bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer‐supported Ziegler–Natta catalysts. I. A preliminary study of catalyst synthesis
Authors: Sun L. , Hsu C. C. , Bacon D. W. 
Published: April 2003

AbstractPolymer‐supported Ziegler–Natta catalysts based on various polymer carriers were synthesized by different methods, including (1) loading TiCl4 directly onto the polymer supports; (2) loading TiCl4 onto the polymer supports modified by magnesium chloride (MgCl2); (3) loading TiCl4 onto the polymer supports modified by Grignard reagent (RMgCl); and (4) loading TiCl4 onto the polymer supports modified by magnesium alkyls (MgR2). The activity and kinetic features of the catalysts for ethylene polymerization were examined. Among the combinations tested, the best was found to be TiCl4/n‐Bu2Mg.Et3Al/poly(ethylene‐co‐acrylic acid) (92:8), which produced a catalyst of very high activity for ethylene polymerization. © 1994 John Wiley & Sons, Inc.
Triblock copolymers based on cyclic ethers: Preparation and properties of tetrahydrofuran and 3,3‐bis(azidomethyl) oxetane triblock copolymers
Authors: Hsiue Ging‐ho , Liu Ying‐Ling , Chiu Yie‐Shun 
Published: April 2003

AbstractNovel energetic thermoplastic elastomers (TPEs) based on tetrahydrofuran (THF) and 3,3‐bis (azidomethyl) oxetane (BAMO) were prepared in this present study by cationic living polymerization. A bifunctional catalyst, triflic anhydride [(CF3SO2)2)O] was selected to be an initiator for the polymerization THF and BAMO. The resulting polymers were characterized by IR, NMR, and DSC, which demonstrated that triblock copolymers with A‐B‐A type were formed. The polymers were indicated from thermogravimetric analysis (TGA) to have decomposed at approximately 243°C. The decomposition enthalpies were determined by DSC. These enthalpies were varied with the poly‐BAMO contents of the copolymers. The synthesized polymers exhibited relatively good mechanical properties and thermoplastic characteristics at room temperature. © 1994 John Wiley & Sons, Inc.
Model prediction of batch emulsion copolymerization as a function of conversion: A sensitivity analysis
Authors: Noël Lilian F. J. , Maxwell Ian A. , Well Willy J. M. Van , German Anton L. 
Published: April 2003

AbstractRecently a model has been developed capable of predicting absolute monomer concentrations and their ratios in the polymer, aqueous, and monomer droplet phases as a function of conversion in batch emulsion copolymerizations without using any adjustable parameters. In this article the sensitivity of model predictions of composition drift toward deviations of 10% in all model parameters (maximum swellabilities of monomer in the polymer phase, water solubilities, reactivity ratios, and monomer and polymer densities) was estimated using the monomer combination methyl methacrylate‐styrene as an example. From the sensitivity analysis it can be concluded that the reactivity ratios are the most important parameters affecting composition drift. The effects of deviations in maximum swellabilities and monomer and polymer densities on composition drift can be neglected, while the water solubility is important only in those cases where the amount of monomer in the aqueous phase cannot be neglected as compared with the total monomer amount. © 1994 John Wiley & Sons, Inc.
Monodisperse polymer beads as packing material for high‐performance liquid chromotography: Effect of divinylbenzene content on the porous and chromatographic properties of poly(styrene‐co‐divinylbenzene) beads prepared in presence of linear polystyrene as a porogen
Authors: Galia Marina , Svec Frantisek , Frechet Jean M. J. 
Published: April 2003

AbstractThe effect of concentration of divinylbenzene on pore size distribution and surface areas of micropores, mesopores, and macropores in uniformly sized porous poly(styrene‐co‐divinylbenzene) beads prepared in the presence of linear polystyrene as a component of the porogenic mixture has been studied. While the total specific surface area was clearly determined by the content of divinylbenzene, the sum of pore volumes for mesopores and macropores as well as their size distribution does not change within a broad range of DVB concentrations. Consequently, the size exclusion chromatography calibration curves are almost identical for all the beads prepared with different percentages of crosslinking monomer. However, the more crosslinked beads have better mechanical and hydrodynamic properties. © 1994 John Wiley & Sons, Inc.
NMR investigations of the possible cross reactions between cyanate and epoxy resins
Authors: Fyee C. A. , Niu J. , Retting S. J. , Wang D. W. , Poliks M. D. 
Published: April 2003

AbstractThe possible cross reactions indicated by solid‐state NMR between cyanate functionalized resin and epoxy functionalized resin have been investigated by using both natural abundance and labeled monofunctional model compounds. These soluble products were isolated and purified by silica gel adsorption chromatography and gel permeation chromatography. They were fully characterized by high resolution 1H‐, 13C‐, 15N‐NMR spectroscopy and by mass spectrometry. The major cross‐reaction product is a racemic mixture of enantiomers, which contain an oxazolidinone ring formed by one cyanate molecule and two epoxy molecules. However, epoxy consumption lags cyanate consumption in the overall reaction as triazine formation from the cyanate is much faster than the two competing reactions, the cross reaction between cyanate and epoxy, and the self‐polymerization of epoxy, under the conditions investigated. The cross reaction between cyanate and epoxy is limited. Approximately 12% of cross reaction between cyanate and epoxy was found in the overall reaction. In addition to the cross reactions of epoxy and cyanate, the reactions of epoxy and the carbamate, which is the major side product for the curing reaction of cyanate resin in solution, have also been investigated, and the mechanism of these reactions discussed. From the reactions of epoxy and carbamate, several products related to cross reaction between epoxy and cyanate have been isolated and identified. It is suggested that the reaction of epoxy and carbamate is one of the pathways in the overall cross reaction between epoxy and cranate resins. Finally, the mechanism of the overall cross‐curing reaction between the diepoxy and dicyanate mixed resins is discussed. © 1994 John Wiley & Sons, Inc.
Elucidation of mechanism for living radical polymerization of styrene with N,N‐diethyldithiocarbamate derivatives as iniferters by the use of spin trapping technique
Authors: Doi Toru , Matsumoto Akikazu , Otsu Takayuki 
Published: April 2003

AbstractThe photodissociation of several N,N‐diethyldithiocarbamate derivatives (RDC), i.e., benzyl, 1‐phenylethyl, 2‐phenylethyl, n‐butyl, sec‐, and tert‐butyl N,N‐diethyldithiocarbamates, was investigated by the spin trapping technique to elucidate the polymerization mechanism of styrene (St) with RDC as iniferters. The scission of RDC occured at two different CS bonds depending on the structure of the alkyl groups of RDC and the cleavage manner was dominated by both resonance and steric effects. It has been confirmed that RDC generating an N,N‐diethyldithiocarbamyl radical acts as an effective iniferter and induces the living radical polymerization of St in homogeneous system. The polymerizations of St with tetraethylthiuram disulfide and p‐xylylene bis(N,N‐diethyldithiocarbamate) were also discussed on the basis of the results of the spin trapping for RDC as the model compounds of the poly(St) chain ends. © 1994 John Wiley & Sons, Inc.
Determining the chromophore in the amylopectin–iodine complex by theoretical and experimental studies
Authors: Davis Heather , Khan Arshad 
Published: April 2003

AbstractA partial hydrolysis of amylose followed by the addition of iodine provides a spectrum almost identical to that of the amylopectin–iodine (API) complex suggesting the involvement of smaller “amylose‐like” units in the API complex. Our theoretical studies on different polyiodine and polyiodide species suggest that a nearly linear I4 unit stabilized within the cavity of a small “amylose‐like” helix is responsible for the characteristic API spectrum. Since there are 2.75 anhydroglucose residues (AGU) for every iodine atom in the amylose–iodine (AI) complex and a structural similarity exists between the API and the AI (amylose–iodine) complexes, we identify (C6H10O5)11I4 to be the chromophore in the API complex. © 1994 John Wiley & Sons, Inc.
Cationic ring‐opening polymerization of bicyclic amide acetals
Authors: Lu Caixia , Odian George 
Published: April 2003

AbstractVarious bicyclic amide acetals were synthesized from the cycloaddition reactions of 2‐substituted‐2‐oxazolines with styrene oxide. Ring‐opening polymerization of the bicyclic amide acetals occurred upon heating in the presence of methyl tosylate. Characterization of the bicyclic amide acetals and their polymers was accomplished by NMR and elemental analysis. Vapor pressure osmometry showed the highest polymer molecular weight was only 2,400. The mechanisms for cycloaddition and polymerization are discussed. © 1994 John Wiley & Sons, Inc.
Multimonomer partitioning in latex systems with moderately water‐soluble monomers
Authors: Schoonbrood H. A. S. , Van Den Boom M. A. T. , German A. L. , Hutovic J. 
Published: April 2003

AbstractSimple equations describing monomer partitioning in latices during intervals 2 and 3 in emulsion polymerization with any number of low to moderately water soluble monomers were derived from the extended Morton equation by making various assumptions. It appears that it is mainly the combinatorial entropy of mixing that governs the partitioning behavior, and that other contributions to the free energy of the monomers in the polymer particles are marginal. Experimental results with styrene, methyl methacrylate, and methyl acrylate confirm the validity of the assumptions. In interval 3 of emulsion polymerization the sum of all contributions to the free energy of the monomers in the particles other than the combinatorial entropy of mixing can be taken as a constant that is dependent only on the monomer composition in the particles and independent of the degree of swelling of the particles. The only parameters one needs to know to calculate the monomer concentrations in all phases with help of the derived equations, are the saturation concentrations of each monomer in the polymer particles, and the saturation concentrations of each monomer in the aqueous phase. © 1994 John Wiley & Sons, Inc.
Photografting of vinyl polymers onto ultrafine inorganic particles: Photopolymerization of vinyl monomers initiated by AZO groups introduced onto these surfaces
Authors: Tsubokawa Norio , Shirai Yukio , Tsuchida Hideyo , Handa Satoshi 
Published: April 2003

AbstractThe photografting of polymers onto ultrafine inorganic particles, such as silica and titanium oxide, initiated by azo groups introduced onto these surfaces was investigated. The introduction of azo groups onto the particles was achieved by the reaction of 4,4′‐azobis(4‐cyanopentanoic acid) with surface isocyanate groups, which were introduced by the treatment with tolylene 2,4‐diisocyanate. It was found that the photopolymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and N‐vinylcarbazole, is initiated by ultrafine particles having azo groups. The corresponding polymers were effectively grafted onto these surfaces through the propagation of the polymer from the surface radicals formed by the photodecomposition of the azo groups: e.g., the percentage of grafting of PMMA and polystyrene onto silica was reached to 112 and 176%, respectively. The percentage of grafting onto silica in the graft polymerization initiated by photodecomposition of surface azo groups was much larger than that initiated by thermal decomposition. Polymer‐grafted ultrafine particles thus obtained gave a stable colloidal dispersion in good solvents for the grafted chain. © 1994 John Wiley & Sons, Inc.
Synthesis of soluble, thermosetting polymides derived from 1,4‐phenylenebis(phenylmaleic anhydride) and aromatic diamines
Authors: Moy T. M. , Konas M. , McGrath J. E. , Fields E. K. 
Published: April 2003

AbstractThe dianhydride monomer 1,4‐phenylenebis(phenylmaleic anhydride) was polymerized with various aromatic diamines in a one‐step solution polymerization to afford high molecular weight, soluble polyimides containing backbone phenylmaleimide structures. The polymides were soluble in amide solvents, chlorinated hydrocarbons, and tetrahydrofuran at 25°C at a concentration of 15% (w/v), displayed molecular weight distributions (Mw/Mn) of 2.0–2.2 as determined by absolute GPC and showed Tg values of 240°C and above as measured by differential scanning calorimetry. In addition, polyimide thermosets were prepared from these materials by thermal cure at 350–360°C. The crosslinked polyimides displayed Tgs 20–25°C higher than their soluble precursors, and chloroform extraction indicated gel fractions ranging from 74–100% after cure. © 1994 John Wiley & Sons, Inc.
Heat‐Resistant thermosetting polyamide and polymides with styrlpyridine segments derived from 2,2′‐(1,4‐phenylenedivinylene) bisaminoquinoline
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractThe nitration of quinaldine by fuming nitric and sulfuric acid afforded nitroquinaldine. It was condensed with a half molar amount of 1,4‐benzenedicarbaldehyde in the presence of acetic anhydride to yield 2,2′‐(1,4‐phenylenedivinylene) bisnitroquinoline. The latter was catalytically hydrogenated to the corresponding diamine, PBAQ. The new polyamide and polymides bearing styrylpyridine segments were prepared utilizing PBAQ as starting material. In addition, a model diamide and diimide were synthesized and characterized IR and 1H‐NMR spectroscopy. Inherent viscosities of polymers ranged from 0.31 to 0.60 dl/g. Certain polymer precursors such as a bismaleimide and bisnadimide were synthesized from the reactions of PBAQ with maleic and nadic anhydride, respectively. Their curing behavior was investigated by DTA. Curing of polyamide, polyimides, and polymer precursors at 240°C for 15 h yielded crosslinked polymers. They were stable up to 329–310°C in N2 or air and afforded a char yield of 67–62% in N2 at 800°C. © 1994 John Wiley & Sons, Inc.
A highly conductive and crystalline graphite‐like polymer from 2,4‐hexadiyn‐1,6‐diol
Authors: Lee Heung Jae , Shim Sang Chul 
Published: April 2003

AbstractPoly‐(2,4‐hexadiyn‐1,6‐diol) (PHDO), prepared by NbCl5/(n‐Bu)4Sn catalyzed metathesis of HDO, was pyrolyzed at various temperatures and electrical and structural properties of resulting polymers were investigated by FT‐IR, Laser Raman, CP/MAS 13C‐NMR and X‐ray diffraction methods. The polymer obtained by pyrolysis of PHDO at 800°C showed a conductivity of about 10 S/cm at room temperature. The structure of the polymer seems to be a graphite‐like crystal consisting of condensed aromatic layers. © 1994 John Wiley & Sons, Inc.
Hydroquinone oxidation catalyzed by pyridine–Cu(II) complexes attached to polyorganosiloxane. II. Elucidation of factors related to catalytic activity
Authors: Nemoto Nobukatsu , Ishii Hiroji , Ihara Manabu , Takamiya Nobuo , Ikeda Koji 
Published: April 2003

AbstractThe oxidation of hydroquinone catalyzed by pyridine‐Cu(II) complexes attached to polyorganosiloxane was investigated in the mixed solvent of methanol/water (vol. ratio 2/1). The catalytic oxidation followed Michaelis‐Menten‐like kinetics. The large k2 term related to a turnover number indicated that the present polymeric catalysts have a remarkable effect on the activation process. The methylene number between the side‐chain acid amido and pyridyl groups of the polymeric ligand was shown to be closely related to the appearance of hydrophobic effects in both the substrate‐binding and the activation processes as deduced from the Michaelis constant and the thermodynamic and activation parameters. The binding parameters for 4‐methoxyphenol with pyridyl‐functionalized polyorganosiloxanes supported that the flexible backbone is also effective in the oxidation of hydroquinone. The Cu(II) complexes with pyridyl‐functionalized polyorganosiloxane would have the structures distorted from square planar formation, which would promote the reduction of Cu(II) to Cu(I), as concluded from ESR spectroscopy and electrochemical measurement. © 1994 John Wiley & Sons, Inc.
Acyclic diene metathesis (ADMET) depolymerization of functionalized furan‐based polymers
Authors: Viswanathan T. , Gomez F. , Wagener K. B. 
Published: April 2003

AbstractAcyclic dience metathesis (ADMET) depolymerization of functionalized furan‐based polymers prepared via aqueous ring‐opening polymerization of 7‐oxanobornenes has been investigated. Results indicate that while very high molecular weight poly [exo‐N‐methyl‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene‐2,3‐dicarboximide] can be depolymerized to oligomers with ease, poly [2,3‐dicarbomethoxy‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene] is more resistant to depolymerization under similar conditions. This difference may be due to differential interaction of the carbonyls in the side chains with the metal atom of the catalyst in the proposed metallacyclobutane intermediate. ADMET depolymerization of poly [2,3‐bis (trifluoromethyl)‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene] was feasible, however, the extent of depolymerization was decreased due to the use of a coordinating solvent (THF) used during the depolymerization process. © 1994 John Wiley & Sons, Inc.
A comparative study of the silent discharge treatment of saturated and unsaturated hydrocarbon polymers
Authors: Greenwood O. D. , Tasker S. , Badyal J. P. S. 
Published: April 2003

AbstractDielectric barrier air discharge treatment of polyethylene, polypropylene, polyisobutylene, polystyrene, and polyisoprene substrates has been characterized by x‐ray photoelectron spectroscopy (XPS). The relative reactivities of these polymers towards silent discharge oxidation are rationalized in terms of ozone molecules interacting with an excited surface. © 1994 John Wiley & Sons, Inc.
Efficiency of radiation‐induced main‐chain scission of poly (methyl methacrylate) depends on the irradiation temperature because of coexisting monomer
Authors: Ichikawa Tsuneki , Oyama Ken‐ichi , Kondoh Tatsu , Yoshida Hiroshi 
Published: April 2003

AbstractEffect of irradiation temperature on the main‐chain scission of poly (methyl methacrylate) (PMMA) caused by γ‐irradiation was studied by means of gel permeation chromatography and ESR spectroscopy. Although no temperature dependency was observed on the scission efficiency for purified PMMA, the efficiency for crude or monomer‐doped purified PMMA was decreased by decreasing the temperature below ca. 200 K. Above 200 K the efficiency was constant and did not depend on the purity of PMMA. ESR study of the irradiated PMMA revealed that the suppression of the scission below 200 K is induced by the addition of methyl methacrylate monomer to primary radical species, which otherwise cause the main‐chain scission by warming the polymer above 200 K. The primary radical generated above 200 K immediately converts to the scission‐type  CH2  Ċ(CH3) COOCH3 radical through the β‐scission of the polymer main chain, so that the efficiency of the scission does not depend on both the impurity and the irradiation temperature. © 1994 John Wiley & Sons, Inc.
Synthesis of poly(biphenylene ketone)s via palladium catalyzed cross‐coupling reactions with ketone diacetals
Authors: Bochmann Manfred , Lu Jianjun 
Published: April 2003

AbstractDibromobenzophenone diacetals (BrC6H4)2C(OR)2 undergo cross‐coupling reactions with (Bu3SnC6H4)2O in the presence of palladium catalysts to give poly (diacetal ether)s whose molecular weights reflect the solubility changes of the growing polymer chains as a function of the diacetal precursors, R = Me < 1/2 CH2CH2 < 1/2 CH2CHMe and are significantly higher than those of polymers derived from dibromobenzophenone. New di‐zinc reagents based on diacetal derivatives were synthesized and used as organometallic coupling reagents with a range of dibromoarenes, resulting in a series of previously inaccessible poly (biphenylene ketone)s and poly (biphenylene ketone sulfone)s. While poly (biphenylene ether ketone)s are insoluble, poly (biphenylene ketone)s readily dissolve in concentrated sulfuric acid. The effects of reaction parameters on the molecular weight of poly (biphenylene ketone) were determined. © 1994 John Wiley & Sons, Inc.
Annealing effects on the thermal properties of liquid crystalline polyurethanes
Authors: Szczepaniak Barbara , Frisch Kurt C. , Penczek Piotr , Rudnik Ewa 
Published: April 2003

AbstractThis work is a continuation of our earlier investigations of liquid crystalline polyurethanes prepared from 4,4′‐bis(2‐hydroxyethoxy) biphenyl (BHBP), 2,4‐tolylene diisocyanate (TDI), and poly (oxytetramethylene) diols (PTMO). The annealing effects on the thermal properties of the investigation polyurethanes are presented for three samples with the same BHBP content, different flexible spacer length, and different molecular weight of the polyurethanes. The annealed polyurethanes were investigated by means of DSC, and polarizing microscopy. The results of the thermal analysis show that the temperatures of phase transitions depend on the annealing temperature and time. These dependences are different for different molecular weights. © 1994 John Wiley & Sons, Inc.
Thermodynamic characterization of interpenetrating polymer networks of poly (carbonate‐urethane) and poly (methyl methacrylate)
Authors: Privalko V. P. , Azarenkov V. P. , Baibak A. V. , Korskanov V. V. , Frisch H. L. , Zhou P. 
Published: April 2003

AbstractCrosslinked poly (methyl methacrylate) and poly (carbonate‐urethane) as well as full interpenetrating network on their base (IPN) were characterized by precise heat capacity measurements in the temperature interval 1.2–150 K. As judged by the positive sign of the excess Gibbs free energy in the whole temperature interval above 30 K, the apparently single‐phase state of IPN is thermodynamically unstable; however, its kinetic stability is ensured by permanent chamical crosslinks prohibiting the incipient phase separation. © 1994 John Wiley & Sons, Inc.
Reactivity and catalytic activity of cationic lonomers for the nucleophilic substitution reactions
Authors: Ohtani Noritaka , Nakaya Makoto , Shirahata Kenji , Yamashita Tsuyoshi 
Published: April 2003

AbstractPolystyrene‐based crosslinked cationic ionomers containing ammonium or phosphonium chlorides (AxRCI and PxBuCI) were reacted with decyl methanesulfonate. The kinetic data were correlated with the swelling behavior of the ionomers and the solution viscosity of the corresponding linear ionomers. The reactivity of the ionomers was independent of the particle size of the ionomer beads, indicating no diffusion control of the reaction. The solvent and the ion content of the ionomers greatly affect the reactivity. In nonpolar solvents with a low acceptor number, AN, such as toluene, the aggregation of ionic groups with an increasing ion content reduces the reactivity. A solvent with a high value of AN, such as chloroform, led a very low reactivity independent of the ion content. Aprotic polar solvent, such as acetonitrila, promoted the dissociation of the ionic groups and furnished a relatively high reactivity independent of the ion content. Several catalytic substitution reactions were carried out under liquid‐solid‐solid triphase conditions. The kinetic results were accounted for in terms of slow nucleophile transport and fast chemical reaction within the ionomer particles. © 1994 John Wiley & Sons, Inc.
Acid catalyzed fullerenation of carbazole polymer
Authors: Thomas Rhys N. 
Published: April 2003

AbstractA new homogeneous fullerenated carbazole polymer has been synthesized, revealing a new substitution pattern for carbazole and a new photodecomposition‐resistant substitution pattern for fullerenes. The synthetic method may be accomplished in one pot via acid catalyzed alkylation. The new polymer has several unusual photovoltaic, charge storage, and photoconductivity capabilities. © 1994 John Wiley & Sons, Inc.