bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photocrosslinking reaction of vinyl‐functional polyphenylsilsesquioxane sensitized with aromatic bisazide compounds
Authors: Yasuda Naoki , Yamamoto Shigeyuki , Wada Yuji , Yanagida Shozo 
Published: August 2002

AbstractPhotochemical reactions of aromatic azide groups were applied for a novel photosensitive silicone ladder polymer, that is, partially vinyl‐substituted polyphenylsilsesquioxane sensitized with aromatic bisazide compounds as a photocrosslinker. The photocrosslinking reaction in this system was investigated from the viewpoint of the efficiency of the photocrosslinker, that is, the ratio of the photocrosslinker consumed for crosslinking. The numbers of photodecomposed azide groups and crosslinks in the polymer were determined by Fourier transform infrared measurements. At a higher bisazide concentration, the predominant reaction of nitrenes formed as the intermediary radical by the photolysis of azide was a coupling reaction that could not contribute to the gelation of the polymer. The ratio of the bisazide compound consumed for crosslinking showed the highest value at its concentration of 3 wt % and decreased with the addition of a larger amount. The semiempirical molecular orbital calculations were applied to the theoretical analysis of the photoreaction of nitrenes using phenylnitrene as a model structure. The calculation results indicated that the coupling reaction of nitrenes should proceed more easily than the photocrosslinking reaction in N2 atmosphere, and the fact that the oxidation of nitrenes should proceed exclusively in the atmosphere including O2 agreed with the experimental results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4196–4205, 2001
Synthesis and characterization of two new aryl cyclobutyl ketoethyl methacrylate monomers and their polymers
Authors: Erol Ibrahim , Ilter Zulfiye , Coskun Mehmet , Ahmedzade Misir 
Published: August 2002

AbstractTwo new methacrylate monomers, 2‐[3‐(6‐tetralino)‐3‐methylcyclobutyl]‐2‐ketoethyl methacrylate (TKEMA) and 2‐(3‐mesityl‐3‐methylcyclobutyl)‐2‐ketoethyl methacrylate (MKEMA), were obtained from the reaction of 1‐chloroacetyl‐3‐methyl‐3‐arylcyclobutane with sodium methacrylate. The oxime and hydrazone derivatives of poly(TKEMA) and poly(MKEMA) were prepared with hydroxylamine and 2,4‐dinitrophenyl hydrazine. Poly(TKEMA) and poly(MKEMA), their oxime and hydrazone derivatives, and the monomers were characterized with Fourier transform infrared and NMR techniques. The glass‐transition temperatures and thermal stability of the polymers and their oxime and hydrazone derivatives were compared. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4167–4173, 2001
Synthesis and characterization of biodegradable poly(ϵ‐caprolactone urethane)s. I. Effect of the polyol molecular weight, catalyst, and chain extender on the molecular and physical characteristics
Authors: Gorna Katarzyna , Polowinski Stefan , Gogolewski Sylwester 
Published: August 2002

AbstractBiodegradable polyurethanes with potential for applications in medical implants were synthesized in bulk with aliphatic hexamethylene diisocyanate, isophorone diisocyanate, poly(ϵ‐caprolactone) diols of various molecular weights, 1,4‐butane diol, 2‐amino‐1‐butanol, thiodiethylene diol, and 2‐mercaptoethyl ether chain extenders. The catalysts used were stannous octoate, dibutyltin dilaurate, ferric acetyl acetonate, magnesium methoxide, zinc octoate, and manganese 2‐ethyl hexanoate. The synthesis reactions were second‐order. All the materials had narrow, unimodal molecular weight distributions and polydispersity indices of 1.5–1.9. The chemical structures of the polyurethanes, as assessed from1H NMR and13C NMR spectra, were in good agreement with the monomer stoichiometric ratios. The glass‐transition temperatures of the materials ranged from −38 to −57 °C and were higher for polymers based on isophorone diisocyanate and with higher hard‐segment contents. For polyurethanes with the same hard‐segment content, there was no effect of the material molecular weight on the thermal properties. The tensile strengths of the materials were 12–63 MPa, and the tensile moduli were 8–107 MPa. These increased with an increasing hard‐segment content. The least effective catalyst was magnesium methoxide, and the most effective was ferric acetyl acetonate. Stannous octoate and manganese 2‐ethyl hexanoate were less effective than dibutyltin dilaurate and zinc octoate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 156–170, 2002
Photoinitiated polymerization of methacrylic monomers in a poly(methyl methacrylate) matrix: A comparative study with other matrices (styrene–butadiene–styrene, polystyrene, and polybutadiene)
Authors: Mateo J. L. , Calvo M. , Bosch P. 
Published: August 2002

AbstractThe kinetics and mechanism of the photoinitiated polymerization of 1,6‐hexanediol dimethacrylate (HDDMA) in a poly(methyl methacrylate) (PMMA) matrix were studied. The maximum double‐bond conversion, the maximum polymerization rate, the intrinsic reactivity, and the kinetic constants for propagation and termination were calculated. For this system, a reaction‐diffusion termination mechanism occurred from the start of the polymerization, and it was predominantly maintained until high monomer concentrations, probably because of the relatively high intermolecular attraction force between the PMMA matrix and HDDMA monomer. In addition, a comparative study of the photoinitiated polymerization of methacrylic monomers in four different polymeric matrices [styrene–butadiene–styrene (SBS), polystyrene (PS), polybutadiene (PB), and PMMA] was carried out. The aggregation state, vitreous or rubbery, of the monomer–matrix system and the intermolecular strength of attraction in the monomer–matrix system and growing macroradical and matrix systems were the principal factors influencing the kinetic and mechanistic behavior of these systems. When PB and SBS were used as matrices, crosslinked polymerized products were obtained as a result of the participation of double bonds of the matrix in the polymerization process (copolymerization). PS sequences in the SBS and PS matrices also took part in the polymerization process through the coupling of the benzylic radical to the growing macroradical. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 120–127, 2002
Investigations of thermal polymerization in the stable free‐radical polymerization of 2‐vinylnaphthalene
Authors: Lizotte Jeremy R. , Erwin Brian M. , Colby Ralph H. , Long Timothy E. 
Published: August 2002

AbstractThe feasibility of utilizing stable free‐radical polymerization (SFRP) in the synthesis of well‐defined poly(2‐vinylnaphthalene) homopolymers has been investigated. Efforts to control molecular weight by manipulating initiator concentration while maintaining a 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO):benzoyl peroxide (BPO) molar ratio of 1.2:1 proved unsuccessful. In addition, systematic variations of the TEMPO: BPO molar ratio did not result in narrow molecular weight distributions. In situ Fourier transform infrared spectroscopy (FTIR) indicated that the rate of monomer disappearance under SFRP and thermal conditions were identical. This observation indicated a lack of control in the presence of the stable free radical, TEMPO. The similarities in chemical structure between styrene and 2‐vinylnaphthalene suggested thermally initiated polymerization occurred via the Mayo mechanism. A kinetic analysis of the thermal polymerization of styrene and 2‐vinylnaphthalene suggested that the additional fused ring in 2‐vinylnaphthalene increased the propensity for thermal polymerization. The observed rate constant for thermal polymerization of 2‐vinylnaphthalene was determined using in situ FTIR spectroscopy and was one order of magnitude greater than styrene, assuming pseudo‐first‐order kinetics. Also, an Arrhenius analysis indicated that the activation energy for the thermal polymerization of 2‐vinylnaphthalene was 30 kJ/mol less than styrene. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 583–590, 2002; DOI 10.1002/pola.10131
Isotopically pure uniform polymers: The final step toward true uniformity in macromolecules
Authors: Vogl Otto , Jaycox Gary D. , Simonsick William J. 
Published: August 2002

AbstractComputer‐based calculations were used to simulate the mass spectra for a number of uniform macromolecules having fixed, well‐defined chain lengths. The presence of naturally occurring carbon, hydrogen, oxygen, and halogen isotopes introduced significant levels of mass heterogeneity into these systems. For a given polymer, mass variability was demonstrated to be a function of both the elemental composition and degree of polymerization of the polymer chain. In many cases, these natural variations in mass exceeded the molecular weight of one or more monomeric repeat units along the polymer backbone, effectively blurring the mass distinction between uniform polymer constructs formed from N and N+1 repeat units. The significance of isotopic diversity and its potential impact on the synthesis and physiochemical properties of highly uniform macromolecules is also discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 923–935, 2002
Synthesis and properties of photoluminescent polymers bearing electron‐facilitating oxadiazole derivative side groups
Authors: Kim J. J. , Kim K.‐S. , Baek S. , Kim H. C. , Ree M. 
Published: August 2002

AbstractPoly(p‐divinylene phenylene) derivatives bearing fluorene and carbazole units in the main chain and 5‐phenyl‐1,3,4‐oxadiazole moieties as side groups were prepared by the polycondensation of a newly synthesized monomer, [2‐(5′‐phenyl‐1′,3′,4′‐oxadiazole‐2′‐yl)‐1,4‐xylylene]bis(triphenyl phosphonium bromide) (OXAD), with 9,9‐dibutylfluorene‐2,2′‐dicarbaldehyde (DBFDA) and 9‐(2‐ethylhexyl)carbazole‐3,6‐dicarbaldehyde (EHCDA), which gave DBFDA–OXAD and EHCDA–OXAD. Analogues of these polymers without the side groups were also synthesized by the reaction of 1,4‐xylene bis(triphenyl phosphonium bromide) (PXYL) with the dicarbaldehydes, which gave DBFDA–PXYL and EHCDA–PXYL. All the synthesized polymers are soluble in organic solvents, giving films of good quality. The polymers are stable beyond 375 °C. They emit blue and blue‐green light, and their quantum yields are 38–79% in solution and 1–24% in film, depending on the fluorene and carbazole units as well as the side groups. In particular, the OXAD‐based polymers contain hole‐facilitating backbones and electron‐facilitating side groups, perhaps allowing these polymers to transport both holes and electrons. Overall, the synthesized polymers are potential candidates for the fabrication of light‐emitting devices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1173–1183, 2002
Effects of salts and copolymer composition on the lower critical solution temperature of poly(methyl 2‐acetamidoacrylate‐co‐methyl methacrylate) solutions
Authors: Okamura Hirokazu , Morihara Yasushi , Masuda Seizo , Minagawa Keiji , Mori Takeshi , Tanaka Masami 
Published: August 2002

AbstractCopolymerizations of methyl 2‐acetamidoacrylate (MAA) with methyl methacrylate (MMA) were carried out at 60 °C in chloroform. Copolymers containing MAA units in the range of 83–90 mol % exhibited a lower critical solution temperature (LCST), although homopolymers of MAA and MMA did not. The LCST of polymer solutions decreased with (1) an increase in the concentration of the copolymer, (2) a decrease in the MAA content in the copolymer, and (3) an increase in the concentration of salts added. The effectiveness of anionic species for reducing the LCST is NO < Cl− < SO < SO. Divalent anion is more effective for lowering the LCST than monovalent anion. However, there is no difference between cationic species in the salting‐out effect. Sodium carbonate and sodium phosphate had a salting‐in effect. Salting‐out coefficients were evaluated from the relationship between the logarithm of solubility of the copolymers and the salt concentration. Salting‐out coefficients of the copolymer depended not on the composition of the copolymers but on the salt added. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1945–1951, 2002
Synthesis and characterization of new organosoluble polyamides derived from bis[4‐(4‐carboxyphenoxy) phenyl]diphenylmethane
Authors: Liaw Der‐Jang , Liaw Been‐Yang , Yang Chao‐Min , Hsu Pei‐Nan , Hwang Chieh‐Ying 
Published: August 2002

AbstractA new dicarboxylic acid containing a diphenylmethylene linkage, bis[4‐(4‐carboxyphenoxy)phenyl]diphenylmethane (BCAPD), was prepared from bis(4‐hydroxphenyl)diphenylmethane and p‐fluorobenzonitrile via an aromatic nucleophilic substitution reaction followed by hydrolysis. A series of novel polyamides were prepared by the direct polycondensation of BCAPD and various aromatic diamines. The polymers were produced with moderate to high inherent viscosities of 0.80–0.85 dL g−1. Nearly all the polymers were readily soluble in polar solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide, in less polar solvents such as pyridine and cyclohexanone, and in tetrahydrofuran. All the polymers were amorphous, and the polyamide films had a tensile strength and a tensile modulus greater than 80 MPa and 2.0 GPa, respectively. These polyamides had glass‐transition temperatures between 249 and 274 °C, and their temperatures at a 10% weight loss were 477–538 and 483–540 °C in nitrogen and air atmospheres, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1156–1161, 2001
Synthesis and characterization of new soluble polyamides containing phthalimide pendent group
Authors: Liaw Der‐Jang , Hsu Pei‐Nan , Chen Jao‐Jin , Liaw Been‐Yang , Hwang Chieh‐Ying 
Published: August 2002

AbstractA dicarboxylic acid monomer, 5‐phthalimidoisophthalic acid, containing a phthalimide pendent group was prepared by the condensation of 5‐aminoisophthalic acid and phthalic anhydride in glacial acetic anhydride. The monomer was reacted with various aromatic diamines to produce polyamides using triphenyl phosphite and pyridine as condensing agents. These polyamides were produced with inherent viscosities of 0.64–1.14 dL · g−1. All the polymers, characterized by wide‐angle X‐ray diffraction, revealed an amorphous nature resulting from the presence of the bulky pendent group. These polyamides exhibited excellent solubility in a variety of solvents such as N‐ methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, dimethyl sulfoxide, pyridine, and cyclohexanone. These polyamides showed glass‐transition temperatures (Tg's) between 247 and 273 °C (by DSC) and 248 and 337 °C (by a dynamic mechanical analyzer). The thermogravimetric analytic measurement revealed the decomposition temperature at 10% weight‐loss temperatures (Td10) ranging from 442 to 530 °C in nitrogen. The polyamides containing phthalimide groups exhibited higher Tg and Td10 values than those having no phthalimide groups. Transparent, tough, and flexible films of these polyamides could be cast from the DMAc solutions. These casting films had tensile strengths ranging from 81 to 126 MPa, elongations at break ranging from 7 to 13%, and tensile moduli ranging from 2.0 to 2.9 GPa. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1557–1563, 2001
New biodegradable polymers from renewable sources: Polyester‐carbonates based on 1,3‐propylene‐co‐1,4‐cyclohexanedimethylene succinate
Authors: Liu Yan , Ranucci Elisabetta , Söderqvist Lindblad Margaretha , Albertsson Ann‐Christine 
Published: August 2002

Abstractα,ω‐Dihydroxy‐terminated copolymeric oligomers of a 1,3‐propylene/1,4‐cyclohexanedimethylene succinate structure were obtained by the thermal polycondensation of 1,3‐propanediol/1,4‐cyclohexanedimethanol/succinic acid mixtures. They were subsequently chain‐extended via phosgene synthesis to high molecular weight aliphatic/alicyclic copolyester‐carbonates. These new polymers, besides having a biodegradable backbone, originate from two monomers, namely, 1,3‐propanediol and succinic acid, which can be obtained by renewable sources. Therefore, they have a potential as environmentally friendly materials. All synthesized materials were characterized in reference to their molecular structure by 1H NMR and 13C NMR. Their molecular weights and molecular weight distributions were determined by size exclusion chromatography, and their main thermal properties were measured by DSC. Spectroscopic characterizations were in full agreement with the proposed structures. 1,4‐Cyclohexanedimethanol was used as a diol comonomer to improve the overall thermal properties of poly(1,3‐propylene succinate). The results of the characterization performed show that the initial expectations were only partially satisfied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2508–2519, 2001
Polyethylene‐poly(L‐lactide) diblock copolymers: Synthesis and compatibilization of poly(L‐lactide)/polyethylene blends
Authors: Wang Yunbing , Hillmyer Marc A. 
Published: August 2002

AbstractA model polyethylene‐poly(L‐lactide) diblock copolymer (PE‐b‐PLLA) was synthesized using hydroxyl‐terminated PE (PE‐OH) as a macroinitiator for the ring‐opening polymerization of L‐lactide. Binary blends, which contained poly(L‐lactide) (PLLA) and very low‐density polyethylene (LDPE), and ternary blends, which contained PLLA, LDPE, and PE‐b‐PLLA, were prepared by solution blending followed by precipitation and compression molding. Particle size analysis and scanning electron microscopy results showed that the particle size and distribution of the LDPE dispersed in the PLLA matrix was sharply decreased upon the addition of PE‐b‐PLLA. The tensile and Izod impact testing results on the ternary blends showed significantly improved toughness as compared to the PLLA homopolymer or the corresponding PLLA/LDPE binary blends. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2755–2766, 2001
Swelling of dextran gel and osmotic pressure of soluble dextran in the presence of salts
Authors: Livney Yoav D. , Ramon Ory , Kesselman Ellina , Cogan Uri , Mizrahi Shimon , Cohen Yachin 
Published: August 2002

AbstractThe swelling of dextran gels (Sephadex) in salt solutions with a water activity of 0.937, compared with the swelling in pure water, exhibited anion specificity as evidenced by an increased swelling ratio in the following order: Na2SO4 < H2O < NaCl < NaSCN. The swelling ratio showed a good linear correlation with the osmotic pressure of dextran (500 kD) in these solutions. The salt‐concentration difference (imbalance) between the polymer‐solution side of the membrane and the polymer‐free permeate side during the osmotic‐pressure measurements positively correlated with the effect of the salt on the polymer osmotic pressure. These phenomena conform to Hofmeister‐type (or lyotropic) behavior. The diminishing augmentation of dextran osmotic pressure and the change in the salt‐concentration imbalance with rising NaSCN concentration imply a positive preferential interaction and adsorption of the salt onto the polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2740–2750, 2001
Sorption and diffusion of carbon dioxide in wood‐fiber/polystyrene composites
Authors: Doroudiani Saeed , Chaffey Charles E. , Kortschot Mark T. 
Published: August 2002

AbstractIn this study, sorption and diffusion of carbon dioxide (CO2) in wood‐fiber/polystyrene composites were investigated. The effects of gas pressure and fiber content on the solubility and diffusion coefficients were evaluated. A statistical analysis indicated that pressure is more important than fiber content in determining the solubility and diffusivity of CO2. An increase in saturation pressure causes an increase in the solubility and diffusion coefficients, whereas inclusion of the fibers decreases both of these properties. Models were developed to predict the uptake and diffusion coefficients of CO2 in the composite samples as functions of pressure and fiber content. A theoretical model based on Henry's law and the Langmuir equation compared favorably to the experimental data for CO2 solubility. This dual mode model also described both the transient sorption and desorption data, but only if the concentration‐dependent value of diffusivity was treated as a history‐dependent parameter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 723–735, 2002
Influence of humidity cycling parameters on the moisture‐accelerated creep of polymeric fibers
Authors: Habeger C. C. , Coffin D. W. , Hojjatie B. 
Published: August 2002

AbstractAccelerated creep is a curious and poorly understood transient moisture effect. The creep rates of most hydrophilic materials increase greatly with moisture content. However, when these same materials are subjected to creep loads in cyclic humidity environments, they often exhibit much higher creep rates than in a constantly humid state. This is called accelerated creep. Previous experimenters reported that accelerated creep was less likely to occur in polymeric fibers. We demonstrate experimentally that this happened only because of their choice of humidity cycling parameters. New results are given for Kevlar, lyocell, nylon‐6,6, and ramie fibers. Other paper scientists have argued that the absence of accelerated creep in single fibers supports a explanation based on fiber network effects for accelerated creep in paper. We argue here that accelerated creep is a more general phenomenon consistent with sorption‐induced stress‐gradient explanations. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2048–2062, 2001
Art therapy with adult bone marrow transplant patients in isolation: a pilot study
Authors: Gabriel Bonnie , Bromberg Elissa , Vandenbovenkamp Jackie , Walka Patricia , Kornblith Alice B. , Luzzatto Paola 
Published: August 2002

AbstractPsycho‐social interventions for cancer patients in isolation for bone marrow transplant (BMT) have been advocated in the recent literature. It is not clear what type of interventions would be most appropriate. This study was conducted at Memorial Sloan‐Kettering Cancer Center (MSKCC), with three aims. (1) To test the feasibility of introducing art therapy as a supportive intervention for adult BMT patients in isolation. Nine patients were seen in art therapy sessions twice a week while in isolation, and were helped to develop free personal images. The three art therapists used the same art therapy program as a model. (2) To assess how patients would use the program. Forty‐two images were made by the nine patients during the art therapy sessions. A thematic analysis of the images showed that the patients used art therapy effectively in three ways: (a) to strengthen their positive feelings, (b) to alleviate their distress, and (c) to clarify their existential/spiritual issues. (3) The third aim was to identify which patients would most benefit from art therapy. Our results suggest that the non‐verbal metaphorical modality of art therapy may be especially beneficial for patients who need to deal with emotional conflicts, and with feelings about life and death, in a safe setting. Copyright © 2001 John Wiley & Sons, Ltd.