bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization behavior of 2,2,6,6‐tetramethylpiperidinyl methacrylate: A monomer carrying a hindered amine group
Authors: Lee C. S. , Lau Wayne W. Y. , Lee S. Y. , Goh S. H. 
Published: April 2003

AbstractCopolymers of 2,2,6,6‐tetramethylpiperidinyl methacrylate (TPMA) with styrene (S) and with methyl methacrylate (MMA) were synthesized using AIBN as initiator. S–TPMA copolymers from feed ranging from 0.10–0.80 mole fractions TPMA and MMA‐TPMA copolymers from feed of 0.04–0.85 mole fractions TPMA were used in the determination of monomer reactivity ratios r1, r2. Four different methods were employed in the calculations of r1 and r2 and all calculated results were in good agreement with each other. The structure of S–TPMA copolymers was inferred to be of an alternating nature while that of MMA–TPMA copolymers was random. Both copolymers are potential hindered amine light stabilizers (HALS) and are expected to be less extractable from, and more compatible with, polystyrene and poly(methyl methacrylate) base polymers.
Preparation and properties of novel soluble aromatic polyimides from 4,4′‐diaminotriphenylamine and aromatic tetracarboxylic dianhydrides
Authors: Oishi Yoshiyuki , Ishida Mina , Kakimoto Masa‐Aki , Imai Yoshio , Kurosaki Toshikazu 
Published: April 2003

AbstractNew aromatic polyimides containing triphenylamine unit were prepared by two different methods, i.e., a conventional two‐step method starting from 4,4′‐diaminotriphenylamine and aromatic tetracarboxylic dianhydrides and the one‐step thioanhydride method starting from the aromatic diamine and aromatic tetracarboxylic dithioanhydrides. Both procedures yielded high‐molecular‐weight polyimides with inherent viscosities of 0.47–1.17 dL/g. Some of these polymers were soluble in organic solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, m‐cresol, and pyridine. All the polyimides afforded transparent, flexible, and tough films, and the color varied from pale yellow to dark red, depending markedly on the tetracarboxylic acid components. The glass transition temperatures (Tgs) of these polyimides were in the range of 287–331°C and the 10% weight loss temperatures were above 520°C in air. The polyimides prepared by the one‐step method exhibited better solubility in organic solvents and had somewhat lower Tgs than the polymers prepared by a conventional two‐step method.
Soluble polyarylenes containing alternating binaphthylene and biphenylene structural units
Authors: Percec Virgil , Okita Shigeru 
Published: April 2003

AbstractThis article describes the synthesis of a novel series of soluble polyarylenes containing alternating binapthylene and biphenylene structural units. They were obtained by the cation‐radical polymerization of bis(1‐naphthyl) biphenyls. The following monomers were synthesized and polymerized : 4,4′‐bis(1‐naphthyl) biphenyl (9), 3,3′‐bis(1‐naphthyl) biphenyl (10), 2,2′‐bis(1‐naphthyl)biphenyl (11), and 2,5‐bis(1‐naphthyl)biphenyl (14). All polymerizations were performed in nitrobenzene using FeCl3 as oxidant. Polymers with number average molecular weights of up to 4000 g/mol were obtained.
Amphiphilic segmented polyurethanes as surface modifying additives
Authors: Kober Maria , Wesslén Bengt 
Published: April 2003

AbstractAmphiphilic segmented polyetherurethanes were prepared from methylene diphenylene diisocyanate (MDI), poly(ethylene glycol) 1500 (PEG), and a fatty acid monoglyceride as a chain extender. The polymers were not soluble in water or methanol, but dissolved readily in organic solvents. The amphiphilic properties were demonstrated as a large hysteresis in the water contact angles, exceeding 110°. The amphiphilic polymers were shown to modify the surface properties of a poly(ether urethane) (PEU) and a poly(ether urethane urea) (PEUU) when added in 1–10 wt %, presumably due to migration of the additive to the surface. The surfaces of particularly the PEU blends became highly amphiphilic, exhibiting contact angles hystereses up to 90–100°. A surface saturation effect was observed at 5% added amphiphilic polymer. A difference in the behavior of PEU and PEUU was ascribed to differences in solubility of the additive in the matrix. On long‐term exposure to water the PEUU blends increased their amphiphilic behavior.
Synthesis and phase‐transfer catalytic activity of crown ethers bound to microporous polystyrene resins by oxyethylene spacers
Authors: Chung Kwang Bo , Tomoi Masao 
Published: April 2003

AbstractCrown ethers bound to microporous polystyrene resins by oxyethylene spacers were prepared by the reaction of monoazacrown ethers with 2‐tosyloxyethoxymethylated or 2‐(2‐tosyloxyethoxy)ethoxymethylated polystyrene resins crosslinked with 2 mol % of divinylbenzene. The activity of the immobilized lariat crowns for halogen exchange reactions under triphase conditions has been studied as a function of catalyst structure, loading, substrate structure, reagent structure, and solvent. The lariat catalysts with extra oxygen donors in the spacer chain exhibited higher activity than the corresponding immobilized catalysts without the donors in the spacer. The increased activity of the catalyst containing 15‐crown‐5 unit and two extra donors for the reaction of 1‐bromooctane with KI was concluded to result from the enhanced complexation with the K+ ion, induced by the cooperative coordination of the crown unit donors and the donors in the spacer chain. The recovered catalysts could be re‐used without decrease in activity.
Polyimides containing nonaromatic nitrogen linkages
Authors: Feld William A. , Le Tieu‐Binh 
Published: April 2003

AbstractTwo diamines, 2,5‐bis (4‐aminophenyl)‐2,5‐diazahexane and 1,4‐bis (4‐aminophenyl)‐1,4‐diazacyclohexane were chosen as components for polyimidizations because they have melting points that differ by nearly 200°C (66–67 and 229–230°C, respectively) and are relatives of p‐nitro‐N,N‐dimethylaniline. The melting points of the model compounds (phthalic anhydride) do not differ by as much as those of the free amines [303–304 and 386°C (DSC), respectively]. Six polyimides were prepared by a two‐step polycondensation of the diamines with pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and 5,5'‐[2,2,2‐trifluoro‐1‐(trifluoromethyl) ethylidene] bis‐1,3‐isobenzofurandione. DSC thermograms failed to indicate any distinct transitions up to 450°C, however, the polyimide prepared from 2,5‐bis (4‐aminophenyl)‐2,5‐diazahexane and pyromellitic dianhydride shows a slight break in its DSC curve at 233°C.
Surface modification. I. Polyacrolein microspheres covalently bonded onto polyethylene
Authors: Margel Shlomo , Cohen Ella , Dolitzky Yehudit , Sivan Orit 
Published: April 2003

AbstractThe synthesis and characterization of novel surfaces composed of polyacrolein microspheres covalently bonded onto polyethylene films are described. These surfaces were prepared through a sequence of reactions carried out onto polyethylene films in order to form primary amine groups at the w position. Polyacrolein microspheres in water were then covalently bonded to these modified polyethylene surfaces. The binding between the microspheres and the modified surfaces is due to the interaction between the aldehyde groups of the microspheres and the amine groups of the modified surfaces to form the polyvalent Schiff base bonds. Fourier transform‐infrared/attenuated total reflection, electron spectroscopy for chemical analysis, contact angle measurements, and scanning electron microscopy have been used for the characterization of the modified polyethylene surfaces.
A new synthetic pathway of segmented tri‐block copolyether
Authors: Sangen Osamu , Masuda Singo , Nakano Hidehiko , Yamana Kazusige , Sasaki Kenichi , Ikeda Naoki 
Published: April 2003

AbstractA new synthetic pathway of A–B–A tri‐block copolyether which is composed of a hydrophilic poly(oxyethylene) unit as an A part and a hydrophobic poly(oxy‐2‐methyl‐trimethylene) unit as a B part is proposed. Telechelic α‐tosyl‐ω‐tosyloxypoly(oxy‐2‐methyl‐trimethylene) derived from tosylation of poly(oxy‐2‐methyl‐trimethylene glycol) (PMTG) was allowed to react with poly(ethylene glycol) (PEG) in the presence of sodium hydroxide. Tg of the resulting A–B–A tri‐block copolyether (PEMG) (M̄n = 1600) was −72°C and its specific gravity [D415] was 1.055.
Thermooxidation of polyarylethersulfone HTA: Oscillations and mechanism
Authors: Brauman S. K. 
Published: April 2003

AbstractChemiluminescence in conjunction with x‐ray photoelectron spectroscopic surface analysis has been used to elucidate the thermooxidation of polyarylethersulfone HTA film between 85 and 110°C. Oscillations have been observed in chemiluminescence at different wavelengths and in the concentration of newly identified sulfine intermediates. A reaction mechanism is proposed to account for the chemiluminescence and product behaviors. This mechanism features parallel intramolecular and intermolecular pathways branching from a common sulfinyl sulfonate intermediate; each branch produces different emittering species. Oscillating behavior appears to be general for polyarylsulfone films.
Accessible new acrylic monomers and polymers as highly transparent organic materials
Authors: Boutevin B. , Rousseau A. , Bosc D. 
Published: April 2003

AbstractTheoretical studies of intrinsic absorption phenomena in organic compounds in a range of wavelengths from visible to near‐infrared (NIR), led us to synthesize acrylic monomers with variable molar number of CH per cubic centimeter, NCH. Thus, halogenoalkyl or aryl α‐chloroacrylates, α‐fluoroacrylates, and methacrylates are prepared. The corresponding homo‐ and copolymers exhibit good thermal (Tg from 120 to 160°C) and optical properties.
Preparation of microspheres by radiation‐induced polymerization. II. Mechanism of microsphere growth
Authors: Naka Yukihiko , Yamamoto Yukio 
Published: April 2003

AbstractThe effects of the monomer concentration were investigated on the preparation of diethylene glycol dimethacrylate (2G) microspheres by radiation‐induced polymerization. The monomer concentration strongly affected the conversion and the shape of the microspheres. The particles were obtained in the range from 2 to 24 vol % of 2G monomer. The effective concentration for the preparation of monodisperse microspheres is around 10 vol %. Higher monomer concentrations up to 24 vol % gave rough surface particles. Considering the effects on the number of microspheres in the solution, the authors introduced the inhibiting region, where one microsphere disturbs the existence of another microsphere, and tried to explain the mechanism of the microsphere growth. The competition between the propagation and the crosslinking reactions is balanced to give the microspheres.
Solid‐state photochemical generation of polymeric polyradicals: Poly(4‐vinylphenoxy) and copolymers with styrene
Authors: Rossitto Frank C. , Lahti Paul M. 
Published: April 2003

AbstractSynthesis of poly(4′‐vinyl‐2,4,6‐tri‐tert‐butyl‐diphenyloxalate) and its 65 : 35 and 19 : 81 copolymers with styrene are described. Rigid phase broad‐band photolysis of the homopolymer with a quartz filtered xenon arc at 77 K results in production of up to 25% of the theoretical number of spins/mol expected for quantitative production of pendant phenoxyl radicals, and shows no major loss of radical signal in the ESR at temperatures below 100 K. Curie law analysis of the temperature dependence of the ESR radical signal intensity for the neat photolyzed homopolymer 1 shows curvature consistent with antiferromagnetic pairing of radical spins at low temperatures. Since through‐bond conjugation of radical spins is not possible in this system, the antiferromagnetic interaction is interpreted in terms of intrachain and/or interchain through‐space exchange interactions.
Synthesis and properties of aromatic polyureas from N,N′‐bis(trimethylsilyl)‐substituted aromatic diamines and aromatic diisocyanates
Authors: Oishi Yoshiyuki , Padmanaban Munirathina , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractSilylated aromatic polyureas were synthesized by the polyaddition of N,N′‐bis(trimethylsilyl)‐substituted aromatic diamines to aromatic diisocyanates in various organic solvents at a temperature ranging from 30 to 100°C. Colorless and transparent films of the silylated polyureas were obtained by casting directly from these solutions in a dry nitrogen atmosphere. The silylated polyureas thermally decomposed at around 200°C and were easily desilylated with alcohol to convert to almost amorphous aromatic polyureas having inherent viscosities of 0.4–1.0 dL/g. The polyureas exhibited better solubility in organic solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, and dimethyl sulfoxide and had somewhat lower thermal decomposition temperatures (around 300°C) than the polyureas prepared by a conventional method from the parent aromatic diamines and diisocyanates.
Synthesis and characterization of 1,3,4‐oxadiazole‐containing polyazomethines
Authors: Saegusa Yasuo , Koshikawa Toshiya , Nakamura Shigeo 
Published: April 2003

AbstractNovel 1,3,4‐oxadiazole‐containing polyazomethines were synthesized by the polycondensation of diamines, 2,5‐bis (m‐aminophenyl)‐1,3,4‐oxadiazole (BMAO) and 2,5‐bis (p‐aminophenyl)‐1,3,4‐oxadiazole (BPAO), with aromatic dialdehydes, isophthalaldehyde and terephthalaldehyde, in m‐cresol at 20°C. These polymers were yellow to orange in color and had reduced viscosities up to 1.13 dL/g and electric conductivity as high as 10−11−10−12 S cm−1. All the polyazomethines were insoluble in common organic solvents but dissolved in concentrated sulfuric acid. Thermogravimetry showed that thermal degradation started at around 400°C in air and nitrogen atmospheres. Doping with iodine markedly increased the conductivity and produced the black‐colored semiconductive polyazomethines with a maximum conductivity of the order of 10−6 S cm−1. Electronic spectra of the undoped polymers indicated a large bathochromic shift of the absorption maxima due to CN bonds of the monomer diamines (285 nm for BMAO and 315 nm for BPAO). This suggests that π‐electrons of the polymers are extensively delocalized along the main chain.
Synthesis and characterization of 1,3,4‐thiadiazole‐containing polyazomethines and copolyazomethines
Authors: Saegusa Yasuo , Takashima Toshio , Nakamura Shigeo 
Published: April 2003

AbstractNovel 1,3,4‐thiadiazole‐containing polyazomethines and copolyazomethines were synthesized by the solution polycondensation, in m‐cresol at 25°C, of aromatic dialdehydes, isophthalaldehyde and terephthalaldehyde, with 2,5‐bis (m‐aminophenyl)‐1,3,4‐thiadiazole (BMAT) and with BMAT and aromatic diamines, bis (4‐aminophenyl) ether and 1,5‐diaminonaphthalene, respectively. These polymers were tan yellow to yellow in color and had reduced viscosities up to 0.32 dL/g in concentrated sulfuric acid and electric conductivity as high as 10−9−10−11 S cm−1 at 25°C. All the polymers were insoluble in common organic solvents but dissolved completely in concentrated sulfuric acid and formic acid. However, they were readily hydrolyzed in concentrated sulfuric acid. X‐ray diffraction diagrams showed that the crystallinity of polyazomethines were low, but copolyazomethines were highly crystalline. These azomethine polymers are highly thermally and thermooxidativelly stable and exhibited no appreciable decomposition up to 400°C in both air and nitrogen atmospheres. Doping with iodine dramatically raised the conductivity and produced the dark brown‐ to completely black‐colored semiconductive polymers with a maximum conductivity of the order of 10−5 S cm−1. Electronic spectra of the undoped polymers indicated a large bathochromic shift of the π−π* absorption band (310 nm) due to CN bonds of BMAT. This result suggests that π‐electrons of the polymers are extensively delocalized along the main chain.
Ion‐exchange rate limitation on a polymer‐supported phase transfer catalytic reaction
Authors: Wang Maw‐Ling , Wu Ho‐Sheng 
Published: April 2003

AbstractThe ion‐exchange rate limitation on the kinetics of the series substitution reactions between hexachlorocyclotriphosphazene (NPCl2)3 and 2,2,2‐trifluoroethanol (HOCH2CF3) by polystyrene‐bound tri‐n‐butylammonium ion in an organic solvent/alkaline solution was studied. It was found that the diffusional limitation involves both ion diffusion and organic reactant diffusion within the catalyst pellet. The displacement reaction rate of (NPCl2)3 in the organic phase was limited by the particle diffusion and the intrinsic reactivity together. The film diffusion in the bulk solution limited the rate of ion exchange. The mass transport of the ion‐exchange step in the aqueous phase was not improved by increasing the concentration of NaOCH2CF3. Drastic kinetic rate improvement was achieved with proper adjustment of the volume of the aqueous solution which was a low concentration of salt in the aqueous phase.
Heteroaromatic polyamides from cyanoimidazoles
Authors: Allan David S. , Rasmussen Paul G. 
Published: April 2003

AbstractThe synthesis of a new class of heteroaromatic polyamides based on cyanoimidazoles are described. The monomer, 2‐amino‐4‐cyanoimidazole‐5‐carboxylic acid (3) is prepared from a two‐step hydrolysis of 2‐amino‐4,5‐dicyanoimidazole (1). A model dimer prepared from condensation of 1 with 4‐cyanoimidazole‐5‐carboxylic acid was structurally characterized by single crystal diffraction. The dimer, C10H8N8O3, crystallizes with Z = 2 and includes two waters of hydration in the P1 space group, a = 7.684 (2), b = 7.864 (3), c = 10.918 (5), α = 100.14 (3), β = 93.15 (3), γ = 103.79 (3). The model dimer is totally planar and shows trans geometry across the amide linkage. The monomer was polymerized by phosphorylation reaction conditions leading to a highly colored oligomeric polyamide. The polymer was characterized by IR spectroscopy, viscometry, GPC chromatography, and luminescence studies. The polymer luminesces strongly under 450 nm laser irradiation at low temperatures.
Fully imidized soluble polyimides based on a novel dianhydride: 2,2′‐dichloro‐4,4′,5,5′‐benzophenone tetracarboxylic dianhydride
Authors: Falcigno Pasquale A. , Jasne Stanley , King Maurice 
Published: April 2003

AbstractWe have synthesized a novel dianhydride, 2,2′‐dichloro‐4,4′,5,5′‐benzophenone tetracarboxylic dianhydride (DCBTDA). Polyimides were synthesized with DCBTDA or 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and several relatively rigid meta‐ and para‐ substituted mononuclear diamines. The BTDA based systems were insoluble in dipolar, aprotic solvents whereas the DCBTDA based polymers displayed enhanced solubility in these solvents. The thermal stability of these polyimides was excellent as measured by 5% weight loss decomposition. The Tg's of the polymers were all above 290°C.
Synthesis of N‐(arylmethyl)diethanolamines and of other pyrenediols: Addition polymerizations of pyrenyl monomers
Authors: Katritzky Alan R. , Zhu Dong‐Wei , Bernard Marek K. 
Published: April 2003

AbstractN‐(Arylmethyl)diethanolamines and other spaced dihydroxy compounds bearing pyrenyl groups were prepared using benzotriazole as a synthetic auxiliary. The potential of these diols as precursors for the preparation of condensation polymers containing pendant polycyclic aryl groups was illustrated by reaction of the pyrenyl derivatives with diisocyanates which afforded the corresponding polyurethane polymers.
Model filled polymers. VIII. Synthesis of crosslinked polymeric beads by seed polymerization
Authors: Zou Dezhong , Sun Liquing , Aklonis J. J. , Salovey R. 
Published: April 2003

AbstractMonodisperse crosslinked polystyrene (PS) and polymethacrylate (PMA) beads of sizes greater than 1 μm in diameter are prepared by particle nucleation onto pre‐existing polymer seeds in a multistage emulsion polymerization, in the absence of emulsifier. An adequate seed number concentration, which decreases with increasing seed size, is necessary to achieve monodisperse beads. Monodisperse multicomposition beads are prepared by polymerizing styrene onto PMA seeds, but not by polymerizing methyl methacrylate onto PS seeds. Phase separation in growing seed particles or surface polymerization following free radical capture may lead to the formation of asymmetric shaped particles.
Anionic polymerization of acrylates. II. Polymerization of 2‐ethylhexyl acrylate initiated by butyllithium/lithium‐tert‐butoxide system in tetrahydrofuran and its mixtures with toluene
Authors: Vlček P. , Kříž J. 
Published: April 2003

AbstractThe anionic polymerization of 2‐ethylhexyl acrylate (EtHA) initiated with the complex butyllithium/lithium‐tert‐butoxide (BuLi/t‐BuOLi) was investigated at −60°C in a medium of various solvating power, i.e., in mixtures of toluene and tetrahydrofuran and in neat tetrahydrofuran. With increasing amount of THF in the mixture the attainable limiting conversion of polymerization decreases; the monomer can be polymerized quantitatively only in a toluene/THF mixture (9/1). Molecular weights of the polymers thus obtained, their distribution, and initiator efficiency are not appreciably affected by the polymerization medium. The molecular weight distribution of the products is medium‐broad (Mw/Mn = 2–2.4), with a hint of bimodality. The 1H‐13C‐NMR, and IR spectra suggest that during the polymerization there is neither any perceptible reesterification of the polymer with the alkoxide nor transmetalation of the monomer with the initiator. In a suitable medium, autotermination of propagation proceeds to a limited extent only, predominantly via intramolecular cyclization of propagating chains; in a medium with a higher content of polar THF, it prevails and terminates propagation before the polymerization of the monomer has been completed. © 1992 John Wiley & Sons, Inc.
Anionic polymerization of acrylates. III. Polymerization of 2‐ethylhexyl acrylate initiated by lithium‐tert‐butoxide
Authors: Vlček P. , Janata M. , Otoupalová J. 
Published: April 2003

AbstractThe polymerization of 2‐ethylhexyl acrylate (EtHA) initiated with lithium‐tert‐butoxide (t‐BuOLi) in tetrahydrofuran (THF) and in the temperature range between −60 and 20°C was investigated. The reaction rate is distinctly temperature‐dependent and at −60°C is already very low, similarly to the polymerization of methacrylates. Molecular weights of the polymers thus formed, particularly at higher temperatures, are inversely proportional to conversion of the monomer due to the slow initiation reaction. This is documented by the low consumption of alkoxide even at long reaction times, which also depends on the reaction temperature. At higher temperatures the polymerization stops spontaneously, due to the greater extent of autotermination reactions. The weak initiating efficiency of the alkoxide decreases still more with decreasing concentration of the monomer during the polymerization, as confirmed by the concentration dependence of the reaction rate in toluene at −20°C. The results suggest a negligible initiating effect of alkoxides in complex bases, particularly at lower polymerization temperatures. © 1992 John Wiley & Sons, Inc.