bluuebunny/crossref_metadata_2025_split huggingface dataset:
Latent cationic palladium(II) phosphine carboxylate complexes for norbornene polymerization
Authors: Thirupathi Natesan , Amoroso Dino , Bell Andrew , Protasiewicz John D. 
Published: November 2008

AbstractThe catalytic efficacy of trans‐[(R3P)2Pd(O2CR′)(LB)][B(C6F5)4] (1) (LB = Lewis base) and [(R3P)2Pd(κ2‐O,O‐O2CR′)][B(C6F5)4] (2) for mass polymerization of 5‐n‐butyl‐2‐norbornene (Butyl‐NB) was investigated. The nature of PR3 and LB in 1 and 2 are the most critical components influencing catalytic activity/latency for the mass polymerization of Butyl‐NB. Further, it was shown that 1 is in general more latent than 2 in mass polymerization of Butyl‐NB. 5‐n‐Decyl‐2‐norbornene (Decyl‐NB) was subjected to solution polymerization in toluene at 63(±3) °C in the presence of several of the aforementioned palladium complexes as catalysts and the polymers obtained were characterized by gel permeation chromatography. Cationic trans‐[(R3P)2PdMe(MeCN)][B(C6F5)4] [R = Cy (3a), and iPr (3b)] and trans‐[(R3P)2PdH (MeCN)][B(C6F5)4] [R = Cy (4a), and iPr (4b)], possible products from thermolysis of trans‐[(R3P)2Pd(O2CMe)(MeCN)][B(C6F5)4] [R = Cy (1a) and iPr (1g)], as well as trans‐[(R3P)2Pd(η3‐C3H5)][B(C6F5)4] [R = Cy (5a), and iPr (5b)], were also examined as catalysts for solution polymerization of Decyl‐NB. A maximum activity of 5360 kg/(molPd h) of 2a was achieved at a Decyl‐NB/Pd: 26,700 ratio which is slightly better than that achieved with 5a [activity: 5030 kg/(molPd h)] but far less compared with 4a [activity: 6110 kg/(molPd h)]. Polydispersity values indicate a single highly homogeneous character of the active catalyst species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 103–110, 2009
Synthesis and properties of monodisperse multi‐triarylamine‐substituted oligothiophenes and 4,7‐bis(2′‐oligothienyl)‐2,1,3‐benzothiadiazoles for organic solar cell applications
Authors: XIA Ping Fang , Lu Jianping , Kwok Chi Ho , Fukutani Hiroshi , Wong Man Shing , Tao Ye 
Published: November 2008

AbstractTwo novel series of monodisperse multi‐triarylamine‐substituted oligothiophenes, G2‐OT(n)‐G2 with thiophene unit (n) varying from 6 to 8, and 4,7‐bis(2′‐oligothienyl)‐2,1,3‐benzothiadiazoles G2‐OT(n)BTD‐G2 (n = 2, 4, 6) have been synthesized by the Suzuki coupling reactions. With an elongation of alkyl‐substituted oligothiophene core or an incorporation of benzothiadiazole into the central core, the absorption and emission spectra of G2‐OT(n)‐G2 and G2‐OT(n)BTD‐G2 series red‐shift substantially with the optical gap reducing to 1.95 eV for G2‐OT(6)BTD‐G2. Alkyl‐substitution onto oligothiophene backbone not only improves the solubility of the highly extended dendrimers but also renders coplanarity of the dendritic oligothiophene backbone at the excited state, which results in the enhancement of fluorescence quantum efficiency. The bulk heterojunction solar cells using these newly synthesized dendritic oligothiophenes as a donor material and [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) as an acceptor material were fabricated and investigated which showed an increase in device performance as compared with those of the lower homologues. On increasing the loading of PCBM from 1.5 to 3 times in the active layer, there was also an enhancement in device performance with power conversion efficiencies of as‐fabricated solar cells increasing from 0.18% to 0.32%. In addition, proper annealing procedure could significantly improve the device performance of the dendrimer‐based photovoltaic cell. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 137–148, 2009
Proton conducting polymers containing 1H‐1,2,3‐triazole moieties
Authors: Martwiset Surangkhana , Yavuzcetin Ozgur , Thorn Michael , Versek Craig , Tuominen Mark , Coughlin E. Bryan 
Published: November 2008

AbstractPolyacrylates containing a different number of 1H‐1,2,3‐triazole groups per repeat unit have been synthesized via conventional free radical polymerization. These polymers were characterized by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Proton conductivity measurements were made using impedance spectroscopy. Introduction of more than one triazole per repeat unit did not result in an increase in conductivity as there was an accompanying increase in glass transition temperature (Tg). A maximum conductivity of 17.5 μS/cm was obtained at 200 °C under anhydrous condition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 188–196, 2009
Biodegradable hyperbranched polyesters derived from 1,1,1‐tris(hydroxymethyl)ethane
Authors: Kricheldorf Hans R. , Behnken Gesa 
Published: November 2008

AbstractLow molar mass hyperbranched polyesters were prepared by polycondensation of 1,1,1‐tris(hydroxymethyl)ethane and various dimethyl esters of aliphatic dicarboxylic acids in bulk. The usefulness of nontoxic bismuth salts as transesterification catalysts for these polycondensations was studied. The maximum conversion increased, and the reaction time decreased in the following sequence of increasing reactivity: dimethyl sebacate < adipate < glutarate < succinate. Regardless of the monomer combination, gelation occurred at conversions > 91.5%. The hyperbranched structure was proven by 1H NMR spectroscopy and the absence of cyclic elements by MALDI‐TOF mass spectrometry. Quantitative acylation of all CH2OH groups was achieved with an excess of acetic anhydride or methycrylic anhydride. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 231–238, 2009
Synthesis and structure of an optically active π‐stacked poly(dibenzofulvene) bearing chiral terminal group
Authors: Nakano Tamaki , Tanikawa Mitsuru , Nakagawa Osamu , Yade Tohru , Sakamoto Takeshi 
Published: November 2008

AbstractDibenzofulvene (DBF) affords a polymer having π‐stacked conformation by anionic, cationic, and free‐radical polymerization. In this study, DBF was polymerized anionically using potassium menthoxide as initiator to obtain optically active poly(DBF) having a chiral menthoxy group as a terminal group. The obtained polymer indicated circular dichroism (CD) absorption bands in the absorption wavelength range of fluorenyl group, indicating that chiral conformation was induced to the stacked main chain by the influence of the terminal group. The CD intensity was reversibly affected by temperature of measurement; hence, the chiral conformation may be rather dynamic. The effect of the terminal group was found to decrease as the chain length increased. Theoretical CD calculation indicated that the obtained polymer has a left‐handed helical conformation and that the dihedral angle between neighboring monomeric units might be about 10–20°. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 239–246, 2009
Copolymerization of ethylene with linear α‐olefins by 2‐phosphinophenolate nickel catalysts
Authors: Guo Cun‐Yue , Peulecke Normen , Kindermann Markus K. , Heinicke Joachim W. 
Published: November 2008

Abstract2‐Dicyclohexyl‐ and 2‐diphenylphosphinophenol, CCHH and PPHH, react with Ni(1,5‐COD)2 to form catalysts for polymerization of ethylene in or copolymerization with α‐olefins. The more P‐basic CCHH/Ni catalyst allows concentration‐dependent incorporation of olefins to give copolymers with isolated side groups and higher molecular weights, whereas the PPHH/Ni catalyst undergoes mainly stabilizing interactions with the olefins and leads to ethylene oligomers with no or marginal olefin incorporation. Pressure–time plots of the batch reactions show that the ethylene conversion is usually slower by catalysis with CCHH/Ni than by PPHH/Ni. The microstructure of the copolymers was determined by 13C NMR spectra, the number of side groups per main chain was estimated by 1H NMR analyses. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 258–266, 2009
Surface engineering of styrene/PEGylated‐fluoroalkyl styrene block copolymer thin films
Authors: Martinelli Elisa , Menghetti Sara , Galli Giancarlo , Glisenti Antonella , Krishnan Sitaraman , Paik Marvin Y. , Ober Christopher K. , Smilgies Detlef‐M. , Fischer Daniel A. 
Published: November 2008

AbstractA series of diblock copolymers prepared from styrenic monomers was synthesized using atom transfer radical polymerization. One block was derived from styrene, whereas the second block was prepared from a styrene modified with an amphiphilic PEGylated‐fluoroalkyl side chain. The surface properties of the resulting polymer films were carefully characterized using dynamic contact angle, XPS, and NEXAFS measurements. The polymer morphology was investigated using atomic force microscope and GISAXS studies. The block copolymers possess surfaces dominated by the fluorinated unit in the dry state and a distinct phase separated microstructure in the thin film. The microstructure of these polymers is strongly influenced by the thin film structure in which it is investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 267–284, 2009
Poly(triphenylamine)s derived from oxidative coupling reaction: Substituent effects on the polymerization, electrochemical, and electro‐optical properties
Authors: Lin Hung‐yi , Liou Guey‐Sheng 
Published: November 2008

AbstractA series of triphenylamine‐based polymers containing electron‐donating methoxy (OCH3) and electron‐withdrawing cyano or nitro (CN or NO2) substituents in the main chains have been designed and investigated. These conjugated polymers (P1–P3) could be readily prepared by oxidative coupling polymerization from monomers (M1–M3) using FeCl3 as an oxidant. The P2 and P3 exhibited moderate high Tg values (203–205 °C) and thermal stability. These polymers in NMP solution showed UV–vis absorption around 288–404 nm and photoluminescence peaks around 435–492 nm. P1–P3 showed reversible oxidation redox couples at Eonset = 0.67, 0.99, and 1.00 V in solution of 0.1 M tetrabutylammonium perchlorate (TBAP)/acetonitrile (CH3CN), respectively. M3 and P3 exhibited reversible reduction redox couples at Eonset = −1.04 and −1.03 V. These polymers also revealed electrochromic characteristic changing color at different potential. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 285–294, 2009
Surface characterization and electrical behavior of polyaniline–polymannuronate nanocomposites
Authors: Basavaraja C. , Veeranagouda Y. , Lee Kyoung , Pierson R. , Huh Do Sung 
Published: November 2008

AbstractConducting polyaniline‐polymannuronate (PANI‐PM) composites were synthesized via in situ deposition techniques. By dissolving different weight percentages of polymannuronate (PM) (5, 10, 15, and 25%), the oxidative polymerization of aniline was achieved through the use of ammonium persulfate as oxidant. Structural morphology, FT‐IR, and X‐ray diffraction (XRD) studies support a strong interaction between PANI and PM. The temperature‐dependent DC conductivity of PANI‐PM composites was studied within the range of 300 ≤ T ≤ 500 °K, presenting evidence for the transport properties of PANI‐PM composites. Conductivity was analyzed through Mott's equation, which leveraged the variable range hopping model in three dimensions. Parameters such as density of states at the Fermi energy, hopping energy, and hopping distance were calculated. Based on the above factors, the synthesis of PANI‐PM composites envisages the future development of biomimetic materials for the creation of a new bionanocomposite as a multicomponent and multifunctional material. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 36–45, 2009
Vibrational spectroscopy analysis of ion conduction mechanism in dispersed phase polymer nanocomposites
Authors: Mohapatra Saumya R. , Thakur Awalendra K. , Choudhary R. N. P. 
Published: November 2008

AbstractA novel combination of dispersed phase polymer nanocomposite electrolyte based on PEO8‐LiClO4+ x wt % nano‐CeO2 has been investigated. A model for ion transport mechanism has been proposed to account for substantial enhancement of its electrical conductivity by ∼ 2 orders of magnitude at low volume fraction of the filler reinforcement in the polymer nanocomposite films. The strength of the proposed model is based on unambiguous evidences from FTIR, TEM, and conductivity analysis. The FTIR results provide clear role of nanofiller concentration on ion–ion interaction quantified in terms of the fraction of free anion and ion‐pairs present in the nanocomposite films and its excellent correlation with conductivity versus filler concentration. The presence of asymmetry in the ν4(ClO4−) band observed at 625 cm−1 is attributed to its resolved degeneracy suggesting the presence of both uncoordinated and cation‐coordinated ClO4− anion in the matrix due to ion–ion and ion–filler interactions assisted by Lewis acid–base interaction. The enhancement in conductivity at low concentration is possibly due to direct interaction of nano‐CeO2 with both polymer host and anions resulting in the release of ionic charges. Drastic conductivity reduction at higher concentration is related to charge immobilization because of ion/ion‐pair entrapment by local clusters of filler as evidenced in TEM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 60–71, 2009
The effects of monoepoxide chain termination and their derived soluble fractions on the structure‐property relationships of controlled epoxy networks
Authors: Marks Maurice J. , Verghese Nikhil E. , O'Connell Carol L. , Mansour Ameara S. 
Published: November 2008

AbstractA new series of monoepoxide terminated controlled epoxy networks (CENs) and a corresponding soluble fraction polymer (SFP) were prepared to further investigate the effects of chain termination on epoxy thermoset structure‐property relationships. CENs having an initial molecular weight between crosslinks (Mc,i) of ∼3000 g/mol using phenylglycidyl ether (PGE) as the chain terminator have thermal and mechanical properties consistent with previously studied monophenol terminated CENs. Glass transition temperature (Tg) decreases monotonically with PGE concentration (ε), whereas fracture toughness decreases sharply at a critical PGE concentration (εc). A PGE terminated SFP was prepared corresponding to the soluble fraction expected for the CEN composition at εc. The SFP behaves as a weak antiplasticizer in these epoxy thermosets;Tgis reduced and follows the inverse rule of mixtures, and fracture toughness is slightly reduced. By difference it is inferred that most of the deterioration of epoxy thermoset properties resulting from incorporation of chain terminators above εcis a result of the presence of nonelastically active pendant chains and by the increase inMc. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 72–79, 2009
Glass transition temperatures in binary polymer blends
Authors: Kalogeras Ioannis M. , Brostow Witold 
Published: November 2008

AbstractKnowledge of the glass transition temperatures (Tgs) as function of composition reflects miscibility (or lack of it) and is decisive for virtually all properties of polymer‐based materials. In this article, we analyze single blend‐average and effective Tgs of miscible polymer blends in full concentration ranges. Shortcomings of the extant equations are discussed to support the need for an alternative. Focusing on the deviation from a linear relationship, defined as ΔTg = Tg − φ1Tg,1 − φ2Tg,2 (where φi and Tg,i are, respectively, the weight fraction and the Tg of the i‐th component), a recently proposed equation for the blend Tg as a function of composition is tested extensively. This equation is simple; a quadratic polynomial centered around 2φ1 − 1 = 0 is defined to represent deviations from linearity, and up to three parameters are used. The number of parameters needed to describe the experimental data, along with their magnitude and sign, provide a measure of the system complexity. For most binary polymer systems tested, the results obtained with the new equation are better than those attained from existing Tg equations. The key parameter of the equation a0 is related to parameters commonly used to represent intersegmental interactions and miscibility in binary polymer blends. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 80–95, 2008
Molecular mobility of nitroxide spin probes in glassy polymers. Quasi‐libration model
Authors: Chernova Daria A. , Vorobiev Andrey KH. 
Published: November 2008

AbstractESR spectra of three spin probes with different molecular volumes: 2,2,6,6‐tetramethyl‐4‐oxopiperidine‐1‐oxyl, di‐p‐anisylnitroxide, and nitroxide derivative of fullerene in glassy polystyrene, polyvinyl trimethylsilane, and Teflon AF‐2400 were calculated numerically within the model of quasi‐libration motions. Temperature ranges, where the model is capable to reproduce spectra within experimental errors, were defined. It was found that simulation of X‐band ESR spectra allows to determine quasi‐libration amplitudes around molecular axes X and Y with accuracy ∼ 3° and around Z axis with accuracy ∼ 15–20°. A shape of distribution of quasi‐libration amplitudes was also determined qualitatively by ESR spectra simulations. It was established that the average amplitude of quasi‐libration motion depends on the free volume of each polymer and geometrical molecular volume of a spin probe. Quasi‐libration amplitudes increase as the temperature increases, and reach the value of 40 degrees. We found that upon further temperature increase, quasi‐libration model becomes inapplicable for quantitative numerical spectra simulation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 107–120, 2009
Predictors of treatment decision evaluation in patients with cancer
Authors: Erci Behice , Özdemir Süreyya 
Published: November 2008

AbstractObjective: The purpose of this study was to examine the predictors of treatment decision evaluation in patients with cancer.Methods: A convenience sample of 199 patients with cancer at a Turkish university hospital completed a structured questionnaire including demographic characteristics and the treatment decision evaluation for patients with cancer in 2006. In analysis of the data, descriptive statistics, and multiple regression analysis were used.Results: The mean scores of the treatment decision evaluation's subscales showed that the patient were uncertain about their satisfaction with the treatment decision. The mean score of the symptom inventory suggested that the patients had moderate‐level symptoms. Education level, marital status, and the severity symptoms of the independent variables were effective predictors of the treatment decision evaluation. Together the independent variables explained 18.7% of the variance of the satisfaction–uncertainty dimension, 9.1% of the variance of the informed choice dimension, and 16% of the variance of the decision control dimension. Overall the independent variables explained 8.3% of the variance of the treatment decision evaluation.Conclusions: The results in this study should increase the awareness of cancer care professionals about a range of treatment decision evaluation and may help them to target particular patient groups for particular support interventions and informed treatment decision. Copyright © 2008 John Wiley & Sons, Ltd.
Gene expression profiles of lysophosphatidic acid‐related molecules in the prostate: Relevance to prostate cancer and benign hyperplasia
Authors: Zeng Yu , Kakehi Yoshiyuki , Nouh Mohammed Ahmed Abdel Muneem , Tsunemori Hiroyuki , Sugimoto Mikio , Wu Xiu‐Xian 
Published: November 2008

AbstractOBJECTIVETo elucidate gene expression profiles of lysophosphatidic acid (LPA)‐related molecules in cancer, pre‐cancerous lesion, and benign hyperplasia of the prostate.MATERIALS AND METHODSProstate tissue samples were surgically obtained from 10 patients with localized prostate cancer and seven patients with invasive bladder cancer. Cancer cells and the corresponding stromal cells from normal prostate, high grade intraepithelial neoplasia (HGPIN), benign hyperplastic glands were isolated by laser capture microdissection. mRNA levels of three LPA receptors, LPA1, LPA2, LPA3, two LPA‐synthesizing enzymes, autotaxin (ATX), acylglycerol kinase (AGK), and a LPA‐degradation enzyme, prostatic acid phosphatase (PAP), were quantitatively assessed. The expression levels of the same genes were also determined in three human prostate cancer cell lines LNCaP, PC‐3, and DU‐145.RESULTSLPA1 mRNA level was significantly decreased in HGPIN and cancer epithelia when compared to the benign glands. LPA3 mRNA level was elevated in cancer epithelia compared to benign glands. LPA3, AGK, and PAP were predominantly expressed in LNCaP cells while LPA1 and ATX gene expressions were found in PC‐3 and Du‐145 cells. In BPH, AGK was abundantly expressed in the stroma while PAP was predominant in epithelial cells.CONCLUSIONSBy acting via LPA3, LPA may play an important role in the development of prostate cancer. Switching of LPA receptor expression from LPA3 to LPA1, may be involved in prostate cancer progression and/or androgen independence. LPA may also play a key role in the development of benign prostatic hyperplasia. Prostate 69:283–292, 2009. © 2008 Wiley‐Liss, Inc.
Conformational preferences of a short Aib/Ala‐based water‐soluble peptide as a function of temperature
Authors: Banerjee Raja , Chattopadhyay Sarbani , Basu Gautam 
Published: November 2008

AbstractThe amino acid Aib predisposes a peptide to be helical with context‐dependent preference for either 310‐ or α‐ or a mixed helical conformation. Short peptides also show an inherent tendency to be unfolded. To characterize helical and unfolded states adopted by water‐soluble Aib‐containing peptides, the conformational preference of Ac‐Ala‐Aib‐Ala‐Lys‐Ala‐Aib‐Lys‐Ala‐Lys‐Ala‐Aib‐Tyr‐NH2was determined by CD, NMR and MD simulations as a function of temperature. Temperature‐dependent CD data indicated the contribution of two major components, each an admixture of helical and extended/polyproline II structures. Both right‐ and left‐handed helical conformations were detected from deconvolution of CD data and13C NMR experiments. The presence of a helical backbone, more pronounced at the N‐terminal, and a temperature‐induced shift in α‐helix/310‐helix equilibrium, more pronounced at the C‐terminal, emerged from NMR data. Starting from polyproline II, the N‐terminal of the peptide folded into a helical backbone in MD simulations within 5 ns at 60°C. Longer simulations showed a mixed‐helical backbone to be stable over the entire peptide at 5°C while at 60°C the mixed‐helix was either stable at the N‐terminus or occurred in short stretches through out the peptide, along with a significant population of polyproline II. Our results point towards conformational heterogeneity of water‐soluble Aib‐based peptide helices and the associated subtleties. The problem of analyzing CD and NMR data of both left‐ and right‐handed helices are discussed, especially the validity of the ellipticity ratio [θ]222/[θ]207, as a reporter of α‐/310‐ population ratio, in right‐ and left‐handed helical mixtures. Proteins 2009. © 2008 Wiley‐Liss, Inc.