Atom‐transfer radical polymerization of methyl methacrylate with α,α′‐dichloroxylene/CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine initiation system under microwave irradiation

The atom‐transfer radical polymerization (ATRP) of methyl methacrylate (MMA), using α,α′‐dichloroxylene as initiator and CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as catalyst was successfully carried out under microwave irradiation (MI). The polymerization of MMA under MI showed linear first‐order rate plots, a linear increase of the number‐average molecular weight with conversion, and low polydispersities, which indicated that the ATRP of MMA was controlled. Using the same experimental conditions, the apparent rate constant (k) under MI (k = 7.6 × 10^?4 s^?1) was higher than that under conventional heating (k = 5.3 × 10^?5 s^?1). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2189–2195, 2004     

Synthesis,characterization, and thermodynamic properties of poly(3‐mesityl‐2‐hydroxypropyl methacrylate)

Poly(3‐mesityl‐2‐hydroxypropyl methacrylate) (PMHPMA) was synthesized in a 1,4‐dioxane solution with 2,2′‐azobisisobutyronitrile as the initiator at 60°C. The homopolymer and its monomer were characterized with ¹H‐ and ¹³C‐NMR, Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and elemental analysis techniques. According to size exclusion chromatography analysis, the number‐average molecular weight, weight‐average molecular weight, and polydispersity index of PMHPMA were 65,864 g/mol, 215,375 g/mol, and 3.275, respectively. According to thermogravimetric analysis, the carbonaceous residue value of PMHPMA was 14% at 500°C. The values of the specific retention volume, adsorption enthalpy, sorption enthalpy, sorption free energy, sorption entropy, partial molar free energy, partial molar heat of mixing, weight fraction activity coefficient of solute probes at infinite dilution (Ω), and Flory–Huggins interaction parameter (χ) were calculated for the interactions of PMHPMA with selected alcohols and alkanes by the inverse gas chromatography method at various temperatures. According to Ω and χ, selected alcohols and alkanes were nonsolvents for PMHPMA at 423–453 K. Also, the solubility parameter of PMHPMA (δ₂) was found to be 24.24 and 26.33 (J/cm³)^0.5 from the slope and intercept of (δ/RT) ? χ/V₁ = (2δ₂/RT)δ₁ ? δ/RT at 443 K, respectively [where δ₁ is the solubility parameter of the probe, V₁ is the molar volume of the solute, T is the column temperature (K), and R is the universal gas constant]. The glass‐transition temperature of PMHPMA was found to be 386 and 385 K by inverse gas chromatography and differential scanning calorimetry techniques, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 101–109, 2006     

Allgemeine Synthesen und rationelle Strukturparameter isomerer Derivate von [3,4]-kondensierten Pyrazolen

General Syntheses and Rational Parameters for Structural Assignment of Isomeric Derivatives of [3,4]-fused Pyrazoles 4 isomeric 1- or 2-methyl-, and 1- or 2-benzyl-pyrazolo[3,4-b]pyridones, i.e. the 4-oxo-types 17a, b or 11a, b and the 6-oxo-types 16a, b or 10a, b , are synthesized unambiguously. Cyclisation of 1-substituted 3- or 5-(1-methyl-2-ethoxycarbonyl-vinylamino)-pyrazoles 9a, b or. 15a, b , which were synthesized from 1-substituted 3- or 5-amino-pyrazoles and ethyl acetoacetate yields 11a, b or 17a, b in downtherm, but 10a, b or 16a, b in presence of acidic catalysts. The acidic cyclisation is preceded by a new rearrangement of 9 or 15 into 1- substituted 3- 27 or 5-amino-4-(1-methyl-2-ethoxycarbonyl-vinyl)-pyrazoles 30 ; mechanism and concurring reactions are explained. Because of their higher electron densities at C-4 it is easier to cyclise derivatives of 5-amino-pyrazoles compared to 3-amino-pyrazoles. All isomeric 1- or 2-substituted 4(6)-chloro-6(4)-methyl-pyrazolo-[3,4-b]pyridines are formed with POCl₃ from the corresponding oxo-compounds. The position of a substituent at N-1 or N-2 of [3,4]-fused pyrazoles can be assigned using the significant ¹H-n.m.r.-parameter Δ = δ — − δ_HMPT (conc. HC—3). If solvent influences are considered, δ(C  O) is a useful ¹³C-n.m.r.-parameter to distinguish the 4-oxo-types ( 11a, b; 17a, b ) from the 6-oxo-types ( 10a, b; 16a, b ) of pyrazolo[3,4-b]pyridones. Further own and lit. dates conc. structural assignment (n.m.r., i.r., u.v.) are discussed critically.     

Synthesis,characterization, and metal‐ion uptake studies of chelating resins derived from formaldehyde‐condensed azodyes of aniline and 4,4′‐diaminodiphenylmethane coupled with phenol/resorcinol

The diazonium salts of aniline and 4,4′‐diaminodiphenylmethane coupled with phenol and resorcinol were condensed with formaldehyde in alkaline media to yield polymeric resins. These polymers were found to readily react with metal ions like Cu²⁺ and UO, forming polychelates. The azodyes, resins, and polychelates were characterized by several instrumental techniques such as elemental analysis, FTIR, ¹H‐NMR, GPC, XRD, TG–DTG, and DSC studies. The chelating capacity of the resins toward Cu²⁺ and UO ions was studied by spectrophotometry. The extent of metal loading of the resins was studied by varying the time of contact, metal‐ion concentration, and pH of the reaction medium. The alkali and alkaline earth metal ions had little effect on the metal‐ion uptake behavior of the resins. The resin derived from the azodye of 4,4′‐diaminodiphenylmethane was found to be more efficient in removing the metal ions from solution than were the resins from aniline. The optimum conditions for effective separation of Cu²⁺ from UO were determined. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3128–3141, 2000     

Die Reaktion von E-ß-Nitro-styrolen mit Pyrazolidon-(3)-azomethiniminen – eine nicht-cisoide 1,3-dipolare Cycloaddition

The Reaction of E-ß-Nitro-styrenes with 3-Pyrazolidone-azomethinimines – a Non-cisoid 1,3-Dipolar Cycloaddition Normal flipping at both ring-N-atoms postulated, the thermal addition of E-β-nitro- 5a or E-(4-chloro-β-nitro)-styrene 5b to 3-pyrazolidone-azomethinimine-1,3-dipoles 4a or 4b formally can yield 8 isomeric pairs of enantiomers, 4 of which are “permitted”(cisoid) and 4 of which are “forbidden” according to the concerted [_π4_s + _π2_s]-mechanism. If the addition of 5 to 4 is regiospecific, 2 “permitted”(cisoid) ( 1 and 6 ) and 2 “forbidden”( 3 and 10 ) isomers are conceivable. From pure 5a and 4a we regiospecifically got 1ref,3trans-diphenyl-2cis-nitro- 6a (75%) and 1ref,3trans-diphenyl-2trans-nitro-5-oxo-perhydropyrazolo[1,2-a]pyrazol 10a (25%), from 5b and 4b the corresponding bis(4-chloro-phenyl)-isomers 6b and 10b . The sodium salts 8a, b , gained from 6a, b and 10a, b , are identical. With H⊕ (D⊕) in water (D₂O) 8a, b give 6a, b (2-deutero- 6a, b = 7 a, b ). The ¹H-n.m.r. spectra of 6a, b, 7a, b, 8a, b, 10a, b , and of the 2-amino-isomers 11a/12a , corresponding to 6a/10a , are discussed. For the first time products of a non-cisoid 1,3-dipolar cycloaddition ( 10a, b ) were isolated. In the discussion (E ⇌ Z)-isomerization of 5a , and conceivable mechanisms of isomerizations 6a → 10a are excluded. Theoretical consequences are suggested.     

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     

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     

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.     

Photochemische Primärprozesse von Xanthenfarbstoffen. III. Blitzlichtspektroskopische Untersuchungen zum Einfluß von kationischen Mizellen auf die Photoredoxprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. III. Investigations of the Influence of Cationic Micelles on the Photoredox Processes of Selenopyronine by Flash Excitation Cationic micelles have no influence on the decay of the triplet state of selenopyronine (³F⁺). The products of photoredox reactions ³F⁺ + ³F⁺ (F⁺) → F^· + F and ³F⁺ + DABCO → F^· + DABCO live longer in the presence of the cationic micelles. The reason for the change of the lifetime is a separation of the photoredox products by micelles. F^. is stored in the interior of the micelles. The positively charged F and DABCO are repelled from the micelles and the electron back transfer is hindered.     

Darstellung und eigenschaften eines ionenaustauschers mit einem 1,3-diketon als Ankergruppe auf der Basis von Polystyrol

Aminopolystyrene is reacted with diketene to an exchanger with 1,3-diketone as anchor group. The capacity for Fe³⁺ ions is 3.2 mmol/g. The exchange comprises a fast and a slow step. The distribution coefficients for UO, Cu²⁺, Ni²⁺ and Fe³⁺ ions are presented as function of pH.     

Allgemeine Synthese 1-substituierter Pyrazolidone-(3) durch nucleophile Grignard-Addition an carbonylstabilisierte Azomethinimine

General Synthesis of 1-Substituted Pyrazolidine-3-ones by Nucleophilic Grignard Addition at Carbonyl-stabilized Azomethinimines By means of Grignard compounds in THF the nucleophilic addition of alkyl, aralkyl or aryl groups at the C-6 atom of carbonyl-stabilized azomethinimines 1 is achieved. This new general synthesis gives high yields of 1-substituted pyrazolidine-3-ones 8 . The C-6-substitution is proved by unambiguous syntheses and by ¹H-n.m.r. C-4-Substituted azomethinimines 1 and Grignard compounds give mixtures of diastereomeric 1-substituted pyrazolidine-3-ones 8 , as indicated by their ¹H- and ¹³C-n.m.r. spectra. The Grignard addition is thus shown to proceed not stereospecifically.     

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     

Intrinsic birefringence of nylon 6

Different values are reported in the literature for the intrinsic birefringence of the crystalline (Δn) and the amorphous (Δn) phases in nylon 6. Mostly, these values have either been determined by extrapolation (and then it is assumed that Δn = Δn) or calculated theoretically. In this study, intrinsic birefringence values Δn and Δn for nylon 6 were determined using the Samuels two-phase model which correlates sonic modulus with structural parameters. Three series of fiber samples were used: (1) isotropic samples of different degrees of crystallinity for estimation of E and E moduli at two temperatures. The following modulus values were obtained: 1.62 × 10⁹ and 6.66 × 10⁹ N/m² for 28.5°C, and 1.81 × 10⁹ and 6.71 × 10⁹ N/m² for ?20°C; (2) anisotropic, amorphous fiber samples for estimation of Δn = 0.076 and E = 1.63 × 10⁹ N/m² at 28.5°C; (3) semicrystalline samples of various draw ratios for estimations of Δn = 0.089 and Δn = 0.078. All measurements were carried out with carefully dried samples to avoid erroneous results caused by moisture.     

Modellrechnungen zum Gegenioneneinfluß auf die kationische Polymerisation; Der Zerfall der gemischten Halogenoantimonate SbCl5Br− und SbClBr

Model Calculations on the Counterion Effect in the Cationic Polymerization; Decay of the Mixed Halogenoantimonates SbCl₅Br⁻ and SbClBr The decay of the halogenoantimonates SbCl₅Br⁻ and SbClBr according to SbCl₅Br⁻ → SbCl₅ + Br⁻ resp. SbCl₄Br + Cl⁻ and SbClBr → SbBr₅ + Cl⁻ resp. SbClBr₄ + Br⁻ has been investigated by the quantum-chemical CNDO/2 method including geometry optimization. The calculations show that the dissociation of the Sb Cl bond needs more energy (7,8 kcal/mol) than the dissociation of the Sb Br bond. Dissociation of the complex anions is facilitated with increasing Br content.     

Structure and properties of poly(vinyl alcohol)–iodine complex formed in the crystal phase of poly(vinyl alcohol) films

The structure and optical properties of the complex formed in the crystal phase of PVA that is caused by soaking at very high iodine concentration are investigated. In the resonance Raman spectra of lightly and heavily iodinated specimens, two Raman shifts appeared at 109 and 161 cm^?1. The 109 cm^?1 peak due to the I mode was much stronger than the 161 cm^?1 peak in a heavily iodinated specimen, whereas the peak was comparable with the 161 cm^?1 peak in a lightly iodinated specimen. The complex formed in the crystal phase is identified as the I mode complex. It has an averaged iodine–iodine distance of 3.2 Å, which is different from the 3.08 Å of the I mode complex formed in the amorphous phase. The effect of KI concentration in the soaking solution on the formation of the complex is also examined. The increased KI concentration in the soaking solutions at a fixed iodine concentration increases the amount of the complex formed in the crystal phase. The change in the hydrogen-bonding state in the crystal phase with the complex formation can be evidenced by IR and NMR. © 1994 John Wiley & Sons, Inc.     

Forced oscillations in continuous flow stirred tank reactors with nonlinear step growth polymerization

The self-step growth polymerization of RA_f monomers in homogeneous, continuous flow stirred tank reactors (HCSTRs) is simulated under conditions of periodic feed concentration (with frequency ω and amplitude α). By having periodic operation, the polydispersity index of the polymer is found to increase by about 35% over the values at steady state. Periodic operation of HCSTRs is found to lead to gelation only for certain values of the frequency and the dimensionless residence time τ^*. Gelling envelopes have been obtained to give conditions under which HCSTRs should be operated. These envelopes can be described in terms of two critical dimensionless residence times, τ and τ such that nongelling operation is always ensured when τ^* < τ. For τ^* > τ, periodic operation always leads to gelation, and HCSTRs cannot be used. For τ < τ^* < τ, the gelling behavior is found to depend on the functionality f, amplitude α, and the dimensionless residence time τ^*.     

Der Substituenteneinfluß auf IR-Spektrenparameter von 4′-phenylsubstituierten (E)-Styryl-methyl-sulfonen

The Influence of Substituents on the I.R. Spectral Parameters of 4′-Phenylsubstituted (E)-Styryl-methyl-sulphones The positions and integrated intensities of the bands corresponding to characteristic vibrations of eight 4′-phenylsubstituted (E)-styryl-methyl-sulphones were determined and correlated with substituent constants. The results demonstrate a linear dependence of the wavenumbers of vSO₂ and VCC vibrations, respectively, with the electrophilic substituent constants σ. Otherwise the square roots of the integrated intensities A^1/2 (v^sso₂) and σ gave no linear correlation. The influence of the substituents on the i.r. spectral parameters is discussed and compared with π-bond orders and π-electron densities. These magnitudes reflect qualitatively the behaviour of i.r. frequencies and intensities of selected absorption bands.     

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     

Effect of magnesium and phosphate ions on the stability of concentrated natural rubber latex and the properties of natural rubber latex–dipped products

The presence of Mg²⁺ ions was found to be a major cause of destabilization of natural rubber (NR) latex. On the other hand, the addition of excess PO ions to remove Mg²⁺ ions could adversely affect the physical properties of dipped products made of NR latex. A series of concentrated latex samples were treated with varying amounts of Mg²⁺ and PO ions. Changes with time in the characteristics of the treated latex samples such as mechanical stability time, volatile fatty acid number, and chemical stability time and in the physical properties of the dipped products such as aged and unaged tensile properties were monitored. The latex batch with a PO ion concentration of 30 ppm was found to produce the best‐quality latex and dipped products. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3120–3124, 2006