Polyzwitterion-to-polyampholyte transition using pH-responsive cycloterpolymers of diallyldimethylammonium chloride, (N,N-diallylammonio)methanecarboxylate and sulfur dioxide

The cycloterpolymerizations of varying proportions of diallyldimethylammonium chloride (I) and N,N-Diallyl-N-carboethoxymethylammonium chloride (II) in the presence of sulfur dioxide afforded a series of cationic (+) polyelectrolytes (CPEs) (III) in excellent yields. CPEs, upon acidic hydrolysis of the ester functionalities of the repeating units of II, resulted in the formation of cationic/zwitterionic (+/±) polymers (IV). pH-responsive zwitterionic units of ammonioethanoate (NH⁺CH₂CO) (having unquenched valency of nitrogen) in IV was converted to its anionic counterparts (NCH₂CO) by treating with equivalent amount of NaOH to give cationic/anionic i.e., ampholytic (+/−) polymers (V) with a charge symmetry or asymmetry arising out of either excess of cationic or anionic centers. The transformations of III to IV to V have thus provided an opportunity to study the effects of the polyelectrolyte-to-polyzwitterion-to-polyampholyte transitions on the solution properties of these polymers. Basicity constants of the carboxylate group (NH⁺CH₂CO) in IV as well as the amine group (NCH₂CO) in V were found to be “apparent” and as such follow the modified Henderson–Hasselbalch equation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electrochemical synthesis and properties of poly(3‐methylthiophene): Novel synthesis of poly(3‐methylthiophene) with pentachlorostannate and hexachloroantimonate

Poly(3‐methylthiophene) (P3‐MeT) doped with different anions were prepared electrochemically in the presence of tetraalkylammonium salts. The new poly(3‐methylthiophene) SnCl and SbCl (P3‐MeT SnCl₅ and P3‐MeT SbCl₆) were prepared electrochemically using tetra‐n‐butylammonium pentachlorostannate and tetra‐n‐butylammonium hexachloroantimonate as the supporting electrolytes. The effect of current density, salt concentration, reaction temperature, and the nature of solvents on the polymer yield and polymer conductivities have been investigated. Cyclic voltammetry of poly(3‐methylthiophene) has been examined at platinum electrode in 1,2‐dichloroethane medium containing n‐Bu₄NSnCl₅, Bu₄NSbCl₆, and Bu₄NClO₄ as the supporting electrolytes in the range of −1.0 to 1.7 V versus SCE in the presence and absence of 3‐methylthiophene. Electrical conductivity, magnetic susceptibility measurements, and structural determination by elemental analysis and infrared studies were also made. Scanning electron microscopy revealed a globular, branched, fibrous and a spongy, fibrous morphology of poly(3‐methylthiophene) SnCl, ClO, and SbCl, respectively. The thermal analysis of the polymers was also investigated. Possible causes for the observed lower conductivity of these polymers have also been discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 91–102, 1999     

Influence of anionic form on thermal degradation of TMAHP–cellulose

Trimethylammoniumhydroxypropyl (TMAHP)–cellulose in 10 anionic forms (F^?, Cl^?, Br^?, I^?, HSO, NO, OH^?, HCO, H₂PO, CH₃COO^?) was prepared, and the influence of each anion on thermal degradation in inert atmosphere was studied. With the help of dynamic and isothermal thermogravimetry (TG) it was found that H₂PO ions had the greatest retarding effect on TMAHP–cellulose degradation. From the values of rate constants it can be seen that all ionic forms of TMAHP–cellulose have the starting rate of thermal degradation greater than unmodified cellulose. The calculated values of activation energy of thermal degradation for different ionic forms are decreasing in following sequence: H₂PO > F^? > NO > I^? > Br^? > HCO > Cl^? > HSO > OH^? > unmodified cellulose > CH₃COO^?. From the results of pyrolyse measurements in combination with gas chromatography and mass spectrometry (Py–GC–MS) it follows that the products of the elimination of quarternary ammonium salts are trimethylamine, 3-hydroxy-2-propanone, and, in the case of OH^? form, water. In all other ionic forms the third product is the corresponding acid.     

Synthesis and electrochemistry of grafted copolymers of cellulose with 4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone,and 9-vinylcarbazole

Some new cellulosic materials, suitable for the adsorption of noble metal ions, were syn-thesized by chemical and electrochemical modification of cellulose. The polymerizable groups were introduced in cellulose with ∼ 80% yield of substitution by esterification with acryloyl chloride. The vinyl monomers (4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone, and 9-vinylcarbazole) were readily grafted into cellulose acrylate via radical polymerization in acetonitrile. The grafted copolymers of cellulose with 4-vinylpyridine and 4-vinylimidazole were reacted with methyl iodide and the corresponding 1-methylpyridinium iodide ( 6 ) and 3-methylimidazolium iodide ( 7 ) copolymers of cellulose were obtained. Copolymers 6 and 7 were transformed into new polymeric regents, differing in anions (ClO, CF₃COO⁻, NO, p-TsO⁻, BF, PF) by using a supporting electrolyte carrying the desired anions through the ion-exchange-electrochemical oxidation of the released iodide at a controlled anodic potential. © 1996 John Wiley & Sons, Inc.     

Studies on acrylate copolymer soap‐free waterborne coatings crosslinked by metal ions

Acrylate copolymers containing hydrophobic monomers (methyl methacrylate, butyl acrylate, styrene, or divinyl benzene) and hydrophilic monomer (acrylic acid) were synthesized by solution polymerization, and neutralized to form the soap‐free hydrosol. The waterborne coating was prepared from the hydrosol crosslinked by M(NH₃) (M²⁺ was Zn²⁺ , Cu²⁺, Ni²⁺ or Co²⁺). ¹³C‐NMR analysis was used to identify the copolymer. The result of GPC showed that the molecular weight of the copolymer was within the range of thermosetting resin for coating. The factors affecting the crosslinking degree of the coating films were studied by DSC and gravimetric analysis. The results indicated that the appropriate crosslinking agent was Zn(NH₃), and the optimum curing condition was heating at 80°C for 30 min. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 91–96, 1999     

4-Chlorosalicylic acid-formaldehyde polymer as a polymeric ligand

Poly(4-chlorosalicylic acid-formaldehyde) was prepared by condensing 4-chlorosalicylic acid with formaldehyde in presence of various acidic catalysts using different molar proportions of the two reactants. The polymer samples were characterized by IR spectra, their M _n determined by vapour pressure osmometry and also by nonaqueous titration and by TGA. Viscosity measurements of selected polymer samples in DMF and 1,4-dioxane showed that solutions exhibited polyelectrolyte behaviour. Intrinsic viscosities of all the polymer samples were measured in 80:20 (v/v) DMF/water containing 1% (w/v) KBr, a medium in which these polymers exhibited normal behaviour. Polymeric metal chelates of Cu²⁺, Fe³⁺, Co²⁺, Mn²⁺, Zn²⁺, and UO with the polymer were prepared and characterized. Chelation and ion-exchanging properties of the polymers were also studied by employing the batch equilibration method.     

Removal of the tetravalent actinide thorium from solution by a biocatalytic system

The aim of this work was to study the effects of pH, a metal complexing reagent (citrate) and the concentration of substrate on the bioaccumulation of tetravalent actinides, using Th⁴⁺ as a model, by a phosphates-catalysed reaction. This yields HPO which precipitates with heavy metals as cell-bound metal phosphate. Poor removal of The from solution was observed, which is in accordance with the solution chemistry of the metal. A considerable improvement in the efficiency of thorium removal was obtained by incorporating ammonium acetate (NH₄Ac) into the solution. Although extensive deposition of polycrustaling NH₄UO₂PO₄ was observed previously by cells that had accumulated UO, no evidence for deposition of cstalline thorium phosphate was obtained by X-ray diffraction analysis. Examination by proton induced X-ray emission (PIXE) analysis. Examination by proton induced X-ray emission (PIXE) analysis showed a non-homogenous thorium deposit of variable phosphorous content.     

Morphological studies of the modified materials: Low-density polyethylene/poly(acrylic acid)/europium(III) and low-density polyethylene/poly(acrylic acid)/uranyl ion

The morphology of low-density polyethylene (LDPE) modified by in situ sorption and thermal polymerization of acrylic acid (AA) in the matrix was examined. The microstructure of the LDPE/poly(acrylic acid) (PAA) materials after Eu³⁺ and UO ion exchange was investigated. The phase behavior of these materials was analyzed using X-ray diffraction, scanning electron microscopy (SEM), and thermal measurements (DSC). The X-ray dif-fraction studies showed that PAA is located at amorphous region of the matrix. The LDPE/PAA surface, as investigate by SEM, was apparently homogeneous before and after Eu³⁺ and UO ion exchange, respectively. Two T_g values were found for the LDPE/PAA material before and after Eu³⁺ ion exchange. Also, three and four T_g values were found for LDPE/PAA after UO ion exchange depending on the amount of UO in the modified matrix. This indicates microphase domains in the LPDE/PAA-, LPDE/PAA/Eu³⁺-, and LPDE/PAA/UO -modified materials, although a lack of visible phase separation in the micrographs was observed. © 1996 John Wiley & Sons, Inc.     

Mass transport process for the adsorption of Cr(VI) onto water‐insoluble cationic starch synthetic polymers in aqueous systems

Dynamic adsorption behaviors between Cr(VI) ion and water‐insoluble amphoteric starches was investigated. It was found that the HCrO ion predominates over the initial pH ∼ 2–4, the CrO ion predominates over the initial pH ∼ 10–12, and both ions coexist over the initial pH ∼ 6–8. The sorption process occurs in two stages: the external mass transport process occurs in the early stage and the intraparticle diffusion process occurs in the long‐term stage. The diffusion coefficient of the early stage (D₁) is larger than that of the long‐term stage (D₂) for the initial pH 4 and pH 10. The diffusion rate of HCrO ion is faster than that of CrO ion for both processes. The D₁ and D₂ values are ∼ 1.38 × 10⁻⁷–10.1 × 10⁻⁷ and ∼ 0.41 × 10⁻⁷–1.60 × 10⁻⁷ cm² s⁻¹, respectively. The ion diffusion rate in both processes is concentration dependent and decreases with increasing initial concentration. The diffusion rate of HCrO ion is more concentration dependent than that of CrO ion for the external mass transport process. In the intraparticle diffusion process, the concentration dependence of the diffusion rate of HCrO and CrO ions is about the same. The external mass transport and intraparticle diffusion processes are endothermic and exothermic, respectively, for the initial pH 4 and pH 10. The k_d values of the external mass transport and intraparticle diffusion processes are ∼ 15.20–30.45 and ∼ −3.53 to −12.67 kJ mol⁻¹, respectively. The diffusion rate of HCrO ion is more temperature dependent than that of CrO ion for both processes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2409–2418, 1999     

Estimation of the energetic parameters associated with the aerobic degradation of quinoline by Comamonas acidovorans in continuous culture

An estimation of the true growth yields and maintenance coefficients for Comamonas acidovorans DSM 6426 under continuous cultivation on quinoline has been performed. The data were checked for consistency using available electron, carbon and nitrogen balances. The true biomass energetic yields, η_max, and energetic maintenance coefficients, m_e, were estimated using two models based on control of growth rate and control of substrate uptake rate, respectively. The estimations were converted to the various familiar true growth yield and maintenance units such as substrate-based (Y, m_S/X), oxygen-based (Y, m) and carbon dioxide-based (Y, m) units. For the complete mineralization of quinoline by C. acidovorans, values of η_max = 0.371 and m_e = 0·0426 h^?1 were obtained.     

Influence of anionic form on thermooxidation of TMAHP–cellulose

With the help of DTA, DTG elementary analysis of carbonized residues and ESR spectroscopy the influence of anionic form on thermooxidation of trimethylammoniumhydroxyprophyl (TMAHP)–cellulose was studied. At 300°C the percentage of carbon in carbonized residue thermolyzed in oxidative atmosphere is higher than for the sample degraded in inert atmosphere. The percentage of hydrogen decreases simultaneously. The concentration of free radicals in thermolyzed residue also increases due to the presence of oxygen. We propose that oxygen is abstracting the hydrogen atoms from polysaccharide and unpaired electrons on carbon atoms are produced. At 400°C the percentage of carbon in residues prepared at inert atmosphere is higher than for residue formed at oxidative atmosphere. Also the concentration of free radicals in thermolyzed residues obtained in inert atmosphere is greater than for those from oxidative ones. That is why suppose that at this temperature oxygen is bonded to polysaccharide residue and free radicals are terminated. From the semiquantitative DTA we can make the following sequence of samples according to their increasing thermooxidative effect: unmodified cellulose < A–HSO < A–Br^? < A–I^? < A–NO < A–H₂PO < A–CH₃COO^? < A–HCO < A–F^? < A–Cl^?1 < A–OH^p?.     

Surface characterization of poly(ethylene terephthalate) film by inverse gas chromatography

The gas-chromatographic retention of a series of n-alkanes at effectively zero coverage was measured on a poly(ethylene terephthalate) film surface, and the free energy of adsorption per—CH₂—segment of n-alkane at zero surface coverage, Δ?, was calculated. This quantity is a direct measure of the London (nonpolar) interactions of the surface. A value of 40 mN/m for γ^1/2, the London Component of the polyester surface free energy, may be estimated from the gas-chromatographic results, in good agreement with results from contact angle measurements. The complete adsorption isotherm and spreading pressure for n-decane were also measured by finite-concentration gas chromatography. The method is restricted to polar or crystalline polymers, where the n-alkane does not penetrate the bulk of the material during the measurements.     

Large-scale anaerobic/aerobic treatment of complex industrial wastewater using immobilized biomass in fluidized bed and air-lift suspension reactors

Warm concentrated industrial wastewaters are preferably treated in an anaerobic reactor for reasons of energy generation and low surplus sludge production. Problems to be solved in the practical application concern a low growth rate of the micro-organisms, their low settling rate, process instability and the need for after treatment of the noxious anaerobic effluent which often contains NH and HS^?. The use of biomass immobilized on small suspended carriers (< 0.5 mm) has proven to be a suitable means to overcome most of these problems. Results are presented on pilot and full-scale pretreatment of industrial wastewater in an anaerobic 2-state fluidized bed reactor for CH₄-production and laboratory and pilot scale post-treatment of the anaerobic effluent, which contains NH and HS^? in an aerobic air-lift suspension reactor for the production of NO and SO.     

Liquid–solid mass transfer for cocurrent gas–liquid upflow through solid foam packings

This article presents the liquid–solid mass transfer characteristics for cocurrent upflow operated gas–liquid solid foam packings. Aluminum foam was used with 10, 20, and 40 pores per linear inch (PPI), coated with 5 wt % Pd on γ‐alumina. The effects of gas velocity (u_g = 0.1?0.8 m m s^?1) and liquid velocity (u_l = 0.02 and 0.04 m m s^?1) are studied using the Pd/Bi catalyzed oxidation of glucose. The volumetric liquid–solid mass transfer coefficient, k_lsa_ls, is approximately the same for 10 PPI and 20 PPI solid foams, ranging from 2 × 10^?2 to 9 × 10^?2 m m s^?1. For 40 PPI solid foam, somewhat lower values for k_lsa_ls were found, ranging from 6 × 10^?3 to 4 × 10^?2 m m s^?1. The intrinsic liquid–solid mass transfer coefficient, k_ls, increases with increasing liquid velocity and was found to be proportional to u. Initially, k_ls decreases with increasing gas velocity and after reaching a minimum value increases with increasing gas velocity. The values for k_ls range from 5.5 × 10^?6 to 8 × 10^?4 m m s^?1, which is in the same range as found for random packings and corrugated sheet packings. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Effect of some anions of some nickel salts on the aqueous polymerization of methyl methacrylate

The aqueous polymerization of methyl methacrylate in the absence and in the presence of some anions of nickel salts was carried out at temperatures of 40°C, 50°C, and 60°C using sodium bisulfite as initiator. The nitrate anion (NO) was found to have the highest catalytic effect and resulted in polymers having the least average molecular weights, while the sulfate anion (SO) was found to have the least catalytic effect and resulted in polymers having the highest average molecular weights. The apparent activation energy for the polymerization process was found to be 4.3, 3.6, 3.8, and 4.8 × 10⁴ J/mol in the absence and in the presence of Ni(NO₃)₂, NiCl₂, and NiSO₄ containing the same amount of nickel (0.00587 g). ¹³C-NMR spectra for the polymers obtained in the absence and in the presence of different nickel anions were found to result in nearly the same tacticity.     

Surface activity and micellar behavior of dimethylamino‐ and trimethylammonium‐ tipped oxyethylene–oxybutylene diblock copolymers in aqueous media

Surface activity and micellar behavior in aqueous media in the temperature range 20–50°C of the two block copolymers, Me₂N(CH₂)₂OE₃₉B₁₈, (DE₄₀B₁₈) and I^?Me₃N⁺(CH₂)₂OE₃₉B₁₈, (TE₄₀B₁₈) in the premicellar and postmicellar regions have been studied by surface tensiometry, viscometry, and densitometry. Where E represents an oxyethylene unit while B an oxybutylene unit. Various fundamental parameters such as, surface excess concentrations (Γ_m), area per molecule (a) at air/water interface and standard Gibbs free energy for adsorption, ΔG have been investigated for the premicellar region at several temperatures. The thermodynamic parameters of micellization such as, critical micelle concentrations, CMC, enthalpy of micellization, ΔH, standard free energy of micellization ΔG, and entropy of micellization ΔS have also been calculated from surface tension measurements. Dilute solution viscosities have been used to estimate the intrinsic viscosities, solute‐solvent interaction parameter and hydration of micelle. Partial specific volume and density of the micelle were obtained from the density measurements at various temperatures. The effect of modifying the end group of the hydrophilic block was investigated by comparing the behavior of trimethylammonium‐ and dimethylamino‐tipped copolymers, designated TE₄₀B₁₈, and DE₄₀B₁₈, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comment

Electrolytic manganese dioxide is dissolved in the mixed non-aqueous solvent dimethyl sulfoxide–sulfur dioxide (DMSO–SO₂) to form manganese disulfate as a final product. Sulfur dioxide does not change the oxidation state of the metal cations in DMSO–SO₂ solvent. However, oxidation of sulfur(IV) to sulfur(VI) is possible. The complete MnO₂ dissolution occurs in 50 min at a stirring speed of 650 rpm, pH 1, 0.2% solids concentration, 35 × 44 mesh particle size, and 36°C. IR and FTIR evidence has been presented in favor of the formation of SO, S₂O, (CH₃)₂S⁺ as intermediate species for the proposed mechanism. In the mixed non-aqueous solvent system the kinetics of leaching is controlled by a mass transport process. The equation 1–?α–(1–α)^2/3 = kt fits the experimental data very well. This is further supported by scanning electron micrographs, which show a product layer formation on the surface of the MnO₂ particle, and by the dependence of k on 1/r.     

Inverse gas chromatography of poly(vinylisobutyl ethers) and polymer-solute thermodynamic interactions

Gas chromatography (GC) retention behavior of atactic and isotactic poly(vinylisobutyl ether) stationary phases has been studied in the temperature range 30–90°C using 16 solutes which include various alkanes, alkylbenzenes, and chlorinated aliphatic hydrocarbons. The bulk sorption equilibrium retention data have been employed to derive various thermodynamic quantities at infinite dilution of solutes in the polymers, viz., χ, χ^*, χ_H, χ_S, X₁₂, δH_S, h . Their dependence on temperature, polymer structure, and chemical nature of solutes has been discussed.     

The degradation and prestabilization of acrylonitrile copolymers

The degradation and prestabilization of polyacrylonitrile (PAN) were investigated with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The initial temperature, initial loss‐weight temperatures, and loss‐weight were significantly lowered when ammonium itaconate (AIA) was used as comonomer. One exothermal peak of PAN (homopolymer) was shown in the DSC curves, while there were four exothermal peaks of poly(AN‐AIA). FTIR spectra results confirm the degradation process of NH groups. During the heating process, NH groups (3030 cm^?1) were changed into NH (2955 cm^?1) and then NH groups (2920 cm^?1). The dissociated H⁺ could initiate the cyclization reactions of C?N companied with heat released. The effect of ammonia on degradation and prestabilization of PAN was also studied. It was found that ammonia could accelerate prestabilization of acrylic precursors. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Molecular weight and molecular weight distribution from dynamic measurements of polymer melts

A method for determining the molecular weight distribution (MWD) of a polymer melt has been developed using the dynamic elastic modulus (G'), plateau modulus (G), and zero shear complex viscosity (η). The cumulative MWD was found to be proportional to a plot of (G'/G)^0.5 vs. measurement frequency (ω). Frequency (ω) was found to be inversely proportional to (MW)^3.4, as expected. Results were scaled to absolute values using the empirical relationship η ∝ (M?_w)^3.4, where M?_w is the weight-average MW. M?_w, M?_n (number-average MW) and M?_w/M?_n calculated from melt measurements were found to agree with size exclusion chromatography usually well within 10 percent for broad and bimodal distribution samples. M?_w/M?_n tended to be approximately 20 percent higher for narrow distribution samples (M?_w/M?_n < 1.2) because we did not account for a finite distribution of relaxation times from a collection of monodisperse polymer chains. We also did not account for the plasticizing effect of short chains mixed with long ones which caused peak positions to be closer together for Theological vs, size exclusive chromatography (SEC) determinations of MW for bimodal distribution blends.