bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Characterization and Preliminary Biological Evaluation of P(HPMA)‐b‐P(LLA) Copolymers: A New Type of Functional Biocompatible Block Copolymer
Authors: Barz Matthias , Wolf Florian K. , Canal Fabiana , Koynov Kaloian , Vicent Maria J. , Frey Holger , Zentel Rudolf 
Published: June 2010

AbstractWe describe a synthetic pathway to functional P(HPMA)‐b‐P(LLA) block copolymers. The synthesis relies on a combination of ring‐opening polymerization of L‐lactide, conversion into a chain transfer agent (CTA) for the RAFT polymerization of pentafluorophenyl methacrylate. A series of block copolymers was prepared that exhibited molecular weights $\overline M _{\rm n}$ ranging from 7 600 to 34 300 g · mol−1, with moderate PDI between 1.3 and 1.45. These reactive precursor polymers have been transformed into biocompatible P(HPMA)‐b‐P(LLA) copolymers and their fluorescently labeled derivatives by facile replacement of the pentafluorophenyl groups. The fluorescence label attached to this new type of a partially degradable amphiphilic block copolymer was used to study cellular uptake in human cervix adenocarcinoma (HeLa) cells as well as aggregation behavior by fluorescence correlation spectroscopy (FCS).magnified image
Conformational Behavior of Bottle‐Brush Polyelectrolytes with Charged and Neutral Side Chains
Authors: Cao Qianqian , Zuo Chuncheng , Li Lujuan , Zhang Nan 
Published: June 2010

AbstractThe conformational transition of a single bottle‐brush polyelectrolyte with charged and neutral side chains is studied through MD simulations. Counterions are included explicitly and no additional salt is added. The structure of the polyelectrolyte and the counterion condensation are found to depend greatly on the Bjerrum length. As the Bjerrum length increases, the neutral side chains in a poor solvent can condense into clusters with variable size. Moreover, the polyelectrolyte forms globular structures at large or very small Bjerrum lengths. This transition is quite different from that in the case of a good solvent, in which there are not observable clusters and a globular structure is only formed at large Bjerrum lengths.magnified image
Thermally curable polyurethanes containing naphthoxazine groups in the main chain
Authors: Yeganeh Hamid , Jangi Abolfazl 
Published: June 2010

AbstractA new methodology has been developed for the modification of polyurethanes with reactive naphthoxazine moieties in order to expand their industrial applicability as electrical insulators. Thermoplastic and organosoluble poly(urethane‐co‐naphthoxazine)s were prepared by the reaction of NCO‐terminated urethane prepolymers made from various soft segments with a naphthoxazine‐containing diol chain extender. The prepared polymers were easily processed into thin films using either solution casting or compression moulding techniques. Heat treatment of these films under optimized conditions (200 °C for 30 min) led to the thermally activated ring‐opening polymerization of naphthoxazine moieties, and consequently crosslinked networks were obtained. All of the starting materials and the final polymeric compounds were fully characterized using spectroscopic methods and their physical and chemical properties evaluated and then correlated with their chemical structures. Due to their good elongation property (up to 70% elongation at break) in comparison to polynaphthoxazines, significant enhancement in decomposition temperature as well as high value of dielectric breakdown strength (up to 30 kV mm−1) in comparison to polyurethanes, these materials are potentially applicable as electrical insulators with service temperatures higher than those for related unmodified polyurethanes. Copyright © 2010 Society of Chemical Industry
pH responsive surfaces with nanoscale topography
Authors: Bousquet Antoine , Ibarboure Emmanuel , Teran Francisco J. , Ruiz Leire , Garay María Teresa , Laza José Manuel , Vilas José Luis , Papon Eric , Rodríguez‐Hernández Juan 
Published: June 2010

AbstractWe report the preparation of nanostructured adaptive polymer surfaces by diffusion of an amphihilic block copolymer toward the interface. The surface segregation of a diblock copolymer, polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA), occurred when blended with high molecular weight polystyrene employed as a matrix. On annealing, the polymer surfaces changed both the chemical composition and the hydrophilicity depending on the environment and pH, respectively. By exposure to either water vapor or air, the surface wettability varied between hydrophilic and hydrophobic. In addition, surface enrichment on diblock copolymer by water vapor annealing led to self‐assembly occurring at the interface. Hence, nanostructured domains can be observed by AFM in liquid media. Moreover, the PAA segments placed at the interface respond to pH and can switch from an extended hydrophilic state at basic pH values to a collapsed hydrophobic state in acidic media. Accordingly, the surface morphology changed from swelled micelles to nanometer size holes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2982–2990, 2010
Investigation of nitroxide radical coupling reaction in wide temperature range and different catalyst system
Authors: Lin Wencheng , Huang Bing , Fu Qiang , Wang Guowei , Huang Junlian 
Published: June 2010

AbstractThe effect of temperature, catalyst system, and the structure of bromine connected groups on the nitroxide radical coupling (NRC) reaction is investigated in details. A series of polymers with different bromine connected groups as poly (tert‐butyl acrylate) (PtBA‐Br), polystyrene (PS‐Br), and poly (methyl methacrylate) (PMMA‐Br) are prepared by atom transfer radical polymerization first, then the bromine‐containing polymers were coupled with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy‐containing poly(ε‐caprolactone) (PCL‐TEMPO) in different catalyst systems as CuBr/PMDETA, Cu0/PMDETA and CuBr/Cu0/PMDETA in the temperature range from 90 °C to 25 °C. The result shows that the catalyst system of CuBr/Cu0/PMDETA is the best one for NRC reaction, in which the NRC reaction could be conducted in high efficiency in the wide temperature range from room temperature to high temperature. The efficiency of NRC reaction between PtBA‐Br and PCL‐TEMPO is more than 85% in the temperature range from 25 to 75 °C, the efficiency between PS‐Br and PCL‐TEMPO is more than 90% from 25 to 90 °C, and the efficiency between PMMA‐Br and PCL‐TEMPO is more than 90% only at the room temperature. The effect of bromine connected groups on the NRC reaction is discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2991–2999, 2010
Synthesis and characterization of a hyperbranched hydrogen bond acidic carbosilane sorbent polymer
Authors: Higgins Bernadette A. , Simonson Duane L. , Houser Eric J. , Kohl James G. , Mcgill R. Andrew 
Published: June 2010

AbstractSorbent polymers can be designed to target molecular interactions with a variety of hazardous chemicals including explosives, chemical agents, narcotics, and toxic industrial chemicals. Applications of functionalized sorbent polymers include preconcentrator devices, SPME fibers, membrane introduction systems, chromatographic stationary phases and coatings for chemical sensors. One common feature of a wide range of hazardous chemicals is their hydrogen bond (h‐b) basicity. In this work, we report on the synthesis and characterization of a h‐b acidic hyperbranched carbosilane fluoroalcohol based sorbent polymer (poly(methyldi(1,1,1‐trifluoro‐2‐trifluoromethyl‐2‐hydroxypent‐4‐enyl)silane; HCSFA2), which is suitable for sorbing these hazardous h‐b basic analytes. Multiple batches of HCSFA2 were characterized with routine composition, spectroscopic, thermal analysis, and inverse gas chromatography (iGC) to evaluate polymer physicochemical properties. In comparison with previously developed h‐b acidic polymers (e.g., FPOL and SXFA), HCSFA2 exhibits a sorption improvement of 10–15 fold for h‐b basic analytes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3000–3009, 2010
One‐step synthesis of hyperbranched polyethylene macroinitiator and its block copolymers with methyl methacrylate or styrene via ATRP
Authors: Wang Wen‐Jun , Liu Pingwei , Li Bo‐Geng , Zhu Shiping 
Published: June 2010

AbstractBlock copolymers of hyperbranched polyethylene (PE) and linear polystyrene (PS) or poly(methyl methacrylate) (PMMA) were synthesized via atom transfer radical polymerization (ATRP) with hyperbranched PE macroinitiators. The PE macroinitiators were synthesized through a “living” polymerization of ethylene catalyzed with a Pd‐diimine catalyst and end‐capped with 4‐chloromethyl styrene as a chain quenching agent in one step. The macroinitiator and block copolymer samples were characterized by gel permeation chromatography, 1H and 13C NMR, and differential scanning calorimetry. The hyperbranched PE chains had narrow molecular weight distribution and contained a single terminal benzyl chloride per chain. Both hyperbranched PE and linear PS or PMMA blocks had well‐controlled molecular weights. Slow initiation was observed in ATRP because of steric effect of hyperbranched structures, resulting in slightly broad polydispersity index in the block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3024–3032, 2010
Bis(β‐enaminoketonato) vanadium (III or IV) complexes as catalysts for olefin polymerization
Authors: Wu Ji‐Qian , Li Bai‐Xiang , Zhang Sen‐Wang , Li Yue‐Sheng 
Published: June 2010

AbstractBis(β‐enaminoketonato) vanadium(III) complexes (2a–c) [O(R1)CC(H)xC(R2)NC6H5]2VCl(THF) and the corresponding vanadium(IV) complexes (3a–c) [O(R1)CC(H)xC(R2) NC6H5]2VO (R1 = (CH2)4, R2 = H, x = 0, a; R1 = C6H5, R2 = H, x = 1, b; R1 = C6H5, R2 = C6H5, x = 1, c) have been synthesized from VCl3(THF)3 and VOCl2(THF)2, respectively, by treating with 2.0 equivalent β‐enaminoketonato ligands in tetrahydrofuran. Structures of 2b and 3a–c were further confirmed by X‐ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et2AlCl. Complexes 2a–c and 3a–c exhibited high catalytic activities (up to 23.76 kg of PE/mmolV h bar), and afforded polymers with unimodal molecular weight distributions at 70 °C indicating the good thermal stability. The catalytic behaviors were influenced not only by the oxidation state of the catalyst precursors but also by the ligand structures. Complexes 2a–c and 3a–c were also effective catalyst precursors for ethylene/1‐hexene copolymerization. The influence of polymerization parameters such as reaction temperature, Al/V molar ratio and hexene feed concentration on the ethylene/hexene copolymerization behaviors have bee also investigated in detail. In addition, the agents such as AlMe3, AliBu3, MeMgBr, MgCl2, and ZnEt2 were applied to control the molecular weight and molecular weight distribution modal. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3062–3072, 2010
Synthesis and properties of cationic polyelectrolyte with regioregular polyalkylthiophene backbone and ionic‐liquid like side groups
Authors: Bondarev Dmitrij , Zedník Jiří , Šloufová Ivana , Sharf Ahmed , Procházka Marek , Pfleger Jiří , Vohlídal Jiří 
Published: June 2010

AbstractHigh‐regioregular poly{3‐[6‐(1‐methylimidazolium‐3‐yl)hexyl]thiophene‐2,5‐diyl bromide}, PMHT‐Br, has been prepared by reaction of high‐regioregular (above 92%) poly[3‐(6‐bromohexyl)thiophene‐2,5‐diyl] with 1‐methylimidazole. PMHT‐Br is soluble in water and water miscible solvents such as methanol, DMSO and shows solvatochromism; λmax (nm): 423 (H2O); 435 (MeOH); 452 (DMSO). Increased absorption band broadening observed for aqueous solution as well as NMR spectra in D2O suggests a micelle‐like structure of PMHT‐Br molecules in these solutions: poly(3‐hexylthiophene) core and 1‐methylimidazolium bromide shell. Despite the disturbing effect of ionic groups, the solid‐state PMHT‐Br shows absorption maximum at 520 nm, the band edge at 660 nm (ca. 1.9 eV), and fluorescence emission with maximum at 635 nm, in a good agreement with the polymer regioregularity. Fluorescence emission maxima: λem (nm): 598 (H2O); 562 (MeOH); 574 (DMSO), occur in a vicinity of corresponding adsorption band edges. Plot of electrical conductivity of PMHT‐Br (measured under the dynamic vacuum conditions, 5 × 10−5 Pa) versus 1/T shows a break at about 70 °C same as the temperature dependence of λmax of the solid PMHT‐Br. These breaks indicate an increase in the mobility of polymer segments and ions within PMHT‐Br; however, a thermal analysis did not provide solid evidence for it. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3073–3081, 2010
Multiple micellar morphologies from tri‐ and tetrablock copoly(2‐oxazoline)s in binary water–ethanol mixtures
Authors: Fustin Charles‐André , Thijs‐Lambermont Hanneke M. L. , Hoeppener Stephanie , Hoogenboom Richard , Schubert Ulrich S. , Gohy Jean‐François 
Published: June 2010

AbstractWe report on the micellization behavior of tri‐ and tetrablock copoly(2‐oxazoline)s in water–ethanol mixtures. The copolymers are based on different combinations of 2‐methyl‐, 2‐ethyl‐, 2‐phenyl‐, and 2‐nonyl‐2‐oxazoline. The solvophilic/solvophobic balance of these copolymers can be tuned thanks to the solubility dependence of the poly(2‐phenyl‐2‐oxazoline) block on the solvent composition. Characterization of the obtained micelles by dynamic light scattering and transmission electron microscopy revealed that their size and morphology depend on the solvophobic content of the copolymers and on the block order. Spherical micelles are always obtained when poly(2‐nonyl‐2‐oxazoline) is the only solvophobic block. When the solvophobic fraction consists of both the poly(2‐phenyl‐2‐oxazoline) and poly(2‐nonyl‐2‐oxazoline) blocks, spherical and cylindrical micelles as well as vesicles have been observed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3095–3102, 2010
Synthesis and morphology of model PS‐b‐PDMS copolymers
Authors: Ninago Mario D. , Satti Angel J. , Ciolino Andrés E. , Vallés Enrique M. , Villar Marcelo A. , Vega Daniel A. , Sanz Alejandro , Nogales Aurora , Rueda Daniel R. 
Published: June 2010

AbstractTrue model linear poly(styrene‐b‐dimethylsiloxane) PS‐b‐PDMS copolymers were synthesized by using sequential addition of monomers and anionic polymerization (high‐vacuum techniques), employing the most recent experimental procedures that allow the controlled polymerization of each monomer to obtain blocks with controlled molar masses. The model diblock copolymers obtained were analyzed by using different techniques, such as size‐exclusion chromatography, 1H NMR, Fourier transform infrared spectroscopy, small angle X‐rays scattering (SAXS), and wide angle X‐rays scattering (WAXS). The PS‐b‐PDMS copolymers obtained showed narrow molar mass distribution and variable PDMS content, ranging from 2 up to 55 wt %. Compacted powder samples were investigated by SAXS to reveal their structure and morphology changes on thermal treatment in the interval from 30 to 200 °C. The sample with the highest PDMS content exhibits a lamellar morphology, whereas two other samples show hexagonally packed cylinders of PDMS in a PS matrix. For the lowest PDMS content samples, the SAXS pattern corresponds to a disordered morphology and did not show any changes on thermal treatment. Detailed information about the morphology of scattering domains was obtained by fitting the SAXS scattering curves. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3119–3127, 2010
On the evolution of the rate of polymerization, number and size distribution of particles in styrene emulsion polymerization above CMC
Authors: Carro Shirley , Herrera‐Ordonez Jorge , Castillo‐Tejas Jorge 
Published: June 2010

AbstractThis work is an extension of a communication reported by two of the authors [Carro and Herrera‐Ordoñez, Macromol Rapid Commun 2006, 27, 274], where bimodal particle size distributions (PSD), obtained by asymmetric flow‐field flow fractionation (AFFF, AF4), were taken as evidence of certain degree of stability of primary particles. Now, emulsion polymerizations of styrene were performed under conditions employed before by other researchers, intending to examine if the behavior observed is general. The number of particles (N) and PSD were studied by means of dynamic light scattering and AF4. By the later, bimodal PSDs were detected in all cases, where the population corresponding to primary particles (diameter <20 nm) depends on reaction conditions. Regarding N, AF4 results show that it is constant during interval II, in contrast to DLS results. Primary particle coagulation was evidenced as minimums in N evolution and the rate of polymerization curves, monitored by calorimetry and gravimetry, which are enhanced when higher particle number is generated and/or the ionic strength is increased. These results suggest that particle coagulation is not as extensive as it would be expected according to the coagulative theory. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3152–3160, 2010
Synthesis and characterization of indenofluorene‐based copolymers containing 2,5‐bis(2‐thienyl)‐N‐arylpyrrole for bulk heterojunction solar cells and polymer light‐emitting diodes
Authors: Tamilavan Vellaiappillai , Sakthivel Pachagounder , Li Yinan , Song Myungkwan , Kim Chul‐Hyun , Jin Sung‐Ho , Hyun Myung Ho 
Published: June 2010

AbstractTwo novel alternating π‐conjugated copolymers, poly[2,8‐(6,6′,12,12′‐tetraoctyl‐6,12‐dihydroindeno‐[1,2b]fluorene‐ alt‐5(1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole) (P1) and poly[2,8‐(6,6′,12,12′‐tetraoctyl‐6,12‐dihydroindeno‐[1,2b]fluorene‐ alt‐5(1‐(p‐octylphenyl)‐2,5‐di(2‐thienyl)pyrrole) (P2), were synthesized via the Suzuki coupling method and their optoelectronic properties were investigated. The resulting polymers P1 and P2 were completely soluble in various common organic solvents and their weight‐average molecular weights (Mw) were 5.66 × 104 (polydispersity: 1.97) and 2.13× 104 (polydispersity: 1.54), respectively. Bulk heterojunction (BHJ) solar cells were fabricated in ITO/PEDOT:PSS/polymer:PC70BM(1:5)/TiOx/Al configurations. The BHJ solar cell with P1:PC70BM (1:5) has a power conversion efficiency (PCE) of 1.12% (Jsc= 3.39 mA/cm2, Voc= 0.67 V, FF = 49.31%), measured using AM 1.5 G solar simulator at 100 mW/cm2 light illumination. We fabricated polymer light‐emitting diodes (PLEDs) in ITO/PEDOT:PSS/emitting polymer:polyethylene glycol (PEG)/Ba/Al configurations. The electroluminescence (EL) maxima of the fabricated PLEDs varied from 526 nm to 556 nm depending on the ratio of the polymer to PEG. The turn‐on voltages of the PLEDs were in the range of 3–8 V depending on the ratio of the polymer to PEG, and the maximum brightness and luminance efficiency were 2103 cd/m2 and 0.37 cd/A at 12 V, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3169–3177, 2010
On the origin of ionic liquid‐induced variations in hydroxypropyl methacrylate propagation rate coefficients
Authors: Jeličić Aleksandra , Köhler Franziska , Winter Alette , Beuermann Sabine 
Published: June 2010

AbstractPulsed laser polymerizations were used to study the propagation kinetics of hydroxypropyl methacrylate (HPMA) in ionic liquids (ILs) and common organic solvents. The functional monomer was chosen to investigate the complex interplay of all interactions between monomer molecules and between monomer and solvent molecules and to obtain a deeper understanding of the impact of these interactions. The solvent effect on the HPMA propagation rate coefficient (kp) was examined using a linear solvation energy relationship (LSER) based on Kamlet‐Taft solvatochromic parameters π*, α, and β. The results suggest that dipolarity/polarizability, associated with π*, and hydrogen bond–donating ability of the solvents, accounted for by α, majorly contribute to variations in kp. Hydrogen bond–accepting (electron pair donating) ability of the solvents (β parameter) is of much lesser importance. In addition, LSER enables the prediction of HPMA kp based on solvatochromic parameters of the solvents. The results suggest that interactions between the hydroxyl group of the monomer and the anion are dominant compared with classical hydrogen bonding between carbonyl and hydroxyl groups of the monomer units. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3188–3199, 2010
Microphase separation in thin films of supramolecular assemblies composed of a triblock copolymer and low‐molecular‐weight additive
Authors: Nandan Bhanu 
Published: June 2010

AbstractThe phase behavior of supramolecular assemblies (SMAs) formed by poly(4‐vinylpyridine)‐block‐polystyrene‐block‐poly(4‐vinylpyridine) (P4VP‐b‐PS‐b‐P4VP) triblock copolymer with 2‐(4′‐hydroxybenzeneazo)benzoic acid (HABA) was investigated with respect to the molar ratio (X) between HABA and 4VP monomer unit in bulk as well as in thin films. The results were compared with SMAs formed by a PS‐b‐P4VP diblock copolymer of similar composition as the triblock but half the molecular weight to ascertain the effect of molecular architecture on microphase separation. In bulk, both the di‐ and triblock SMAs showed composition‐dependent morphological transitions, which could be tuned by HABA/4VP molar ratio. The domain spacing of the SMA was not significantly affected by the molecular architecture of the constituting block copolymers. In thin films also, both the di‐ and triblock SMAs showed more or less similar morphological transitions depending on X. Interestingly, the domain orientation of the cylindrical or lamellar microdomains in the SMAs was influenced by the molecular architecture of the block copolymer. After chloroform annealing, although the diblock SMAs showed in‐plane orientation of the domains, triblock SMAs showed perpendicular domain orientation. The perpendicular orientation of the microdomains in triblock was favored because it allowed the mid‐PS blocks to acquire normal distribution of loop and bridged conformations. Furthermore, the orientation of the lamellar and cylindrical microdomains of the diblock SMAs was found to switch to perpendicular orientation after annealing in 1,4‐dioxane vapors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1594–1605, 2010
Effects of castration on insulin levels and glucose tolerance in the mouse differ from those in man
Authors: Inoue Takamitsu , Zakikhani Mahvash , David Stéphanie , Algire Carolyn , Blouin Marie‐José , Pollak Michael 
Published: June 2010

AbstractBACKGROUNDPlasma insulin concentration is increased in prostate cancer patients during androgen deprivation therapy (ADT) and hyperinsulinemia has been associated with aggressive prostate cancer behavior. To investigate the possible role of castration‐induced hyperinsulinemia as a mechanism that may attenuate the beneficial effects of ADT in patients with prostate cancer, a murine model would be useful. We therefore investigated long‐term metabolic effects of castration in several mouse models.METHODSWe studied the long‐term influence of castration on energy intake, body weight, glucose tolerance, plasma‐insulin, plasma insulin‐like growth factor‐1 (IGF‐1), plasma adiponectin, and plasma leptin in C57BL/6, Swiss nu/nu, and CB17 scid mice receiving various diets. In each case, mice were randomized to have either bilateral orchiectomy or a sham operation.RESULTSEnergy intake, body weight, blood glucose levels in glucose tolerance test, plasma insulin, plasma IGF‐1, and plasma leptin level in all had a trend to be decreased in castrated as compared to sham operated mice. Plasma adiponectin level was increased in the castrated mice.CONCLUSIONSThe effects of castration on glucose, insulin, and related markers in several mouse models studied does not coincide with clinical observations; further studies in this area will require clinical research and/or the use of alternate models such as the dog. Prostate 70: 1628–1635, 2010. © 2010 Wiley‐Liss, Inc.