bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidations of alkenes catalyzed by a Mn(III) porphyrin and cationic polymer latexes
Authors: Zhu Weiming , Ford Warren T. 
Published: April 2003

AbstractThree types of cationic polymer latexes were prepared by emulsion copolymerization of vinylbenzyl chloride, divinylbenzene and a third monomer, vinyl octadecyl ether, styrene, or n‐decyl methacrylate, followed by quaternization with trimethylamine. The latexes had 44–71 nm diam and polydispersity indices of 1.06–1.10. Vinyl octadecyl ether did not copolymerize but hydrolyzed under the polymerization conditions to produce 1‐octadecanol, which as a coemulsifier gave highly viscous latexes. The tetraanion 5,10,15,20‐tetrakis‐(2,6‐dichloro‐3‐sulfonatophenyl) porphinatomanganese (III) chloride bound irreversibly to the cationic latexes and was an active catalyst for oxidations of alkenes by sodium hypochlorite and potassium peroxymonosulfate in the absence of added organic solvent. The porphyrin catalyst in the latexes was more active than in solution. Porphyrin catalysis gave epoxides concurrently with competing uncatalyzed hypochlorous acid oxidations to complex mixtures of allylic chlorides, allylic alcohols, α,β‐unsaturated ketones, and chlorohydrins.
The synthesis of a mesogenic poly(azine‐ether) by polyetherification via cesium diphenoxides and α,ω‐dibromoalkanes
Authors: Cimecioglu A. L. , Weiss R. A. 
Published: April 2003

AbstractThe synthesis of a poly(azine–ether) via Williamson etherification using the cesium salt of 4–hydroxyacetophenone azine and 1,10–dibromodecane was carried out in N‐methyl–2–pyrrolidone. The heterogeneous reaction proceeded readily at temperatures from ambient to 150°C. Polymers of varying molecular weight with essentially alkyl bromide end groups were produced either by changing the polymerization temperature or by using an excess of the organic substrate. The thermal stability of the polymers was molecular weight dependent and those with the highest DPn exhibited monotropic nematic mesomorphism.
A fluorine‐containing hydrophobically associating polymer. I. Synthesis and solution properties of copolymers of acrylamide and fluorine‐containing acrylates or methacrylates
Authors: Zhang Y.‐X. , Da A.‐H. , Butler G. B. , Hogen‐Esch T. E. 
Published: April 2003

AbstractFluorine‐containing hydrophobically associating polymers have been synthesized by copolymerization of acrylamide with a small amount of an acrylate or methacrylate having a fluorocarbon containing ester group. It was found that hydrophobic associations occurring between these fluorocarbon chains was stronger than the interactions of the corresponding hydrocarbon comonomers and depend on the length of the fluorocarbon chain. The rheological properties of the copolymer solutions were studied. The solutions were found to be highly pseudoplastic but the viscosity loss was completely reversible upon removal of shear. Evidence for hydrophobic association of the fluorocarbon groups was obtained by the dependence of the Brookfield viscosity on temperature, the addition of NaCl, and the addition of organic solvents, urea, and surfactants.
Perfluorinated anion exchange membranes: Preparation and preliminary tests of dialysis
Authors: Elmidaoui Azzeddine , Belcadi Said , Houdus Yves , Cohen Thierry , Gavach Claude 
Published: April 2003

AbstractUsing the preirradiation technique a kinetic study of the grafting of the 4‐vinyl pyridine (V4P) and an aliphatic ammonium monomer (ALAM) onto the copolymer film of ethylene–tetrafluoroethylene (ETFE) has been performed. The influence of dose, temperature, and concentration of monomer, reticular agent, and inhibitor were investigated. The results are discussed on the basis of the interactions between monomer diffusibility and viscosity of the medium. The characteristics of some membranes were determined. Their applicability to the recovery of acid by dialysis is demonstrated.
On the behavior of organophosphorus lactam derivatives during anionic polymerization of ε‐caprolactam
Authors: Mateva R. , Dencheva N. 
Published: April 2003

AbstractThis article deals with the anionic polymerization of ε‐caprolactam in the presence of N‐substituted phosphorus‐containing derivatives of ε‐caprolactam: diethyl‐(N‐caprolactam)‐phosphonite (PL1); diethyl‐(N‐caprolactam)‐phosphonate (PL2), and 2,5‐dichlorophenyl‐bis‐(N‐caprolactam)‐phosphinate (PL3). It has been found out that PL1 and PL3 had an accelerating effect on the anionic polymerization of ε‐caprolactam. The polymerization runs at high velocity and high degree of conversion. PL2 does not accelerate the anionic polymerization of ε‐caprolactam, but when the polymerization is activated by a strong activator of acyl lactam type, and the PL2 concentration is commensurate with that of the activator, the process runs at a slightly lower rate and at a relatively high degree of conversion. The kinetics of the anionic polymerization in the presence of the three compounds was investigated. Equations describing the effect of the reagents on the polymerization rate were suggested. The activating energy of the polymerization was found out. The different actions of PL1, PL2, and PL3 during the anionic polymerization of ε‐caprolactam were explained by their structural differences.
Melt‐polymerizable bisimido‐bisphthalonitriles containing silicon, fluoro, and ether groups: Synthesis, characterization, and NMR study
Authors: Kumar Devendra , Razdan Uday , Gupta Alka D. 
Published: April 2003

AbstractVarious melt‐polymerizable bisimido‐bisphthalonitrile polymer precursors were synthesized by the reaction of 4‐aminophthalonitrile (4‐APN) with bis(3,4‐dicarboxyphenyl) dimethylsilane dianhydride (SIDA), 4,4′‐hexafluoroisopropylidene diphthalic anhydride (6FDA), bis(3,4‐dicarboxyphenyl)ether dianhydride (ODPA), and 3,3′, 4,4′‐tetracarboxylichenzophen+ne dianhydride (BTDA) in an aprotic solvent. The synthesized monomers showed crystalline melting at 269 and 271°C. Elemental analysis, differential thermal analysis (DTA), infrared (IR), nuclear magnetic resonance (1H‐NMR) and mass spectral studies were carried out to characterize the synthesized monomers. Thermogravimetric analysis (TGA) of the synthesized monomers showed their thermal stability at 410–400°C. A detailed study and NMR investigation of the first step of condensation reaction was carried out and indicated the formation of a transient charge transfer complex. Thermal cyclization of the formed intermediate, however, gave the required monomers. A preliminary study demonstrated that melt‐polymerization of the synthesized monomers gave thermallystable, tough polymers.
Preparation of poly(2,4‐dichloro‐6‐vinyl‐1,3,5‐triazine‐co‐styrene)s as polymer supports containing two replaceable groups in monomer unit
Authors: Kondo Shuji , Yamamoto Takashi , Mase Masahito , Kunisada Hideo , Yuki Yasuo 
Published: April 2003

AbstractPoly(2,4‐dichloro‐6‐vinyl‐1,3,5‐triazine‐co‐styrene)s were prepared by the reaction of poly(2,4‐diamino‐6‐vinyl‐1,3,5‐triazine‐co‐styrene)s with hydrochloric acid, and followed by treatment with thionyl chloride and N,N‐dimethylformamide. The chlorine atoms in the resulted polymers were replaced readily by several nucleophiles such as amide, alkoxide, and mercaptide to afford the corresponding polymers in moderate yields. Among these, polymers containing oligo (oxyethylene) groups at both 2 and 4 positions of 1,3,5‐triazine ring worked effectively as phase transfer catalysts for the reaction of n‐octyl bromide with alkali metal thiocyanates in toluene–water systems. However, polystyrenes containing only one oligo (oxyethylene) group in monomer unit scarcely exhibited the activity under these conditions although the degree of loading of the functional group was almost the same. The activity depended on the number of oxyethylene units, and the selectivity to alkali metal ions was also observed. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of graft copolymers of methacrylonitrile/methacrylate mixtures onto amylomaize by the ceric ion method
Authors: Vázquez B. , Goñi I. , Gurruchaga M. , Valero M. , Guzmán G. Martín 
Published: April 2003

AbstractGraft polymerizations of mixtures of methacrylonitrile with n‐alkyl methacrylales onto amylomaize were carried out. The graft copolymers were characterized by both IR and 13C‐NMR spectroscopies. The influence of the monomer feed on the grafting parameters has been studied. The variation of these parameters with the mole fraction of methacrylate in the feed for the first three systems studied, MAN/MMA, MAN/EMA and MAN/BMA, was similar: thus, percent grafting (%G, percent weight of grafted polymer with respect to grafted amylomaize), percent grafted amylomaize (%GA, percent weight of grafted amylomaize with respect to initial amylomaize), percent grafting conversion (%Cg, percent weight of grafted polymer with respect to initial monomer), and percent total conversion (%Ct, percent weight of total acrylic polymer with respect to initial monomer) were increased, but percent grafting efficiency (%GE, percent weight of graft copolymer with respect to total polymer) decreased. The system MAN/HMA presented values of grafting parameters lower than those of the previous systems. The optimum values were obtained at 0.6 HMA mole fraction in the monomer feed. When the number of carbon atoms of the n‐alkyl group rises from 1 to 4, the increase of the n‐alkyl group length gives rise to increases of the %G %Cg and %Ct values and decreases of the %GE and %GA values. For the largest methacrylate, the grafting reaction appears to be controlled by the lesser accessibility of the monomer to the active sites of the carbohydrate. © 1992 John Wiley & Sons, Inc.
Chemical reactions and reactivity of primary, secondary, and tertiary diamines with acid functionalized polymers
Authors: Song Zhiqiang , Baker Warren E. 
Published: April 2003

AbstractReactive melt processing of different types of diamines with polyethylene containing carboxylic acid groups and polystyrene containing anhydride groups was carried out. The reactivity of primary, secondary, and tertiary diamines with these acid polymers was determined using various techniques. Molecular weight increases due to crosslinking were observed through (1) changes in the torque during the reactive processing, (2) decrease in melt flow indices, and (3) decrease in solubility of the reaction products. The chemical compositions of the reaction products were examined by Fourier transform infrared (FTIR) spectroscopy. Thermal analysis using differential scanning calorimetry (DSC) was carried out to determine the crystallization behavior, glass transition temperatures, and thermal stabilities of the reaction products. Results show that the primary amine is the most reactive towards carboxylic acid or anhydride groups followed by the secondary and then the tertiary amine. Anhydride groups on polymers are of higher activity towards secondary or primary amino groups than carboxylic acid groups in the nucleophilic acyl substitution reactions. Reaction products crosslinked with the primary diamine are less stable than their parent acidic polymers. On the other hand, crosslinking with the secondary or tertiary diamine gives products with higher thermal stability than the parent acidic polymers. The formation of reversible and irreversible crosslinks with different types of diamines is also reported. © 1992 John Wiley & Sons, Inc.
The kinetics of polyolefin oxidation in aqueous media
Authors: Henry Jacqueline L. , Ruaya Ascencion L. , Garton Andrew 
Published: April 2003

AbstractThe thermal oxidation, at 75–92°C, of antioxidant‐free low‐density polyethylene (LDPE) is faster in most aqueous environments than in air. The accelerative environments include water, solutions of sodium salts, and a basic buffer. However, an acidic buffer retards oxidation. Transition metal salts are not examined here since their catalytic effect is wellknown. The acceleration is predominantly a surface phenomenon, and so is most obvious in thin polymer films. For antioxidant‐containing polyolefins, complications arise because of the possibility of extraction of stabilizers, but the trend in oxidative lifetime is similar to that of the antioxidant‐free specimens, and the antioxidants are observed to react chemically during the aging process. For example, a commercial crosslinked polyethylene (XLPE) shows a reduction in thermo‐oxidative lifetime of at least a factor of two in aqueous environments compared to air. High‐density polyethylene (HDPE) and polypropylene (PP) show similar behavior, but the magnitude of the effect of aqueous environments is less. This phenomenon is discussed in terms of nucleophilic attack by peroxy anions on hydroperoxides.
Amphiphilic gels for peptide synthesis
Authors: Arshady Reza , Fallah Fereidoon 
Published: April 2003

AbstractA new class of “amphiphilic” copoly(styrene‐acrylamide)s of potential interest for peptide synthesis is described. As examples of the new polymers, those carrying nitrophenol or piperazine functionality were used for model reactions in peptide synthesis, and were found to be substantially more efficient than similar reagents derived from polystyrene, polydimethylacrylamide or silica gel. Due to their amphiphilic structure, the new resins have general substrate compatibility and are permeated by all of the commonly used solvents, including toluene and ethyl acetate on the one hand, through dimethylformamide, to dimethylsulfoxide and water on the other. The improved performance of the new polymers is attributed to their alternating amphiphilic structure and favorable polymer–solvent–substrate interactions. © 1992 John Wiley & Sons, Inc.
Metal arene complexation of polybenzyl: Preparation and methylation
Authors: Baumberger Thomas R. , Woolsey Neil F. 
Published: April 2003

AbstractPolybenzyl has been complexed with the chromium tricarbonyl moiety by thermal treatment with chromium hexacarbonyl. The aryl rings of the product were complexed with the chromium tricarbonyl moiety to the extent of 41–63%. Assessment of the degree of complexation was satisfactorily carried out by elemental chromium analysis or by 13C‐NMR methods which agreed within 5%. GPC was less satisfactory. TGA analysis of the complexed polymers suggested the possibility of cross‐linking on thermal treatment. The benzylic groups of the polymer complex were methylated with base and methyl iodide in up to 88% of the complexed arene activated methylene groups. © 1992 John Wiley & Sons, Inc.
Poly(3,3′‐dimethoxy‐2,2′‐bithiophene): Synthesis and comparison with poly(3‐methoxythiophene)
Authors: Hasik Magdalena , Laska Jadwiga Ewa , Pron Adam , Kulszewicz‐Bajer Irena , Koziel Krzysztof , Lapkowski Mieczyslaw 
Published: April 2003

AbstractA new electroactive polymer, namely poly(3,3′‐dimethoxy‐2,2′‐bithiophene) has been prepared by voltammetric polymerization of 3,3′‐dimethoxy‐2,2′‐bithiophene. Due to a different coupling pattern (equivalent to “head‐to‐head,” and “tail‐to‐tail” coupled alkoxythiophene rings), poly(3,3′‐dimethoxy‐2,2′‐bithiophene) exhibits different voltammetric properties than the corresponding “head‐to‐tail” coupled polymer, i.e., poly(3‐methoxythiophene). Poly(3,3′‐dimethoxy‐2,2′‐bithiophene) gives very sharp oxidation and reduction peaks indicating an abrupt insulator to conductor transition. This hypothesis was corroborated by the studies of relative resistance as a function of electrode potential. Sharper and better‐defined redox peaks may indicate better stereoregularity of poly(3,3′‐dimethoxy‐2,2′‐bithiophene) as compared to poly(3‐methoxythiophene) since in this compound the 5,5′‐coupling positions are geometrically equivalent and no coupling defects are expected. © 1992 John Wiley & Sons, Inc.
The mechanical and magnetic alignment of liquid crystalline epoxy thermosets
Authors: Barclay G. G. , McNamee S. G. , Ober C. K. , Papathomas K. I. , Wang D. W. 
Published: April 2003

AbstractThe processing of a new series of liquid crystalline (LC) epoxy networks was evaluated. Above the glass transition temperature, the low crosslink density networks could be mechanically aligned. The mechanically oriented networks readily lost orientation upon heating. Highly anisotropic liquid crystalline (LC) epoxy networks were also prepared by aligning the mesophase of the prepolymer during the curing process under the influence of a magnetic field. Orientation parameters (f) of 0.13 to 0.57 were achieved by these processes as determined by x‐ray diffraction analysis. The ability of the magnetically aligned networks to retain their orientation above the glass transition temperature was determined by time‐resolved x‐ray diffraction. The stability of the alignment of these networks was found to depend on crosslink density. The effect of the anisotropy of these networks was investigated by measuring the coefficient of thermal expansion (CTE). In the aligned networks, there was a substantial reduction in CTE parallel to the direction of the applied field compared to the randomly oriented networks. © 1992 John Wiley & Sons, Inc.
New poly(amide‐imide)s syntheses. I. Soluble high‐temperature poly(amide‐imide)s derived from 2,5‐bis(4‐trimellitimidophenyl)‐3,4‐diphenylthiophene and various aromatic diamines
Authors: Yang Chin‐Ping , Yen Yung‐Yu 
Published: April 2003

AbstractNovel aromatic poly(amide‐imide)s with high inherent viscosities were prepared by direct polycondensation reaction of 2,5‐bis(4‐trimellitimidophenyl)‐3,4‐diphenylthiophene (IV) and aromatic diamines using triphenyl phosphite in the N‐methyl–2‐pyrrolidone (NMP)/pyridine solution containing dissolved CaCl2. The diimide‐diacid IV was readily obtained by the condensation reaction of 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene (III1) with trimellitic anhydride. The obtained poly(amide‐imide)s showed high thermostability. Their decomposition temperatures at 10% weight loss in nitrogen atmospheres were above 550°C and the anaerobic char yield at 800°C ranged from 48 to 68%. Almost all the poly(amide‐imide)s showed high glass transition temperatures above 300°C by differential scanning calorimetry (DSC) measurements. These polymers were readily soluble in various organic solvents and could be cast into transparent, tough, and flexible films. Their casting films showed obvious yield points in the stress‐strain curves and had strength at break up to 74.2 MPa, elongation to break up to 70.1%, and initial modulus up to 4.56 GPa. The factors affecting the reaction of diimide‐diacid IV and 4,4′‐oxydianiline in view of monomer concentration, reaction temperature, and amount of CaCl2 were also investigated. © 1992 John Wiley & Sons, Inc.
Characterization of conducting copolymers of 2,2′‐bithiophene and pyrrole by cyclic voltammetry and UV/visible spectroscopy
Authors: Peters Eric M. , Van Dyke John D. 
Published: April 2003

AbstractSeveral polymers have been prepared by electropolymerization of mixtures of pyrrole (PY) and 2,2′‐bithiophene (BT). Cyclic voltammetry on prepared polymer films shows three anodic oxidation peaks, two of which match the oxidation potentials of homopolymeric PY and BT, and a third which is intermediate. UV/visible spectroscopy displays a unique spectrum for each of the reduced and oxidized forms of these polymers. Nernstian plots from UV/visible data exhibit three well‐defined redox couples in polymer films produced at 1.3 V. Overall, the data strongly support the formation of a copolymer, consisting of three distinct oxidizable units. Two of these can be attributed to short blocks of either PY or BT, and a third to random and alternate groupings of PY and BT. The polymers produced are electrically conductive, but the conductivity drops rapidly as BT units are introduced into a homopolymer of PY. © 1992 John Wiley & Sons, Inc.
Autoxidation of 2‐mercaptoethanol catalyzed by cobalt(II) phthalocyaninetetrasulfonate on colloidal particles
Authors: Babu Sunkara Hari , Ford Warren T. 
Published: April 2003

AbstractCobalt(II) phthalocyaninetetrasulfonate (CoPcTS) is a highly active catalyst in aqueous media for the autoxidation of thiols to disulfides, and cationic polymers further enhance the activity. In this work we tested a variety of cationic polymer supports for the CoPcTS‐catalyzed autoxidation of 2‐mercaptoethanol in aqueous dispersions at 25°C. The order of activities is cationic polyelectrolytes > cationic polymer colloids > cationic colloidal silica > aqueous solution > ion exchange resins. Spectroscopic studies indicate that the high activity of the polyelectrolytes correlates with their ability to aggregate the CoPcTS. © 1992 John Wiley & Sons, Inc.
Mechanism of anionic polymerization of phenylacetylene
Authors: Kobryanskii V. M. 
Published: April 2003

AbstractAnionic polymerization of phenylacetylene in the presence of butyllithium has been studied. It was shown that the process of polymerization is accompanied by the appearance and growth of the ESR signal with pronounced superfine structure. The model of polymerization was suggested according to which formation of low molecular polyphenylacetylene is caused the destruction of the active centers by means of electron transfer from the active center to the conjugated chain. This type of electron transfer may also be the fundamental reaction limiting the chain length in cationic polymerization of acetylene monomers. © 1992 John Wiley & Sons, Inc.
Optically clear simultaneous interpenetrating polymer networks based on poly(ethylene glycol) diacrylate and epoxy. I. Preparation and characterization
Authors: Lin Mu‐Shih , Jeng Kuen‐Tay 
Published: April 2003

AbstractPoly(ethylene glycol) diacrylate was synthesized from poly(ethylene glycol) of molecular weight 600 with acryloyl chloride in a molar ratio of 1:2. Poly(ethylene glycol) diacrylate (PEGDA) was then blended with diglycidyl ether of bisphenol A (DGEBA) in various ratios, followed by curing with 2,2′‐azobisisobutyronitrile (AIBN) and isophronediamine (IPDA) simultaneously. Viscosity changes before and during IPN formation were examined with a Brookfield viscometer. Formation of H‐bonding and functional group changes were investigated with FTIR. Exothermic curing thermograms were recorded with dynamic DSC. Optically clear IPNs thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and scanning electron microscopy (SEM) to check possible compatibility of the two networks. Experimental results revealed that during IPN formation hydrogen bonds between PEGDA and DGEBA and interlock of networks had profound effect on viscosity change and pot‐life. Complete compatibility of the IPNs was found as DGEBA content was higher than 50% by weight. The compatibility between PEGDA and DGEBA networks was evidenced from inner shift of a single damping peak in RDS. In the meantime, SEM micrographs confirmed the coincidence with the result of RDS © 1992 John Wiley &Sons, Inc.
N‐alkoxy‐pyridinium and N‐alkoxy‐quinolinium salts as initiators for cationic photopolymerizations
Authors: Yaḡci Y. , Kornowski A. , Schnabel W. 
Published: April 2003

AbstractThe polymerization of n‐butyl vinyl ether (BVE), cyclohexene oxide (CHO) and 3,4‐epoxycyclohexyl(methyl)‐3′,4′‐epoxycyclohexane carboxylate (EEC) was initiated upon UV irradiation (λinc > 300 nm) of dichloromethane solutions containing N‐ethoxy‐2‐methylpyridinium (V), N‐ethoxy‐4‐phenyl‐pyridinium (VI) or N‐ethoxy‐isoquinolinium hexafluorophosphate (VII). Whereas the bifunctional EEC was converted into an insoluble gel, BVE and CHO formed polymers of molar mass: Mw = 2 X 104−2 X 105 (PCHO) and Mw ≈ 2 X 104 (PBVE). Protons are formed with a rather high quantum yield [ø(H+) = 0.48 on irradiating VII in dichloromethane; titration with sodium p‐nitrophenolate] and it is, therefore, assumed that the polymerization is initiated by photochemically generated protons. © 1992 John Wiley & Sons, Inc.