bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of amine‐cyclic anhydride reactions in moderately polar solutions
Authors: Padwa Allen R. , Sasaki Yoro , Wolske Kurt A. , Macosko Christopher W. 
Published: April 2003

AbstractThe validity of extrapolating the reactivity of low molar mass compounds in solution to the polymer‐analogous chemistry between polymer‐bound functionality is investigated for the reaction of primary amines with cyclic anhydrides in the moderately polar solvents, anisole and tetraethyleneglycol dimethylether. The kinetics of amic‐acid formation and imidization of polymeric and small molecule mixtures measured by Fourier‐Transform Infrared Spectroscopy at near‐ambient and elevated temperatures are compared. A Significant decrease in both reaction rates is observed upon changing the primary amine from aliphatic to benzylic, benzylic to 1,2‐diphenylethylamine, and 1,2‐diphenylethylamine to polystyrene‐bound 1,2‐diphenylethylamine. Reasons for the influence of polymer‐bound chemical functionality on the reaction rates for these amines are discussed. The imidization step is found to be rate limiting in the reaction of phthalic anhydride with benzylamine at the functional group concentrations reported (0.14M or less). © 1995 John Wiley & Sons, Inc.
Copolymerization of butadiene and styrene with a gadolinium tricarboxylate catalyst
Authors: Kobayashi Eiichi , Kaita Shojiro , Aoshima Sadahito , Furukawa Junji 
Published: April 2003

AbstractHomo‐ and copolymerizations of butadiene (BD) and styrene (St) were carried out by gadolinium catalysts having various tricarboxylate ligands [Gd(OCOR)3: R = CH3, CH2Cl, CHCl2, CCl3, and CF3], to investigate the effects of ligands and discuss the cis polymerization mechanism. Polymerization of BD with Gd(OCOR)3—(i—Bu)3Al—Et2AlCl catalysts was carried out in hexane at 50°C. By each catalyst, poly(BD) having a high cis content (cis = 97–99%) in 22–85% yields for 2–24 h were obtained. The ligands with low pKa values increased the polymerization activity as follows: R of Gd(OCOR)3: CF3 > CCl3 > CHCl2 > CH2Cl ∼ CH3. On the other hand, in the polymerization of St or copolymerization of BD and St under similar conditions, the highest activity was attained by a Gd(OCOCCI3)3‐ based catalyst. The difference in the optimum ligand among the homo‐ and copolymerization of BD and St was discussed on the basis of energy levels of the catalysts. In the copolymers of BD and St, the cis‐1,4 content of the BD unit decreased with increasing St content. Furthermore, according to the diad analysis of copolymers (St content ∼ 14.5 mol %) by 13C NMR spectroscopy, the low cis value of the BD unit was observed in the St‐BD diad (cis/trans/vinyl = 24/53/23), while the high cis value of the BD unit remained in the BD‐BD diad (cis/trans/vinyl = 89/10/1). These results suggest that the terminal BD unit is controlled by the cis configuration by the coordination between the penultimate cis vinylene unit and the gadolinium metal catalyst, whereas the presence of the penultimate St unit interferes with cis polymerization of the terminal BD unit. The difference in the coordination mechanism in the course of polymerization between rare earth metal and transition metal catalysts such as the Ni(acac)2 and Co(acac)3‐based catalyst was also discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of polyimides derived from 1,7‐bis(4‐aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides
Authors: Yang Chin‐Ping , Lin Jiun‐Hung 
Published: April 2003

AbstractThe novel diamine, 1,7‐bis(4‐aminophenoxy)naphthalene (1,7‐BAPON), was synthesized and used to prepared polyimides. 1,7‐BAPON was synthesized through the nucleophilic displacement of 1,7‐dihydroxynaphthalene withp‐fluoronitrobenzene in the presence of K2CO3followed by catalytic‐reduction. Polyimides were prepared from 1,7‐BAPON and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that included ring‐opening polyaddition to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities of 0.74‐2.48 dL/g. Most of the polyimides formed tough, creasible films. These polyimides had glass transition temperatures between 247–278°C and their 10% weight loss temperatures were recorded in the range of 515–575°C in nitrogen atmosphere. © 1995 John Wiley & Sons, Inc.
Living cationic polymerization of isobutyl vinyl ether by the carboxyl group of the carbon black/zinc chloride initiating system
Authors: Yoshikawa Sachio , Nishizaka Rie , Oyanagi Ken'ichi , Tsubokawa Norio 
Published: April 2003

AbstractThe effect of zinc chloride (ZnCl2) on the cationic polymerization of isobutyl vinyl ether (IBVE) initiated by carboxyl groups on a carbon black surface was investigated. Although the polymerization of IBVE was initiated by carboxyl groups on the surface, the rate of polymerization was small and the molecular weight distribution (MWD) of poly IBVE was very broad. The rate of the polymerization was found to be drastically increased, and 100% monomer conversion was achieved in a short time by the addition of ZnCl2. The number‐average molecular weights (Mn) of the polyIBVE were directly proportional to monomer conversion in the polymerization initiated by the carbon black/ZnCl2 system. By addition of the monomer at the end of the first‐stage polymerization, the added monomer was smoothly polymerized at the same rate as in the first stage. The Mn of the polymer was in excellent agreement with the calculated value, assuming the polyIBVE chain forms per unit carboxyl group on the surface and MWD was narrow (Mw/Mn = 1.2 ∼ 1.3). Based on the results, it is concluded that carbon black/ZnCl2 system has an ability to initiate the living cationic polymerization of IBVE. Furthermore, it was found that polyIBVE was grafted onto the carbon black surface after the quenching of the living polymer with methanol. © 1995 John Wiley & Sons, Inc.
Phase separation of copolyurethanes: A study of annealing and slow solvent evaporation methods by FTIR
Authors: Gower L. A. , Lyman D. J. 
Published: April 2003

AbstractCopolyether‐urethane‐ureas based on methylene bis(4‐phenylisocyanate), polypropylene glycol (or polytetramethylene glycol), and ethylene diamine showed improvement in packing order within the already present phases when subject to both thermal annealing and slow solvent evaporation techniques using glass as the casting substrate. However, formation of these copolymer films directly onto IR salt crystals led to major disturbances in the copolymer morphology due to the dissolving of inorganic salt into the polymer casting solution. These disturbances appear to be caused by a salt‐urea segment interaction. The urea amide I band (1635 cm−1) appears to be a sensitive indicator of such changes in these copolymers. © 1995 John Wiley & Sons, Inc.
Retardation of dibenzo polyether‐formaldehyde resin formation by alkali‐metal cations
Authors: Zhao Qiang , Bartsch Richard A. 
Published: April 2003

AbstractMacrocyclic polyethers are well‐known complexing agents for alkali‐metal and alkaline earth‐metal cations. The influence of alkali‐metal cations upon the polycondensation rate of acyclic and cyclic dibenzo polyethers with formaldehyde in formic acid and alkali‐metal cation sorption by some of the resultant resins have been investigated. For certain dibenzo polyether and alkali‐metal cation combinations, polymer formation is markedly reduced. The alkali‐metal cation that provides the best fit for the macrocyclic polyether cavity produces the greatest retardation of polymer formation. It is proposed that metal ion complexation renders the dibenzo polyether monomer inert to polymerization under the reaction conditions. No template effect for alkali‐metal cation sorption by dibenzo polyether carboxylic acid resins was observed. © 1995 John Wiley & Sons, Inc.
Molecular engineering of liquid crystalline polymers by “living” polymerization. XXXII. Synthesis and “living” cationic polymerization of 3‐fluoro‐4′‐(ω‐vinyloxyalkoxy)‐4‐biphenylyl (2r,3s)‐2‐fluoro‐3‐methylpentanoate with undecanyl and octyl alkyl groups
Authors: Perce Virgil , Oda Hiroji 
Published: April 2003

AbstractThe synthesis and “living” cationic polymerization of 3‐fluoro‐4′‐(11‐vinyloxyundecany‐loxy)‐4‐biphenylyl (2R,3S)‐2‐fluoro‐3‐methylpentanoate (12‐11) and 3‐fluoro‐4′‐(8‐vi‐nyloxyoctyloxy)‐4‐biphenylyl (2R,3S)‐2‐fluoro‐3‐methylpentanoate (12‐8) are presented. Poly (12‐11)s and poly (12‐8)s with degrees of polymerization from 4.0 to 16.5 and poly‐dispersities ≤ 1.13 have been synthesized and characterized by differential scanning cal‐orimetry (DSC) and thermal optical polarized microscopy. Over the entire range of molecular weights poly (12‐11)s and poly (12‐8)s exhibit an enantiotropic SA and an unidentified SX phase. In addition, regardless of its molecular weight, poly (12‐8) exhibits a S*c phase in between the SA and Sx phases. Poly (12‐11) and poly (12‐8) show lower transition tem‐peratures and broader temperature ranges of all their mesophases as compared to the corresponding polymers without a fluorine atom on the biphenyl group. The role of the connecting group between the biphenyl and chiral group of the mesogenic unit on the phase behavior of these polymers is also discussed. Copolymers of 12‐8 with (2R,3S)‐2‐fluoro‐3‐methylpentyl 4′‐(11‐vinyloxyundecanyloxy)biphenyl‐4‐carboxylate (13‐11) {i.e., poly‐[(12‐8)‐co‐(13‐11)] (X/Y), where X/Y represents the molar ratio of monomer 12‐8 to monomer 13‐11} with DP of ca. 11 and polydispersities lower than 1.23 were also syn‐thesized and characterized. Their SA and S*c mesophases exhibit continuous dependences of composition and this support the assignment of the mesophases exhibited by poly (12‐8). © 1995 John Wiley & Sons, Inc.
Block copolymerization of alkoxyallenes by the living coordination system with a π‐allylnickel catalyst
Authors: Tomita Ikuyoshi , Abe Toru , Takagi Koji , Endo Takeshi 
Published: April 2003

AbstractBlock copolymers of alkoxyallenes were obtained in high yield by the two‐stage living coordi‐nation polymerization of two kinds of alkoxyallenes using an allylnickel catalyst. The resulting copolymers had narrow molecular weight distributions (∼ 1.1), regardless of the order of the monomer additions. When an alkoxyallene‐bearing hydrophilic substituent was used as a co‐monomer for the block copolymerization with that bearing a hydrophobic one, the resulting copolymer showed amphiphilic properties. For example, a block copolymer obtained by the copolymerization of n‐hexyloxyallene with diethylene glycol allenyl methyl ether was soluble in water as well as n‐hexane. © 1995 John Wiley & Sons, Inc.
Chemical modification of butyl rubber. III. Butyl rubber with D‐maltose derivative as pendant groups
Authors: Ikeda Yuko , Nakamura Yuka , Kajiwara Kanji , Kohjiya Shinzo 
Published: April 2003

AbstractA new type of amphiphilic elastomer was synthesized, which consisted of butyl rubber and a D‐maltose derivative as a backbone and side groups, respectively. The synthesis was accomplished by the sequence of the three following reactions: (1) Hydroxyl groups of D‐maltonolactone were protected by a trimethylsilyl group. (2) The resulting maltonolactone derivative was subjected to a reaction with chemically modified butyl rubber having pendant amino groups. (3) The protecting trimethylsilyl groups on the maltose residues were removed by treating with tetra‐n‐butylammonium fluoride. This new amphiphilic elastomer behaved as a thermoplastic elastomer and showed good mechanical properties. The saccharide seg‐ments aggregated in the hydrophobic butyl rubber matrix to form a microphase‐separated structure, as confirmed by differential scanning calorimetry, transmission electron mi‐croscopy, small‐angle x‐ray scattering, and dynamic mechanical measurements. The ag‐gregated saccharide domains are estimated to function both as crosslinking sites and rein‐forcing fillers in the rubber matrix. © 1995 John Wiley & Sons, Inc.
Main chain liquid crystalline ionic polymers with thermotropic and lyotropic mesophases
Authors: Jegal J. G. , Blumstein A. 
Published: April 2003

AbstractAn ionogenic main chain liquid crystalline polymer was synthesized. In contrast to previous studies the charged sites were incorporated into the flexible spacer and not into the mesogenic group. This was done through quaternization of 1,2‐bis(4‐pyridylethane) with a biphenyl‐4,4′‐nonanoxytoluenesulphonate. The polymer displayed thermotropic and lyotropic me‐sophases. The thermotropic mesophase was smectic. Organic counterions such as meth‐ylsulfonates and p‐toluenesulfonates were found to be favorable to the development of mesophases, due to the increased solubility and lower isotropisation temperatures, when compared to bromide counterion containing polymers. Easy supercooling, dependence on thermal history, and the development of batonnet textures on cooling from the melt were also observed. © 1995 John Wiley & Sons, Inc.
Preparation of a novel HALS polypropylene stabilizer
Authors: Ekman Kenneth , Ekholm Lars , Näsman Jan H. 
Published: April 2003

AbstractThe radiation induced graft copolymerization of m‐isopropenyl‐α,α‐dimethyl benzyl iso‐cyanate (m‐TMI) and styrene onto polypropylene was carried out. The extent of grafting increased with increasing amount of styrene and with increased radiation dose. A graft load of 180% was obtained by immersing a 50 kGy pre‐irradiated film in a monomer solution containing 25 mol % m‐TMI and 75 mol % styrene. The graft copolymer is suitable for covalently binding nonpolymerizable stabilizers with a suitable nucleophilic moiety. In this work the isocyanate moiety of the graft copolymer was allowed to react with 4‐amino‐2,2,6,6‐tetramethyl piperidine, a hindered amine light stabilizer. Fourier trans‐formed infrared spectroscopy confirmed the formation of an urea moiety. © 1995 John Wiley & Sons, Inc.
Reversible photodimerization of coumarin derivatives dispersed in poly(vinyl acetate)
Authors: Chen Yun , Chou Cheng‐Fu 
Published: April 2003

AbstractFour photoreactive coumarin derivatives were successfully synthesized from 7‐hydroxy‐coumarin and 7‐hydroxy‐4‐methylcoumarin, i.e., 7‐propionyloxy‐4‐methylcoumarin (M1), 7‐palmitoyloxy‐4‐methylcoumarin (M2), 7‐propionyloxycoumarin (M3), and 7‐palmitoy‐loxycoumarin (M4). Reversible photodimerization (350 or 300 nm) and photocleavage (254 nm) of these coumarin derivatives dispersed in poly(vinyl acetate) (PVAc) were investigated by tracing their UV absorbance variations at 310 nm. The M2 and M4 with long palmitoyl chain show much better photoreaction reversibility than M1 and M3 with short propionyl chain. Moreover, photodimerization rate (under 350 nm) of M2 is greater than 200 times of that of M1. This has been explained by the formation of suitable conformation for revers‐ible photodimerization due to the hydrophobic interactions. Photodimerization of M2 is ca. 3 times quicker than that of M4, indicating 4‐methyl substitution enhances pho‐todimerization. The influence of photodimerization wavelength (350 and 300 nm) and photosensitizer (benzophenone) have also been investigated in detail. © 1995 John Wiley & Sons. Inc.
Poly(Ether sulfone)s made from 4,4′‐dihydroxystilbene and 4,4′‐difluorodiphenylsulfone: Synthesis, crosslinking, and epoxidation with hydrogen peroxide
Authors: Gao Chunping , Hay Allan S. 
Published: April 2003

AbstractHigh molecular weight polymers from trans‐4,4′‐dihydroxystilbene, bisphenols, and 4,4′‐difluorodiphenylsulfone were synthesized by a nucleophilic displacement reaction using DMAc as solvent in the presence of potassium carbonate. Characterization and crosslinking studies of these polymers were carried out by DSC, TGA, TMA, x‐ray diffraction, and solution and solid NMR. It was found that all polymers can be crosslinked to some extent on heating to 350°C. We also studied the epoxidation of these polymers with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate (3—) as the catalyst in a biphasic system. The epoxidized polymers are thermally cross‐linkable. Very efficient crosslinking was obtained by heating the epoxidized polymers at 350°C under nitrogen. © 1995 John Wiley & Sons, Inc.
Photocrosslinking of functionalized rubber. II. Photoinitiated cationic polymerization of epoxidized liquid natural rubber
Authors: Decker C. , Le Xuan H. , Thi Viet T. Nguyen 
Published: April 2003

AbstractLow molecular weight epoxidized natural rubber has been crosslinked within seconds by UV irradiation in the presence of a triarylsulfonium salt. The photoinitiated cationic ring‐opening polymerization was studied quantitatively by infrared spectroscopy and shown to proceed with surprisingly long kinetic chains in such solid medium. The high conversion (60%) needed for complete insolubilization, together with the presence of tetrahydrofuran structures, argue in favor of an intramolecular polymerization process involving neighboring epoxy groups. The photoinitiator concentration has a strong influence on the rate and extent of the reaction, as well as on the depth of cure profile. Because of an efficient dark process, close to 100% conversion was reached upon storage of the irradiated elastomer at ambient, with a concomitant increase of the gel fraction and the polymer hardness. The grafting of pendent acrylate groups onto the polymer chain leads to a three‐fold decrease of the initial rate of polymerization of the epoxide. The photocuring of natural rubber bearing both epoxy and acrylate groups generates a dual polymer network which combines the properties of the two moieties. © 1995 John Wiley & Sons, Inc.
Olefin terpolymerizations. III. Symmetry, sterics, and monomer structure in ansa‐zirconocenium catalysis of EPDM synthesis
Authors: Yu Zhengtian , Marques Maria , Rausch Marvin D. , Chien James C. W. 
Published: April 2003

AbstractEthylenebis (η5‐fluorenyl) zirconium dichloride (1) and rac‐dimethylsilylene bis (1‐η5‐in‐denyl) zirconium dichloride (2) were activated with methylaluminoxane (MAO) to catalyze ethylene (E) propylene (P) copolymerizations. The former produces high MW copolymer at 20°C rich in ethylene with reactivity ratio values of rE = 1.7 and rP <0.01, whereas the latter produces lower MW random copolymers with rE = 1.32 and rp = 0.36. Ethylidene norbornene (ENB) complexes with 1/MAO but does not undergo insertion in the presence of E and P. In contrast, 2/MAO catalyzes terpolymerization incorporating 9‐15 mol % of ENB with slightly lower MW and activity than the corresponding copolymerizations. In comparison, 1,4–hexadiene was incorporated by 2/MAO with much lower A and MW. Terpolymerizations were also conducted with vinylcyclohexene using both catalyst systems. The steric and electronic effects in these processes were discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and degradabilities of polyesters from 1,4:3,6‐dianhydrohexitols and aliphatic dicarboxylic acids
Authors: Okada Masahiko , Okada Yasunari , Aoi Keigo 
Published: April 2003

AbstractSix different polyesters (6a–6c and 7a–7c) were prepared by the bulk polycondensations of the respective combinations of 1,4:3,6‐dianhydro‐D‐glucitol (3) and 1,4:3,6‐dianhydro‐D‐mannitol (4) with succinyl dichloride (5a), glutaryl dichloride (5b), and adipoyl dichloride (5c) at 140–180°C. Polyesters having number average molecular weights up to 2.6 ×104 were obtained in high yields. Only polyester 7a based on 4 and 5a was partially crystalline, whereas all the other polyesters were amorphous. Thin films of these polyesters except that of 7a were spontancously hydrolyzed in a neutral phosphate buffer solution at 50°C, whereas they were reluctant to be hydrolyzed at 27°C. The polyesters were more or less degraded at 27°C by treatment with an activated sludge or by prolonged burial in soil. © 1995 John Wiley & Sons, Inc.
Poly(diarylsilmethylene)s, I. Synthesis and characterization
Authors: Ogawa Takuya , Tachikawa Mamoru , Kushibiki Nobuo , Murakami Masashi 
Published: April 2003

AbstractPoly(diarylsilmethylene)s with phenyl or tolyl substituents on Si atoms were synthesized by ring‐opening polymerization of corresponding 1,1,3,3‐tetraaryl‐1,3‐disilacyclobutanes, and were characterized by means of DSC, x‐ray diffraction and melt viscosity measurements. Three preparative routes including catalytic and noncatalytic polymerization methods were examined to see differences in properties of the resulting polymers. The polymers thus obtained were crystalline and soluble in limited solvents such as diphenyl sulfone at tem‐peratures above 250°C. Poly(diphenylsilmethylene) exhibited a melting temperature of about 350°C, whereas those of polymers with tolyl groups were observed in a temperature range between 310 and 330°C. The melt viscosity of the poly(diarylsilmethylene)s was measured to obtain insight into the molecular weights of the polymers, and the results indicated that the molecular weights are modifiable by varying the monomer‐to‐catalyst ratio when solution polymerization is employed. The DSC and x‐ray studies were also carried out with focusing on the melting and crystallization behavior of these polymers. © 1995 John Wiley & Sons, Inc.
Radical polymerization behavior of ethyl ortho‐formylphenyl fumarate involving intramolecular hydrogen abstraction
Authors: Sato Tsuneyuki , Shimooka Sumio , Seno Makiko , Tanaka Hitoshi 
Published: April 2003

AbstractThe radical polymerization behavior of ethyl ortho‐formyl‐phenyl fumarate (EFPF) using dimethyl 2,2′‐azobisisobutyrate (MAIB) as initiator was studied in benzene kinetically and ESR spectroscopically. The polymerization rate (Rp) at 60°C was given by Rp = k[MAIB]0.76[EFPF]0.56. The number‐average molecular weight of poly(EFPF) was in the range of 1600–2900. EFPF was also easily photopolymerized at room temperature without any photosensitizer probably because of the photosensitivity of the formyl group of monomer. Analysis of 1H− and 13C‐NMR spectra of the resulting polymer revealed that the radical polymerization of EFPF proceeds in a complicated manner involving vinyl addition and intramolecular hydrogen‐abstraction. The polymerization system was found to involve ESR‐observable poly(EFPF) radicals under the actual polymerization conditions. ESR‐determined rate constant (2.4–4.0 L/mol s) of propagation at 60°C increased with decreasing monomer concentration, which is mainly responsible for the observed low de‐pendency of Rp on the EFPF concentration. Copolymerizations of EFPF with some vinyl monomers were also examined. © 1995 John Wiley & Sons, Inc.
Electrical conductivity of thermally degraded poly(vinyl chloride)–polyacrylonitrile blends
Authors: Chatterjee Nandini , Palit Sunanda K. , Maiti Mrinal M. 
Published: April 2003

AbstractFinely powdered blends of poly(vinyl chloride) (PVC) and polyacrylonitrile (PAN) have been thermally degraded at 275°C for 24 h in an inert atmosphere to effect complete de‐hydrochlorination of PVC to a conjugated polyene structure and simultaneous internal polymerization of nitrile groups in PAN to a conjugated polyimine sequence. The room temperature d.c. conductivity of the degraded blends showed clear synergistic behavior. A maximum conductivity has been observed with a blend of 60 PAN/40 PVC which is about 4 orders of magnitude over the linearly weighted average conductivity of the individual degraded homopolymers. The results have been interpreted in terms of a possible donor‐acceptor interaction between the degraded homopolymers leading to mutual doping and, hence, an enhanced electrical conductivity. © 1995 John Wiley & Sons, Inc.