bluuebunny/crossref_metadata_2025_split huggingface dataset:
High performance semiconducting polymers containing bis(bithiophenyl dithienothiophene)‐based repeating groups for organic thin film transistors
Authors: Kim Kyung Hwan , Chung Dae Sung , Park Chan Eon , Choi Dong Hoon 
Published: November 2010

AbstractNew dithienothiophene‐containing conjugated polymers, such as poly(2,6‐bis(2‐thiophenyl‐3‐dodecylthiophene‐2‐yl)dithieno[3,2‐b;2′,3′‐d]thiophene, 4 and poly(2,6‐bis (2‐thiophenyl‐4‐dodecylthiophene‐2‐yl)dithieno[3,2‐b;2′,3′‐d]thiophene, 8 have been successfully synthesized via Stille coupling reactions using dodecyl‐substituted thiophene‐based monomers, bistributyltin dithienothiophene, and bistributyltin bithiophene; these polymers have been fully characterized. The main difference between the two polymers is the substitution position of the dodecyl side chains in the repeating group. Grazing‐incidence X‐ray diffraction (GI‐XRD) gave clear evidence of edge‐on orientation of polycrystallites to the substrate. The semiconducting properties of the two polymers have been evaluated in organic thin film transistors (OTFTs). The two conjugated polymers 4 and 8 exhibit fairly high hole carrier mobilities as high as μave = 0.05 cm2/Vs (ION/OFF = 3.42 × 104) and μave = 0.01 cm2/Vs, (ION/OFF = 1.3 × 105), respectively, after thermal annealing process. The solvent annealed films underwent reorganization of the molecules to induce higher crystallinity. Well‐defined atomic force microscopy (AFM) topography supported a significant improvement in TFT device performance. The hole carrier mobilities of the solvent annealed films are comparable to those obtained for a thermally annealed sample, and were one‐order higher than those obtained with a pristine sample. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
One‐step synthesis of ladder‐type fused poly(benzopentalene) derivatives with tunable energy levels by variable substituents
Authors: Wang Dong , Michinobu Tsuyoshi 
Published: November 2010

AbstractNovel ladder‐type conjugated polymers, fused poly (benzopentalene) derivatives, were synthesized from the readily accessible 1,4‐dibromo‐2,5‐diethynylbenzene derivatives by the Pd‐catalyzed self‐polycondensation in one‐step with high yields. The low solubility of the ladder structure was suggested when the triisopropylsilyl substituents were selected. However, when longer alkyl chains were introduced into the peripheral moieties, such as the dialkylanilino (DAA) and alkyloxyphenyl groups, a high solubility was achieved and the number‐average molecular weight (Mn) reached 18,000. The UV‐Vis absorption spectral shapes of the polymers were similar to the reported dibenzopentalene derivatives, except for the bathochromically shifted end absorptions. This result suggests an extension of the π‐conjugated systems due to the polymerization. Moreover, the almost defect‐free structure of the ladder‐type polymers was confirmed by the quantitative tetracyanoethylene (TCNE) addition to the DAA‐activated alkynes. The titration experiments of TCNE to the polymers revealed the number of terminal alkynes, which enabled us to calculate the molecular weight of the polymers. The calculated molecular weight was consistent with that determined by GPC. After the TCNE addition, the polymer band gaps reasonably decreased as suggested by the UV‐Vis‐NIR absorption and electrochemical measurements. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Enhanced redox stability and electrochromic properties of aromatic polyamides based on N,N‐bis(4‐carboxyphenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine
Authors: Wang Hui‐Min , Hsiao Sheng‐Huei 
Published: November 2010

AbstractA new bis(triphenylamine)‐type dicarboxylic acid monomer, N,N‐bis(4‐carboxyphenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine, was prepared by a well‐established procedure and led to a new family of redox‐active aromatic polyamides with di‐tert‐butyl‐substituted N,N,N′,N′‐tetraphenylphenylenediamine (TPPA) segments. The resulting polyamides were amorphous with good solubility in many organic solvents, and most of them could be solution cast into flexible polymer films. The polyamides exhibited high thermal stability with glass‐transition temperatures in the range of 247–293 °C and 10% weight‐loss temperatures in excess of 500 °C. They showed well‐defined and reversible redox couples during oxidative scanning, with a strong color change from a colorless or pale yellowish neutral form to green and blue oxidized forms. They had enhanced redox stability and electrochromic performance when compared with the corresponding analogs without tert‐butyl substituents on the TPPA unit. The polyamide with TPPA units in both the diacid and diamine components shows multicolored electrochromic behavior. A polyamide containing both the cathodic coloring anthraquinone chromophore and the anodic coloring TPPA chromophore has the ability to show red, green, and blue states, toward single‐component RGB electrochromics. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Conjugated polymer covalently modified multiwalled carbon nanotubes for optical limiting
Authors: Niu Lijuan , Li Peipei , Chen Yu , Wang Jun , Zhang Jinjuan , Zhang Bin , Blau Werner J. 
Published: November 2010

AbstractA new soluble multiwalled carbon nanotubes (MWNTs) covalently functionalized with conjugated polymer PCBF, in which the wt % of MWNTs is approximately calculated as 7.3%, and the average thickness of PCBF covalently grafted onto MWNTs is 10.4 nm, was synthesized by an amidation reaction. In contrast to the starting polymer PCBF‐NH2, grafting of PCBF onto MWNTs led to a 0.3 eV red‐shift of the N1s XPS peak at 399.7 eV assigning to N in the unreacted NH2moieties in the resulting copolymer structure and an appearance of new peak at 402 eV corresponding to N bound to the carbonyl C (i.e., NHCO). Unlike PCBF‐NH2, which only displayed a weak optical limiting response at 532 nm, Z‐scan for MWNT‐PCBF exhibited a much broader reduction in transmission and a scattering accompanying on the focus of the lens at both 532 and 1064 nm, indicating a prominent broadband optical limiting response. The thermally induced nonlinear scattering is responsible for the optical limiting. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Pursuit of reinitiation efficiency of resonance‐stabilized monomeric allyl radical generated via “degradative monomer chain transfer” in allyl polymerization
Authors: Inoue Satoshi , Kumagai Takeo , Tamezawa Hajime , Aota Hiroyuki , Matsumoto Akira , Yokoyama Katsutoshi , Matoba Yasuo , Shibano Michirou 
Published: November 2010

AbstractFor a deeper understanding of allyl polymerization mechanism, the reinitiation efficiency of resonance‐stabilized monomeric allyl radical was pursued because in allyl polymerization it is commonly conceived that the monomeric allyl radical generated via the allylic hydrogen abstraction of growing polymer radical from monomer, i.e., “degradative monomer chain transfer,” has much less tendency to initiate a new polymer chain and, therefore, this monomer chain transfer is essentially a termination reaction. Based on the renewed allyl polymerization mechanism in our preceding article, the monomer chain transfer constant in the polymerization of allyl benzoate was estimated to be 2.7 × 10−2 at 80 °C under the polymerization condition, where the coupling termination reaction of growing polymer radical with allyl radical was negligible and, concurrently, the reinitiation reaction of allyl radical was enhanced significantly. The reinitiation efficiencies of monomeric allyl radical were pursued by the dead‐end polymerizations of allyl benzoate at 80, 105, and 130 °C using a small amount of initiators; they increased remarkably with raised temperature. Thus, the enhanced reinitiation reactivity of allyl radical at an elevated temperature could bias the well‐known degradative monomer chain transfer characteristic of allyl polymerization toward the chain transfer in common vinyl polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Controlled grafting of cellulose esters using SET‐LRP process
Authors: Vlček Petr , Raus Vladimír , Janata Miroslav , Kříž Jaroslav , Sikora Antonín 
Published: November 2010

AbstractHere, we present the first example of application of single‐electron transfer living radical polymerization (SET‐LRP) process to a controlled grafting of cellulose esters, cellulose diacetate (CDA), and cellulose acetate butyrate (CAB). The cellulose ester macroinitiators with various functionality densities have been prepared by acylation of the backbones with 2‐bromoisobutyryl (BrIB) and dichloroacetyl (DCA) groups, respectively. Methacrylate monomers were polymerized using DCA‐functionalized macroinitiators in the presence of pentamethyldiethylene triamine as a ligand. At 30 °C, the reaction is rather slow, reaching about 10% conversion after 3 to 6 h of polymerization, whereas the higher temperature (60 °C) perceptibly speeds up the polymerization so that methyl methacrylate (MMA) conversion is ∼30% after 5 h. Graft copolymers with random‐type and diblock‐type grafts having amphiphilic character were also synthesized. For acrylate grafting (BuA and t‐BuA), BrIB‐functionalized macroinitiators are more convenient in a combination with a low concentration of Cu(0) and Me6TREN as a ligand and polymerization is detectably faster even at the lower temperature than that of MMA. Kinetic studies show “living” character of both the graftings. Important advantages of SET‐LRP, compared with classic ATRP, are (i) higher polymerization rate, (ii) lower extent of recombination of the growing grafts and (iii) negligible coloration of the products with catalytic residua, so that the prepared polymers do not require additional careful purification. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
A single‐layer approach to electrochromic materials
Authors: Percec Simona , Tilford Susan 
Published: November 2010

AbstractThis study is focused on the development of electrochromic (EC) materials that could be incorporated into electrically‐driven switchable devices such as electrochromogenic glasses. The ultimate goal of this research is to depart from the complexity of the EC device construction which is in use today. Such construction consists of three layers each of them incorporating a specific functionality: the electrochromophore, the electrolyte and the ion storage, assembled between two transparent or reflective electrodes. In most of these conventional devices the electrolyte layer is a liquid or a gel. Since solid‐state EC devices are of high commercial interest, we are exploring various avenues to reduce the number of layers to one layer that is all‐solid and electrochromically/electrolytically and ionically functional. The design strategy is based on the use of polymers such as poly(epichlorohydrin‐co‐ethylene oxide), poly(vinyl butyral) and poly(ethylene‐co‐methacrylic acid) ionomer, to which EC properties were introduced by grafting reactions with specifically synthesized carbazole derivatives. A combination of analytical techniques was used to characterize the monomers and the carbazole‐grafted polymers. A proof of concept was demonstrated for a single‐layer, all‐solid‐state EC device consisting of a film of poly(ECH‐co‐EO) containing pendent carbazole groups, assembled between two transparent electrodes, Sn‐doped In2O3 oxide‐coated glasses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Influence of the poly(propylene imine) generation in the LC properties of ionic codendrimers bearing fluorinated and perhydrogenated chains
Authors: Hernández‐Ainsa Silvia , Barberá Joaquín , Marcos Mercedes , Serrano José Luis 
Published: November 2010

AbstractA series of codendrimers constituted by the first five generations of poly(propylene imine) (PPI) ionically substituted with 2H,2H,3H,3H‐perfluoroundecanoic acid (af) and undecanoic acid (ac) in a fixed ratio (1:3) (af:ac) have been synthesized and their supramolecular organization has been investigated both in the liquid crystalline state and on a surface. Incompatibility generated by combining fluorinated and perhydrogenated chains in the same molecule causes a peculiar mesomorphic behavior depending on the generation of the codendrimers. Thus smectic A, frustrated smectic A or rectangular columnar mesophases have been detected. Despite their different liquid crystalline organization, they are capable to self‐assemble in homogeneous molecular length layers on a surface, namely mica as revealed by atomic force microscopy (AFM) experiments. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 278–285, 2011
Porphyrin‐functionalized amphiphilic diblock copolypeptides for photodynamic therapy
Authors: Li Ze‐Yong , Wang Hui‐Yuan , Li Cao , Zhang Xiao‐Lu , Wu Xiao‐Jun , Qin Si‐Yong , Zhang Xian‐Zheng , Zhuo Ren‐Xi 
Published: November 2010

AbstractA series of amphiphilic diblock copolypeptides (ADCs), 5‐(4‐aminophenyl)‐10,15,20‐triphenyl‐porphyrin (APP) conjugated poly(L‐leucine)‐block‐polylysine (APP‐LnKm) with different molar ratios of L‐leucine unit and lysine unit were designed and synthesized. The optimized composition of the polypeptide was determined to be APP‐L109K186, which has high fluorescence quantum yield and could self‐assemble into micelles in an aqueous medium with mean particle size <30 nm. The in vitro study indicates that APP‐L109K186 shows no significant dark cytotoxicity when the concentration is below 200 mg L−1 for HepG2 and HeLa cells. In contrast, the polymer exhibits apparent phototoxicity with low IC50 values toward HepG2 and HeLa cells, implying that the potential high photodynamic therapy efficacy of the polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Optically active helical polymer from radical polymerization of menthyl vinyl ketone
Authors: Wu Shi , Yang Nianfa , Liu Yanling , Cao Jing , Hu Hai , Sun Yunkai , Liu Ji 
Published: November 2010

AbstractMenthyl vinyl ketone (MVK) was radically polymerized to obtain a polymer with excess of one‐handed helical sense. Like as the anionically polymerized poly‐MVK, the radically polymerized poly‐MVK also kept stable one‐handed helical conformation in solvent. The optical rotation and the circular dichroism signal intensity of the radically polymerized poly‐MVK were larger than that of the anionically polymerized poly‐MVK. The molecular weight of the radically polymerized poly‐MVK was much larger than that of the THF‐soluble part of the anionically polymerized poly‐MVK. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Synthesis of cationic N‐[3‐(dimethylamino)propyl]methacrylamide brushes on silicon wafer via surface‐initiated RAFT polymerization
Authors: Gurbuz Nergiz , Demirci Serkan , Yavuz Serkan , Caykara Tuncer 
Published: November 2010

AbstractSurface‐initiated reversible addition‐fragmentation chain transfer (SI‐RAFT) polymerization of N‐[3‐(dimethylamino)propyl]methacrylamide (DMAPMA) on the silicon wafer was conducted in attempt to create controllable cationic polymer films. The RAFT agent‐immobilized substrate was prepared by the silanization of hydroxyl groups on silicon wafer with 3‐aminopropylthriethoxysilane (APTS) and by the amide reaction of amine groups of APTS with ester groups of 4‐cyano‐4‐((thiobenzoyl) sulfanyl) pentanoic succinimide ester (CPSE); followed by the RAFT polymerization of DMAPMA using a “free” RAFT agent, that is, 4‐cyanopentanoic acid dithiobenzoate (CPAD) and an initiator, that is, 4,4′‐azobis‐4‐cyanopentanoic acid (CPA). The formation of homogeneous tethered poly(N‐[3‐(dimethylamino)propyl]methacrylamide) [poly(DMAPMA)] brushes, whose thickness can be tuned by reaction time varying, is evidenced by using the combination of grazing angle attenuated total reflectance‐Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, and water contact‐angle measurements. The calculation of grafting parameters from the number‐average molecular weight, Mn (g/mol) and ellipsometric thickness, h (nm) values indicated the synthesis of densely grafted poly(DMAPMA) films and allowed us to predict a polymerization time for forming a “brush‐like” conformation for the chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of zwitterionic polymer by SET‐LRP at room temperature in aqueous
Authors: Ding Wei , Lv Chongfu , Sun Ying , Liu Xiaojun , Yu Tao , Qu Guangmiao , Luan Huoxin 
Published: November 2010

AbstractThe Cu0‐mediated single electron transfer‐living radical polymerization of acrylamide andN,N‐dimethyl‐N‐methacryloyloxyethyl‐N‐sulfobutyl ammonium in aqueous at 25 °C using 2‐chloropropionamide as initiator with Cu0powder/tris‐(2‐dimethylamino ethyl)amine (Me6‐TREN) as catalyst system is studied. The results showed the characteristic of the “living” polymerization that were theMnof polymers increased linearly with monomer conversion and the ln([M]0/[M]) increased linearly with time too, meanwhile the narrow molecular of weight distributions were found at most cases. Because of the high rate constant of propagation and bimolecular termination of the acrylamide, the external addition of CuCl2is required to mediate deactivation the early stage of polymerization. In addition, the disproportionation constant of CuIX/L in H2O is higher than in other solvents and the coordination of amino group and CuIItakes place easily, so the isopropanol orN,N‐dimethylformamide is added to control the polymerization. High conversions were achieved within short time and the polymers prepared showed good antipolyelectrolyte properties in inorganic salts solutions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Magnetoresistance and anomalous thermal hysteresis in La0.67Ca0.33MnO3/CaCu3Ti4O12 composites
Authors: Hua Luo Jiang , Hua HeJing 
Published: November 2010

AbstractThe (1 − x) La0.67Ca0.33MnO3(LCMO)/xCaCu3Ti4O12 (CCTO) (x = 0, 0.01, 0.03, 0.05, and 0.10) composites were fabricated by the sol–gel method and investigated in detail for their electrical transport and magnetoresistance (MR) properties. The X‐ray diffraction and scanning electronic microscopy analysis reveal that both LCMO and CCTO phases are distributed in the composites. Compared with pure LCMO, an obvious enhancement of MR is observed over a wide temperature range for the composites at high external magnetic field. Under 3 T field, the MR increases to a maximum value of 73.4% for x = 0.1 composite. Simultaneously, the thermal hysteresis behavior in resistivity is observed in x = 0.03, 0.05, and 0.1 samples, respectively. The MR enhancement and the abnormal experimental observations are attributed to the enhanced spin disorder at grain boundaries induced by the interaction product layer between LCMO and CCTO.
First‐principles study of CrB4 as a high shear modulus compound
Authors: Xu Hong Bin , Wang Yuan Xu , Lo V. C. 
Published: November 2010

AbstractFirst‐principles calculations were carried out to investigate the synthesized orthorhombic CrB4. Our calculations show that the shear modulus of orthorhombic CrB4 is much higher than that of superhard WB4. Moreover, its shear modulus is larger than its bulk modulus. Boron atoms in CrB4 form a strong covalent cage which dramatically increases its mechanical strength. The calculated elastic constants imply that CrB4 is elastically stable. The calculated density of states shows that CrB4 is metallic. The appearance of pesudogap near the Fermi level means that CrB4 is a stable compound. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of Nelumbo nucifera Rhizome Extract on Cell Proliferation and Neuroblast Differentiation in the Hippocampal Dentate Gyrus in a Scopolamine‐induced Amnesia Animal Model
Authors: Yoo Dae Young , Kim Woosuk , Yoo Ki‐Yeon , Lee Choong Hyun , Choi Jung Hoon , Kang Il‐Jun , Yoon Yeo Sung , Kim Dong‐Woo , Won Moo‐Ho , Hwang In Koo 
Published: November 2010

AbstractA large aquatic herb, Nelumbo nucifera Gaertn, has psychopharmacological effects similar to minor tranquillizers and antistress agents. This study examined the effects of Nelumbo nucifera rhizome extracts (NRE) on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus (DG) of a rat model of scopolamine‐induced amnesia. Immunohistochemical markers included Ki67, an endogenous marker for active cell cycle, and doublecortin (DCX), a marker for immature neurons and migratory neuroblasts. Scopolamine was administered for 28 days via an ALzet minipump (44 mg/mL delivered at 2.5 µL/h). NRE was administered by gavage, 1 g/kg per day for 28 days. The administration of scopolamine significantly reduced the number of Ki67‐ and DCX‐immunoreactive cells in the DG, whereas scopolamine did not induce any significant changes in mature neurons in the DG. The administration of NRE significantly ameliorated the scopolamine‐induced reduction of Ki67‐ and DCX‐immunoreactive cells in the DG. In addition, the administration of NRE significantly restored the scopolamine‐induced reduction of brain‐derived neurotrophic factor in DG homogenates. These results suggest that NRE can ameliorate the scopolamine‐induced reductions of cell proliferation, neuroblast differentiation and BDNF levels. Copyright © 2010 John Wiley & Sons, Ltd.
Compared ability of garlic (Allium sativum) extract or α‐tocopherol + magnesium association to reduce metabolic disorders and oxidative stress in diabetic rats
Authors: Hfaiedh Najla , Murat Jean Claude , Elfeki Abdellfattah 
Published: November 2010

AbstractSince some complications of diabetes mellitus may be caused or exacerbated by an oxidative stress, the protective effects of (1) a garlic (Allium sativum) aqueous extract or (2) a combination of α‐tocopherol and magnesium were investigated comparatively in alloxan‐diabetic rats. Garlic extract (1 mL of extract corresponding to 300 mg fresh garlic/kg) or α‐tocopherol (100 mg/kg) + MgCl2(200 mg/kg body weight) were i.p. injected to rats, once a day for 4 weeks. Lipid peroxidation levels and the activities of superoxide‐dismutase, catalase and glutathione peroxidase were then measured in liver and pancreas. Under our experimental conditions, garlic extract or α‐tocopherol + Mg were found to (1) significantly reduce the plasma levels of glucose, total cholesterol and triglyceride and (2) lactate dehydrogenase, alkaline phosphatase and transaminase activities in blood of diabetic animals. In addition, treatment with garlic extract or α‐tocopherol + magnesium appeared to exert an antioxidative activity demonstrated (1) by the increase of catalase, superoxide‐dismutase and glutathione‐peroxidase activities in liver and pancreas, and (2) a lowering of lipid peroxidation level in these organs. In conclusion, both garlic extract and α‐tocopherol + magnesium association were found to alleviate diabetes‐associated metabolic disorders and oxidative stress in rats. Copyright © 2010 John Wiley & Sons, Ltd.