bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method for grafting poly(acrylic acid) onto nylon 6,6 using amine end groups on nylon surface
Authors: Tobiesen Finn Andrew , Michielsen Stephen 
Published: August 2002

AbstractSeveral methods have been developed for grafting materials to the surface of polymers to alter their surface characteristics. This article reports a procedure for grafting poly(acrylic acid) (PAA) onto nylon 6,6 films via the naturally occurring amine end groups of nylon 6,6 using N‐hydroxy‐succinimide in conjunction with 1‐ethyl‐3‐ (3‐dimethylaminopropyl)carbodiimide hydrochloride (EDC) facilitated amidazation. Reaction conditions were investigated with respect to PAA molecular weight, activator concentrations, reaction temperature, and time. X‐ray photoelectron spectroscopy showed that surface coverage of more than 50% was consistently achieved for 250 kD PAA. The maximum grafting occurred at room temperature with a large excess of EDC with a reaction time of 30 min. The same level of grafting can be achieved using smaller amounts of EDC at 60 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 719–728, 2002; DOI 10.1002/pola.10149
Synthesis and structural analysis of functionalized poly (ϵ‐caprolactone)‐based three‐arm star polymers
Authors: Lang Meidong , Wong Renee Puisan , Chu Chih‐Chang 
Published: August 2002

AbstractHydroxyl‐functionalized three‐arm poly(ϵ‐caprolactone)s (PGCL‐OHs) were synthesized by the ring‐opening polymerization of ϵ‐caprolactone in the presence of glycerol (as the core) and stannous octoate. The effect of the feed ratio of ϵ‐caprolactone to glycerol on the ring‐opening polymerization was studied. These three‐arm PGCL‐OHs were then converted into double‐bond‐functionalized three‐arm poly(ϵ‐caprolactone)s (PGCL‐Mas) by the reaction of PGCL‐OH with maleic anhydride in the melt at 130 °C. The quantitative conversion of hydroxyl functionality was achieved at a low molecular weight. The resulting PGCL‐OH and PGCL‐Ma were characterized with gel permeation chromatography, Fourier transform infrared, 1H NMR, 13C NMR, and differential scanning calorimetry. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1127–1141, 2002
Synthesis and properties of polyimides derived from 9,10‐dialkyloxy‐1,2,3,4,5,6,7,8‐octahydro‐2,3,6,7‐anthracenetetracarboxylic 2,3:6,7‐dianhydrides
Authors: Kim Yong Seok , Jung Jin Chul 
Published: August 2002

AbstractA series of new polyimides containing alicyclic units and alkyloxy side chains were prepared from 9,10‐dialkyloxy‐1,2,3,4,5,6,7,8‐octahydro‐2,3,6,7‐anthracenetetracarboxylic 2,3:6,7‐dianhydrides and various aromatic diamines. Their physical properties and structures were investigated. Polymers were obtained with inherent viscosities of 0.24–0.53 dL/g. In comparison with the aromatic polyimides, most polymers were readily soluble in common organic solvent such as N‐methylpyrrolidone and m‐cresol. These polymers had glass‐transition temperatures between 111 and 296 °C depending on the structure of the repeating unit and 10% weight‐loss temperatures of 418–477 °C in nitrogen. Wide‐angle X‐ray diffractometry for as‐polymerized samples revealed very low crystallinity and layered structures, which were better developed in the polymers with longer side chains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1764–1774, 2002
Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)
Authors: Park Sung‐Young , Park Hee‐Young , Lee Hwa‐Soo , Park Sang‐Wook , Ha Chang‐Sik , Park Dae‐Won 
Published: August 2002

AbstractThis study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001
Star‐shaped fluorescent polypeptides
Authors: Klok Harm‐Anton , Hernández Juan Rodríguez , Becker Stefan , Müllen Klaus 
Published: August 2002

AbstractTwo series of novel, four‐arm, star‐shaped polypeptides were prepared via the ring‐opening polymerization of γ‐benzyl‐L‐glutamate N‐carboxyanhydride and ϵ‐benzyloxycarbonyl‐L‐lysine N‐carboxyanhydride with a tetra‐amino‐substituted perylene fluorophore as the initiator. The removal of the α‐amino acid side‐chain‐protecting groups resulted in unprecedented water‐soluble, perylene‐functionalized, star‐shaped polypeptides that showed strong fluorescence in aqueous solution. One of the features that distinguished these water‐soluble star polypeptides from most other star polymers was that the conformation of the arms could be reversibly changed from a random coil into an α helix by variations in the pH of the aqueous solution. These star polypeptides might be of interest for the development of novel fluorescent probes or as traceable, stimuli‐sensitive molecular containers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1572–1583, 2001
Synthesis and characterization of nonaqueous dispersion particles with photolabile α‐heptadecylphenacyl ester stabilizer chains
Authors: Zhou Chunlin , Winnik Mitchell A. , Jao Tze‐Chi 
Published: August 2002

AbstractWe describe a new method for the synthesis of core–shell photolabile nanoparticles. The synthesis begins with the batch emulsion copolymerization of n‐butyl methacrylate (BMA) and ethylene glycol dimethacrylate to form small (20‐nm‐diameter) crosslinked particles with a narrow size distribution. These seeds are then used for a second‐stage emulsion copolymerizations in which BMA and various polar monomers, including methacrylic acid, are added under monomer‐starved conditions. After characterization of the particles, they are transferred to an N,N‐dimethylformamide solution. The cesium salt of the carboxylic acid groups is reacted with 2‐bromo‐1‐phenyl‐octadecan‐1‐one to convert various fractions of the COOH groups to the corresponding 2‐benzoylheptadecyl ester groups. These aliphatic ester groups render the surface sufficiently hydrophobic that the particles can be dispersed in common aliphatic hydrocarbons solvents to yield colloidal dispersions, sterically stabilized by the dangling aliphatic chains. Ester groups with a phenyl ketone attached to the β‐carbon are photolabile. Irradiation of the particles with UV light detaches the sterically stabilizing chains from the particle and transforms the surface groups back to COOH groups. This leads to flocculation of the particles. The emphasis in this article is on the optimization of the particle synthesis and the characterization of the particles obtained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2642–2657, 2001
Stereospecific and molecular weight‐controlled polymerization of 1,3‐butadiene with Co(acac)3‐MAO catalyst
Authors: Endo Kiyoshi , Hatakeyama Naoyoshi 
Published: August 2002

AbstractThe polymerization of butadiene (Bd) with Co(acac)3 in combination with methylaluminoxane (MAO) was investigated. The polymerization of Bd with Co(acac)3‐MAO catalysts proceeded to give cis‐1,4 polymers (94 – 97%) bearing high molecular weights (40 × 104) with relatively narrow molecular weight distributions (Mw's/Mn's). The molecular weight of the polymers increased linearly with the polymer yield, and the line passed through an original point. The polydispersities of the polymers kept almost constant during reaction time. This indicates that the microstructure and molecular weight of the polymers can be controlled in the polymerization of Bd with the Co(acac)3‐MAO catalyst. The effects of reaction temperature, Bd concentration, and the MAO/Co molar ratio on the cis‐1,4 microstructure and high molecular weight polymer in the polymerization of Bd with Co(acac)3‐MAO catalyst were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2793–2798, 2001
Polyfluorenes: Twenty years of progress
Authors: Leclerc Mario 
Published: August 2002

AbstractPolyfluorenes are an important class of electroactive and photoactive materials. In the last three years this research field has literally exploded because of polyfluorenes' exceptional electrooptical properties for applications in light‐emitting diodes. This is the only family of conjugated polymers that emit colors spanning the entire visible range with high efficiency and low operating voltage. Other unusual optical and electrical properties are made possible with polyfluorene derivatives, such as thermochromism and conducting base‐doped polyelectrolytes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2867–2873, 2001
Synthesis of polyethylene hybrid copolymers containing polyhedral oligomeric silsesquioxane prepared with ring‐opening metathesis copolymerization
Authors: Zheng Lei , Farris Richard J. , Coughlin E. Bryan 
Published: August 2002

AbstractRing‐opening metathesis copolymerizations of cyclooctene and the polyhedral oligomeric silsesquioxane (POSS) monomer 1‐[2‐(5‐norbornen‐2‐yl)ethyl]‐3,5,7,9,11,13,15‐heptacyclopentylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane (POSS–norbornylene) were performed with Grubbs's catalyst, RuCl2(CHPh)(PCy3)2. Random copolymers were formed and fully characterized with POSS loadings as high as 55 wt %. Diimide reduction of these copolymers afforded polyethylene–POSS random copolymers. Thermogravimetric analysis of the polyethylene–POSS copolymers under air showed a 70 °C improvement, relative to a polyethylene control sample of similar molecular weight, in the onset of decomposition temperature based on 5% mass loss. The homopolymer of POSS–norbornylene was also synthesized. This polymer had a rigid backbone according to 1H NMR evidence of broad olefinic signals. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2920–2928, 2001
Synthesis and characterization of alternating copolymers containing triphenylamine as hole‐transporting units
Authors: Li Hongchao , Geng Yanhou , Tong Shuwen , Tong Hui , Hua Rong , Su Guangping , Wang Lixiang , Jing Xiabin , Wang Fosong 
Published: August 2002

AbstractA series of light‐emitting poly(p‐phenylene vinylene)s with triphenylamine units as hole‐transporting moieties in the main chain were synthesized via Wittig condensation in good yields. The newly formed vinylene double bonds possessed a trans configuration, which was confirmed by Fourier transform infrared and NMR spectroscopy. The high glass‐transition temperature (83–155 °C) and high decomposition temperature (>300 °C) suggested that the resulting copolymers possessed high thermal stability. These copolymers, especially TAAPV1, possessed a high weight‐average molecular weight (47,144) and a low polydispersity index (1.55). All the copolymers could be dissolved in common organic solvents, such as tetrahydrofuran (THF), CHCl3, CH2Cl2, and toluene, and exhibited intense photoluminescence in THF (the emission maxima were located from 478 to 535 nm) and in film (from 478 to 578 nm). The low onsets of the oxidation potential (0.6–0.75 V) suggested that the alternating copolymers possessed a good hole‐transporting property due to the incorporation of triphenylamine moieties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3278–3286, 2001
Velocity‐correlation analysis in polymer–solvent mixtures
Authors: Vergara Alessandro , Paduano Luigi , Sartorio Roberto 
Published: August 2002

AbstractThe subject of this article is the combined interpretation of intradiffusion and mutual‐diffusion data for polymer–solvent mixtures in terms of integrals over velocity self‐correlation functions and velocity cross‐correlation functions. The combination of mutual‐diffusion, intradiffusion, and activity data allows the evaluation of velocity‐correlation coefficients (VCCs) and distinct‐diffusion coefficients in systems containing one monodisperse solute. This study is the first attempt to extend these approaches to polymers that are polydisperse solutes. Because of the polydispersity, this correlation analysis may become critical for polymers. Its application to polydisperse samples requires the reduction of intradiffusion and mutual‐diffusion coefficients to the same average. After such a reduction, the VCCs and distinct‐diffusion coefficients are evaluated for a homologous series of poly(ethylene glycol)s (PEGs). Attractive PEG–PEG interactions depend on the chain length and concentration of PEG. In this analysis, network formation in PEG–water systems appears to be a smooth process. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 43–51, 2002
Development of a simultaneous measurement system of x‐ray diffraction and raman spectra: Application to structural study of crystalline‐phase transitions of chain molecules
Authors: Tashiro Kohji , Kariyo Sobiroh , Nishimori Akihito , Fujii Takashi , Saragai Seishi , Nakamoto Shinsuke , Kawaguchi Tatsuya , Maatsumoto Akikazu , Rangsiman Orapin 
Published: August 2002

AbstractThe development of a bench‐top‐type system for simultaneous measurement of X‐ray diffraction and Raman spectra has been made to investigate structural changes in the phase transitions of chain molecules such as polyethylene, n‐alkane, and so forth from various viewpoints. For the X‐ray diffraction measurement an imaging plate or a charge‐coupled device camera was used as a two‐dimensional detector. For the Raman spectral measurement a miniature Raman spectrometer was used with optical fibers for the irradiation of incident laser beams and collection of scattered signals. For example, in the heating process of the n‐C30H62 sample, the phase transition from orthorhombic‐to‐hexagonal lattices could be detected clearly by the X‐ray and Raman measurements. By comparing these two different types of data in detail, an intimate relationship between conformational disordering and rotational motion of molecular chains is detected more clearly than before. Also, similar discussion can be made for the orthorhombic‐to‐hexagonal phase transition of the geometrically constrained polyethylene sample occurring immediately below the melting point. Another example concerns the structural change in the photoinduced solid‐state polymerization of cis,cis‐diethylmuconate single crystal. From the shifts in the X‐ray reflection position and Raman frequency characteristic of the produced polymer, it was found that the molecular deformation of the polymer chains and lattice strain was induced in the early stage of the polymerization reaction. For the ferroelectric‐phase transition of vinylidene fluoride copolymer, the simultaneous measurement was made for collecting triple information of small‐angle and wide‐angle X‐ray scatterings and Raman spectra to know the relationship between the structural change in the crystal lattice and the morphological change in the lamellar stacking mode. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 495–506, 2002; DOI 10.1002/polb.10112
Film‐formation property of vinylidene chloride‐methyl methacrylate copolymer latex. I. Effect of emulsion‐polymerization process
Authors: Sakai Hideki , Kodani Takahiko , Takayama Atsuko , Nomura Mamoru 
Published: August 2002

AbstractChanges in minimum film‐formation temperature (MFFT) during storage of latexes prepared from 91:9 wt % vinylidene chloride (VDC)‐methyl methacrylate (MMA) monomer mixture by seeded batch and seeded semicontinuous emulsion polymerization were investigated, with attention centered on polymer‐crystallization behavior during storage in the dispersed state. MFFT of latex prepared by the seeded batch process rose to 47 °C, whereas that of latex prepared by seeded semicontinuous process remained below 14 °C with storage at 20 °C for 12 weeks. Infrared absorption of latexes in the dispersed state and wide‐angle X‐ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes both indicated a much greater increase in polymer crystallinity during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Analysis of the copolymer composition drift calculated from reactivity ratios and 1H NMR analysis indicated a wider sequence distribution and longer VDC sequences in polymer prepared by the seeded batch process than in polymer prepared by the seeded semicontinuous process. This explained the higher rate of crystallization during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Rising crystallinity during storage in the dispersed state is believed to have caused the MFFT rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 939–947, 2002
Crystal structure and morphology of biaxially oriented polyamide 12 films
Authors: Rhee Sangkeun , White James L. 
Published: August 2002

AbstractThe structural and morphological characteristics of biaxially oriented polyamide 12 films are described on the basis of the results from differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), polarized FT‐IR spectroscopy, and small angle X‐ray scattering (SAXS). The WAXD patterns of the oriented polyamide 12 films indicated only the monoclinic γ crystal with little dimensional changes of its unit cell depending on the stretching conditions. The crystallographic angles (α = γ = 90°, β = 121°) that were determined via the WAXD patterns confirmed the monoclinic symmetry of the γ crystal. Annealing the films stretched at 115 °C in boiling 20% formic acid solution did not result in structural changes of the crystalline unit cell. The chain‐axis repeat distance of 31.9 Å for the γ crystal was experimentally obtained with (0 26 0) planes. It was shortened as compared with that of all‐trans conformation. For films having primary orientation to MD, normals to the basal plane of folded‐chain lamellae were parallel to MD (primary stretch direction) resulting in two‐point SAXS patterns. Growth in long spacing with an increase of stretch temperature was discovered. Annealing the films induced further elongation in long spacing. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1189–1200, 2002
Correlation between digital clubbing and pulmonary function in cystic fibrosis
Authors: Nakamura Craig T. , Ng Gladys Y. , Paton James Y. , Keens Thomas G. , Witmer James C. , Bautista‐Bolduc Daisy , Woo Marlyn S. 
Published: August 2002

AbstractThe correlation between digital clubbing and certain pulmonary function derangements (hypoxemia and FEV1) was previously described. However, the relationship between digital clubbing and other measures of pulmonary function or the presence of liver disease in patients with cystic fibrosis (CF) is poorly defined. Hence we compared the digital clubbing index (CI: ratio of distal phalangeal depth to interphalangeal depth) of 100 patients with CF (43 males, 57 females; mean age, 15.7 ± 7.3 years) with that of 100 age‐ and gender‐matched healthy controls. Digital clubbing was defined as a CI ≥ 1.00 (mean + 2.6 SD; 99% of normal subjects). The CI and its relationship to pulmonary function and to liver disease was then evaluated in the CF patients.Digital clubbing was present in 75/100 (75%) of CF patients but was absent in all controls (P < 0.0001). In CF patients, CI was inversely correlated with PaO2 (r = −0.555; P < 0.001), FEV1 (r = −0.499; P < 0.001), and FEF25–75% (r = −0.404; P < 0.001), and was positively correlated with RV (r = 0.285; P < 0.05) and the slope of phase 3 of single‐breath nitrogen washout (SP3N2) (r = 0.532; P < 0.01). There was no significant correlation between CI and age (r = 0.020; P = 0.84), TLC (r = −0.097; P = 0.34), PaCO2 (r = 0.167; P = 0.10), or history of liver disease (P = 0.08).We conclude that in CF, the degree of digital clubbing is related to degree of hypoxemia, airways obstruction, hyperinflation, and nonuniformity of ventilation. Pediatr Pulmonol. 2002; 33:332–338. © 2002 Wiley‐Liss, Inc.
Serial changes in levels of IL‐6 and IL‐1β in premature infants at risk for bronchopulmonary dysplasia*
Authors: Kazzi S. Nadya J. , Romero Roberto , McLaughlin Kathleen , Ager Joel , Janisse James 
Published: August 2002

AbstractThe aim of this study was to define the inflammatory changes occurring in the lungs of infants at risk for bronchopulmonary dysplasia (BPD) over the first 28 days of life, and to define an optimal strategy for steroids therapy in the prevention of BPD. We measured levels of interleukin‐6 (IL‐6) and interleukin‐1 beta (IL‐1β) in tracheal aspirate (TA) samples and blood of premature infants with severe respiratory distress syndrome RDS (n = 45) on the first day of life prior to initiation of surfactant therapy and on days 5–7, 12–14, 19–21, and 26–28. Levels of IL‐6 and IL‐1β were determined with a commercially available enzyme‐linked immunoassay. Logistic regression analyses were performed in order to examine differences in trends in levels of IL‐6 and IL‐1β between groups of infants. Infants were divided into group I (n = 30, FiO2 ≤ 0.35 at 28 days) and group II (n = 15, FiO2 > 0.35 based on their likelihood of developing BPD at 36 weeks postconceptional age (PCA).The infants were comparable with respect to mean ( ± SEM) birth weight (895 ± 33 g vs. 900 ± 40 g), gestational age (27 ± 0.38 weeks vs. 27 ± 0.54 weeks), and severity of respiratory illness at entry into the study (mean airway pressure: 12 ± 1 cmH2O vs. 12 ± 1 cmH2O, and oxygen index: 15 ± 2 vs. 19 ± 4) (group I vs. group II, respectively). Logistic regression analyses failed to reveal any significant differences in linear trends of levels of IL‐6 and IL‐1β in TA samples between both groups of infants. No particular pattern of change in levels of IL‐6 or IL‐1β could be identified among groups of infants. Levels of IL‐6 and IL‐1β in TA samples on the first day of life failed to predict the need for FiO2 > 0.35 at 28 days of age.We could not identify an increasing trend or a specific pattern of changes in postnatal levels of IL‐6 or IL‐1β in TA samples of infants who were at greater risk of developing BPD at 36 weeks PCA compared to infants who were not. Pediatr Pulmonol. 2001; 31:220–226. © 2001 Wiley‐Liss, Inc.