bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium‐catalyzed ring‐opening metathesis polymerization
Authors: Nishihara Yasushi , Doi Yukiko , Izawa Seisuke , Li Horng‐Yi , Inoue Yoshiaki , Kojima Masaaki , Chen Jwu‐Ting , Takagi Kentaro 
Published: December 2009

AbstractDoubly fuctionalized polar norbornenes bearing the cyano and ester groups in 2,3‐positions are synthesized and enantiomers are separated by high performance liquid chromatography (HPLC) with a chiral stationary phase. These optically active monomers are polymerized by ruthenium carbene catalysts, and high yields of the polymers were obtained. The chiral monomer bearing ethyl ester gave an optically active polymer of lower, but opposite sign of optical rotation (monomer [α]D = +61.0°, polymer [α]D = −3.1°). The circular dichroism (CD) of the obtained chiral polymers gave a Cotton effect. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 485–491, 2010
Conjugated copolymers comprised cyanophenyl‐substituted spirobifluorene and tricarbazole‐triphenylamine repeat units for blue‐light‐emitting diodes
Authors: Lin Ying , Chen Zhi‐Kuan , Ye Teng‐Ling , Dai Yan‐Feng , Ma Dong‐Ge , Ma Zhun , Liu Qin‐De , Chen Yu 
Published: December 2009

AbstractA series of conjugated blue‐light‐emitting copolymers, PTC‐1, PTC‐2, and PTC‐3, comprised different ratios of electron‐withdrawing segments (spirobifluorene substituted with cyanophenyl groups) and electron‐donating segments (tricarbazole‐triphenylamines), has been synthesized. The structures of these polymers were characterized and their thermal, photophysical, electrochemical, and electroluminescence properties were measured. Incorporation of rigid spirobifluorene units into the copolymers led to blue‐shifted absorption peaks in dilute toluene solution. Cyclic voltammetric measurement indicated the bandgaps of the polymers were in the range of 2.77–2.94 eV. It was found that increasing cyanophenyl‐spirobifluorene content in the polymer backbone lowered both the HOMO and LUMO energy levels of the copolymers, which was beneficial for electron injection/transporting in the polymer layer of the device. OLED device evaluation indicated that all the polymers emitted sky blue to deep blue light when the pure polymers were used as the emissive layers in the devices with a configuration of ITO/PEDOT:PSS/polymers/CsF/Ca/Al. The devices have been optimized by doping 30 wt % PBD into the polymer layers. Among the doped devices, PTC‐2 showed the best performance with the turn‐on voltage of 3.0 V, maximum brightness of 7257 cd/m2, maximum current efficiency of 1.76 cd/A, and CIE coordinates of (0.15, 0.14). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 292–301, 2010
Multistimuli responsive amphiphilic graft poly(ether amine): Synthesis, characterization, and self‐assembly in aqueous solution
Authors: Ren Yanrong , Jiang Xuesong , Yin Guilin , Yin Jie 
Published: December 2009

AbstractWe reported that multiresponsive amphiphilic graft poly(ether amine)s (agPEAs) comprised of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic octadecyl alkyl chain as side‐chain were prepared through one‐pot synthesis. In aqueous solution, these obtained agPEAs can self‐assemble into stable nanomicelles, whose aggregation can be controlled by temperature, pH, and ionic strength with tunable cloud point (CP). In the presence of these obtained agPEAs, hydrophobic dye Nile red can be dispersed into aqueous solution and hydrophilic dye methyl orange can be dispersed into nonpolar toluene. The agPEAs are expected to be potential in application such as encapsulation and controlled release of drugs, due to their simple synthesis, amphiphilicity, and multistimuli response. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 327–335, 2010
Effects of external donors and hydrogen concentration on oligomer formation and chain end distribution in propylene polymerization with Ziegler‐Natta catalysts
Authors: Vestberg Torvald , Denifl Peter , Parkinson Matthew , WilÉN Carl‐Eric 
Published: December 2009

AbstractThe effect of type and concentration of external donor and hydrogen concentration on oligomer formation and chain end distribution were studied. Bulk polymerization of propylene was carried out with two different Ziegler‐Natta catalysts at 70 °C, one a novel self‐supported catalyst (A) and the other a conventional MgCl2‐supported catalyst (B) with triethyl aluminum as cocatalyst. The external donors used were dicyclopentyl dimethoxy silane (DCP) and cyclohexylmethyl dimethoxy silane (CHM). The oligomer amount was shown to be strongly dependent on the molecular weight of the polymer. Catalyst A gave approximately 50 % lower oligomer content than catalyst B due to narrower molecular weight distribution in case of catalyst A. More n‐Bu‐terminated chain ends were found for catalyst A indicating more frequent 2,1 insertions. Catalyst A also gave more vinylidene‐terminated oligomers, suggesting that chain transfer to monomer, responsible for the vinylidene chain ends, was a more important chain termination mechanism for this catalyst, especially at low hydrogen concentration. Low site selectivity, due to low external donor concentration or use of a weak external donor (CHM), was also found to increase formation of vinylidene‐terminated oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 351–358, 2010
Alternating copolymerization of carbon dioxide and propylene oxide under bifunctional cobalt salen complexes: Role of Lewis base substituent covalent bonded on salen ligand
Authors: Liu Binyuan , Gao Yanhao , Zhao Xin , Yan Weidong , Wang Xianhong 
Published: December 2009

AbstractAlternating copolymerization of propylene oxide (PO) and carbon dioxide (CO2) was realized under mild conditions with a moderate turnover frequency (TOF), employing sole bifunctional cobalt salen complexes containing Lewis acid metal center and covalent bonded Lewis base on the ligand. Variation of the covalent bonded Lewis base substituents on the salen ligands could tailor the catalytic activity with TOF changing from 19.3 to 34.9 h−1, polymeric/cyclic carbonate selectivity from 95.3 to 72.8%, and the head‐to‐tail structure in the polymer from 72.2 to 86.0%. The IR analysis confirmed that the Lewis base moiety on one molecule could coordinate with cobalt center of adjacent molecule, playing similar role to the Salen metal complex/Lewis base binary catalytic system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 359–365, 2010
Synthesis and characterization of cross‐linkable ruthenium complex dye and its application on dye‐sensitized solar cells
Authors: Liu Ken‐Yen , Hsu Chiao‐Ling , Chang Shun‐Hsing , Chen Jian‐Ging , Ho Kuo‐Chuan , Lin King‐Fu 
Published: December 2009

AbstractA new crosslinkable light sensitizer, Ru(2,2′‐bipyridine‐4,4′‐bicarboxylic acid)(4,4′‐bis(11‐dodecenyl)‐2,2′‐bipyridine)(NCS)2, denoted as Ru‐C for titanium oxide nanocrystalline‐based solar cells was synthesized with its crosslinking properties invesitigated by Fourier‐transform infrared and UV‐vis absorption spectroscopies. After crosslinking by itself or copolymerizing with methyacrylic acid, their sensitized solar cells with poly(methylacrylate)‐gelled electrolyte system not only attained more than 5% of power conversion efficiency at AM 1.5 illumination (100 mW/cm2), but also gave rise to long storage life. To the best our knowledge, this is the first crosslinkable dye ever applied to the DSSC in the literature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 366–372, 2010
Thermoregulated phase‐transfer catalysis via PEG‐armed Ru(II)‐bearing microgel core star polymers: Efficient and reusable Ru(II) catalysts for aqueous transfer hydrogenation of ketones
Authors: Terashima Takaya , Ouchi Makoto , Ando Tsuyoshi , Sawamoto Mitsuo 
Published: December 2009

AbstractThermoregulated phase‐transfer catalysis for the transfer hydrogenation of 2‐octanone in 2‐propanol/H2O biphasic media was achieved with ruthenium‐bearing microgel‐core star polymers with amphiphilic, thermosensitive poly(ethylene glycol) (PEG) arms [Ru(II)‐PEG star], which were directly prepared by the ruthenium‐catalyzed living radical polymerization in conjunction with a phosphine ligand‐carrying styrene derivative. The star polymers were first placed in the aqueous (lower) layer at room temperature and immediately moved into the organic (upper) layer at 100 °C, and once again, moved down to the aqueous layer (lower) upon cooling the solution to room temperature. The Ru(II)‐PEG star catalyst was clearly superior to the original Ru(II) catalyst and related non‐microgel catalysts [Ru(II)‐PEG block] in terms of activity and recovery/recycle, due to the unique designer structure of the microgel‐core star polymers. Other substrates (less hydrophobic alkyl ketones and aromatic ketone) were also efficiently hydrogenated into the corresponding sec‐alcohols with the star catalyst in aqueous media. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 373–379, 2010
Dendronized polymers via Diels–Alder “click” reaction
Authors: Tonga Murat , Cengiz Nergiz , Kose Meliha Merve , Dede Tuna , Sanyal Amitav 
Published: December 2009

AbstractA modular approach toward the synthesis of polymers containing dendron groups as side chains is developed using the Diels–Alder “click” reaction. For this purpose, a styrene‐based polymer appended with anthracene groups as reactive side chains was synthesized. First through third‐generation polyester dendrons containing furan‐protected maleimide groups at their focal point were synthesized. Facile, reagent‐free, thermal Diels–Alder cycloaddition between the anthracene‐containing polymer and latent‐reactive dendrons leads to quantitative functionalization of the polymer chains to afford dendronized polymers. The efficiency of this functionalization step was monitored using 1H and 13C NMR spectroscopy and FTIR and UV–vis spectrometry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 410–416, 2010
Copolymerization of ethylene with 1‐hexene promoted by novel multi‐chelated non‐metallocene complexes with imine bridged imidazole ligand
Authors: Ma Lifu , Wang Hongli , Yi Jianjun , Huang Qigu , Gao Kejing , Yang Wantai 
Published: December 2009

AbstractA series of novel bridged multi‐chelated non‐metallocene catalysts is synthesized by the treatment ofN,N‐imidazole,N,N‐dimethylimidazole, andN,N‐benzimidazole withn‐BuLi, 2,6‐dimethylaniline, and MCl4(M = Ti, Zr) in THF. These catalysts are used for copolymerization of ethylene with 1‐hexene after activated by methylaluminoxane (MAO). The effects of polymerization temperature, Al/M molar ratio, and pressure of monomer on ethylene copolymerization behaviors are investigated in detail. These results reveal that these catalysts are favorable for copolymerization of ethylene with 1‐hexene featured high catalytic activity and high comonomer incorporation. The copolymer is characterized by13C NMR, WAXD, GPC, and DSC. The results confirm that the obtained copolymer features broad molecular weight distribution (MWD) about 33–35 and high 1‐hexene incorporation up to 9.2 mol %, melting temperature of the copolymer depends on the content of 1‐hexene incorporation within the copolymer chain and 1‐hexene unit in the copolymer chain isolates by ethylene units. The homopolymer of ethylene has broader MWD with 42–46. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 417–424, 2010
Effect of shear on the crystallization of the poly(ether ether ketone)
Authors: Zhao Guiyan , Men Yongfeng , Wu Zhonghua , Ji Xiangling , Jiang Wei 
Published: December 2009

AbstractThe effect of shear on the crystallization behavior of the poly(ether ether ketone) (PEEK) has been investigated by means of ex situ wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering, and differential scanning calorimetry (DSC). The changes of the intensity of WAXD patterns along shear direction of the PEEK induced by short‐term shear were observed when the samples crystallized at 330 °C. The results showed that the dimensions of the crystallites perpendicular to the (110) and (111) planes reduced with the increase of shear rate, whereas the dimensions of the crystallites perpendicular to (200) plane increased with the increase of shear rate. Moreover, increasing shear rate can lead to the increase of the crystallinity as well as the average thickness of the crystalline layers. Correspondingly, a new melting peak at higher temperature was found during the subsequent DSC scanning when the shear rate was increased to 30 s−1. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 220–225, 2010
Study of the quiescent and shear‐induced crystallization kinetics of intercalated PTT/MMT nanocomposites
Authors: Favaro Márcia M. , Rego Bruna T. , Branciforti Márcia C. , Bretas Rosario E. S. 
Published: December 2009

AbstractAn intercalated nanocomposite made of montmorillonite nanoclay, MMT, and poly(trimethylene terephthalate), PTT, was produced by twin screw extrusion and characterized by wide angle X‐ray diffraction, WAXD, and transmission electron microscopy, TEM. The quiescent isothermal and non‐isothermal and the flow‐induced crystallization of the nanocomposite were studied by differential scanning calorimetry, DSC, polarized light optical microscopy, PLOM, and rheometry. The quiescent results showed that the nanoclay acted as an efficient nucleating agent for the PTT, which result in an anticipation of the transition temperature between regimes II and III of crystallization. The fold interfacial free energy, σe, of the PTT in the nanocomposite during regime III was lower than in the pure state; that is, the pure PTT developed spherulites, whereas in the nanocomposite it produced a paracrystalline morphology. Under shear rate, the total times for crystallization in the nanocomposite were higher than in the pure PTT. In flow‐induced crystallization, a fibrillar nucleus must be formed as a result of chain orientation. In the nanocomposite, chain orientation only occurred after the percolated structure was broken. Therefore, the formation of a fibrillar nucleus in the nanocomposite took more time, which increased the total crystallization time. Inc. J Polym Sci Part B: Polym Phys 48: 113–127, 2010
Polymer chain of freely‐jointed segments in nematic molecular mean‐field
Authors: Walasek Janusz 
Published: December 2009

AbstractThe distribution function of orientations of a segment, which interacts with the orienting field and is within the chain with given the end‐to‐end distance‐vector, is calculated. The number of segments per chain is finite. The Lagrange method of conditional minimization of the chain free energy (the Helmholtz function) functional is used. Constraints for the segment orientations stem from fixed the chain end‐to‐end distance‐vector. Hence, Lagrange multipliers, energy, free energy, and entropy, for the chain with given the end‐to‐end distance‐vector, are calculated. Then, the distribution function of values of that vector is obtained. Furthermore, an average free energy per chain inside the polymer network with given a topological structure, the system self‐deformation, and modulus of elasticity are calculated and discussed in Gaussian limit, that is, for the number of segments per chain tending to infinity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 138–144, 2010
Effects of carbon nanotubes on dynamic mechanical property, thermal property, and crystal structure of poly(L‐lactic acid)
Authors: Shieh Yeong‐Tarng , Liu Gin‐Lung , Twu Yawo‐Kuo , Wang Tzong‐Liu , Yang Chien‐Hsin 
Published: December 2009

AbstractEffects of carbon nanotubes (CNT) on the dynamic mechanical property, thermal property, and crystal structure of poly(L‐lactic acid) (PLLA) were investigated. Dynamic mechanical analysis (DMA) found that CNT via grafting modification with PLLA (CNT‐g‐PLLA) could result in effective reinforcing effects. Tan δ of DMA found that CNT‐g‐PLLA was compatible with the PLLA matrix, giving a single Tg of the composite with a higher CNT‐g‐PLLA loading giving a higher Tg of the composite. Wide angle X‐ray diffraction (WAXD) data demonstrated that CNT could assist the disorder‐to‐order (α′‐to‐α) transition in PLLA crystals but did not lead to a more compact chain packing of the crystal lattice in PLLA composites than in pure PLLA. The equilibrium melting temperature (T) obtained from Hoffman‐Weeks plots were found to increase with increasing CNT‐g‐PLLA content. Small angle X‐ray scattering data revealed that thicknesses of crystal layer and amorphous layer of PLLA both decreased with increasing CNT contents. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 145–152, 2010
Microfibrillated cellulose/cellulose acetate composites: Effect of surface treatment
Authors: Lu Jue , Drzal Lawrence T. 
Published: December 2009

AbstractMicrofibrillated cellulose (MFC), which consists of a web‐like array of cellulose fibrils having a diameter in the range of 10–100 nm, was incorporated into a cellulose acetate (CA) matrix to form a totally biobased structural composite. Untreated and a 3‐aminopropyltriethoxysilane (APS) surface treated MFC was combined with a CA matrix by film casting from an acetone suspension. The effectiveness of the surface treatment was determined by infrared spectroscopy and X‐ray photoelectron spectroscopy. The Young's moduli of APS treated MFC composite films increase with increasing MFC content from 1.9 GPa for the CA to 4.1 GPa at 7.5 wt % of MFC, which is more than doubled. The tensile strength of the composite film increases to a maximum of 63.5 MPa at 2.5 wt % compared to the CA which has a value of 38 MPa. The thermal stability of composites with treated MFC is also better than the untreated MFC. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 153–161, 2010
Vibrational dynamics and heat capacity in poly(L‐lactic acid)
Authors: Porwal Vikas , Singh Mahendra , Chaturvedi Deepika , Tandon Poonam , Dayal Gupta Vishwambhar 
Published: December 2009

AbstractPoly(L‐lactic acid) (PLLA) (CH(CH3) COO)n is a biodegradable polymer, which exhibits many applications in the biomedical field and where thermoplastics are employed. A comprehensive study of the normal modes and their dispersion in PLLA using Wilson′s GF matrix method as modified by Higgs is being reported. Assignments of calculated normal modes have been made and characteristic features of dispersion curves are discussed. Heat capacity has been calculated via density‐of‐states using Debye relation in the temperature range 10–250 K, which is in fairly good agreement with the experimental data. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 175–182, 2010
Coping with parental cancer: web‐based peer support in children
Authors: Giesbers J. , Verdonck‐de Leeuw I. M. , van Zuuren F. J. , Kleverlaan N. , van der Linden M. H. 
Published: December 2009

AbstractObjective: To investigate the use and content of web‐based peer support in children coping with parental cancer.Methods: In children aged above 12 years, 158 forum discussions on the Dutch website www.kankerspoken.nl in a time‐period of 3 months were investigated. Age, gender, number of discussions, participation and main activities on the website were quantitatively assessed. Contents of the discussions were qualitatively analyzed.Results: In total, 129 children and 8 adults participated on the website with an average age of 15.3 years. The majority was female (80%). On average, a child was on‐line for 3 days and participated in 4 to 5 forum discussions. Main activities on the website were sharing personal experience, providing encouragement/support, providing and seeking information or advice and seeking contact outside of the website. Qualitative content analysis revealed that children regularly faced emotional problems and experienced a lack of understanding and communication in their direct environment.Conclusions: In dealing with parental cancer, children experience a variety of difficulties. This study offers a window into the use of web‐based peer support by children dealing with parental cancer. Copyright © 2009 John Wiley & Sons, Ltd.
Radiocarbon dating of fossil wood remains buried by the Piancabella rock glacier, Blenio Valley (Ticino, southern Swiss Alps): Implications for rock glacier, treeline and climate history
Authors: Scapozza Cristian , Lambiel Christophe , Reynard Emmanuel , Fallot Jean‐Michel , Antognini Marco , Schoeneich Philippe 
Published: December 2009

AbstractFossil wood stem remains of larch (Larix decidua) found 1 m below the surface at the base of the front of the Piancabella rock glacier (46°27′02″N, 9°00′07″E, 2480 m a.s.l.) had a conventional age range of 845 ± 50 14C y BP (UZ‐5545/ETH‐34417), corresponding to a calibrated calendar age range of 1040–1280 AD (790 ± 120 cal BP) with a statistical probability of 95.4 per cent. Based on geomorphological, climatological and geophysical observations, we infer that (1) the treeline in the Medieval Warm Period was about 200 m higher than in the middle of the 20th century, which corresponds to a mean summer temperature as much as 1.2°C warmer than in AD 1950, and (2) that ice within this rock glacier is probably several centuries old and so predates recent climatic events such as the Little Ice Age. Copyright © 2009 John Wiley & Sons, Ltd.
Implementation of the GaN lateral polarity junction in a MESFET utilizing polar doping selectivity
Authors: Collazo Ramón , Mita Seiji , Xie Jinqiao , Rice Anthony , Tweedie James , Dalmau Rafael , Sitar Zlatko 
Published: December 2009

AbstractThe difference in surface energies between the Ga‐polar orientation and the N‐polar orientation of GaN translates into a completely different behavior for the incorporation of intentional and unintentional impurities. Oxygen is found to be an impurity with higher concentration in the N‐polar films than in Ga‐polar films and is the cause of n‐type conductivity observed in N‐polar films. Utilizing this doping selectivity we fabricated a depletion‐mode metal‐semiconductor field effect transistor (MESFET) with n‐type N‐polar domains as source and drain and a Ga‐polar channel on polarity‐patterned wafers. The difference in the electronic properties of the different domains, i.e., as‐grown N‐polar domains are n‐type conductive and Ga‐polar domains are insulating, allows for laterally selective doped areas that can be realized for improving contact resistance to the n‐type conduction channel. Basically, the N‐polar domains acted as the ohmic contacts to the channel localized in a Ga‐polar domain. A MESFET with a Schottky gate was fabricated as an example of implementation of this novel structure showing a lowering in the specific contact resistivity.