bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultraviolet spectrophotometric studies of the reactivity of a water‐soluble polymer containing pendant 8‐hydroxyquinoline moieties with metal ions
Authors: Hamaya Takeo , Hiratani Kazuhisa , Ohashi Kosaburo 
Published: April 2003

AbstractThe water‐soluble polymer 4 containing pendant 8‐hydroxyquinoline (oxine) moieties was prepared and its reactivity with metal ions was studied by means of ultraviolet (UV) spectrophotometry. Polymer 4 was found to form complexes with metal ions in a mole ratio of 2 : 1 (oxine : metal), which is also obtained for the metal complexes of model compound 3 except for the Mg2+ complex. Polymer 4 hardly reacts with Mg2+, while model compound 3 forms a 1 : 1 mol/mol complex. The stability of the complexes of polymer 4 with metal ions was found to decrease in the following order: Cu2+ > Ni2+ > Zn2+ > Cd2+ > Hg2+ > Mg2+.
Synthesis and NMR characterization of a series of linear monodisperse poly(aryl ether ketone) and poly(aryl ether sulfone) oligomers
Authors: Finocchiaro Paolo , Montaudo Giorgio , Mertoli Patrizia , Samperi Filippo 
Published: April 2003

AbstractNew poly(aryl ether ketone) and poly(aryl ether sulfone) monodisperse model oligomers were synthesized in good yield via nucleophilic reactions. They were characterized by means of 1H and 13C NMR spectroscopy, and all chemical shifts were assigned to the corresponding nuclei. Both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, CO and SO2 bridges, but in all oligomers, nuclei with similar electronic environments are very close to each other no matter what the sequence or the length of the oligomer is. Only quaternary carbons are more sensitive to the nature of the bridging groups, and therefore their chemical shifts can be of utility in sequencing the polymers.
Compatibilization and structure of poly(propylene)/nylon‐12 blends
Authors: Tang Tao , Li Hongyun , Huang Baotong 
Published: April 2003

AbstractIn this paper, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) were used to study the structure and compatibilization of poly(propylene) (PP)/nylon‐12 (PA 12) blends. The compatibilization of maleated PP(PP‐MA) and graft copolymer (PP‐MA‐g‐PEO) of PP‐MA and poly(ethylene oxide) (PEO) in PP/PA 12 blends was observed from the morphology of the fracture surface of PP/PA12 blends. The compatibilization mechanism was investigated. The DSC results showed that there was nucleation between PP and PA12. This was attributed to the unusual epitaxial relationship. The effect of PA12 on the crystalline structure of PP was studied by means of WAXD.
Polymères porteurs de dérivés du glycérol, 10. Fixation de l'acide naphtyl‐1 acétique sur le poly(acide méthacrylique)
Authors: Soutif Jean‐Claude , Karkab Said , Brosse Jean‐Claude 
Published: April 2003

AbstractGlycidyl (2,3‐epoxypropyl) esters are convenient reagents for the fixation of carboxylic acid moieties on polymeric support of the polyacid type. This way of synthesis was applied to 1‐naphthylacetic acid on poly(methacrylic acid). Esterification of 1‐naphthylacetyl chloride by glycidol (2,3‐epoxy‐1‐propanol) and addition of 1‐naphthylacetic acid on epichlorohydrin (1‐chloro‐2,3‐epoxypropane) with subsequent reformation of the oxirane ring have been used for the synthesis of the glycidyl ester but the reaction of the potassium salt of the acid with epichlorohydrin leads to a better yield. Addition of 1‐naphthylacetic acid on glycidyl acetate was studied in N,N‐dimethylformamide (DMF) and acetonitrile. The best results were obtained in DMF. The reaction is of first order with respect of epoxide, but 2nd order applies when the solvent is acetonitrile. The same reaction conditions as for glycidyl acetate were used for the chemical modification of poly(methacrylic acid) with glycidyl 1‐naphthylacetate except that methanol was used as the solvent.
Studies on the behavior of photodegradation of poly(cyclohexylmethylsilane)
Authors: Chen Deben , Hu Huiping 
Published: April 2003

AbstractThe fluorescence spectra of poly(cyclohexylmethylsilaane) (PCHMS) solutions or films before and after ultraviolet irradiation in air were studied. The experimental results showed that the positions of the fluoresence peaks shift to shorter wavelength and the fluorescence intensities decrease gradually with increasing UV irradiation time. The results of UV spectra, GPC and ESCA, and IR spectra of PCHMS solutions or films upon UV exposure in air indicate that these phenomena are in accordance with a combined process of photodegradation and photooxidation, which lead to a decrease of the molecular weights and formation of siloxane structures in the polysilane main chains.
Kinetices of polymerization of 1‐octene with the catalyst system VOCl3‐AlEt3 (or AlEt2Br)
Authors: Kothandaraman Harimurthi , Devi Muthusamy Saroja 
Published: April 2003

AbstractKinetic studies of the polymerization of 1‐octene with the Ziegler‐Natta catalyst systems VOCl3—AlEt3 (I) and VOCl3—AlEt2Br (II) are reported. The effect of the various parameters such as the Al/V ratio, catalyst and monomer concentrations, reaction time, aging time and temperature on rate of reaction and molecular weight of polymer were studied. Each of these parameters has a profound effect on the polymer yield and the rate of the reaction for both systems. The rate of polymerization increases linearly with increasing temperature, catalyst and monomer concentrations. The reaction is first order with respect to both the monomer and the catalyst concentration in the two catalyst systems studied. From the Arrhenius plot the overall activation energy of polymerization for the two systems was found to be 51,2 and 43,5 kJ/mol, respectively. The mechanism of polymerization is discussed on the basis of the dependence of the polymerization rate on the alkylaluminium concentration.
Quantitative aspects of charge transfer in polyaniline during its electrodeposition and electrochemical degradation
Authors: Orata Duke , Matheka Anderson , Munge Bernard 
Published: April 2003

AbstractThe results presented in this paper reveal that the electrochemical degradation of polyaniline is strongly dependent on the potential window. Substantial agreement is observed between calculated and experimentally obtained values for the electrochemical parameters of films, i.e. peak current and charge. These results also reveal that the efficiency of the cyclic redox process is well below 100%.
UV/VIS‐spektroskopischer Nachweis einer selektiven Komplexbildung zwischen WOCl4 und trimethylaluminium. Ein weg zur Charakterisierung von methylaluminoxanen
Authors: Thorn‐Csányi Emma , Dehmel Jörg , Halle Olaf , Sciborski Winfried 
Published: April 2003

AbstractThe kinetic analysis of the reaction between WOCl4 and trimethylaluminium (TMA) shows that TMA forms a 2 : 1 mol/mol‐complex with WOCl4 before it acts as an alkylating agent. The reaction steps can be observed separately because rate constants kcomplex formation ≫ kalkylation and ultraviolet/visible (UV/VIS) absorption coefficients ϵcomplex ≠ ϵWOCl4. The rapid change of the WOCl4‐UV/VIS‐spectrum is typical for TMA and cannot be observed with methylaluminoxane (MAO) or with dimethylaluminium chloride. Due to the selective complex formation it is possible to determine the exact content of “free” TMA in MAO.
Study of polyampholyte hydrogels and interpenetrating polyelectrolyte networks based on 4‐(but‐3‐en‐1‐ynyl)‐1‐methylpiperidin‐4‐ol
Authors: Kudaibergenov Sarkyt E. , Nurgalieva Dametken E. , Bekturov Esen A. , Shaikhutdinov Erengaip M. , Nurkeeva Zauresh S. , Sigitov Vladimir B. 
Published: April 2003

AbstractPolyampholyte hydrogels and interpenetrating polyelectrolyte networks (IPPN) based on 4‐(but‐3‐en‐1‐ynyl)‐1‐methylpiperidin‐4‐ol (1) have been synthesized by γ‐irradiation polymerization. The influence of the pH and ionic strength of the solution on the degree of swelling ϕ for both polyampholyte hydrogels and IPPN has been studied. The shrinking and swelling behaviour of crosslinked samples was explained by the formation or destruction of intra‐ and interpoly‐electrolyte complexes.
Synthesis and characterization of new siloxane‐modified addition polyimides
Authors: Laurienzo Paola , Malinconico Mario , Perenze Nicoletta , Segre Anna Laura 
Published: April 2003

AbstractA new series of polyimides was synthesized by addition polymerization of 4,4′‐(bismaleimido)‐diphenylmethane, 1,4‐piperazine and an amino‐terminated polydimethylsiloxane. The synthesis was carried out in m‐cresol solution following a two‐step procedure. Copolymers containing 15 and 20 wt.‐% of the polydimethylsiloxane elastomer were prepared, together with the unmodified base copolymer. Infrared spectroscopy, 13C and 1H NMR, thermal and thermogravimetric analyses were used to characterize the copolymers. The DSC curves of all the samples showed an exotherm in the temperature range 230–280°C, attributable to curing and addition reactions involving the chain‐end groups. Different glass transition temperatures (Tg) were observed, depending on the elastomer content. Thermogravimetric analysis indicated that no significant changes occur in the thermal stability of rubber‐modified copolymers.
Nucleation of particles in seeded emulsion polymerization of vinyl acetate with poly(vinyl alcohol) as emulsifier
Authors: Lepizzera Stephane M. , Hamielec Archie E. 
Published: April 2003

AbstractSeeded emulsion polymerizations of vinyl acetate with and without poly(vinyl alcohol) were carried out in a batch reactor. Two types of poly(vinyl alcohol) (different molecular weights but the same degree of hydrolysis) have been investigated. In the absence of poly(vinyl alcohol) no new nucleation was observed, while in its presence new particles were formed, giving a bimodal particle size distribution. The number of new particles was greater with the higher‐molecular‐weight poly(vinyl alcohol). Compared with emulsifier‐free seeded emulsion polymerization, the reaction rate increased when the higher‐molecular‐weight poly(vinyl alcohol) was used. However, the polymerization rate decreased when the lower‐molecular‐weight poly(vinyl alcohol) was applied. It was also shown that for seeded emulsion polymerization of vinyl acetate in the absence of poly(vinyl alcohol), the kinetics follows Smith‐Ewart case III theory. These observations are discussed and a theory is proposed to explain the effect of macromolecular emulsifier on the nucleation of particles in seeded emulsion polymerization. This theory involves nucleation of new particles via precipitation of “copolymer” poly(vinyl alcohol)‐poly(vinyl acetate) radicals in the water phase.
Synthesis and characterization of poly(1‐benzoylthiosemicarbazide) and poly(1,3,4‐thiadiazole amine) from 2‐(p‐aminophenyl)‐1,3,4‐oxadiazoline‐5‐thione via ring‐opening process
Authors: Saegusa Yasuo , Ozeki Yasuhiro , Harada Shigeo , Nakamura Shigeo 
Published: April 2003

AbstractA novel thermally stable and semiconducting polyheterocycle, poly(1,3,4‐thiadiazole amine), was synthesized from 2‐(p‐aminophenyl)‐1,3,4‐oxadiazoline‐5‐thione via ring‐opening. The polymer is a new class of ordered alternating copoly(aniline) containing 1,3,4‐thiadiazole heterocyclic units. An investigation of the reaction of 2‐phenyl‐1,3,4‐oxadiazoline‐5‐thione with aniline was conducted as a model reaction for the polymerization, and poly(phosphoric acid) (PPA) and phosphorus pentoxide/methanesulfonic acid (PPMA) were found to be favorable both as condensing agent and solvent for the formation of 2‐anilino‐5‐phenyl‐1,3,4‐thiadiazole as a model compound. The polymerization was carried out both by two‐step procedure that included ring‐opening self‐polyaddition giving poly(1‐benzoylthiosemicarbazide), followed by cyclodehydration to poly(1,3,4‐thiadiazole amine), and by a one‐step procedure including cyclodehydration in situ. The poly(1‐benzoylthiosemicarbazide) which was formed in the first step in m‐cresol had reduced viscosities up to 0,42 dL·g−1, and it was converted to poly(1,3,4‐thiadiazole amine) by treating in PPA or PPMA. Poly(1,3,4‐thiadiazole amine) having reduced viscosities up to 0,25 dL·g−1 was also synthesized by the direct one‐step polymerization in PPA or PPMA. The polymer is highly thermally stable and exhibited no weight loss up to 350°C under nitrogen. Its electric conductivity was less than 10−10 S·cm−1 at ambient temperature, but markedly increased to 2,9·10−7 S·cm−1 upon doping with iodine.
Preparation and properties of copolyamides‐6,6F and copolyamides‐4,8F containing oligo(tetrafluoroethylene)segments
Authors: Steinhauser Norbert , Mülhaupt Rolf 
Published: April 2003

AbstractTwo families of copolyamides‐6,6F and copolyamides‐4,8F containing various amounts of bis‐ and tris(tetrafluoroethylene) segments were prepared to study the influence of such fluorine‐containing segments on bulk and surface properties. In a solution polycondensation process telechelic aliphatic diamines, obtained by reacting dimethyl α,ω‐dicarboxylatooligo(tetrafluoroethylene)s with excess diamines, e. g., tetramethylenediamine and hexamethylenediamine, were polymerized with activated bis(4‐nitrophenyl) adipate and bis(4‐nitrophenyl) suberate. In the presence of various stoichiometric amounts of the aliphatic diamines, the fluorine content varied between 0 and 39 wt.‐% and the inherent viscosities between 0,27 and 1,02 dL/g. As content and segment length of the oligo(tetrafluoroethylene) segments increased, the polymer solubilities in organic solvents and the contact angles to water increased, whereas melting temperatures, crystallinities (as measured by means of differential scanning calorimetry and wide‐angle X‐ray scattering (WAXS)) and thermal stabilities (as determined by means of thermogravimetric analysis of the weight loss encountered at elevated temperatures) were reduced markedly. The WAXS measurements reflected changes of crystal structures with increasing fluorine content.
Preparation and characterization of silica‐ and magnesia‐supported poly(3‐aminopropylsiloxane)‐platinum complexes and their catalytic activity in the oxidation of cyclohexanol and cyclopentanol with molecular oxygen
Authors: Jia Cheng‐Guo , Liang Fu‐Yan , Tang Liang‐Jie , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: April 2003

AbstractWe have prepared silica‐ and magnesia‐supported poly(3‐aminopropylsiloxane)‐platinum complexes (abbreviated as SiO2‐PAPSPt and MgO‐PAPSPt, respectively) in which mixed valent platinum is coordinated by amino groups and aggregated to a certain extent. MgO‐PAPSPt contains low‐valent, very small and almost homogeneously dispersed platinum aggregates (diameter ca. 20 Å) and is highly active, stable and recyclable in the oxidation of cyclohexanol and cyclopentanol under atmospheric pressure of oxygen. In contrast, large platinum aggregates (ca. 30–100 Å, 60 Å on an average) are found in SiO2‐PAPSPt, and almost no zero‐valent platinum is present. We assume this is the reason for its very low activity in oxidations under the same conditions.
Metathesis polymerization of endo‐5‐ and exo‐5‐chloromethylbicyclo[2.2.1]hept‐2‐ene and of 5,5‐bis(chloromethyl)bicyclo[2.2.1]hept‐2‐ene; microstructure of the polymers
Authors: Ivin Kenneth J. , Lam Luk‐Mui , Rooney John J. 
Published: April 2003

AbstractThe three title monomers were polymerized using a variety of Ru‐, Ir‐, Mo‐, W‐ and Re‐based metathesis catalyst systems to yield polymers having a wide range of cis double bond contents in each case. The 13C NMR spectra of the polymers were interpreted in terms of cis/trans, head/tail and m/r microstructures. No head‐tail bias was observed in any of the polymers.
Assignment of the 1H and 13C NMR spectra and stereochemical analysis of radical‐initiated poly(1‐naphthylmethyl acrylate) and poly[2‐(1‐naphthyl)ethyl acrylate]
Authors: Spyros Apostolos , Dais Photis , Heatley Frank 
Published: April 2003

AbstractResonances in the 1H and 13C NMR spectra of free‐radical polymerised poly(1‐naphthylmethyl acrylate) (PNMA) and poly[2‐(1‐naphthyl)ethyl acrylate] (PNEA) have been assigned using two‐dimensional techniques. The stereosequence distribution in both polymers obeyed Bernoullian statistics with probabilities of an isotactic diad of 0,43 in PNMA and 0,39 in PNEA.
Synthesis of α,ω‐dialkenyl isotactic poly(propylene) using bis(4‐methyl‐3‐pentenyl)zinc as a chain transfer reagent
Authors: Kurosawa Hiroki , Shiono Takeshi , Soga Kazuo 
Published: April 2003

AbstractPropene polymerization was conducted with the catalyst system composed of TiCl3 and bis(4‐methyl‐3‐pentenyl)zinc (BMPZ) in the absence or presence of Al(C2H5)2Cl. The catalyst system with or without Al(C2H5)2Cl gave isotactic poly(propylene) (PP) with a lower molecular weight as compared to the TiCl3/Al(C2H5)2Cl system. From the 1H and 13C NMR analyses, it was found that the polymer produced with the TiCl3/BMPZ catalyst possesses a 2,6‐dimethyl‐5‐heptenyl group and a Zn‐PP bond at the initial and terminal ends, respectively. The Zn‐terminated end was then converted to a vinyl group by coupling with allyl bromide in the presence of N‐methylimidazole to obtain isotactic PP having CC double bonds at both chain ends.
Determination of cloud‐point, shadow and other coexistence curves in multicomponent systems from measurements of phase volume ratios
Authors: Borchard Werner , Frahn Stephanie , Fischer Volker 
Published: April 2003

AbstractLiquid‐liquid demixing of polydisperse polymer systems is described by volume balance equations relating the phase volume ratio to the bulk concentration of a polymer and its equilibrium concentrations. It is shown that in a system of a solvent and a polydisperse polymer, cloud‐point and shadow curves and the concentrations of coexisting phases may be obtained from the linearized volume or mass conservation equation. Also half meter curves for different phase volume ratios are obtained. The intersection of the half meter curve for equal phase volumina of coexisting phases with the cloud‐point or shadow curve leads to a determination of the critical point. The findings are illustrated in the system poly(ethylene oxide)/water, where the thresholds of cloud‐point and shadow curves do not coincide with the critical demixing point. This is typical of a multicomponent polymer/solvent system.
Intramolecular energy transfer in bichromophoric diesters containing anthracene and naphthalene groups separated by different numbers of methylene spacers
Authors: Bravo Julio , Mendicuti Francisco , Saiz Enrique , Mattice Wayne L. 
Published: April 2003

AbstractSteady state fluorescence has been used to study the efficiency of nonradiative singlet energy transfer from naphthalene to anthracene in naph‐COO(CH2)mOOC‐anth for m of 2–6. A theoretical analysis has also been performed, using the rotational isomeric state model, of the conformations of these molecules. The experiments clearly demonstrate the presence of nonradiative singlet energy transfer in the bichromophoric compounds, with an efficiency that depends on the solvent and on m. The combination of the experiments and the theoretical analysis establishes that the Förster radius for this system is 1,6 ± 0,2 nm.
Synthesis and properties of aromatic telechelic monodisperse diols, 1. Radical‐initiated addition of 10‐undecen‐1‐ol to new aromatic α,ω‐dithiols
Authors: Améduri Bruno , Boutevin Bernard , Khamlichi Mohammed , Robin Jean‐Jacques , El Idrissi Abderrahman , Ramdani Abdelkarim 
Published: April 2003

AbstractThe synthesis of aromatic telechelic monodisperse diols produced from the radical‐initiated addition reaction of a two‐fold excess of 10‐undecen‐1‐ol and new α,ω‐dithiols is presented. The dithiols were prepared by esterification of thioglycolic acid with monodisperse telechelic diols obtained by fractionation of oligo(ethylene terephthalate)s and oligo(tetramethylene terephthalate)s. In all the cases, the long‐chain α,ω‐diols were produced selectively and quantitatively. The diols are soluble in most organic solvents, contrary to classical oligo(ethylene terephthalate)s and oligo(tetramethylene terephthalate)s.
End‐group analysis of poly(phenyl glycidyl ether), 1. Hydroxylic groups using 1H and 13C nuclear magnetic resonance
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia 
Published: April 2003

AbstractThe hydroxylic end‐groups in the soluble fraction of poly(phenyl glycidyl ether) (PPGE) obtained with the aluminium isopropoxide (AIP)/ZnCl2 initiator system are studied using nuclear magnetic resonance spectroscopy (NMR). To achieve complete assignment, model compounds are synthesized and their carbamate and trifluoroacetate derivatives obtained from trichloroacetyl isocyanate (TAI) and trifluoroacetic anhydride (TFAA) are prepared. These derivatizating reagents allow primary and secondary alcohols to be distinguished, since upfield or downfield shifts are produced, and at the same time they have the potential of separating overlapping peaks. Several PPGEs with different degrees of regularity are also synthesized using various initiator systems. Thus, it is possible to identify the carbon signals of both final hydroxylic groups and their adjacent units, and the presence of two types of unit linked to secondary hydroxylic end‐groups is demonstrated. Likewise, in the soluble fraction prepared with AIP/ZnCl2 the absence of the irregular units linked to secondary hydroxylic end‐group is demonstrated, so proving the high regularity of this fraction.
End‐group analysis of poly(phenyl glycidyl ether), 2. Hydroxylic groups using 19F nuclear magnetic resonance
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia 
Published: April 2003

AbstractThe hydroxylic end‐groups in the soluble fraction of poly(phenyl glycidyl ether) (PPGE) obtained with the aluminium isopropoxide (AIP)/ZnCl2 initiator system are studied using 19F NMR spectroscopy. Derivatization as trifluoroacetate esters affords poor structural information and handle difficulties. Hexafluoroacetone (HFA) hemiketalic adducts are much more easily prepared and offer more information, allowing not only to distinguish between primary and secondary alcohols but showing a clear sensitivity to the tacticity. This method is successful to calculate the percentage of hydroxylic end‐group in the polymer chain. In the case of an irregular PPGE sample, obtained with AIP alone as initiator, it is possible to identify three different hydroxylic end‐groups.
Synthesis and molecular weight characterization of low molecular weight end‐functionalized poly(4‐acryloylmorpholine)
Authors: Ranucci Elisabetta , Spagnoli Gloria , Sartore Luciana , Ferruti Paolo , Caliceti Paolo , Schiavon Oddone , Veronese Francesco M. 
Published: April 2003

AbstractNew amphiphilic oligomers ending at one side with a reactive function were synthesized by radical polymerization of a vinyl monomer,N‐acryloylmorpholine, in the presence of functionalized chain‐transfer agents (CTAs). The oligomers were characterized in terms of molecular weight and molecular weight distribution, by means of analytical size‐exclusion chromatography (SEC) working in buffered aqueous media. This has been accomplished by determining a calibration curve for a set of SEC columns, with poly(N‐acryloylmorpholine) standards purposely obtained by means of preparative SEC. The transfer constantCTof some CTAs towardsN‐acryloylmorpholine has been estimated to be approximately 1.