bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of phenol and derivatives on atom transfer radical polymerization in the presence of air
Authors: Gnanou Yves , Hizal Gürkan 
Published: December 2003

AbstractThe various phenolic compounds in conjunction with Cu(II) or Cu(I)‐N,N,N′,N″,N″‐pentamethyl diethylenetriamine (PMDETA) complexes are used to initiate atom transfer radical polymerization (ATRP) of methyl methacrylate, styrene, and methyl acrylate in the presence of a limited amount of air at temperatures in the range of 80–110 °C. Meanwhile, an effort is directed toward the elucidation of the role of phenol and derivatives in ATRP catalyzed by Cu(II)/PMDETA. The catalytic sequence involves the formation of Cu(I) by electron transfer from phenol to Cu(II); Cu(I) so formed can then react in two distinctly different ways: with organic halide to form a propagating radical or with oxygen to form copper salt in its higher oxidation state; and regeneration of Cu(I) by excess phenol. Such regeneration of Cu(I) would be expected to lead to polymerization as a result of the consumption of oxygen and phenol as well. The phenols with electron releasing groups tended to increase the conversion of the polymerization. In this respect, sodium phenoxide, a more effective additive was found, whereas p‐nitro phenol was the least effective. The obtained polymers displayed the common features of a controlled polymerization such as molecular weight control and low polydispersity index value (Mw/Mn < 1.5). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 351–359, 2004
UV grafting of methacrylic acid and acrylic acid on high‐density polyethylene in different solvents and the wettability of grafted high‐density polyethylene. II. Wettability
Authors: Wang Huiliang , Brown Hugh R. 
Published: December 2003

AbstractThe wettability of high‐density polyethylene grafted with methacrylic acid is strongly influenced by the nature of the grafting solvent. Here, the wettability is expressed by the water contact angle and absorbency. The initial (10‐s) contact angle of polyethylene (PE) grafted in acetone/water solution decreased rapidly with the extent of grafting at low grafting levels and then remained independent of the grafting level at about 50°. When a water droplet was left on the surface for a longer time, its contact angle decreased to a very low value in the period of about 10 min. For the PE samples grafted in dichloromethane, petroleum ether, cyclohexane, and chloroform, there was only a small decrease (10°) in the contact angle of water from that observed on pure PE, even when the extent of grafting was very large. The PE films grafted in these organic solvents also took a much longer time than PE films grafted in acetone/ water solution to obtain equilibrium water absorbency. The water absorbency of PE films grafted in 30% acetone/water solution was about twice that of PE films grafted in the other solvents at the same extent of grafting. These results suggested that for the solvents other than acetone/water, the grafted layer is partially buried below the surface of PE. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 263–270, 2004
Synthesis and properties of organosoluble polyimides based on 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone
Authors: Yang Chin‐Ping , Su Yu‐Yang 
Published: December 2003

AbstractA novel, fluorinated diamine monomer with the ether–ketone group, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone (2), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 4,4′‐dihydroxybenzophenone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Flourinated polyimides (PIs) 5a–f and copolyimides (co‐PIs) 5c/a–f were synthesized from 2 and various commercial aromatic dianhydrides via thermal or chemical imidization. PIs 5a–f had inherent viscosities ranging from 0.72 to 1.22 dL/g. Besides the chemical imidization of 5c(C), the 5(C) series were soluble in amide‐type solvents and even in less polar solvents, but PIs 5a–f prepared via thermal imidization were insoluble. PI films 5a–f exhibited tensile strengths ranging from 92 to 112 MPa, elongations at break from 8 to 15%, and initial moduli from 2.0 to 2.1 GPa. The glass‐transition temperatures of the 5 series were in the range of 232–278 °C, and the 10% weight‐loss temperatures were above 535 °C, with more than a 50% char yield at 800 °C in nitrogen. In comparison of the PI 5 series with the analogous non‐fluorinated PIs 6 series based on 4,4′‐bis(4‐aminophenoxy)benzophenone, the 5 series revealed better solubility, lower color intensity, dielectric constant, and moisture absorption. Their PI films had cutoff wavelengths between 370 and 410 nm, b* values ranging from 9.6 to 58.3, dielectric constants of 3.05–3.64 (1 MHz), with moisture absorption in the range of 0.08–0.38 wt %. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 222–236, 2004
Self‐organized liquid‐crystalline polyethers obtained by grafting tapered mesogenic groups onto poly(epichlorohydrin): Toward biomimetic ion channels 2
Authors: Ronda Joan Carles , Reina José Antonio , Giamberini Marta 
Published: December 2003

AbstractA set of high‐molecular‐weight, new, side‐chain liquid‐crystalline polyethers was obtained by chemical modification of poly(epichlorohydrin) with potassium 3,4,5‐tris[4‐(n‐dodecan‐1‐yloxy)benzyloxy]benzoate. The degree of modification depended on the reaction conditions and ranged from 39 to 58%. The highest value was an apparent modification plateau. NMR characterization indicated no side reactions of any kind (e.g., deshydrohalogenation). All random‐grafted copolymers had hexagonal columnar mesophases with the exception of the least modified copolymer, which had a nematic columnar mesophase. X‐ray diffraction experiments performed on mechanically oriented samples showed that tapered groups were tilted with respect to the column axes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 326–340, 2004
Ultraviolet grafting of methacrylic acid and acrylic acid on high‐density polyethylene in different solvents and the wettability of grafted high‐density polyethylene. I. Grafting
Authors: Wang Huiliang , Brown Hugh R. 
Published: December 2003

AbstractMethacrylic acid (MAA) and acrylic acid (AA) were grafted onto high‐density polyethylene (PE) with UV initiation and a range of solvents. With acetone as the solvent, MAA was more easily grafted onto PE when the photoinitiator benzophenone was precoated on PE than when it was dissolved in the monomer solution. The grafting was faster in aliphatic solvents than in polar solvents or a UV‐adsorbing aromatic solvent (toluene). Acetone itself could initiate the photografting of both MAA and AA onto PE when it was mixed with water. The extent of grafting of MAA onto PE showed a maximum when there was about 40% acetone in the mixture. For AA, when the acetone/water concentration was 10%, the extent of grafting increased rapidly with the irradiation time. At higher acetone concentrations, the extent of grafting was low. Atomic force microscopy images showed that the surface topography of PE grafted with MAA in acetone/water was quite different from that obtained when the grafting was performed in other organic solvents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 253–262, 2004
Polymeric ruthenium bipyridine complexes: New potential materials for polymer solar cells
Authors: Marin Veronica , Holder Elisabeth , Schubert Ulrich S. 
Published: December 2003

AbstractMethyl methacrylate‐containing bipyridine monomers were synthesized with a hydoxy‐functionalized bipyridine. The 4′‐methyl group of the 2,2′‐bipyridine was used to introduce hydoxy‐functionalized alkyl spacers of two different lengths. Two, different synthetic routes were applied for the preparation of the hydoxy‐functionalized bipyridineviaa bromo‐(C7spacer) or a silylated‐(C3spacer) intermediate. A copolymer of poly(methyl methacrylate) with bipyridine units in the side chains was prepared by free‐radical copolymerization and characterized with1H NMR, ultraviolet–visible, and IR spectroscopy as well as gel permeation chromatography. The bipyridine units of the copolymer were reacted with ruthenium bipyridine precursors. The resulting graft copolymers displayed promising photophysical and electrochemical properties, opening interesting perspectives for applications in the field of solar‐cell devices. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 374–385, 2004
Asymmetric polymerization using C1 resources
Authors: Nozaki Kyoko 
Published: December 2003

AbstractTwo examples of asymmetric alternating copolymerization, (1) the alternating copolymerization of α‐olefins (monosubstituted ethenes) with carbon monoxide and (2) the alternating copolymerization of meso‐epoxide with carbon dioxide, are described, and the meaning of chirality in polymer synthesis is emphasized. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 215–221, 2004
Anisotropic elastic moduli and Poisson's ratios of a poly(ethylene terephthalate) film
Authors: Zhang S. L. , Li J. C. M. 
Published: December 2003

AbstractExpressions for the directional dependence of Young's modulus and Poisson's ratio were derived for a general material under plane‐stress conditions. Experiments with a laser extensometer to measure the Young's modulus and Poisson's ratio directly by a tension test are described, and the results are compared with the theoretical expressions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 260–266, 2004
Effect of supercritical carbon dioxide on the crystallization and melting behavior of linear bisphenol A polycarbonate
Authors: Liao Xia , Wang Jin , Li Gang , He Jiasong 
Published: December 2003

AbstractThe crystallization and melting behavior of bisphenol A polycarbonate treated with supercritical carbon dioxide (CO2) has been investigated with differential scanning calorimetry. Supercritical CO2 depresses the crystallization temperature (Tc) of polycarbonate (PC). The lower melting point of PC crystals increase nonlinearly with increasing treatment temperature. This indicates that the depression of Tc is not a constant at the same pressure. Tc decreases faster at a higher treatment temperature than at a lower temperature. The leveling off of the depression in Tc at higher pressures is due to the antiplasticization effect of the hydrostatic pressure of CO2. The melting curves of PC show two melting endotherms. The lower melting peak moves to a higher temperature with increasing treatment temperature, pressure, and time. The higher temperature peak moves toward a higher temperature as the treatment temperature is increased, whereas this peak is independent of the treatment pressure, time, and heating rate. The double melting peaks observed for PC can be attributed to the melting of crystals with different stability mechanisms. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 280–285, 2004
Optical and electroluminescent properties of novel poly(aryl ether)s with isolated carbazole and p‐quaterphenyl fluorophores
Authors: Chen Yun , Hwang Shiao‐Wen , Chen Shinn‐Horng 
Published: December 2003

AbstractWe report the optical and electroluminescent properties of four novel poly(aryl ether)s (P1–P4) consisting of alternate isolated hole‐transporting [carbazole or 3,6‐bis(styryl)carbazole] and electron‐transporting [dicyano‐p‐quaterphenyl or bis(trifluoromethyl)‐p‐quaterphenyl] fluorophores. The photoluminescence (PL) spectra of the four polymeric films show maximum peaks around 407–413 nm for P1, P2 and 442–447 nm for P3, P4. The PL spectra of P1∼P4 are dependent on the composition of the two isolated fluorophores. According to the observation of relative quantum yield in poor solvent (cyclohexane), P2 containing more bulky trifluoromethyl groups in p‐quaterphenyl segments prevented aggregate quenching processes more than P1. Compared with P1 and P2 with carbazole segments, P3 and P4 with 3,6‐bis(styryl)carbazole segments exhibited less interchain interaction and a low threshold electric field in a single‐layer device. The p‐quaterphenyl and carbazole [or 3,6‐bis(styryl)carbazole] segments were regarded as electron‐transporting and hole‐transporting units, respectively, in the single‐layer light‐emitting diodes (Al/P1–P4/ITO). In the double‐layer device (ITO/MEH‐PPV/P2/Al), the maximum luminance was doubled, and the threshold electric fields diminished because P2 functioned as an electron‐transporting and hole‐blocking layer. Furthermore, the voltage‐tunable multicolor emission from orange to green was observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 333–340, 2004
Characterization of photoresists for ArF‐excimer laser lithography using monoenergetic positron beams
Authors: Uedono A. , Ohdaira T. , Suzuki R. , Mikado T. , Fukui S. , Kimura S. , Miyamoto H. , Nemoto H. 
Published: December 2003

AbstractThe volume and depth distributions of open spaces in photoresist films designed for ArF‐excimer laser light exposure were studied with monoenergetic positron beams. We measured the Doppler broadening spectra of the annihilation radiation and lifetime spectra of positrons for acrylate and cyclic olefin‐co‐maleic anhydride (COMA) polymers spin‐coated onto Si wafers with methyl amyl ketone, cyclohexanone, and propylene glycol methyl ether acetate solvents. The volume of open spaces in both prebaked acrylate and COMA films was estimated to be 0.12 nm3. The volume of open spaces in acrylate films decreased up to 20% by postexposure baking, but no large change was observed for COMA films. The decrease in the open volume was attributed to the removal of large molecules (adamantyl) from flexible main chains after the chemically amplified reaction of acrylate. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 341–346, 2004
Pressure and temperature dependence of the gas‐transport properties of dense poly[2,6‐toluene‐2,2‐bis(3,4‐dicarboxylphenyl)hexafluoropropane diimide] membranes
Authors: Chung Tai‐Shung , Cao Chun , Wang Rong 
Published: December 2003

AbstractThe gas‐transport properties of poly[2,6‐toluene‐2,2‐bis(3,4‐dicarboxylphenyl)hexafluoropropane diimide] (6FDA‐2,6‐DAT) have been investigated. The sorption behavior of dense 6FDA‐2,6‐DAT membranes is well described by the dual‐mode sorption model and has certain relationships with the critical temperatures of the penetrants. The solubility coefficient decreases with an increase in either the pressure or temperature. The temperature dependence of the diffusivity coefficient increases with an increase in the penetrant size, as the order of the activation energy for the diffusion jump is CH4 > N2 > O2 > CO2. Also, the average diffusion coefficient increases with increasing pressure for all the gases tested. As a combined contribution from sorption and diffusion, permeability decreases with increases in the pressure and the kinetic diameter of the penetrant molecules. Even up to 32.7 atm, no plasticization phenomenon can be observed on flat dense 6FDA‐2,6‐DAT membranes from their permeability–pressure curves. However, just as for other gases, the absolute value of the heat of sorption of CO2 decreases with increasing pressure at a low‐pressure range, but the trend changes when the feed pressure is greater than 10 atm. This implies that CO2‐induced plasticization may occur and reduce the positive enthalpy required to create a site into which a penetrant can be sorbed. Therefore, a better diagnosis of the inherent threshold pressure for the plasticization of a glassy polymer membrane may involve examining the absolute value of the heat of sorption as a function of pressure and identifying the turning point at which the gradient of the absolute value of the heat of sorption against pressure turns from a negative value to a positive one. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 354–364, 2004
Preparation of the polymer–clay nanocomposites in exfoliated state by interface stabilization
Authors: Lee Sang‐Soo , Kim Junkyung 
Published: December 2003

AbstractTo suppress the repulsive interfacial energy between hydrophilic clay and a hydrophobic polymer matrix for polymer–clay nanocomposites, a third component of amphiphilic nature such as poly(ϵ‐caprolactone) (PCL) was introduced into the styrene–acrylonitrile copolymers (SAN)/Na‐montmorillonite system. Once ϵ‐caprolactone was polymerized in the presence of Na‐montmorillonite, the successful ring‐opening polymerization of ϵ‐caprolactone and the well‐developed exfoliated structure of PCL/Na‐montmorillonite mixture were confirmed. Thereafter, SAN was melt‐mixed with PCL/Na‐montmorillonite nanocomposite, and the SAN matrix and PCL fraction were completely miscible to form a homogeneous mixture with retention of the exfoliated state of Na‐montmorillonite, exhibiting that PCL effectively stabilizes the repulsive polymer–clay interface and contributes to the improvement of the mechanical properties of nanocomposites. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 246–252, 2004
Structure and properties of the mesophase of syndiotactic polystyrene—III. Selective sorption of the mesophase of syndiotactic polystyrene
Authors: Mohri S. , Rani D. Amutha , Yamamoto Y. , Tsujita Y. , Yoshimizu H. 
Published: December 2003

AbstractSyndiotactic polystyrene (sPS) has various crystalline forms such as α, β, γ, and δ forms, and a mesophase depending on the preparation method. In this study, we focused on the mesophase with the molecular cavity of sPS, which is obtained by step‐wise extraction of the guest molecules from the sPS δ form. To prepare the mesophase containing different shapes and sizes of the cavity, two kinds of the sPS δ form membrane cast from either toluene or chloroform solution were first prepared and then the guest molecules were removed by a step‐wise extraction method using acetone and methanol. We could succeed in the preparation of two kinds of mesophase with different shapes and sizes of the molecular cavity. Either toluene or chloroform vapor sorption to the sPS mesophase membranes was examined at 25 °C. Sorption analysis indicates that the mesophase with large molecular cavities can mainly sorb large molecules; on the other hand, the mesophase with small cavities can sorb only the small molecules, and is unable to sorb a large amount of large molecule because the cavity was too small to sorb the large molecules. Therefore, the sPS mesophase membrane has sorption selectivity based on the size of the molecular cavity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 238–245, 2004
Comparison of active cycle of breathing and high‐frequency oscillation jacket in children with cystic fibrosis
Authors: Phillips Gillian E. , Pike Sarah E. , Jaffé Adam , Bush Andrew 
Published: December 2003

AbstractHigh‐frequency chest compressions (HFCC) have been suggested as an alternative to conventional chest physiotherapy to aid sputum clearance in patients with cystic fibrosis (CF). We aimed to compare the active cycle of breathing techniques (ACBT) with the Hayek Oscillator Cuirass, performing HFCC on secretion clearance in children with CF during an exacerbation. Ten children (7 males; median age, 14 years; range, 9–16) received either two supervised sessions using HFCC or two self‐treatment ACBT sessions in random order on successive days. Baseline pulmonary function was similar prior to treatments. Sputum weight increased significantly with ACBT compared with HFCC during treatment (5.2 g vs. 1.1 g, P < 0.005, morning; 4.1 g vs. 0.7 g, P < 0.01, afternoon). Pulmonary function improved significantly after morning ACBT (forced vital capacity (FVC): 2.67 l to 2.76 l, P < 0.03; forced expiratory volume in 1 sec (FEV1): 1.59 l to 1.62 l, P < 0.03). Following afternoon ACBT, there was a significant increase in FVC (2.64 to 2.79, P < 0.02), but no significant change in FEV1. Pulmonary function did not change at any time following HFCC. Compared with ACBT, HFCC by Hayek Cuirass is not an effective airway clearance treatment modality for children with CF during an infective exacerbation. Pediatr Pulmonol. 2004; 37:71–75. © 2004 Wiley‐Liss, Inc.
Lower airway obstruction, bronchial hyperresponsiveness, and primary pulmonary hypertension in children
Authors: Rastogi Deepa , Ngai Pakkay , Barst Robyn J. , Koumbourlis Anastassios C. 
Published: December 2003

AbstractWe investigated the prevalence and reversibility of lower airway obstruction (LAO) and its correlation with pulmonary artery pressure in children with primary pulmonary hypertension (PPH). The analysis was performed retrospectively in a cohort of children with PPH between 5–18 years of age. PPH was defined as mean pulmonary artery pressure (PAPm) >25 mmHg at rest, or >30 mmHg during exercise, with normal pulmonary capillary wedge pressure in the absence of other causes. Lower airway function was assessed by spirometry and maximal expiratory flow‐volume curves. Lung volumes were measured by body plethysmography. Patients were assigned according to their pattern of lung function into “normal,” “obstructive,” and “restrictive” groups. The reversibility of LAO was defined as an increase of ≥15% from baseline in forced expiratory volume at 1 sec (FEV1) and/or ≥20% in forced expiratory flow at 25–75% of forced vital capacity (FEF25–75%) in response to nebulized albuterol. An “obstructive” pattern was found in 23 children (59%), a “restrictive” pattern in 2 children (5%), and a “normal” pattern in 14 children (36%). Response to bronchodilator was documented in 78% of children with an “obstructive” pattern and in 22% of those with a “normal” pattern. The PAPm showed a significant positive correlation with the TLC, RV, and RV/TLC, but a negative one with the ratio FEV1/FVC. Our findings suggest that reversible LAO is the most common lung function abnormality among pediatric patients with PPH. Whether airway reactivity is a cause of or the result of PPH remains to be determined. Pediatr Pulmonol. 2004; 37:50–55. © 2004 Wiley‐Liss, Inc.
Airway resistance by the interrupter technique: Which algorithm for measuring pressure?
Authors: Pao C.S. , Healy M.J.R. , McKenzie S.A. 
Published: December 2003

AbstractAirway resistance using the interrupter technique (Rint) can be measured using commercial devices which employ different algorithms for estimating pressure change. We aim to describe differences in Rint due to algorithm. We compared Rint and change in Rint after bronchodilator, using four algorithms to estimate pressure change following interruption: 1) two‐point back‐extrapolation to interruption from points 70 msec and 30 msec from interruption, and similarly 2) to 15 msec from interruption, 3) at two‐thirds from interruption, and 4) near end‐interruption. Flow was measured immediately before interruption. Our subjects were 39 asymptomatic children 2–5 years old with previous intermittent wheeze. Rint differed significantly with algorithm. Geometric mean Rint (95% confidence interval (CI)) for algorithms 1–4 were 1.21 kPa · l−1 · sec (1.18–1.24 kPa · l−1 · sec), 1.31 kPa · l−1 · sec (1.28–1.34 kPa · l−1 · sec), 1.57 kPa · l−1 · sec (1.54–1.61 kPa · l−1 · sec) and 1.71 kPa · l−1 · sec (1.67–1.75 kPa · l−1 · sec), respectively. Measurement of change in Rint following bronchodilator (BDR) did not differ on average with algorithm. Geometric means (95% CI) for BDR measurements for algorithms 1–4 were 29.9% (26.0–34.0%), 30.4% (26.4–34.5%), 32.9% (28.8–37.1%), and 31.7% (27.6–35.8%), respectively. However, measurement of change in individuals could differ by up to 40%, depending on algorithm. In conclusion, there are significant differences in Rint, depending on algorithm used to estimate pressure change. Measurement of change in Rint is unaffected on average, although in individuals there could be significant differences. Each laboratory should state its method and use the same algorithm for longitudinal and group data. Pediatr Pulmonol. 2004; 37:31–36. © 2004 Wiley‐Liss, Inc.