition process of IE11. Some thermodynamic parameters for the ion exchanger were calculated by the application of the rate theory of the first‐order reaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3159–3167, 2003     

Metallization of crosslinked acrylate resin by reduction of polymer‐incorporated metal ion

Crosslinked acrylate resin were prepared by the radical polymerization of poly(ethylene glycol) diacrylate (ADE400) with 2,2′‐azobisisobutyronitrile in the presence of cobalt (II) chloride at 100°C for 48 h. Metallization behavior of the CoCl₂‐containing acrylate resin by reduction with aqueous sodium tetrahydroborate solution at 25°C was investigated by means of infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and electron probe microanalysis. As a result, the surface of the crosslinked acrylate resin was successfully metallized by the reduction, and the cobalt layer generated at the side of a polypropylene plate used in the preparation of film was thicker and smoother than the air side. Most of the chlorine ion in the film passed in the reduction solution. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3864–3868, 2004     

Grafting and phosphonic acid functionalization of hyperbranched polyamidoamine polymer onto ultrafine silica

In this study, grafting of hyperbranched polyamidoamine (PAMAM) polymer onto ultrafine silica followed by functionalization via the introduction of phosphonic acid groups into the branch ends was performed. First, an initiating site was incorporated into the silica surface by reacting the silica silanol group with 3‐aminopropyltriethoxysilane, producing amino‐functionalized silica. The free amine group content was altered by varying the ratio of methanol to water in the hydrolysis step of the silanization reaction. Grafting of PAMAM was attained by three rounds of sequential Michael addition of silica amino groups to methyl acrylate and amidation of the resulting terminal methyl ester groups with ethylenediamine. Completion of the grafting reaction in each step was clearly confirmed using FTIR analysis. Excessive ethylenediamine and unattached hyperbranched PAMAM present in the reaction product were removed by dialysis with a molecular weight cutoff of 6000–7000 Daltons. However, the amino group content determined in each step was found to be significantly lower than theoretically expected, perhaps indicative of side reactions and, in later stages, steric hindrance. The resultant hyperbranched PAMAM‐grafted onto silica was functionalized by phosphorylation of the terminal amino groups by a Mannich type reaction, producing the phosphorylated hyperbranched PAMAM‐grafted silica. Then its application on cotton fabric to produce fire‐retardant cellulose was tentatively investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electroless copper plating on acrylonitrile butadiene styrene material surfaces without chromic acid etching and a palladium catalyst

Hydrolysis modification of nitrile groups on acrylonitrile butadiene styrene (ABS) plate surfaces into carboxylic acid groups was investigated to find a new recipe for electroless copper plating of ABS plate surfaces without etching reactions using chromic acid and also without a palladium catalyst. Hydrolysis modification of nitrile groups was successfully conducted in an aqueous sodium hydroxide (NaOH) solution (70 wt %) at 80°C for more than 72 h, and nitrile groups were modified into carboxylic acid groups. The hydrolysis modification was accelerated by the addition of dioxane as a supplement to the aqueous NaOH solution. The modification, when an aqueous mixture solution of NaOH (35 wt %) and dioxane (10 wt %) was used as a reagent, was accomplished at 65°C in 30 min. The hydrolyzed ABS plate surfaces were successfully metalized by electroless copper plating. A silver catalyst, instead of a palladium catalyst, was usable in the electroless copper‐plating process. Adhesion between the deposited copper metal and ABS plate surface was perfect for the Scotch tape test. Consequently, we propose a new recipe for an electroless copper‐plating process without an etching process using chromic acid and without a palladium catalyst. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Improvement of the Nafion–polytetrafluoroethylene membranes for potential direct methanol fuel cell use by reduction of the methanol crossover

The possibility of ultrathin Nafion/expanded polytetrafluoroethylene (ePTFE) membranes used as proton‐exchange membranes (PEMs) for direct methanol fuel cells (DMFCs) was investigated in this study. Nafion/ePTFE membranes with a thickness of ～ 14 μm were promoted by self‐assembling Pd nanoparticles on the surface to reduce the methanol crossover. The loading of the Pd nanoparticles assembled on the membranes was 1.6–1.8 μg/cm² and had little effect on the high conductivity of the Nafion membranes. With the self‐assembly of Pd nanoparticles, the methanol permeation noticeably decreased from 340 to 28 mA/cm². As a result, the open‐ circuit voltage of the Nafion/ePTFE membranes that were self‐assembled for 48 h had a more significant increase from 0.55 to 0.73 V. The reduction of methanol crossover significantly increased the DMFC voltage‐current performance, and this means that self‐assembled Nafion/polytetrafluoroethylene PEMs have promise in DMFCs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Removal of phosphate ions with a chemically modified chitosan/metal‐ion complex

The adsorption of metal ions (Mo⁶⁺, Cu²⁺, Fe²⁺, and Fe³⁺) was examined on chemically modified chitosans with a higher fatty acid glycidyl (CGCs), and the adsorption of Cu²⁺ was examined on ethylenediamine tetraacetic acid dianhydride modified CGCs (EDTA‐CGCs) synthesized by the reaction of the CGCs with ethylenediamine tetraacetic acid dianhydride. The adsorption of phosphate ions onto the resulting substrate/metal‐ion complex was measured. Mo⁶⁺ depicted remarkable adsorption toward the CGCs, although all the Mo⁶⁺ was desorbed under the adsorption conditions of the phosphate ions. The other metal ions were adsorbed to some extent on CGCs by chelating to the amino group in the substrate, except for CGC‐1, which had the highest degree of substitution (83.9%). Considerable amounts of Fe²⁺ were adsorbed onto CGCs; however, only a limited number of phosphate ions was adsorbed onto the substrate/metal‐ion complex. As a result, the following adsorbent/metal‐ion complexes gave higher adsorption ability toward phosphate ions: CGC‐4/Cu²⁺, CGC‐4/Fe³⁺, and EDTA‐CGC‐3/Fe³⁺. Where, CGC‐3 is a chemically modified chitosan with the degree of substitution of 26.5 percentage, and CGC‐4 is one with the degree of substitution of 16.0 percentage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel sorbents based on silica coated with polyethylenimine and crosslinked with poly(carboxylic acid): Preparation and characterization

Novel sorbents based on silica coated with polyethylenimine (SilPEI) and crosslinked with poly(carboxylic acid) were prepared and characterized. These sorbents are to be used for heavy metal decontamination of aqueous solutions and have to be prepared in easy and ecological ways. A part of the carboxylic moieties [from ethylenediaminetetraacetic acid (EDTA) or citric acid] reacts with some of the amine groups of polyethylenimine, initially coated onto the silica, whereas the other part remains free for further metal complexation. By changing various parameters (temperature, pH, presence or absence of an amide‐forming agent), the conditions to prepare the best sorbent—that is, the sorbent exhibiting both a high capacity for metal complexation and good stability in an acidic medium (conditions for metal desorption or stripping)—were defined. The sorbent was prepared by a reaction of 1 g of SilPEI and 1 g of EDTA in water at 0°C, pH 6, during 10 h, using 0.5 g of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride as a coupling agent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 799–805, 2003     

Grafting of hyperbranched aromatic polyamide onto silica nanoparticles

Hyperbranched aromatic polyamide grafted nano-silica particles were successfully prepared via “one-pot” melt polycondensation. The particles were firstly treated with a silane coupling agent to introduce amine groups as the growth points, and then grafting of the hyperbranched polymers started from the modified surface. The percentage grafting can be as high as 32.8%. The key reaction conditions, including feeding ratio, reaction temperature and time, were carefully investigated to determine a set of optimal grafting parameters. It was found that the significant steric hindrance between the hyperbranched polymers during graft polymerization played a key role in controlling molecular structure of the grafted polymers, while adsorption of grafting monomer onto SiO₂ particles prior to the reaction facilitated higher degree of branching and apparent molecular weight of ungrafted polymers.     

Preparation and characterization of silica/polypyrrole core‐shell colloidal particles in the presence of ethanol as the cosolvent

The silica/polypyrrole core‐shell composites were fabricated by in situ chemical polymerization of pyrrole monomer on the surface of the silica spheres. Silica sol particles with narrow size distributions were prepared by hydrolysis of tetraethoxysilane with sol–gel method. Polypyrrole shell was obtained by chemical polymerization of pyrrole monomer on the surface of the silica spheres in the water–ethanol mixture. It can be seen from the experiment, with the adding of small amount of ethanol cosolvent to the aqueous reaction solution, a uniform coating of polypyrrole appeared on the surface of silica. The core‐shell morphology of composite particles prepared with variation ethanol adding amount was analyzed by TEM. Meanwhile, the conductivity of the core‐shell composite is found to be enhanced apparently compared with those prepared from pure aqueous system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thiol‐containing ionic liquid for the modification of styrene–butadiene rubber/silica composites

To introduce thiol–ene chemistry in the modification of composites by ionic liquid (IL), a novel functional IL, 1‐methylimidazolium mercaptopropionate (MimMP), was synthesized and investigated as a modifier for styrene–butadiene rubber/silica composites. MimMP could be hydrogen‐bonded with silica and react with the double bonds of rubber chains via thiol–ene chemistry. The filler networking, curing behavior, filler dispersion, crosslink density, and mechanical performance were fully studied. The filler networking in the uncured rubber compounds was effectively restrained. The vulcanization was largely accelerated by MimMP. The interfacial interaction was quantitatively evaluated and found to consistently increase with increasing MimMP. The mechanical performance and abrasion resistance of the modified vulcanizates improved considerably. The remarkable improvements were mainly ascribed to the improved interfacial structure comprised of MimMP–silica hydrogen bonding and MimMP–rubber covalent bonds via thiol–ene chemistry. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

纳米无机氧化物粒子表面接枝改性

本文对纳米无机氧化物粒子表面的接枝改性作了论述,重点介绍了纳米粒子表面官能团引发的接枝聚合(自由基聚合、阴离子集合、阳离子聚合),并对各种接枝方法以及其发展情况进行了评价。同时对树状接枝进行了简要的介绍。