bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and sulfonation of poly(arylene ether)s containing tetraphenyl methane moieties
Authors: Wang L. , Meng Y. Z. , Wang S. J. , Hay A. S. 
Published: February 2004

AbstractNovel poly(arylene ether)s with sulfonic acid containing pendent groups were successfully synthesized by the nucleophilic displacement of aromatic dihalides with bisphenols in an aprotic solvent in the presence of excess potassium carbonate followed by sulfonation with chlorosulfonic acid. The sulfonation took place only at the controlled positions on the phenyl rings due to the novel bisphenol structures designed. The sulfonic acid group containing polymers were very soluble in common organic solvents, such as dimethyl sulfoxide, N,N′‐dimethylacetamide, and dimethylformamide, but swelled only slightly in water. These sulfonic acid group containing polymers were readily cast into tough and smooth films from organic solvents. The synthesized polymers had high glass‐transition temperatures of 171.0–240.7 °C and high molecular weights of 15,600–33,000 Da. These films could potentially be used as proton‐exchange membranes for fuel cells. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1779–1788, 2004
Synthesis and characterization of original functional polymers of tetrafluoroethylene and 4,5,5‐trifluoro‐4‐ene pentyl acetate
Authors: Kostov George , Améduri Bruno , Boutevin Bernard , Bauduin Gérard , Stankova Maya 
Published: February 2004

AbstractThe bulk radical copolymerization of tetrafluoroethylene (TFE) with 4,5,5‐trifluoro‐4‐ene pentyl acetate (FAc), initiated by tert‐butyl peroxypivalate to synthesize original, functionalized fluorinated poly(TFE‐co‐FAc), was investigated. FAc monomer was prepared from a five‐step process. The copolymerization was carried out in batch at different initial monomer molar ratios ([TFE]o/[FAc]o ranging from 95/5 to 10/90 mol %) and at different initiator concentrations (ranging between 0.075 and 1.100 mol % about the monomers) at 70 °C. All the experiments revealed the production of fluorooligomers as evidenced by an allylic‐transfer reaction from FAc. The microstructure of these copolymers (i.e., the molar percentage of both monomers in the copolymers) was assessed by 19F NMR spectroscopy. From the kinetics of copolymerization, two key characteristics were determined. First, the reaction order to the initiator (being 1.07) and that of FAc monomer (0.85) showed a heterogeneous character of the copolymerization and monomolecular chain‐transfer reaction to FAc. Second, from the Tidwell and Mortimer method, the reactivity ratios of both comonomers were determined, showing a tendency to alternance in a wide range of initial monomeric ratios (30/70–70/30): rFAc = 0.20 ± 0.26 and rTFE = 0.18 ± 0.15. Alfrey and Price's Q and e values of FAc were calculated by Greenley's technique [QFAc = 0.098 (from QTFE = 0.032) and eFAc = 1.23 (vs eTFE = 1.63)], indicating that FAc is a strong electron‐withdrawing monomer as TFE. The normalized monomer‐diad and triad fractions as a function of the polymer composition were obtained from the comonomer sequence‐distribution procedure. The average molecular weights and molecular weight distributions as well as the thermal properties (glass‐transition temperature and decomposition temperature) of the fluorocopolymers were assessed and are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1693–1706, 2004
Synthesis of polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers
Authors: Nasser‐Eddine Mohamad , Reutenauer Simone , Delaite Christelle , Hurtrez Guy , Dumas Philippe 
Published: February 2004

AbstractThree alternative routes, using the heterobifunctional macroinitiator technique, have been developed to obtain polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers. Only the route showing the reverse initiation of tert‐butyl methacrylate on potassium alkoxide leads to the pure star, whereas the other strategies lead to incomplete initiation because of either an increase in the side reactions, such as transesterification, or a decrease in the accessibility toward bulky catalysts. These limits are linked to the particular location of the initiating group at the junction of the two blocks of the copolymer precursor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1745–1751, 2004
Synthesis and characterization of 2,2‐bis(methylol)propionic acid dendrimers with different cores and terminal groups
Authors: Malkoch Michael , Claesson Hans , Löwenhielm Peter , Malmström Eva , Hult Anders 
Published: February 2004

AbstractThree sets of aliphatic polyester dendrimers based on 2,2‐bis(methylol)propionic acid (bis‐MPA) were synthesized. Two of the sets had benzylidene terminal groups and either a trimethylolpropane or triphenolic core moiety. The last set had acetonide terminal groups and a triphenolic core moiety. Benzylidene‐[G#1]‐anhydride and acetonide‐[G#1]‐anhydride were used as the reactive building blocks in the construction of all dendrimers. The large excess of building blocks used in the coupling reactions initially resulted in considerable material loss. This waste was eliminated through the development of a recycling method. 1H and 13C NMR and matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) analysis were used to verify the purity of all compounds. Size exclusion chromatography (SEC) was used, as well as MALDI‐TOF, for molecular weight determinations. The SEC measurements were conducted with a universal calibration method and an online right‐angle laser light scattering detector. Measured dendrimer molecular weights were close to their theoretical molar masses. Observations were also made of the hydrodynamic radius and intrinsic viscosity for the different dendrimers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1758–1767, 2004
Synthesis and optical properties of novel blue‐light‐emitting poly(p‐phenylene vinylene) derivatives with pendant oxadiazole or cyano groups
Authors: Mikroyannidis John A. , Spiliopoulos Ioakim K. 
Published: February 2004

AbstractTwo novel poly(p‐phenylene vinylene) polymers, which carried side substituents with cyano groups or 1,3,4‐oxadiazole, were synthesized by Heck coupling. They consisted of alternating conjugated segments and nonconjugated aliphatic spacers. The polymers had moderate molecular weights, were amorphous, and dissolved readily in tetrahydrofuran and halogenated organic solvents. They were stable up to approximately 340 °C in N2 and 290 °C in air, and the anaerobic char yield was around 60% at 800 °C. The polymer with cyano side groups emitted blue light in solutions and thin films with identical photoluminescence (PL) maximum at 450 nm; this supported the idea that chain interactions were hindered even in the solid state. The PL maximum of this polymer in thin films was blueshifted upon annealing at 120 °C, indicating a thermochromic effect as a result of conformational changes in the polymer backbone. The polymer containing side substituents with oxadiazole rings emitted blue light in solutions with a PL maximum at 474 nm and blue‐greenish light in thin films with a PL maximum at 511 nm. The PL quantum yields of the polymers in tetrahydrofuran were 0.13–0.24. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1768–1778, 2004
Preparation and properties of silylated PTFE/SiO2 organic–inorganic hybrids via sol–gel process
Authors: Chen Yung‐Chih , Tsai Chi‐Che , Lee Yu‐Der 
Published: February 2004

AbstractA study on poly(tetrafluoroethylene) (PTFE) reinforced with tetraethoxysilanes (TEOS) derived SiO2 is described. It included the manufacturing process of SiO2‐reinforced PTFE and the effects of silylation agent on the properties of the hybrid material, such as porosity, hydrophobic, thermal resistance, dielectric and mechanical properties, and microstructure. PTFE/SiO2 hybrids of 50 wt % SiO2 loading were prepared via a sol–gel process and were shaped by a two‐roll milling machine. Trimethylchlorosilane and hexamethydisilazane were used as the silylation agents. Our results showed that the water absorption and dielectric loss of PTFE/SiO2 hybrid had significantly improved with silylation agent. The silylation process replaced SiOH with SiCH3 on the surface of the TEOS‐derived silica colloidal particle. The existence of trimethylsilyl [Si(CH3)3] on the surface of the modified PTFE/SiO2 hybrid was confirmed via infrared and solid‐state 29Si magic‐angle spinning nuclear magnetic resonance spectra. Nitrogen‐sorption techniques were used to characterize the modified and unmodified PTFE/SiO2 hybrids. The microstructure of SiO2 in the matrix was also evaluated with scanning electron microscopy and transmission electron microscopy. Our results showed that the silylated sol–gel‐derived PTFE/SiO2 hybrids had exhibited high porosity (53.7%) with nanosize pores (10–40 nm) and nanosize colloidal particles (20–50 nm). This manifests itself as have the ultralow dielectric properties (Dk = 1.9 and Df = 0.0021), low coefficient of thermal expansion (66.5 ppm/°C), high tensile modulus (141 MPa), excellent thermal resistance (Td = 612 °C), and an increased hydrophobia (θ = 114°); moreover, the hydrophobic property of the PTFE/SiO2 hybrid was thermally stable up to 400 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1789–1807, 2004
Michael Polanyi and the discovery of co‐catalysis: Discussion of an autobiographical letter from Michael Polanyi, FRS to Peter H. Plesch of 17 December 1963
Authors: Plesch P. H. 
Published: February 2004

AbstractThe origin of this memoir was a letter from Michael Polanyi (M. P.) to the present writer (P. H. P.) about their researches in the mid‐1940s into the mechanism of what are now called cationic polymerizations, at the University of Manchester (England). M. P. analyzes his tactics and the mistakes made in directing this research.When the Manchester‐trained researchers made little progress with what was a very recalcitrant problem, M. P. thinking that scientists from a different background might be more sucessful, got P. H. P., from Cambridge, to work with an Oxford‐trained chemist. They recognized that the likely cause of the irreproducibility of these polymerizations was the apparatus used which permitted access of atmospheric moisture to the reaction mixtures containing the moisture‐sensitive catalytic metal halides. Because the only method for following the very fast polymerizations was by monitoring the accompanying temperature rise, and the reactions had to be done below ambient temperature, the reaction vessel needed to be adiabatic, that is a Dewar (Thermos) flask; hence the problem of how to cool its contents. The solution was P. H. P.'s invention of the pseudo‐Dewar vessel, the Dewar space of which, instead of being evacuated permanently, could be filled with air or evacuated. This device permitted the reaction mixture to be made up and cooled, and the reactions to be started without contact with the atmosphere. Thus it was found that isobutene polymerizations, which had stopped unaccountably, could be restarted by water vapor. P. H. P. termed water a “co‐catalyst”. The consequent “Manchester” theory recognized the monohydrate of TiCl4 as a protonic acid and saw the initiation as due to the protonation of the monomer, with the formation of a tert‐carbenium ion, and these ions, formed repetitively, became the propagating species.The Manchester theory was rapidly accepted because it could also explain observations on other related reactions. The involvement of ions established a link with non‐aqueous electrochemistry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1537–1546, 2004
Modeling hydrology, metribuzin degradation and metribuzin transport in macroporous tilled and no‐till silt loam soil using RZWQM
Authors: Malone Robert W , Ma Liwang , Don Wauchope R , Ahuja Lajpat R , Rojas Kenneth W , Ma Qingli , Warner Richard , Byers Matt 
Published: February 2004

AbstractDue to the complex nature of pesticide transport, process‐based models can be difficult to use. For example, pesticide transport can be effected by macropore flow, and can be further complicated by sorption, desorption and degradation occurring at different rates in different soil compartments. We have used the Root Zone Water Quality Model (RZWQM) to investigate these phenomena with field data that included two management conditions (till and no‐till) and metribuzin concentrations in percolate, runoff and soil. Metribuzin degradation and transport were simulated using three pesticide sorption models available in RZWQM: (a) instantaneous equilibrium‐only (EO); (b) equilibrium‐kinetic (EK, includes sites with slow desorption and no degradation); (c) equilibrium‐bound (EB, includes irreversibly bound sites with relatively slow degradation). Site‐specific RZWQM input included water retention curves from four soil depths, saturated hydraulic conductivity from four soil depths and the metribuzin partition coefficient. The calibrated parameters were macropore radius, surface crust saturated hydraulic conductivity, kinetic parameters, irreversible binding parameters and metribuzin half‐life. The results indicate that (1) simulated metribuzin persistence was more accurate using the EK (root mean square error, RMSE = 0.03 kg ha−1) and EB (RMSE = 0.03 kg ha−1) sorption models compared to the EO (RMSE = 0.08 kg ha−1) model because of slowing metribuzin degradation rate with time and (2) simulating macropore flow resulted in prediction of metribuzin transport in percolate over the simulation period within a factor of two of that observed using all three pesticide sorption models. Moreover, little difference in simulated daily transport was observed between the three pesticide sorption models, except that the EB model substantially under‐predicted metribuzin transport in runoff and percolate >30 days after application when transported concentrations were relatively low. This suggests that when macropore flow and hydrology are accurately simulated, metribuzin transport in the field may be adequately simulated using a relatively simple, equilibrium‐only pesticide model. Published in 2004 for SCI by John Wiley & Sons, Ltd.
Metabolism of imidacloprid in Apis mellifera
Authors: Suchail Séverine , Debrauwer Laurent , Belzunces Luc P 
Published: February 2004

AbstractBiotransformation of imidacloprid and the appearance of olefin and 5‐hydroxyimidacloprid metabolites in the honeybee were studied by HPLC‐MS/MS analysis. Honeybees were treated orally with imidacloprid at 20 and 50 µg kg−1 bee. Imidacloprid was metabolised relatively quickly and thoroughly. Twenty minutes after the beginning of imidacloprid ingestion, the sum of the residues from the three compounds amounted to only 70% of the actual given dose. Imidacloprid, 5‐hydroxyimidacloprid and olefin represented, respectively, 50%, 9% and 8% of the actual ingested dose. Six and 24 h, respectively, after ingestion of imidacloprid at 20 and 50 µg kg−1 bee, imidacloprid could no longer be detected in the honeybee. Imidacloprid had a half‐life ranging between 4.5 and 5 h and was rapidly metabolised into 5‐hydroxyimidacloprid and olefin. Except 5‐hydroxyimidacloprid in the 20 µg kg−1 treatment, these two metabolites presented a peak value 4 h after ingestion of the 20 and 50 µg kg−1 doses. This time fully coincided with the appearance of mortality induced by imidacloprid after acute oral intoxication. These results suggested that the immediate neurotoxicity symptoms are due to the action of imidacloprid, whereas 5‐hydroxyimidacloprid and/or olefin are involved in honeybee mortality. In addition, it was likely that the 30% of residues undetected 20 min after intoxication were imidacloprid metabolites, although not 5‐hydroxyimidacloprid or olefin. Thus, 5‐hydroxyimidacloprid and olefin could not be the major metabolites in the worker bees. Copyright © 2003 Society of Chemical Industry
Sorption of aged dicamba residues in soil
Authors: Menasseri Safya , Koskinen William C , Yen Pau Yong 
Published: February 2004

AbstractThe effect of aging (residence time in soil) on dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) and a major metabolite, 3,6‐dichlorosalicylic acid (3,6‐DCSA) sorption was determined in an unamended and a carbon‐amended sandy loam and in a silt loam soil. During the incubation, sequential solvent extraction with 0.01 M calcium chloride solution and aqueous acetonitrile + hydrochloric acid was used to determine the solution and sorbed concentrations of dicamba and 3,6‐DSCA, and sorption coefficients were calculated. Dicamba was weakly sorbed to soil (Kd <0.7). In contrast to some other classes of pesticides, sorption of dicamba did not significantly increase with aging, at least not until <15% of the applied dicamba remained. 3,6‐DSCA was strongly sorbed to soil (Kd >8) and the Kd‐a value increased by a factor of 2–6 during a 28‐day aging period. Addition of a carbon source to the soil had minimal effect on the strength of sorption of aged dicamba. However, it did appear to decrease 3,6‐DSCA availability to soil micro‐organisms; once formed 3,6‐DSCA was not further mineralized. While it appears that sorption can be well characterized for weakly sorbed pesticides using the batch equilibration method with freshly treated soils, this procedure may not be adequate for more strongly sorbed pesticides and their degradates. Copyright © 2003 Society of Chemical Industry
Effectiveness of twelve insecticides applied topically to diapausing larvae of the codling moth, Cydia pomonella L
Authors: Pasquier Denis , Charmillot Pierre‐Joseph 
Published: February 2004

AbstractDose–mortality curves were established for 12 insecticides administered by topical application to diapausing larvae from a susceptible codling moth strain. Toxicity varied greatly among the insecticides tested. LC50 values ranged from 0.1 mg kg−1 for fenoxycarb to over 2800 mg kg−1 for diflubenzuron and indoxacarb. Discriminating dose levels were determined from dose‐mortality reference curves for the detection of resistance in field‐collected diapausing larvae. Copyright © 2003 Society of Chemical Industry
Application of the Root Zone Water Quality Model (RZWQM) to pesticide fate and transport: an overview
Authors: Malone Robert W , Ahuja Lajpat R , Ma Liwang , Don Wauchope R , Ma Qingli , Rojas Kenneth W 
Published: February 2004

AbstractPesticide transport models are tools used to develop improved pesticide management strategies, study pesticide processes under different conditions (management, soils, climates, etc) and illuminate aspects of a system in need of more field or laboratory study. This paper briefly overviews RZWQM history and distinguishing features, overviews key RZWQM components and reviews RZWQM validation studies. RZWQM is a physically based agricultural systems model that includes sub‐models to simulate: infiltration, runoff, water distribution and chemical movement in the soil; macropore flow and chemical movement through macropores; evapotranspiration (ET); heat transport; plant growth; organic matter/nitrogen cycling; pesticide processes; chemical transfer to runoff; and the effect of agricultural management practices on these processes. Research to date shows that if key input parameters are calibrated, RZWQM can adequately simulate the processes involved with pesticide transport (ET, soil‐water content, percolation and runoff, plant growth and pesticide fate). A review of the validation studies revealed that (1) accurate parameterization of restricting soil layers (low permeability horizons) may improve simulated soil‐water content; (2) simulating pesticide sorption kinetics may improve simulated soil pesticide concentration with time (persistence) and depth and (3) calibrating the pesticide half‐life is generally necessary for accurate pesticide persistence simulations. This overview/review provides insight into the processes involved with the RZWQM pesticide component and helps identify model weaknesses, model strengths and successful modeling strategies. Published in 2004 for SCI by John Wiley & Sons, Ltd.
The pesticide module of the Root Zone Water Quality Model (RZWQM): testing and sensitivity analysis of selected algorithms for pesticide fate and surface runoff
Authors: Ma Qingli , Wauchope R Don , Rojas Kenneth W , Ahuja Lajpat R , Ma Liwang , Malone Robert W 
Published: February 2004

AbstractThe Root Zone Water Quality Model (RZWQM) is a one‐dimensional, numerical model for simulating water movement and chemical transport under a variety of management and weather scenarios at the field scale. The pesticide module of RZWQM includes detailed algorithms that describe the complex interactions between pesticides and the environment. We have simulated a range of situations with RZWQM, including foliar interception and washoff of a multiply applied insecticide (chlorpyrifos) to growing corn, and herbicides (alachlor, atrazine, flumetsulam) with pH‐dependent soil sorption, to examine whether the model appears to generate reasonable results. The model was also tested using chlorpyrifos and flumetsulam for the sensitivity of its predictions of chemical fate and water and pesticide runoff to various input parameters. The model appears to generate reasonable representations of the fate and partitioning of surface‐ and foliar‐applied chemicals, and the sorption of weakly acidic or basic pesticides, processes that are becoming increasingly important for describing adequately the environmental behavior of newer pesticides. However, the kinetic sorption algorithms for charged pesticides appear to be faulty. Of the 29 parameters and variables analyzed, chlorpyrifos half‐life, the Freundlich adsorption exponent, the fraction of kinetic sorption sites, air temperature, soil bulk density, soil‐water content at 33 kPa suction head and rainfall were most sensitive for predictions of chlorpyrifos residues in soil. The latter three inputs and the saturated hydraulic conductivity of the soil and surface crusts were most sensitive for predictions of surface water runoff and water‐phase loss of chlorpyrifos. In addition, predictions of flumetsulam (a weak acid) runoff and dynamics in soil were sensitive to the Freundlich equilibrium adsorption constant, soil pH and its dissociation coefficient. Published in 2004 for SCI by John Wiley & Sons, Ltd.