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981.
ThesystemsconsistingofafluorophorelinkedtoacrownethermoietyareeXtensivelyinvestigated'-'.Sincedrasticchangesintheirphotophysicalpropertiescanbeobservedbycomplexationwithion,theycanbeusedforionicdetection"'.Recentreportsfocusonazamacrocyclicderivativeswithfluorophores"',inwhichthefluorophoreandcrownethermoietywerelinkedvianitrogenatom.Thepresenceofabasicnitrogenatomwhichiseasytobeprotonatedleadstoelthancementoffluorescencequantumyield""'.Wereplacedthenitrogenatomofthecrownbyoxygenwhichisexpect… 相似文献
982.
Li Yuan Xiaoyan Ma Aijuan Gu Hongxia Yan Guozheng Liang Wei Wang Jianyan Wu 《先进技术聚合物》2009,20(11):826-833
4,4′‐Bismaleimidodiphenylmethane (BMIPM)/O,O′‐diallylbisphenol A (BA) system was modified by organic rectorite (OREC) to develop a novel BMI/BA/OREC nanocomposite. The effect of OREC on the viscosity and reactivity of BMIPM/BA system was investigated. The mechanical properties of BMIPM/BA/OREC composites such as the flexural and impact strength were evaluated. The morphology of cured BMIPM/BA/OREC systems was investigated by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The hot water resistance of BMIPM/BA/OREC systems was discussed. The thermal property of BMIPM/BA/OREC systems was investigated using thermogravimetric analysis (TGA). The dynamic mechanical properties of BMIPM/BA/OREC systems were also measured. Results show that the addition of OREC has a significant influence on the reactivity of the BMIPM/BA system. Proper content of OREC can improve the flexural strength, impact strength, and hot water resistance of a BMIPM/BA system. The addition of OREC cannot decrease the thermal degradation temperature of cured BMIPM/BA system with a slight sacrifice of the glass transition temperature (Tg). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
983.
Andreas Mautner Xiaohua Qin Harald Wutzel Samuel C. Ligon Barbara Kapeller Doris Moser Guenter Russmueller Juergen Stampfl Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2013,51(1):203-212
Monomers for radical photopolymerization based on vinyl esters (VEs) have recently been identified as suitable alternatives to (meth)acrylates on account of their low irritancy and cytotoxicity. The drawback of most VEs with abstractable hydrogens is their relatively low reactivity compared with (meth)acrylates. Within this article, we proved by photo‐differential scanning calorimetry measurements and real‐time Fourier transform infrared spectroscopy that the thiol‐ene concept is able to improve the photoreactivity of these VEs to a large extent to a level between those of acrylates and methacrylates. Other VEs have now a reactivity of at least the level of similar acrylates. Mechanical properties as determined by Dynamic Mechanical Analysis and Charpy impact tests showed significant toughening of these materials. Furthermore, we were able to confirm low toxicity of all components by osteoblast cell culture experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
984.
Yanhui Chen Ganji Zhong Benjamin S. Hsiao Zhongming Li 《Journal of Polymer Science.Polymer Physics》2013,51(22):1618-1631
The structure evolution of the oriented layer (skin) and unoriented layer (core) from injection‐molded isotactic polypropylene samples upon uniaxial drawing is probed by in situ synchrotron X‐ray scattering. The X‐ray data analysis approach, called “halo method”, is used to semiquantitatively identify the transformation process of crystal phase upon uniaxial drawing. The results verify the validation of the stress‐induced crystal fragmentation and recrystallization process in the deformation of the injection‐molded samples under different temperatures. Furthermore, the end of strain softening region in the engineering stress‐strain curves explicitly corresponds to the transition point from the stress‐induced crystal fragmentation to recrystallization process. Basically, the skin and core layers of the injection‐molded parts share the similar deformation mechanism as aforementioned. The stretching temperature which dramatically affects the relative strength between the entanglement‐induced tie chains and the adjacent crystalline lamellae determines the crystal structural evolution upon drawing. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1618–1631 相似文献
985.
By proving an L2-gradient estimate for the corresponding Galerkin approximations, the log-Harnack inequality is established for the semigroup associated to a class of stochastic Burgers equations. As applications, we derive the strong Feller property of the semigroup, the irreducibility of the solution, the entropy-cost inequality for the adjoint semigroup, and entropy upper bounds of the transition density. 相似文献
986.
Hemi Qu Jing Luo Xiaojie Zhang Chunyan Chi 《Journal of polymer science. Part A, Polymer chemistry》2010,48(1):186-194
Synthesis of n‐type organic semiconductors with high electron mobilities, good environmental stability, and good processability is an urgent task in current organic electronics. This is because most of π‐conjugated materials are p‐type and prefer to transport positive hole carriers. In this article, a series of new dicarboxylic imide‐substituted poly(p‐phenylene vinylenes) (DI‐PPVs) were first synthesized. They exhibited a high electron affinity of 3.60 eV and thus are able to transport electrons. The polymers showed tunable solubility in common organic solvents and high chemical and thermal stability. They remain rigidity of the PPV backbone, and strong interchain π‐stacking was observed in thin films by X‐ray diffraction measurement. All these suggested that these polymers could serve as good candidates as n‐type semiconductors in organic electronic devices such as n‐channel field‐effect transistors and all polymer‐based solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 186–194, 2010 相似文献
987.
HU Fang ZHANG Chun-hua ZHANG Song MING Xing CHEN Gang WEI Ying-jin WANG Chun-zhong . School of Materials Science Engineering Shenyang University of Technology Shenyang P. R. China . College of Physics State Key Laboratory of Superhard Materials Jilin University Changchun . College of Physical Science Technology Huanggang Normal University Huanggang 《高等学校化学研究》2011,(3):528-530
1 Introduction Low-dimensional nanostructures, such as nanorods, nanowires, and nanotubes, have received much attention for their superior optical, electrical, catalytic and magnetic properties. 相似文献
988.
《Journal of Coordination Chemistry》2012,65(21):3473-3483
Two Co(II) coordination polymers, [CoL(npa)]·2H2O (1) and [CoL(Hnpa)2] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H2npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ2-bridging mode and connecting two Co2+ cations to generate a 26-membered Co2L2 loop. The npa2? link adjacent Co2L2 loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa? adopt a μ1-η0?:?η1 coordination to connect adjacent Co2+ cations into a 2-D polymeric layer. The μ2-bridging L ligands connect adjacent 2-D [Co(Hnpa)]n polymeric layers into a 3-D NaCl-like framework. The Co2+ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated. 相似文献
989.
Sheng Chen Jun Qiu He‐Lou Xie Hai‐Liang Zhang 《Journal of polymer science. Part A, Polymer chemistry》2013,51(13):2804-2816
Based on 2, 5‐bis[(4‐alkoxyphenyl)oxycarbonyl]styrenes (M‐OCm, m is the number of the carbons of alkyl tails, m = 1, 4, and 18), three series of binary copolymers with high‐molecular weights, {poly(M‐OC1‐co‐M‐OC4), poly(M‐OC1‐co‐M‐OC18), and poly(M‐OC4‐co‐M‐OC18)} have been prepared via free‐radical polymerization. The random nature of the copolymers was expected on the basis of the assumed similar reactivities because of the analogous monomers. The phase behaviors of copolymers were studied by DSC, POM, and one‐dimensional wide‐angle X‐ray diffraction. The results showed that liquid crystalline (LC) phase structures of copolymers, containing smectic phase, reentrant isotropic phase, columnar phase. and isotropic phase, were strongly depended on the composition and the alkyl length due to the competing among the steric effect, the microphase separation and the driving force of the entropy. When one of them occupied a dominant position, the LC phase structure can be presented for the copolymers. Otherwise, the LC phase structure is lost despite the pair of corresponding homopolymers forming mesogenic structure. Therefore, through copolymerization, LC behavior of the mesogen‐jacketed liquid crystalline polymers can be greatly varied. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2804–2816 相似文献
990.
Tanmoy Dutta Yong Li Aaron L. Thornton Da‐Ming Zhu Zhonghua Peng 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3818-3828
Donor‐acceptor conjugated polymers containing a new imide‐functionalized naphthodithiophene (INDT) as the acceptor unit and a 2,2'‐bithiophene with varied substituents as the donor unit have been synthesized. The bandgaps of these polymers depend strongly on the dihedral angle of the 2,2'‐bithiophene unit. The 3,3'‐dialkoxy substitution (polymers PDOR / PBOR ) leads to near planar bithiophene conformation due to the well‐known S–O short contact, while the 3,3'‐dialkyl substitution (polymer PDR ) results in significant twisting due to the steric effect. Consequently PDOR / PBOR shows the lowest bandgap of 1.82/1.85 eV while PDR has a bandgap of 2.38 eV. Bulk‐heterojunction solar cells of the polymer/fullerene blends have been fabricated. Preliminary results show that PBOR gives the best device performance with power conversion efficiencies as high as 2.45% in air without any thermal annealing treatment, indicating the promising potential of INDT‐containing conjugated polymers for efficient solar cells. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3818–3828 相似文献