bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization behaviour of 2,5‐dimethylene‐ 2,5‐dihydrofuran
Authors: Itoh Takahito , Katoh Ichiro , Satoh Toshiya , Iwatsuki Shouji 
Published: April 2003

AbstractSpontaneous homopolymerization of 2,5‐dimethylene‐2,5‐dihydrofuran (DDF) was studied. The polymerization rates in two different initial monomer concentrations of DDF were analyzed with the first‐order and second‐order kinetics, and the homopolymerization of DDF was found to obey the first‐order kinetics. The Arrhenius plot of the apparent rate constants at 30, 40, 50, and 60° gave an overall activation energy of 68.0 kJ/mol for the polymerization of DDF. From the comparison of the apparent rate constants at –78° and the time (the so‐called half‐life time) to decrease in half the monomer concentration for DDF with the corresponding values for p‐xylylene (QM), DDF was found to be a less reactive monomer than QM. The copolymerizations of DDF with vinyl monomers such as acrylonitrile (AN), α‐chloroacrylonitrile (CIAN), diethyl fumarate (DEF), and fumaronitrile (FN) were carried out in chloroform at 50° in the presence of AIBN to obtain the monomer reactivity ratios r1(DDF) = 30.0 ± 3.0 and r2 (AN) = 0 for the DDF‐AN system, r1 (DDF) = 1.55 ± 0.2 and r2(CIAN) = 0 for the DDF‐CIAN system, r1(DDF) = 3.88 ± 0.2 and r2(DEF) = 0 for the DDF‐DEF system, and r1(DDF) = 2.41 ± 0.1 and r2 (FN) = 0 for the DDF‐FN system, respectively. As the monomer reactivity ratios of r2 for all systems were zero, Q and e values of DDF were calculated from the combination of two r1 (DDF) values of any two copolymerization systems to be the 7.64 to 6.63 ×1021 range for Q and the –0.70 to –6.31 range for e, indicating that DDF is a highly conjugative and electron‐donating monomer. © 1995 John Wiley & Sons, Inc.
Synthesis and property of soluble poly(1,1′‐dialkyl‐3,3′‐ferrocenylenevinylene)s via titanium‐induced dicarbonyl‐coupling reaction of 1,1′‐dialkylferrocene‐3,3′‐dicarbaldehydes
Authors: Itoh Takahito , Saitoh Hiroki , Iwatsuki Shouji 
Published: April 2003

Abstract1,1′‐Dialkylferrocene‐3,3′‐dicarbaldehydes (1a–c) with long alkyl chains such as ethyl, hexyl, and dodecyl groups were prepared in 13–25% yield via three‐step reactions. The titanium‐induced dicarbonyl‐coupling reaction of 1a–c gave poly(1,1′‐dialkyl‐3,3′‐ferrocenylenevi‐nylene)s (2a–c) in quantitative yields, which were the molecular weights of 3000–10,000 and highly soluble in chloroform, benzene, and hexane. The electrical conductivity and the third‐order nonlinear optical susceptibility for poly(1,1′‐dihexyl‐3,3′‐ferrocenylenevinylene) (2b) were estimated to be 1 × 10−2 S/cm on doping with iodine and 1–4 × 10−12 esu at a wavelength of 1–2.4 μm, respectively. © 1995 John Wiley & Sons, Inc.
Control of surfactant level in starve‐fed emulsion polymerization. I. Sulfate‐containing oligomers: Preparation and application as surfactant in emulsion polymerization
Authors: Wang Zhiyu , Paine Anthony J. , Rudin Alfred 
Published: April 2003

AbstractIt is well known that the amount of surfactant must be carefully controlled during starve‐fed emulsion polymerization processes. Too little surfactant leads to emulsion instability and coagulation, while too much surfactant leads to secondary particle formation. Although these relationships are qualitatively understood in the art, there is little quantitative basis to guide the synthetic chemist, especially in multistep starve‐fed emulsion polymerization processes to make larger supermicron particles. We have developed a method, which will be described in a companion article, to control the surfactant level by monitoring the surface tension during polymerization. In order to quantitatively predict how much surfactant to add at any given time, one needs to know in advance the adsorption characteristics of the soap. Further complicating the matter is the formation of “in situ” or oligomeric surfactant during polymerization with aqueous initiators such as ammonium persulfate.This work demonstrates how to prepare surface‐active oligomers and how to make latex particles using them as surfactant. First, we established the mass balance for the initiator‐derived sulfate groups in seed latexes by conductometric, potentiometric, and iodometric titrations. Based on the characterization of seed latexes, a method for determining the effective sulfate concentration has been developed. When surface‐active oligomers were used as the only surfactant, we obtained a series of monodisperse, supermicron copolymer latex particles with diameters up to 3.22 μm. This is a similar result to that obtained with a commercially made anionic surfactant. © 1995 John Wiley & Sons, Inc.
Studies on the polymerization mechanism of 3‐nitratomethyl‐3′‐methyloxetane and 3‐azidomethyl‐3′‐methyloxetane and the synthesis of their respective triblock copolymers with tetrahydrofuran
Authors: Liu Ying‐Ling , Hsiue Ging‐Ho , Chiu Yie‐Shun 
Published: April 2003

AbstractNovel energetic oxetane derivatives, 3‐nitratomethyl‐3′‐methyloxetane (NMMO) and 3‐azidomethyl‐3′‐methyloxetane (AMMO), were used as monomers in a triflic anhydride [(CF3SO2)2O] initiating polymerization system. The “living cationic” characteristics of the polymerization were investigated and confirmed via a 19F NMR technique. This living polymerization system was, thus, utilized in the synthesis of well‐defined block copolymers. Novel polymers of the A—B—A— type with various molecular weights (M̄w = 14320–40660) and low polydispersity indexes (PDI = 1.11–1.29) were obtained. Two glass transition temperatures (Tg) near the respective Tgs of the homopolymers were found in the DSC thermograms of the block copolymers. The THF/AMMO copolymers were shown to possess higher thermal stability compared to THF/NMMO copolymers from thermogravimetric analysis (TGA). © 1995 John Wiley & Sons, Inc.
Preparation and properties of polyurethane networks based on α,ω‐difunctional poly(hexafluoropropylene oxide)
Authors: Proudmore Martin , Ding Ji‐Feng , Mobbs Richard H. , Yeates Stephen G. , Price Colin , Booth Colin 
Published: April 2003

AbstractPoly(hexafluoropropylene oxide), poly(HFPO), networks were prepared from functional polymers by end linking via urethane groups. The prepolymers were characterized by NMR spectroscopy and GPC. The networks were characterized by determination of the number of network chains from the shear modulus, and were snown to contain both trifunctional crosslinks and difunctional links. The properties of the networks were investigated by a range of techniques. Compared with fully‐fluorinated networks formed via triazine cross‐links, investigated previously, the urethane‐linked networks were more readily prepared but were poorer elastomers, were less thermally stable, and were less resistant to swelling by common polar solvents. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of polyimides from 4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride
Authors: Gao Jian Ping , Wang Zhi Yuan 
Published: April 2003

Abstract4,4′‐Binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride was synthesized from 4‐chloro‐1,8‐naphthalic anhydride and polymerized with aromatic and pliphatic diamines in m‐cresol or N‐methyl‐2‐pyrrolidinone (NMP). The polyimides, except for two derived from p‐phenylenediamine and hydrazine, are soluble in 1,1,2,2‐tetrachloroethane and NMP. Their intrinsic viscosities ranged from 0.36 to 2.20 dL/g. The polymers showed excellent thermal and thermooxidative stabilities and displayed weak glass transition temperatures. Young's moduli of some polymer films were in the range of 2.5 and 5.4 GPa at 30°C. The aliphatic polyimides exhibited a stronger fluorescence than the aromatic polyimides. © 1995 John Wiley & Sons, Inc.
Solvation effect in thermal decomposition of 2,2′‐azoisobutyronitrile
Authors: Szafko J. , Feist W. 
Published: April 2003

AbstractThe solvation effect in the thermal decomposition of a radical initiator (AIBN) in monomer–solvent mixtures is discussed. Equations were derived which comprise the initiator decomposition constant as a function of the monomer mole fraction for chosen types of solvation. In addition, equations were deduced presenting the concentrations and partial relative decomposition rates for the solvated initiator species as a function of the monomer mole fraction. The equations obtained were compared to the experimental literature data and possible dependences of decomposition constants on monomer concentration were simulated for various solvated species. The simulated relationships were found to be straight lines, curves of saturated type (possessing a plateau), S‐shaped curves, and maximum or minimum curves. © 1995 John Wiley & Sons, Inc.
Radical polymerization of micelle‐forming monomers in water
Authors: Egorov Vladislav V. 
Published: April 2003

AbstractPhoto‐ and thermoinitiated radical polymerization of surface‐active monomers with various structures was investigated in solution and in micelles in water. The relationship between kinetics and the structure of monomer associates was represented in the form of a universal curve. A model and kinetic description of polymerization in spherical micelles of monomer was proposed. The problem of micelle fixation by polymerization was solved. © 1995 John Wiley & Sons, Inc.
Compartmentalized polymerization initiated by oil‐soluble initiators. Calculation of average number of radicals per particle
Authors: Mørk Preben C. , Ugelstad John , Aasen Jan Ole 
Published: April 2003

AbstractExpressions for calculating the stationary state distribution of radicals in compartmentalized systems with a constant number of reaction loci containing an oil‐soluble initiator are given. Besides pairwise formation of radicals in the particles, desorption and reabsorption, water phase termination, solubility of the initiator in the aqueous phase, and the possibility of formation of a single radical species are taken into consideration. The calculation is based on a probabilistic analysis leading to a third‐order recurrence relation solved using confluent, hypergeometric Kummer functions. Some calculated curves illustrating the de‐pendence of the average number of radicals per particle on various relevant parameters are included. © 1995 John Wiley & Sons, Inc.
Photoinitiated cationic polymerization of oxetane formulated with oxirane
Authors: Sasaki Hiroshi , Rudzinński Jerzy M. , Kakuchi Toyoji 
Published: April 2003

AbstractPhotoinitiated cationic polymerization of oxetane, oxirane (epoxide), and a formulation of both was carried out and their reactivity compared. To investigate a formulated system of oxetane and oxirane in photoinitiated cationic polymerization, computational and experimental methods were used. In the computational study, we employed a semiempirical molecular orbital method (AM1). On the other hand, the reactivities of each system were evaluated and compared experimentally by a real‐time FT‐IR method. The computational study reveals that oxetane seems to polymerize in SN2 mechanism, but two possibilities, of SN1 mechanism through the α‐cleavage and of SN2 mechanism through β‐cleavage, are implied for oxirane. Using the real‐time FT‐IR method, the formulation of oxetane and oxirane was proved to possess rather high reactivities of oxetane toward photoinitiated cationic polymerization. The formulated system exhibited slightly lower number‐average molecular weight than oxetane but higher than oxirane. These experimental observations are well explained in terms of the calculated reaction paths. © 1995 John Wiley & Sons, Inc.
Electroinitiated polymerization of allylphenylether
Authors: Şen Şadi , Usanmaz Ali , Önal Ahmet M. 
Published: April 2003

AbstractElectroinitiated polymerization of allylphenylether via constant potential electrolysis was accomplished in acetonitrile at room temperature. Electroinitiated polymerization of the monomer yielded insoluble polymers on the surface of the anode together with soluble polymers in the bulk solution. The structural analyses of the polymers were done by 1H‐NMR and FTIR spectroscopy. 1H‐NMR results showed that monosubstituted aromatic ring of the monomer becomes tri‐substituted during the electroinitiated polymerization. The effect of monomer concentration and applied potential on the rate of electroinitiated polymerization were also studied. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of thianthrene‐containing poly(benzoxazole)s
Authors: Johnson Randy A. , Mathias Lon J. 
Published: April 2003

AbstractNew thioether‐ and thianthrene‐containing poly(benzoxazole)s (PBOs) were synthesized from 4,4′‐thiobis[3‐chlorobenzoic acid] and thianthrene‐2,7‐ and ‐2,8‐dicarbonyl chlorides with commercially available bis‐o‐aminophenols. Polymers were prepared via solution polycondensation in poly(phosphoric acid) at 90–200°C. Transparent PBO films were cast directly from polymerization mixtures or m‐cresol. The films were flexible and tough. Non‐fluorinated PBOs were soluble only in strong acids and AlCl3/NO2R systems by forming complexes with the benzoxazole heterocycle Glass transition temperatures ranged from 298–450°C, and thermogravimetric analysis showed good thermal stabilities in both air and nitrogen atmospheres. © 1995 John Wiley & Sons, Inc.
Curing of a maleimide model compound
Authors: Maes C. , Devaux J. , Legras R. , Parsons I. W. 
Published: April 2003

AbstractA monofunctional maleimide‐ended model compound was synthesized and purified. The thermal curing of this compound was followed by size exclusion chromatography and the molecular masses of the oligomers formed during the curing reaction were determined by mass spectroscopy. It was found that high molecular mass species were not thermally stable. At high temperature and after enough time, a strong decrease in the polydispersity of the oligomers and a significantly preferential formation of trimer were observed. From 13C‐NMR characterization, a five membered ring structure was found for the trimer, which explains the thermal stability of this species. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of aromatic polyamides with oligobenzamide pendent groups. I. Poly‐5‐(4‐benzoylamino‐1‐benzoylamino)isophthalamides
Authors: Lozano Angel E. , Abajo Javier De , De La Campa José G. , Preston Jack 
Published: April 2003

AbstractA series of polyisophthalamides having pendent oligomeric benzamide groups were prepared by the Yamazaki reaction from common aromatic diamines and 5‐(4‐benzoylamino‐1‐benzoylamino)isophthalic acid. The latter was synthesized from 5‐aminoisophthalic acid in a three‐step synthesis by successive incorporation of benzamido groups. The new polymers were characterized by NMR, DSC, TGA, and WAXD and the properties were compared to those of corresponding unsubstituted polyisophthalamides. All of the polymers were essentially amorphous and their Tgs were about 20°C higher than the reference polymers. Initial thermal decomposition temperatures ranged from 375 to 420°C. All of the polymers were soluble in aprotic polar solvents without added salts. Properties of particular note were: the water uptake, which was particularly high, ranging from 7.5 to 18.2%, and the temporary insolubilization in concentrated sulfuric acid of films of the polymers heated for a short time to ≥ 200°C. © 1995 John Wiley & Sons, Inc.
Synthesis of reactive copolyesters derived from isophthaloyl chloride, bisphenol a, and aliphatic diols with additional reactive groups
Authors: Wang Chonghui , Nakamura Shigeo 
Published: April 2003

AbstractCopolycondensation of isophthaloyl chloride, bisphenol A, and aliphatic diols with additional reactive groups were performed in the presence of triethylamine by a trimethyl phosphate/cyclohexane organic/organic interfacial method. The composition of idol and bisphenol A residues in the resulting copolyesters is very close to that in the feed from the initial stage of reaction. The resulting copolyesters with reactive groups can be used for the preparation of various functional polymers. The mechanism of an organic/organic interfacial polycondensation was also discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and kinetics of polymerization of unsaturated monomers with OH groups in their structure. II. 3‐hydroxyneopentyl methacrylate
Authors: Iglesias M. T. , Guzmán J. , Riande E. 
Published: April 2003

AbstractThe synthesis of unsaturated monomers containing one or more hydroxyl groups by reaction between polyalcohols (number of OH, n≥2) and monoacid chlorides has been theoretically analyzed. The difficulties were shown involved in the preparation of these monomers with a high degree of purity even in the most favorable case of the completely substituted compound. The calculated mole fractions of the two monomers that can be obtained by reaction between neopentylglycol and methacryloyl chloride were compared with the experimental ones. Kinetic experiments of the polymerization of 3‐hydroxyneopentyl methacrylate and 2‐hydroxyethyl methacrylate were carried out at different temperatures in 1,4‐dioxane for the former monomer and dioxane and absolute ethanol for the latter. Dilatometric techniques and nonlinear least‐squares methods were used to obtain kinetic data and to determine the kinetic constants, respectively. In homogeneous solution the values of kp/k1/2t for the 3‐hydroxyneopentyl methacrylate and 2‐hydroxyethyl methacrylate was determined by 13C‐NMR spectroscopy and the molar fractions of tactic triads and dyads were calculated from different resonance signals. The polymers are predominantly syndiotactic and follow a Bernoullian distribution of tactic sequences. Finally, the glass transition temperatures of both polymers, determined calorimetrically, were 145 and 89°C, respectively. © 1995 John Wiley & Sons, Inc.
On the exotherm of polyacrylonitrile. II. Examination of deuterated polymers
Authors: Peebles L. H. , Snow A. W. , Peters W. C. 
Published: April 2003

AbstractA series of α‐, β,β‐, and α,β,β‐deuterium‐labelled acrylonitrile monomers were prepared and polymerized. Secondary deuterium isotope effects on the polymerization and on the pyrolysis reactions that precede carbon fiber formation were observed. When deuterium is in the α‐position, the polymerization rate is greater and the molecular weight is higher. It is proposed that either the propagation rate constant or both that constant and the termination rate constant are increased on deuterium substitution. In differential scanning calorimetry, the polyacrylonitrile exotherm occurs at higher temperatures and is narrower when deuterium is substituted at the α‐position. On the other hand, the thermal gravimetric analysis activation energy for weight loss of polymer at temperatures below the acrylic exotherm is lower when deuterium is in the α‐position, relative to the α‐hydrogen polymers. As there is no correlation between the weight loss energy of activation and the various exotherm parameters, the weight loss energy of activation and the various exotherm parameters, the weight loss and exotherm are considered to be independent events. Examination of the distribution of deuterium substituted ammonia species evolved during 100–240°C thermal treatment of the α‐and β, β‐deuterated polyacrylonitriles provides a clear indication that both the α‐ and β‐positions are directly involved in hydrogen migration to nitrogen, but the mechanism of ammonia generation remains unclear. © 1995 John Wiley & Sons, Inc.
Polymerization of methyl methacrylate with cobalt acetylacetonate‐diethyl zinc catalyst system
Authors: Ravikumar L. , Ramarajan K. , Venkatarao K. 
Published: April 2003

AbstractPolymerization of methyl methacrylate was studied with a cobalt acetylacetonate‐diethyl zinc catalyst initiator system in benzene medium at 40°C. When the stoichiometric ratio of Zn/Co is 2, the activity for polymerization is found to be maximum. The structure of the obtained polymethyl methacrylate is compared with that obtained using a free‐radical initiator such as benzoyl peroxide. The structure of polymer and the M̄w/M̄n values indicate that cobalt acetylacetonate‐zinc diethyl system has pronounced free‐radical characteristics. A suitable mechanism is proposed from the kinetic studies. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of polyimides endcapped with phenylethynylphthalic anhydride
Authors: Meyer G. W. , Glass T. E. , Grubbs H. J. , McGrath J. E. 
Published: April 2003

AbstractThe synthesis of high glass transition temperature (Tg > 300°C), amorphous, soluble, poly‐imide oligomers of controlled molecular weight endcapped with 4‐phenylethynylphthalic anhydride endcapping agent is described. The 4‐phenylethynylphthalic anhydride was employed to afford a higher curing temperature (380–420°C) which widens the processing window compared to unsubstituted acetylene‐endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester‐acid of various dianhydrides and aromatic diamines. A “ one‐pot” procedure utilizing NMP as the solvent and o‐dichlo‐robenzene as the azeotroping agent reproducibly produced fully imidized, but yet soluble wholly aromatic polyimides. Thermally cured samples were prepared with gel contents of up to 98% that displayed good solvent resistance. Glass transition temperatures comparable to high molecular weight linear analogs were produced. These polyimides also show excellent thermal stability as judged by thermogravimetric analysis (TGA). Model phenylethynyl imide compounds were synthesized and used to follow and elucidate the nature of the products formed from the phenylethynyl curing by using high temperature magic‐angle 13C nuclear magnetic resonance (MAS NMR). Preliminary results indicate that the cure reaction can be followed by MAS NMR. However, the nature of the products being formed during the curing process is difficult to determine by the solid‐state MAS NMR alone. Differential scanning calorimetry (DSC) data clearly show that the model system does indeed melt and displays a wide window before the strong cure exotherm is observed. © 1995 John Wiley & Sons, Inc.
Study on curing reaction of epoxy resin modified with prepolymers containing spiro orthocarbonate
Authors: Pan Caiyuan , Qi Longwu , Bai Ruke 
Published: April 2003

AbstractPrepolymers were prepared by the reaction of 3,9‐dihydroxyethyl‐3′9′‐dibenzyl‐1,5,7,11‐tetraoxaspiro(5,5)undecane with 4,4′‐diphenylmethane diisocyanate (MDI) and 1,6‐hexa‐methylene diisocyanate (HDI). The number‐average molecular weights of the prepolymers can be controlled by changing the mole ratios of spiro compound and diisocyanates. Kinetic studies of the cure reaction for the epoxy resin system modified with or without prepolymers were followed by a HLX‐1 dynamic torsional vibration apparatus. The results indicated that gel time (tg) and activation energy (Ea) increased as the content of prepolymers in the epoxy resin system increased. A difference with the cure reaction of the pure epoxy resin, the second‐order reaction for the epoxy resin modified with the prepolymers, was obtained. Rate constants (k) of the cure reaction are 0.231 min−1 for the epoxy resin, and 0.312 min−1 for the modified epoxy resin. The mechanism of the cure reaction was discussed. © 1995 John Wiley & Sons, Inc.