Water-soluble copolymers in conjunction with ultrafiltration membranes to remove arsenate ions

Water-soluble polymer poly[3-methacryloylamine)propyl)trimethyl ammonium chloride, P(ClMPTA) and the copolymer with 4-vinyl pyridine, poly[(3-methacryloylamine)propyl) trimethylammonium chloride-co-4-vinyl pyridine], P(ClMPTA-co-4VP) were synthesized by radical polymerization, at different feed mole ratios ClMPTA:4VP 1:1, 1:2, and 2:1. The copolymer compositions were determined by FT-IR and H-NMR spectroscopy and analyzed by TG-DSC. The liquid-phase polymer-based retention (LPR) technique was used to study the water-soluble polymers’ arsenic removal properties. The solution’s conductivity properties were evaluated at different pH. The copolymers can bind more selectively divalent anionic arsenic species from an aqueous solution (pH 8 ≥ pH 6 > pH 4). Assays for the mol ratio copolymer: As(V) 75:1, 37.5:1, 20:1, 10:1, and 5:1 at arsenic concentrations of 10 and 37.5 ppm were carried out. Apparently, the behavior of the copolymers with the solution’s pH was similar to pure cationic homopolymer; however, when the retention capacity was expressed as real mass of quaternary ammonium comonomer, the retention values were enhanced for lowest mol ratio 10:1 and 5:1. The retention capacity of exchanger with quaternary ammonium group was improved in presence of a weak base 4-vinyl pyridine comonomer, differently to the behavior showed by those copolymers of ClMPTA with acrylic acid groups as comonomer.     

Influences of co‐monomers and electrolyte acidity on morphological structure of copper‐in‐copolymer gradient film

In this paper, the influences of composition of copolymers and acidity of electrolyte in an electrochemical reactor on morphological structure of copper‐in‐polymer gradient composite film were investigated. For binary copolymers, poly(acrylonitrile‐co‐methyl acrylate) [P(AN‐co‐MA)] and poly(acrylonitrile‐co‐sodium allyl sulfonate) [P(AN‐co‐SAS)], the charged group ? SO in P(AN‐co‐SAS) improves the swelling of the copolymer phase and copper reduction to form gradient morphology; the carboxylic ester group in P(AN‐co‐MA) is not effective because of its poor hydrophilicity, but it is a cooperating component with P(AN‐co‐SAS) to avoid excess of counterion (i.e., Na⁺) in SCF, which might severely interrupt Cu²⁺ coexistence. The swelling of the polymer phase is helpful to decrease the energy of the transfer ions in SCF and to enhance copper deposition and gradient formation. The increase of surface energy because of cluster growth raises the surface energy level of deposited Cu⁰ clusters. The conteraction between these two energy factors allows the size of clusters to be 50–100 nm. The appropriate H⁺ concentration improves active Cu²⁺ reduction and thus deposited gradient copper phase in the copolymer matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 373–380, 2004     

Effect of different anchor groups on adsorption behavior and effectiveness of poly(N,N‐dimethylacrylamide‐co‐Ca 2‐acrylamido‐2‐methylpropanesulfonate) as cement fluid loss additive in presence of acetone–formaldehyde–sulfite dispersant

The impact of various anchor groups on adsorption behavior of AMPS® copolymers was studied. The anchor groups differ in anionic charge density. Copolymer adsorption and water retention of oil well cement slurries achieved from CaAMPS®‐co‐NNDMA in the presence of an acetone–formaldehyde–sulfite (AFS) dispersant were improved by incorporation of minor amounts (～ 1% by weight of polymer) of acrylic acid (CaAMPS®‐co‐NNDMA‐co‐AA), maleic acid anhydride (CaAMPS®‐co‐NNDMA‐co‐MAA), or vinyl phosphonic acid (CaAMPS®‐co‐NNDMA‐co‐VPA), respectively. Performance of these terpolymers was studied by measuring static filtration properties of oil well cement slurries at 27°C and 70 bar pressure. All fluid loss additives possess comparable molar masses and show the same adsorption behavior and effectiveness when no other admixture is present. In the presence of AFS dispersant, however, adsorption of CaAMPS®‐co‐NNDMA and hence fluid loss control is dramatically reduced, whereas effectiveness of CaAMPS®‐co‐NNDMA‐co‐AA is less influenced because of acrylic acid incorporated as additional anchor group. Even more, CaAMPS®‐co‐NNDMA‐co‐MAA combined with AFS allows simultaneous adsorption of both polymers and thus produces good fluid loss control. CaAMPS®‐co‐NNDMA‐co‐VPA no longer allows adsorption of AFS dispersant. This was also confirmed by rheological measurements. The results show that, in a binary admixture system, adsorption of the anionic polymer with anchor groups possessing higher charge density is preferred. Surface affinity of the anchor groups studied increase in the order ? SO → ? COO^? → vic‐(? COO^?)₂→ ? PO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation,characterization, and metal ion retention capacity of Co(II) and Ni(II) from poly(p‐HO‐ and p‐Cl‐phenylmaleimide‐co‐2‐hydroxypropylmethacrylate) using the ultra filtration technique

p‐Chlorophenylmaleimide and p‐hydroxyphenylmaleimide with 2‐hydroxypropyl methacrylate were synthesized by radical polymerization, and the metal ion retention capacity and thermal behavior of the copolymers were evaluated. The copolymers were obtained by solution radical polymerization with a 0.50 : 0.50 feed monomer ratio. The maximum retention capacity (MRC) for the removal of two metal ions, Co(II) and Ni(II) in aqueous phase were determined using the liquid‐phase polymer based retention technique. Inorganic ion interactions with the hydrophilic polymer were determined as a function of pH. The metal ion retention capacity does not depend strongly on the pH. Metal ion retention increased with an increase of pH for a copolymer composition 0.50 : 0.50. At different pH, the MRC of the poly(p‐chlorophenylmaleimide‐co‐2‐hydroxypropylmethacrylate) for Co(II) and Ni(II) ions varied from 44.1 to 48.6 mg/g and from 41.5 mg/g to 46.0 mg/g, respectively; while the MRC of poly(p‐hydroxyphenylmaleimide‐co‐2‐hydroxypropyl methacrylate) for Co(II) and Ni(II) ions varied from 28.4 to 35.6 mg/g and from 27.2 to 30.8 mg/g, respectively. The copolymers and copolymer–metal complexes were characterized by elemental analysis, FT‐IR, ¹H NMR spectroscopy, and thermal behavior. The thermal behavior of the copolymer and polymer–metal complexes were studied using differential scanning calorimetry and thermogravimetry techniques under nitrogen atmosphere. The thermal decomposition temperature and T_g were influenced by the binding‐metal ion on the copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Carbon‐13 nuclear magnetic resonance investigation of styrene–α‐methylstyrene copolymers

A copolymer based on α‐methylstyrene (AMS) was investigated by nuclear magnetic resonance (NMR). The styrene‐co‐α‐methylstyrene (SAMS) was analyzed by solution and solid‐state NMR techniques. Three copolymers of SAMS with different compositions presented a particular behavior. The solution results showed the copolymer microstructure and the AMS content. The carbon‐13 spectra of SAMS C indicated that the AMS CH₃ signal was detected at three distinct chemical shifts, because of the different comonomer‐sequences distribution. The proton spin–lattice relaxation time in the rotating frame (Tρ) parameter was chosen because it permits the evaluation of changes in the molecular mobility. The values of Tρ found for the copolymers confirmed the random distribution in the samples. The copolymer with a low quantity of AMS (1.7%), when analyzed by this relaxation parameter, showed lower values that were interpreted as an antiplasticization effect. The SAMS copolymer with a higher AMS quantity showed a plasticization effect. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 261–266, 2001     

A water‐developable negative photoresist based on the photocrosslinking of N‐phenylamide groups with reduced environmental impact

A water‐developable negative photoresist based on the photocrosslinking of N‐phenylamide groups was prepared by the copolymerization of 4‐styrenesulfonic acid sodium salts (SSS) with N‐phenylmethacrylamide (copolymer A) or p‐hydroxy‐N‐phenylmethacrylamide (copolymer B), and its properties such as solubility changes, photochemical reaction, and photoresist characteristics were studied. The copolymer containing a relatively higher amount of SSS units was soluble in water. Solubility changes of the copolymers in the various buffer solutions of pH 4 ～ 11 and in water upon irradiation were observed by the measurement of insoluble fraction. The copolymers were soluble in water before irradiation, whereas they became insoluble upon irradiation with the UV light of 254 nm. The photochemical reaction of the copolymer studied by the UV and IR absorption spectroscopies indicated that a photo‐Fries rearrangement was favored for copolymer A, whereas a photocrosslinking reaction was predominate for copolymer B. Resist properties of the copolymers were studied by measurement of the normalized thickness and by development of the micropattern. Negative tone images with a resolution of 1 μm were obtained with these materials that have a sensitivity (D) of ～ 1100 mJ/cm² with an aqueous developing process.© 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1172–1180, 2002     

Functional polymers for colloidal applications. XIV. Syntheses of styrene–maleic anhydride copolymers with different charges and their ability to disperse kaolinite particles

Four kinds of styrene/maleic–anhydride (SMA) copolymer‐derived dispersants with different charged forms were synthesized and characterized with ¹H‐NMR. These four different dispersants contained carboxylic acid groups and exhibited characteristics indicative of anionic, cationic, zwitterionic, or nonionic surfactants as pH was changed. The charge properties of these copolymers changes with pH, and their ability to disperse clay particles under low and high pH were assessed by measuring viscosity or sedimentation, as well as Scanning Electron Microscopy (SEM). The results showed that the dispersing abilities are functions of pH of the system. It was found that SMA‐N [Poly(styrene‐co‐β‐N,N‐dimethylpropylamino) maleic acid, sodium salt)] exhibits the best dispersing ability, the fastest rate of sedimentation, and the smallest sedimentation volume at pH = 2, and SMA‐Na [poly(styrene‐co‐maleic acid, disodium salt)] exhibits the better dispersing ability at pH = 7 and 12. In addition, the aggregation behavior of the dispersants characterized by fluorescence spectroscopy revealed that the degree of aggregation for all dispersants at high concentration increases in the order: SMA‐Na < SMA‐B [poly(styrene‐co‐B‐imino‐propyl‐N‐trimethylammonium acetate) maleic acid, disodium salt)] < SMA‐N < SMA‐Q [poly(styrene‐co‐β‐imino‐propyl‐N‐trimethylammonium sulfate) maleic acid, sodium salt)]. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 592–602, 2000     

Nonionic water‐soluble polymer: Preparation,characterization, and application of poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) as a polychelatogen

The free‐radical copolymerization of water‐soluble poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) was carried out with a feed monomer ratio of 75:25 mol %, and the total monomer concentration was 2.67M. The synthesis of the copolymer was carried out in dioxane at 70°C with benzoyl peroxide as the initiator. The copolymer composition was obtained with elemental analysis and ¹H‐NMR spectroscopy. The water‐soluble polymer was characterized with elemental analysis, Fourier transform infrared, ¹H‐ and ¹³C‐NMR spectroscopy, and thermal analysis. Additionally, viscosimetric measurements of the copolymer were performed. The thermal behavior of the copolymer and its complexes were investigated with differential scanning calorimetry (DSC) and thermogravimetry techniques under a nitrogen atmosphere. The copolymer showed high thermal stability and a glass transition in the DSC curves. The separation of various metal ions by the water‐soluble poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) reagent in the aqueous phase with liquid‐phase polymer‐based retention was investigated. The method was based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molar‐mass species from the polymer/metal‐ion complex formed. Poly(1‐vinyl‐2‐pyrrolidone‐co‐hydroxyethylmethacrylate) could bind metal ions such as Cr(III), Co(II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(III) in aqueous solutions at pHs 3, 5, and 7. The retention percentage for all the metal ions in the polymer was increased at pH 7, at which the maximum retention capacity could be observed. The interaction of inorganic ions with the hydrophilic polymer was determined as a function of the pH and filtration factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 178–185, 2006     

Isothermal crystallization of metallocene‐based propylene/α‐olefin copolymers

Isothermal crystallization and subsequent melting behavior of two propylene/hexene‐1 copolymers and two propylene/octene‐1 copolymers prepared with metallocene catalyst were investigated. It is found that γ‐modification is predominant in all copolymers. The Avrami exponent shows a weak dependency on comonomer content and comonomer type. At higher crystallization temperatures (T_c) the crystallization rate constant changes more rapidly with T_c and the crystallization half‐time substantially increases. Double melting peaks were also observed at high T_c, which is attributed to the inhomogeneous distribution of comonomer units along the polymer chains and the existence of crystals with different lamellar thicknesses. The equilibrium melting temperatures (T) of the copolymers were obtained by Hoffman–Weeks extrapolation. It was found that the T decreases with increasing comonomer content, but are independent of comonomer type, implying that comonomer units are excluded from the crystal lattice. Dilation of the crystal lattice was also observed, which depends on crystallization, comonomer content, and comonomer type. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 240–247, 2005     

Evaluation of EVA–PVAc blend behavior by 1‐D and 2‐D solid‐state NMR

Ethylene‐co‐vinyl acetate and poly(vinyl acetate) blends were prepared in different proportions by melting in a HAAKE Rheomix mixer. The blends were prepared at a fixed temperature, rotation rate, and processing time. High‐resolution solid‐state nuclear magnetic resonance was chosen to characterize the blends with respect to structure–mobility–compatibility employing magic angle spinning with cross polarization and high‐power hydrogen decoupling and the measurements of the proton spin–lattice relaxation time in the rotating frame (Tρ). The miscibility between polymer chains was also studied by two‐dimensional ¹H–¹³C shift correlation (HETCOR). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 221–226, 1999     

A novel approach for albumin determination in aqueous media by using temperature‐ and pH‐sensitive N‐isopropylacrylamide‐co‐N‐[3‐(dimethylamino)‐propyl]methacrylamide random copolymers

Random copolymers of N‐isopropylacrylamide (NIPA) and N‐[3‐(dimethylamino)propyl]methacrylamide (DMAPM) were synthesized by solution polymerization using azobisizobutyronitrile as the initiator in 1,4‐dioxane at 60°C. NIPA‐co‐DMAPM copolymer exhibited both temperature and pH sensitivity. Thermally reversible phase transitions were observed both in the acidic and the alkaline pH regions for copolymers produced with different DMAPM/NIPA feed ratios. The pH dependency of the lower critical solution temperature (LCST) was stronger for copolymers produced with higher DMAPM feed concentrations. NIPA‐co‐DMAPM random copolymer was also sensitive to the albumin concentration. In the presence of albumin, thermally irreversible phase transitions were observed in slightly acidic and neutral media. However, reversible transitions were obtained in aqueous media containing albumin at basic pH. The phase‐transition temperature of NIPA‐co‐DMAPM copolymer significantly decreased with increasing albumin concentration at both acidic and alkaline pH values. This behavior was explained by albumin binding onto the copolymer chains by means of H‐bond formation between the dimethylamino groups of the copolymer and the carboxyl groups of albumin. For a certain range of albumin concentration, the phase‐transition temperature exhibited a linear decrease with increasing albumin concentration. By utilizing this behavior, a simple albumin assay was developed. The results indicated that NIPA‐co‐DMAPM copolymer could be utilized as a new reagent for the determination of albumin concentration in the aqueous medium. The proposed method was valid for the albumin concentration range of 0–4000 μg/mL. The protein concentrations commonly utilized in biotechnological studies fall in the range of the proposed method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2060–2071, 2002; DOI 10.1002/app.10503     

Synthesis,characterization, and metal complexation of poly(N‐phenylmaleimide‐co‐acrylic acid) and poly(N‐phenylmaleimide‐co‐acrylamide) as polychelatogens in aqueous solution

We carried out the free‐radical copolymerization of N‐phenylmaleimide with acrylic acid and acrylamide with an equimolar feed monomer ratio. We carried out the synthesis of the copolymers in dioxane at 70°C with benzoyl peroxide as the initiator and a total monomer concentration of 2.5M. The copolymer compositions were obtained by elemental analysis and ¹H‐NMR spectroscopy. The hydrophilic polymers were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹H‐NMR spectroscopy, and thermal analysis. Additionally, viscosimetric measurements of the copolymers were performed. Hydrophilic poly(N‐phenylmaleimide‐co‐acrylic acid) and poly(N‐phenylmaleimide‐co‐acrylamide) were used for the separation of a series of metal ions in the aqueous phase with the liquid‐phase polymer‐based retention method in the heterogeneous phase. The method is based on the retention of inorganic ions by the polymer in conjunction with membrane filtration and subsequent separation of low‐molecular‐mass species from the formed polymer/metal‐ion complex. The polymer could bind several metal ions, such as Cr(III), Co (II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(III) inorganic ions, in aqueous solution at pH values of 3, 5, and 7. The interaction of the inorganic ions with the hydrophilic polymer was determined as a function of pH and a filtration factor. Hydrophilic polymeric reagents with strong metal‐complexing properties were synthesized and used to separate those complexed from noncomplexed ions in the heterogeneous phase. The polymers exhibited a high retention capability at pH values of 5 and 7. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Effect of pH,ionic strength,and temperature on uranyl ion adsorption by poly(N‐vinyl 2‐pyrrolidone‐g‐tartaric acid) hydrogels

Poly‐electrolyte N‐vinyl 2‐pyrrolidone‐g‐tartaric acid (PVP‐g‐TA) hydrogels with varying compositions were prepared in the form of rods from ternary mixtures of N‐vinyl 2‐pyrrolidone/tartaric acid/water. The effect of external stimuli, such as the solution pH, ionic strength, and temperature, on uranyl adsorption by these hydrogels was investigated. Uranyl adsorption capacities of the hydrogels were determined to be 53.2–72.2 (mg UO/g dry gel) at pH 1.8, and 35.3–60.7 (mg UO/g dry gel) at pH 3.8, depending on the amount of TA in the hydrogel. The adsorption studies have shown that the temperature and the ionic strength of the swelling solution also influence uranyl ion adsorption by PVP‐g‐TA hydrogels. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2219–2226, 2000     

Removal of metal ions by water‐soluble polymacromonomers in conjunction with ultrafiltration membrane

The macromonomer polyethylene glycol methylether methacrylate was homo‐ and copolymerized with 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid under three feed monomer ratios. The initiator used was ammonium peroxydisulfate (0.2 mol %). All the polymers were completely soluble in water. The copolymer composition was determined by elemental analysis. The metal ion interaction capability of the three polymers was investigated through the liquid‐phase polymer‐based retention (LPR) technique at different values of pH and filtration factor Z. The highest metal ion retention ability was observed at pH 5.0. The homopolymer showed a high selectivity for Ni(II) ions at pH 3.0. The copolymers (PEGMEM)_1.51‐co‐(APSA)_1.00 and (PEGMEM)_1.00‐co‐(APSA)_1.95 showed a high selectivity for Cr(III) ions at pH 3.0. The maximum retention capacity, in general, was similar for the homo‐ and copolymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2955–2960, 2004     

Liquid-phase polymer-based retention and coupled electrocatalytic oxidation to remove Arsenic in the presence of competitive species

The goal was to remove arsenate species in the presence of competitive anions by coupling of liquid-phase polymer-based retention, LPR, a procedure based on the selective As(V) adsorption properties of cationic water-soluble polymers, with an electro-catalytic oxidation process (EO) of As(III) into its more easily removable As(V). The electro-catalytic oxidation of As(III) to As(V) was performed with an organic supporting electrolyte, poly[3-(methacryloylamine)propyl)]trimethyl ammonium chloride, P(ClMPTA), which is recognized as an efficient reagent in removing divalent arsenate species. The bulk electro-catalytic conversion of As(III) to As(V) was carried out with a Pt-gauze electrode, and the resulting mixtures were introduced into a LPR cell to remove the As(V)-polymer adducts. Using P(ClMPTA) and ammonium salts at a 20:1 polymer:As(III) molar ratio at pH 8, complete (100%) Arsenic retention was achieved. For binary mixtures of Arsenic with competitive anions (e.g., SO₄ ²⁻, HPO₄ ²⁻, NO₃ ⁻, and NO₂ ⁻), the retention profile varied in the range 100–70%. In addition, the As(V) retention efficiency was found to be directly related to the consumed charge in the mol ratio As(III) in solution with competitive anionic species.     

Water‐soluble copolymers of 1‐vinyl‐2‐pyrrolidone and acrylamide derivatives: synthesis,characterization, and metal binding capability studied by liquid‐phase polymer‐based retention technique

Radical copolymerizations of 1‐vinyl‐2‐pyrrolidone with acrylamide and N,N′‐dimethylacrylamide at different feed ratios were investigated. The copolymers were characterized by Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR spectroscopy. The copolymer composition was determined from the ¹H NMR spectra and found to be statistical. The metal complexation of poly(acrylamide‐co‐1‐vinyl‐2‐pyrrolidone) and poly(N,N′‐dimethylacrylamide‐co‐1‐vinyl‐2‐pyrrolidone) for the metal ions Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Fe(III), and Cr(III) were investigated in an aqueous phase. The liquid‐phase polymer‐based retention method is based on the retention of inorganic ions by soluble polymers in a membrane filtration cell and subsequent separation of low‐molecular compounds from the polymer complex formed. The metal ion interaction with the hydrophilic polymers was determined as a function of the pH and the filtration factor. Poly(N,N‐dimethylacrylamide‐co‐1‐vinyl‐2‐pyrrolidone) showed a higher affinity for the metal ions than poly(acrylamide‐co‐1‐vinyl‐2‐pyrrolidone). According to the interaction pattern obtained, Cr(III) and Cu(II) formed the most stable complexes at pH 7. Pb(II) and Zn(II) were not retained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 741–750, 1999     

Synthesis,characterization and application of poly[(1‐vinyl‐2‐pyrrolidone)‐co‐(2‐hydroxyethyl methacrylate)] as controlled‐release polymeric system for 2,4‐dichlorophenoxyacetic chloride using an ultrafiltration technique

BACKGROUND: Polymers supporting chemicals used in agriculture have recently been developed to overcome the serious environmental problems of conventional agrochemicals. The success of these formulations is based on a suitable choice of polymer support. Degradable polymeric hydrogels are of particular interest. The gradual release of the bioactive agent can be achieved by hydrolytic or enzymatic cleavage of the linking bond. RESULTS: In this context, poly[(1‐vinyl‐2‐pyrrolidone)‐co‐(2‐hydroxyethyl methacrylate)] [poly(NVP‐co‐HEMA)] has been used as a bioactive carrier reagent. Herein, we report a controlled‐release system with the herbicide 2,4‐dichlorophenoxyacetic acid (2,4‐D) using an ultrafiltration system. Hydrolysis was studied by testing the release at various pH values. A high release with poly(NVP‐co‐HEMA)–2,4‐D was observed at pH = 7 and 10 after two days (Z = 2). The release percentage of copolymer–herbicide increased at pH = 10. It showed release values between 79.0 and 94.5%. Poly(NVP‐co‐HEMA)–herbicide can release a bioactive compound in aqueous solution at pH = 3, 7 and 10. CONCLUSION: Based on the results of homogeneous hydrolysis, it is argued that the herbicide release rate depends on the pH of the reaction environment. This functional polymer could be employed as a biodegradable material for applications in agrichemical release. Copyright © 2008 Society of Chemical Industry     

Water‐soluble polymers: Optimization of arsenate species retention by ultrafiltration

The liquid‐phase polymer‐based retention (LPR) technique was employed to study the retention of arsenate species by poly(vinylbenzyl trimethylammonium chloride), P(ClVBTA), and poly[2‐(acryloyloxy)ethyltrimethylammonium chloride], P(ClAETA). The effect of parameters such as polymer concentration, time exposure, competition of sulfate and phosphate anions, and the use of natural systems as drinking water on the retention of As(V) species was analyzed. The mole ratios of polymer : As(V) of (31 : 1), (20 : 1), (10 : 1), (6 : 1), and (3 : 1) by using the washing method at pH 8 and 6 were assayed. The retention capacity was a function of polymer concentration and pH. The optimum mole ratio of polymer : As(V) was (20 : 1) for all pHs studied and all polymeric structures. The polymer's activity recovery assays were performed by washing at pH 2 and 3. A 95% As(V) elimination was achieved from polymers. A study of competition in the presence of other anions was performed at the same polymer : As(V) ratio (20 : 1). At pH 8 and at the same concentration of arsenate anions, sulfate, and phosphate anions, no important competition on arsenic retention was observed. Assays for P(ClVBTA) at pH 8 and mole ratio of polymer : As(V) (20 : 1), (40 : 1), and (60 : 1) using drinking water showed that the efficiency was higher under these conditions for the three As(V) retention cases. An unbuffered system with drinking water was tested for washing and enrichment methods by determining the maximum saturation capacity of the P(ClVBTA) polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Accelerating effect of NaNO2 on the polymer plating of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts

Organic polymer plating properties of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts were investigated in the presence of various supporting electrolytes. Among these, the NaNO₂ supporting electrolyte greatly accelerated the film formation rate in polymer plating. The accelerating effect of NaNO₂ was further confirmed by comparing plating potentials in the presence of NaNO₂ and Na₂CO₃. The potentiostatic polymer plating of DAN in the presence of the NaNO₂ supporting electrolyte took place in the potential range of 1.65–1.8 V (compared against saturated calomel electrode reference). Film formation was influenced by such factors as the pH of solution and both the chemical structure and the concentration of triazine dithiol. In polymer platings, NO anions are thought to be electrochemically oxidized to yield NO radicals and these radicals react with DAN to yield new thiyl radicals. The thiyl radicals in the DAN molecules couple with each other by means of disulfide bonds, resulting in the growth of polymer film. Organic polymer plating films are shown to contain disulfide bonds, monosulfide bonds obtained by the reaction between allyl groups and thiyl radicals, and network chains. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2300–2309, 2001     

Determination of crystallinity ratio and some physicochemical properties of poly(4‐methyl‐1‐pentene)

It was determined that the thermal stability of poly(4‐methyl‐1‐pentene) (P4MP) was maintained up to 424°C in an inert atmosphere by thermogravimetric analysis. The retention diagrams of ethyl acetate, tert‐butyl acetate, and benzene on P4MP were plotted at temperatures between 30 and 280°C by inverse gas chromatography (IGC) technique. Melting temperature of the polymer was determined as 230 and 239.5°C by IGC and differential scanning calorimetry (DSC), respectively. The percent crystallinity of P4MP was obtained from the retention diagrams at temperatures below melting point. The percent crystallinity obtained by IGC is in good agreement with the ones obtained by DSC. Then, specific retention volume, V, weight fraction activity coefficient, Ω, Flory‐Huggins polymer‐solvent interaction parameter, χ, equation‐of‐state polymer‐solvent interaction parameter, χ, and effective exchange energy parameter, X_eff of octane, nonane, decane, undecane, dodecane, tridecane, n‐butyl acetate, isobutyl acetate, isoamyl acetate with P4MP, were determined between 240 and 280°C by IGC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009