bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of core‐shell latexes by redox initiation at ambient temperatures
Authors: Lee Sharon , Rudin Alfred 
Published: April 2003

AbstractCore‐shell polymer composites made by two‐stage emulsion polymerizations are useful in many applications. In systems involving a hydrophilic/hydrophobic polymer pair, a core‐shell arrangement is thermodynamically unfavorable and may be difficult to achieve. To counteract the thermodynamic forces in such a system, the mobility of the phases can be reduced to such an extent that a core‐shell morphology is achieved. This was accomplished in a PMMA/PS two‐stage system by lowering the second‐stage polymerization temperature to room temperature using a redox initiator. At this relatively low temperature, a core‐shell morphology was obtained even when the second‐stage was carried out as a batch polymerization. © 1992 John Wiley & Sons, Inc.
Synthesis and properties of segmented aromatic poly(ether sulfone)‐amide and poly(ether sulfone)‐imide copolymers
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew segmented aromatic poly(ether sulfone)‐amide and poly(ether sulfone)‐imide copolymers were synthesized by the chain extension of α,w‐diamine‐terminated poly(ether sulfone) oligomer with both aromatic dicarboxylic acid chlorides and tetracarboxylic dianhydrides, respectively. Crystallization of the poly(ether sulfone)unit was suppressed by the introduction of amide or imide linkage along the polymer backbone, giving amorphous copolymers that were +eadily soluble in various organic solvents. The copolymers had somewhat higher glass transition temperatures than the parent poly(ether sulfone). They afforded transparent and tough films by solution casting. © 1992 John Wiley & Sons, Inc.
The effect of radical trapping reagents upon formation of poly(α‐tetrahydrothiophenio para‐xylylene) polyelectrolytes by the wessling soluble precursor method
Authors: Denton Frank R. , Lahti Paul M. , Karasz Frank E. 
Published: April 2003

AbstractMolecular weights were studied by gel permeation chromatography of derivatized poly(α‐tetrahydrothiophenio para‐xylylene) chloride produced by aqueous or methanolic base‐induced polymerization of 1,4‐bis(tetrahydrothiopheniomethyl) benzene dichloride, both with and without a variety of added polymerization inhibiting agents. Efficient radical scavenging agents such as 2,2,6,6‐tetramethylpiperidinoxyl and hydrogen atom donor 2,4,6‐tri‐tert‐butylaniline reduced the degree of polymerization of the reactive α‐(tetrahydrothiophenium chloride)‐para‐xylylene intermediate produced in this chemistry, and in some cases completely suppressed formation of high polymer. These two traps did not affect the equilibrium production of the para‐xylylene by UV‐Vis spectral analysis; hence they must affect the subsequent polymerization chain propagation steps in the mechanism. Electron spin resonance studies of polymerization in the presence of 0.00025 equiv of TEMPO showed disappearance of the spin label, a result consistent with a radical scavenging process. The results suggest that production of high molecular weight poly(α‐tetrahydrothiophenio para‐xylylene) chloride proceeds through a radical chain propagation sequence. © 1992 John Wiley & Sons, Inc.
Graft polymerization of methyl methacrylate from silica initiated by peroxide groups introduced onto the surface
Authors: Tsubokawa Norio , Ishida Hisanori 
Published: April 2003

AbstractThe surface grafting onto ultrafine silica by the radical polymerization of methyl methacrylate (MMA) initiated by peroxide groups introduced onto the surface was investigated. The introduction of peroxide groups onto the silica surface was achieved by the reaction of hydrogen peroxide with chlorosilyl groups, which were introduced by the treatment of silica with thionyl chloride. The content of diisopropylbenzene peroxide and tert‐butyl peroxide groups introduced onto the silica according to the above method was determined to be 0.11 and 0.08 mmol/g, respectively. It was found that the polymerization of MMA is initiated by silica having these peroxide groups. In the polymerization, polyMMA was grafted onto silica surface: the percentage of grafting reached about 70%. Therefore, it was concluded that the polymerization of MMA is initiated by surface radicals formed by the decomposition of peroxide groups on silica and polyMMA is grafted through the propagation from the surface. During the polymerization, ungrafted polyMMA was also formed because of the formation of initiator fragments by the decomposition of peroxide groups: the grafting efficiency of the graft polymerization was 30–40%. PolyMMA‐grafted silica produced a stable colloidal dispersion in organic solvents for polyMMA. © 1992 John Wiley & Sons, Inc.
Formose reaction by polymer‐supported thiazolium salts
Authors: Yamashita K. , Wakao N. , Nango M. , Tsuda K. 
Published: April 2003

AbstractThiazolium salt polymers synthesized by quaternization of 4‐(4′‐vinylphenyl)thiazole (VPT) polymers with methyl iodide had a highly catalytic activity for “the formose reaction.” Their catalytic activities were comparable to that of a low molecular weight analog, 3‐methyl‐4‐phenylthiazolium iodide (MPTI). In the reaction catalyzed by the polymer catalyst, a main product, dihydroxyacetone (DHA), was detected by gas‐liquid chromatography. The polymer catalysts were easily recovered from the reaction mixture and reused with a sustained catalytic activity. © 1992 John Wiley & Sons, Inc.
15N‐, 1H‐, and 13C‐NMR chemical shifts and electronic properties of aromatic diamines and dianhydrides
Authors: Ando Shinji , Matsuura Tohru , Sasaki Shigekuni 
Published: April 2003

AbstractWe measured the 15N‐, 1H‐, and 13C‐NMR chemical shifts for a series of aromatic diamines and aromatic tetracarboxylic dianhydrides dissolved in DMSO‐d6, and discuss the relationships between these chemical shifts and the rate constants of acylation (k) as well as such electronic‐property‐related parameters such as ionization potential (IP), electronic affinity (EA), and the energy ε of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The 15N chemical shifts of the amino group of diamines (δN) depend monotonically on the logarithm of k (log k) and on IP. We inferred the reactivities of diamines whose acylation rates have not been measured from their δN, and we propose an arrangement of diamines in the order of their reactivity. The 1H chemical shift of amino hydrogens (δH) and the 13C chemical shift of carbons bonded to nitrogen (δC) are roughly proportional to δN, but these shifts are not as closely correlated with log k and IP. Although the 13C chemical shifts of the carbonyl carbon of dianhydrides (δC,) varies much less than the δC and δN of diamines, δC, can be an index of acylation reactivity for dianhydrides because it is closely correlated with εLUMO. These facts indicate that the chemical shifts of diamines and dianhydrides are displaced according to their electron‐donor and electron‐acceptor properties, and that these chemical shifts can be used as indices of the electronic properties of monomers. Changes in reactivity caused by the introduction of trifluoromethyl groups into diamines and dianhydrides are inferred from the displacements of δN and δC © 1992 John Wiley & Sons, Inc.
Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. VII. Preparation and properties of polyzirconoxanes as a precursor for zirconia fibers by the hydrolysis of bis (ethyl acetoacetato) zirconium dialkoxide
Authors: Gunji Takahiro , Goto Hitoshi , Kimata Yoshinori , Nagao Yukinori , Misono Takahisa , Abe Yoshimoto 
Published: April 2003

AbstractAcid‐catalyzed hydolysis of bis(ethyl acetoacetato) zirconium dialkoxide in methanol or THF was investigated. The hydrolysis of the chelates in the molar ratios of H2O/ chelate = 1.0–2.0 and HCl/chelate = 0.1–0.2 provided concentrated solutions (ca. 83 wt %) of polyzirconoxanes (PZO) which showed excellent spinnability and stability to self‐condensation. Continuous gel fibers were prepared by dry spinning the solutions. Polyzirconoxanes were isolated as powders when the concentrated solution was precipitated with hexane. Silylation allowed the investigation of the structure of PZO. It was confirmed to be the polymers of a low degree of polymerization with the ligand and hydroxy group as pendants. © 1992 John Wiley & Sons, Inc.
Syntheses and characterizations of allyl cellulose and glycidyl cellulose
Authors: Lin Mu‐Shih , Huang Chung‐Song 
Published: April 2003

AbstractAllyl cellulose was synthesized by reacting cellulose with allyl bromide in homogeneous LiCl/DMAc solution containing NaOH powder. The degree of substitution (DS) per anhydroglucose (AHG) unit was determined by titrating the allyl cellulose with bromine in chloroform solution, and an allyl DS of 2.80 was found. Glycidyl cellulose was then prepared by reacting this allyl cellulose with peracetic acid in methylene chloride at ambient temperature for 6 days. The measured reaction rate constant was 1.33 × 10−3 min−1. The glycidyl cellulose thus obtained with a glycidyl DS of 2.58 was determined by titrating the product with perchloric acid in conjunction with tetrabutylammonium iodide. The 2.58 of glycidyl DS was also confirmed by 1H‐NMR integration. Both allyl cellulose and glycidyl cellulose were analyzed and characterized with FTIR, 1H‐NMR, 13C‐NMR, TGA, and GPC. During epoxidation of allyl cellulose, possible side reaction leading to ester formation was evidenced from the continuous increase of vCO at 1735 cm−1 in FTIR analyses. In addition, a bimodal distribution and a decreased molecular weight for glycidyl cellulose were found from GPC data, which might suggest a possible chain scission at the cellulosic ether linkage. © 1992 John Wiley & Sons, Inc.
Free‐radical homopolymerization and copolymerization of ethyl α‐hydroxymethylacrylate in tetrahydrofuran
Authors: Fernández‐Monreal M. C. , Cuervo R. , Madruga E. L. 
Published: April 2003

AbstractEthyl α‐hydroxymethylacrylate (EHMA) was polymerized in a 3 mol/L tetrahydrofuran solution at 50°C, using 2–2' azobisisobutyronitrile as initiator. The kinetic behavior indicates a higher polymerization rate for EHMA than for methyl methacrylate (MMA). Copolymerization reaction between MMA and EHMA, under the same experimental conditions, was carried out and values of rMMA = 1.264 and rEHMA = 1.285 were found for the reactivity ratios. The comparison of triad sequences as determined from Bernouillian statistic to those calculated from the experimental spliting of O‐methyl and α‐methyl 1H‐NMR signals of the copolymers confirm the obtained results. © 1992 John Wiley & Sons, Inc.
Thermolysis of polyarylate model compounds
Authors: Leblanc Jean‐Pierre , Huang Jianing , Padias Anne Buyle , Hall H. K. 
Published: April 2003

AbstractThermal decompositions and pyrolyses of p‐tert‐butylphenol, 4,4'‐isopropylidenediphenol (BPA), and their acetate and pivalate esters as model compounds for the polyarylate synthesis have been performed. Acetate esters decompose chiefly into phenols and ketene. Pivalate esters, unable to form ketene, are more stable. Acetates and pivalates undergo homolytic cleavage both at ester and alkyl groups. Styrene derivatives stabilize acetate esters, considerably reducing the amount of phenol formed during the decomposition. No intensely colored aromatic compounds were found, although this result is probably an artifact of the methods used. From this study we conclude that ketene is one source of colored materials during polyarylate synthesis. © 1992 John Wiley & Sons, Inc.
Photocrosslinking of copolymers of vinyloxyethyl methacrylate–styrene initiated by sulfonium salts. I. Transient species formed on photolysis of sulfonium salt
Authors: Lin Mao‐Peng , Kim Haeng‐Boo , Ikeda Tomiki , Endo Takeshi 
Published: April 2003

AbstractBenzyl cation was detected by transient absorption spectroscopy with a spectroscopic multichannel analyzer on pulse excitation (fourth harmonic of Nd:YAG laser, 266 nm; 10 ns fwhm) of benzyl(4‐hydroxyphenyl) methylsulfonium hexafluoroantimonate(BSS) in 1,2‐dichloroethane (EDC). The benzyl cation was long‐lived (lifetime, 59 ms) at room temperature and quenched by a vinyl ether compound. The formation of the benzyl cation as active species on photolysis of BSS is in contrast to the formation of Brønsted acids in other sulfonium salts so far reported. © 1992 John Wiley & Sons, Inc.
Aromatic polyisophthalamides with N‐benzylidene pendant groups
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractA new series of modified polyisophthalamides bearing N‐benzylidene pendant groups was prepared by reacting various aromatic diamines with 5‐(N‐benzylidene) isophthalic acid. The latter was synthesized from the reaction of 5‐aminoisophthalic acid with benzaldehyde and characterized by IR and 1H‐NMR spectroscopy. Triphenyl phosphite and pyridine was used as condensing agents for preparing polyamides. In addition, the corresponding unsubstituted polyisophthalamides were prepared under identical experimental conditions for comparative purposes. Characterization of modified polyamides was accomplished by IR as well as inherent viscosity measurements. They showed a slightly lower solubility in various media than the corresponding unsubstituted polyamides. The cured modified polyamides displayed significantly higher thermal stability than the cured unsubstituted polyamides. They were stable up to 355–308°C in N2 or air and afforded anaerobic char yield of 66–61% at 800°C. © 1992 John Wiley & Sons, Inc.
Photoinitiation of acrylamide polymerization using the dianions of rhodizonic and croconic acids
Authors: Zhao B. , Back M. H. 
Published: April 2003

AbstractPolymerization of acrylamide has been initiated by the photochemical reactions of the dianions of croconic acid (1,2‐dihydroxycyclopentenetrione) and rhodizonic acid (1,2‐dihydroxycyclohexenetetrone) in the presence of various acceptor molecules. Photoinitiation was most efficient with croconic acid where a maximum quantum yield for polymerization of 2 x 103 was observed in neutral solution. Kinetic studies using this initiator showed that the rate of polymerization was a linear function of the concentration of monomer and proportional to the square root of the light absorbed by the croconate dianion. The rate of initiation of radicals calculated from the rate of polymerization was compared with the rate of production of radicals calculated from previous studies of the photochemistry of the croconate dianion and the mechanism of photoinitiation is discussed. © 1992 John Wiley & Sons, Inc.
Substrate temperature effects on film chemistry in plasma deposition of organics. III. Analysis by static secondary ion mass spectrometry
Authors: López Gabriel P. , Chilkoti Ashutosh , Briggs David , Ratner Buddy D. 
Published: April 2003

AbstractStatic secondary ion mass spectrometry (SIMS) was used to examine the effect of reducing the substrate temperature during the radio frequency plasma deposition of organic films. Studies of two polymerizable plasma precursors (2‐hydroxyethyl methacrylate and acrylic acid) and one nonpolymerizable precursor (acetone) deposited without substrate cooling and with liquid nitrogen cooling are presented. Acetone deposited with methanol/dry ice cooling was also investigated. Spectra of polymerizable precursors were analyzed by comparison to spectra for the corresponding conventionally‐polymerized polymer films [i.e., poly(hydroxyethyl methacrylate) and poly(acrylic acid)]. Acetone spectra were interpreted by reference to SIMS analysis of plasma‐deposited films prepared from isotopically‐labelled acetone and to reference homopolymers. Comparison of the SIMS spectra of films deposited at different substrate temperatures indicates that a reduction in substrate temperature generally results in higher intensity of peaks characteristic of oxygenated ion structures. SIMS also suggests that the reduction of substrate temperature results in less polymer unsaturation and fewer structures which form by hydrogen redistribution during the deposition process. These results support the hypothesis that deposition at low substrate temperatures leads to an increase in the proportion of precursor incorporated into the film without substantial fragmentation. Corroborative results from high resolution x‐ray photoelectron spectroscopy (XPS) and assays for precursor functional groups by chemical derivatization reactions in conjunction with XPS are also presented. © 1992 John Wiley & Sons, Inc.
Model filled polymers. XI. Synthesis of monodisperse crosslinked polymethacrylonitrile beads
Authors: Zou Dezhong , Aklonis J. J. , Salovey R. 
Published: April 2003

AbstractMonodisperse polymethacrylonitrile beads of varied size and crosslink density are prepared by emulsion copolymerization of methacrylonitrile and allylmethacrylate in the absence of emulsifier. The particle size is very sensitive to polymerization temperature and initiator concentration. Because of a nitrile group effect, the maximum conversion varies with reaction conditions. The highest conversion obtained was 82%. © 1992 John Wiley & Sons, Inc.
Photochemistry of macromolecular metal complexes. III. Synthesis, spectral and electrochemical properties of macromolecular bound protoporphyrin in aqueous solution
Authors: Narayanan V. , Natarajan P. 
Published: April 2003

AbstractThe macromolecular bound protoporphyrin IX and its metal complexes, poly‐(protoporphyrin‐co‐acrylamide), cobalt(II) [poly(protoporphyrin‐co‐acrylamide)], zinc‐(II)[poly(protoporphyrin‐co‐acrylamide)], and manganese(III) [poly(protoporphyrin‐co‐acrylamide)] chloride were synthesized. The absorption and emission spectra have been obtained for the macromolecular porphyrins. The lifetime of the excited singlet state of the protoporphyrin IX was found to decrease from 13.7 to 6.2 ns after polymerization. The cyclic voltammograms of polymeric protoporphyrin coated electrodes have been obtained. © 1992 John Wiley & Sons, Inc.
Syntheses and properties of polymers from perchloro‐p‐xylene, perclorobi‐p‐tolyl, and perchloro‐m‐xylene with Fe(CO)5 as dechlorinating agent
Authors: Fors P. , Juliá L. , Riera J. , Tura J. M. , Sauló J. 
Published: April 2003

AbstractWe describe a new method for the polymerization of perchloroaromatic compounds using Fe(CO)5 as a dechlorinating agent which allows the syntheses of perchloropoly‐1,4‐phenylene vinylene (8), perchloropoly‐4,4'‐biphenylene vinylene (9), and perchloropoly‐1,3‐phenylene vinylene (10) from perchloro‐p‐xylene (5), perchlorobi‐p‐tolyl (6), and perchloro‐m‐xylene (7), respectively. Polymer 10, a new macromolecular chlorocarbon, was characterized by elemental analysis and infrared and ultraviolet spectra. The molecular weights (MW's) of the polymers were estimated by osmometry. The XPS spectra of these polymers are discussed. Their thermal properties were studied by thermogravimetry. Electron spin resonance (ESR) studies and some preliminary conductivity measurements, made after doping the polymers with SbF5, are reported. © 1992 John Wiley & Sons, Inc.
Synthesis of poly(arylene ethyne)s via palladium‐catalyzed cross‐coupling reactions with Cu and Sn reagents
Authors: Bochmann M. , Kelly K. 
Published: April 2003

AbstractComparative studies have been carried out of the effectiveness of two organometallic coupling reagents for the synthesis of poly(alkynylarene)s via palladium catalyzed cross‐coupling reactions of dialkynes with organic dibromides. In comparison to copper reagents, monomeric difunctional trialkyltin acetylides show increased thermal stability which allows reactions to be performed at higher temperatures; they give oligomeric and polymeric materials of improved molecular weight. By contrast, the inferior solubility of copper acetylides limits chain growth, and above 140°C the Pd/Cul system is prone to homopolymerization of the dialkyne. The coupling reactions are solvent‐dependent but not strongly influenced by the nature of the palladium precursor complex or the phosphine ligand. © 1992 John Wiley & Sons, Inc.
Kinetic studies on the n‐alkyl acrylate polymerization
Authors: Subrahmanyam B. , Baruah S. D. , Rahman M. , Baruah J. N. , Dass N. N. 
Published: April 2003

AbstractKinetic studies on the polymerization of n‐butyl acrylate and n‐octadecyl acrylate in toluene at 70°C with benzoyl peroxide as initiator are reported. High monomer orders of 1.55 and 1.75 were obtained for n‐butyl and n‐octadecyl acrylates, respectively. Though the initiator order in butyl acrylate polymerization was 0.5, the octadecyl acrylate polymerization showed less than square root initiator order. The activation energy for the polymerization of both the acrylates was determined. Autoacceleration was found even at low conversions. The autoacceleration was influenced by both monomer and initiator concentration. Molecular weight data was presented in support of the gel effect. © 1992 John Wiley & Sons, Inc.
New liquid crystal polyethers and polyesters based on diphenylbutadiene mesogens
Authors: Mates T. E. , Ober C. K. 
Published: April 2003

AbstractNew liquid‐crystalline (LC) polymers and small molecules have been synthesized based on the 1,4‐diphenylbutadiene mesogen, a chromophore with χ(3) nonlinear optical properties. Polyethers were formed by phase‐transfer reaction, and polyesters were prepared by Schotten‐Bauman polymerization from these 4,4'‐bisphenolic mesogenic structures. Liquid crystallinity was examined using differential scanning calorimetry (DSC) and optical microscopy. Most of the model compounds were found to be nematic. All mesomorphic polymers were nematic and displayed LC ranges of up to 50°C as well as a wide diversity of melting points. The melting points varied with the flexible (methylene) spacer length and were strongly dependent upon the presence of substituents in the mesogenic core. Crosslinking and cis‐trans isomerization were observed under the influence of heat and ultraviolet radiation. © 1992 John Wiley & Sons, Inc.
Polyimides derived from diels‐alder polymerization of furfuryl‐substituted maleamic acids or from the reaction of bismaleamic with bisfurfurylpyromellitamic acids
Authors: Diakoumakos Constantinos D. , Mikroyannidis John A. 
Published: April 2003

AbstractCertain AB or AA and BB Diels‐Alder polymer precursors bearing maleimide and furan segments were synthesized, characterized, and polymerized. Particularly, the monomaleamic acid derived from 4,4'‐diaminodiphenylmethane, reacted with the monofurfurylpyromellitamic acid to yield a triamic acid which was cyclodehydrated to the corresponding triimide. A polyimide was obtained upon heat‐curing of triimide or the intermediate triamic acid. In addition, equimolar amounts of N,N'‐bismaleimido‐4,4'‐diphenylmethane (BMDM) and bisfurfurylpyromellitimide or their intermediate diamic acids were cured to afford a polyimide. The polymer precursors were characterized by IR and 1H‐NMR spectroscopy and their curing behavior was investigated by DTA. It was shown that the Diels‐Alder polymerization of monomers took place at lower temperature than that required for crosslinking of BMDM. The thermal stabilities of polymers were ascertained by TGA and isothermal gravimetric analysis (IGA). The synthesized Diels‐Alder polymers were remarkably more heat‐resistant than the crosslinked polymer obtained from BMDM or its intermediate bismaleamic acid. They were stable up to about 360°C in N2 or air and afforded anaerobic char yield of 58% at 800°C. © 1992 John Wiley & Sons, Inc.