共查询到20条相似文献,搜索用时 15 毫秒
1.
A simple route for the preparation of 3,4,6-substituted pyridazines is described by using Tebbe olefination of esters then Diels–Alder reaction of the resulting enol ethers with tetrazine. 相似文献
2.
Rozhkov A. V. Basova G. V. Korshunov A. O. Bochkarev L. N. Glukhova T. A. Il´ichev V. A. 《Russian Chemical Bulletin》2015,64(8):1949-1954
Russian Chemical Bulletin - New norbornene monomer, viz., 5-[(bicyclo[2.2.1]hept-5-en-2-ylmethoxy)methyl]-8-[(dimesitylboryl)oxy]quinoline (1), was synthesized. The copolymers based on monomer 1... 相似文献
3.
N-Substituted glycine peptoid oligomers were synthesized to incorporate a photoresponsive azobenzene side chain. The ability of this side chain to undergo reversible photoisomerization was established, and the cis- to trans-azobenzene thermal isomerization of this side chain was investigated. Circular dichroism studies indicated that trans- to cis-azobenzene isomerization does not significantly alter the backbone conformation in a series of peptoids thought to have well-defined structures. 相似文献
4.
M. Steuer M. Hrth M. Ballauff 《Journal of polymer science. Part A, Polymer chemistry》1993,31(6):1609-1619
The synthesis of stiff-chain poly(1,4-phenylene terephthalamide)s substituted by two as well as by four flexible side chains per repeating unit is described. The solubility of the materials bearing only two side chains is still very low. Appending of four side chains leads to polyamides which dissolve in common organic solvents. All polyamides reported herein form layered structures in the solid state as well as in the mesophase. Polyamides with two side chains have a very weak tendency for crystallization and do not exhibit a transition to the isotropic state even for the longest side chains. Polyamides with four side chains show three reversible thermal transitions: a disordering transition of the side chains, a transition to a layered, smectic-like mesophase, and finally the transition to an isotropic melt. It is shown that the phase behavior of these materials is mainly governed by the strong segregation of main- and side-chains which can be compared best to the microphase separation in block copolymers. © 1993 John Wiley & Sons, Inc. 相似文献
5.
M. Ballauff 《Journal of Polymer Science.Polymer Physics》1987,25(4):739-747
We present a theoretical treatment of nematic-isotropic phase equilibria in mixtures which consist of random coils and comblike polymers, the latter components being composed of a rigid backbone and flexible side chains. The mixing partition function is evaluated by using the Flory lattice model. The comblike component is characterized by the axial ratio xr of its rigid main chain and the number of flexible side chains z, each containing m segments. The coiled component is described by its number of segments xc. The net exchange energy of mixing is assumed to be zero; i.e., we consider athermal solutions. It is shown that the flexible side chains attached to the rigid main chains markedly enhance the compatibility in the isotropic phase. If the ratio of the volume fraction of the side chains to the volume fraction of the main chains is high enough, there is even a finite range of concentration where the random coils mix homogeneously with the comblike component. This is in contrast to mixtures of rods and coils, which have been shown by Flory to be incompatible over nearly the full range of composition. These conclusions hold true only when ordered states are involved. For comblike polymers with flexible backbones mixed with random coils in isotropic melts, the resulting free energy of mixing is given by the familiar Flory-Huggins expression. 相似文献
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Various functionalized steroidal side chains were conveniently accessed by a modified Julia olefination strategy using a common sulfone donor and an appropriate α-branched aldehyde acceptor. For the coupling of these hindered classes of reaction partners (and in contrast to typically observed trends), the benzothiazolyl(BT)-sulfone anion gave superior outcomes compared to the phenyltetrazolyl(PT)-sulfone anion. 相似文献
8.
Takahiro Sasamori Megumi Kobayashi Noriyoshi Nagahora Yusuke Sugiyama Norihiro Tokitoh 《Silicon Chemistry》2007,3(3-4):199-207
Several types of overcrowded ferrocenylsilanes, Tbt(Fc)SiX2(Tbt=2, 4, 6-tris[bis(trimethylsilyl)methyl]phenyl, Fc=ferrocenyl, X = H, OH, and Br) were synthesized and characterized. In addition, DFT calculations for ferrocenylsilanediol systems indicated
the existence of the intramolecular hydrogen bonding between the Fe atom and H–O moiety in Tbt(Fc)Si(OH)2.
Dedicated to Professor Mitsuo Kira on the occasion of his 2005 Wacker Awardy 相似文献
9.
The optical properties of substituted fluorenones with diverse structures have been analyzed using molecular orbital calculations in order to understand the structure-property relations. Based on theoretical predictions, synthesis of some model compounds has been attempted. The experimentally obtained optical properties are in close agreement with the theoretically obtained results. 相似文献
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11.
Ali Alaaeddine Andrew Hess Frédéric Boschet Harry Allcock Bruno Ameduri 《Journal of polymer science. Part A, Polymer chemistry》2013,51(4):977-986
The synthesis and characterization of novel poly(CTFE‐g‐oligoEO) graft copolymers [chlorotrifluoroethylene (CTFE) and ethylene oxide (EO)] are presented. First, vinyl ether monomers bearing oligo(EO) were prepared by transetherification of ω‐hydroxyoligo(EO) with ethyl vinyl ether catalyzed by a palladium complex in 70–84% yields. Two vinyl ethers of different molecular weights (three and 10 EO units) were thus obtained. Then, radical copolymerization of the above vinyl ethers with CTFE led to alternating poly(CTFE‐alt‐VE) copolymers that bore oligo(OE) side chains in satisfactory yields (65%). These original poly(CTFE‐g‐oligoEO) graft copolymers were characterized by 1H, 19F, and 13C NMR spectroscopy. Their molecular weights reached 19,000 g mol?1, and their thermal properties were investigated while their glass transition temperatures ranged between ?42 and ?36 °C. Their thermogravimetric analyses under air showed decomposition temperatures of 270 °C with 10% weight loss (Td,10%). These novel copolymers are of potential interest as polymer electrolytes in lithium ion batteries, showing room temperature conductivities ranging from 4.49 × 10?7 to 1.45 × 10?6 S cm?1 for unplasticized material. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
12.
Hirotsugu Kawashima Kohsuke Kawabata Hiromasa Goto 《Journal of polymer science. Part A, Polymer chemistry》2012,50(8):1530-1538
A poly(p‐phenylenevinylene) derivative bearing conjugated side chains (polyCPV) was synthesized by Migita‐Kosugi‐Stille type coupling polycondensation reaction. This polymer contains phenylenevinylene units in both the main chain and the side chains. UV–vis absorption and fluorescence emission spectroscopies revealed a well‐developed π‐conjugation of the polyCPV. The absorption band of the polymer was extended to long wavelengths. A fluorescent emission maximum of polyCPV is located at considerably longer wavelengths than that of the conjugated side chain monomer. Electron spin resonance measurements of polyCPV confirmed generation of charge species in both the main chain and the side chains via iodine doping. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
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T. Takahashi P. Miller Y. M. Chen L. Samuelson D. Galotti B. K. Mandal J. Kumar S. K. Tripathy 《Journal of Polymer Science.Polymer Physics》1993,31(2):165-173
Langmuir-Blodgett (LB) film formation has been investigated for polymers in which non-linear optical (NLO) moieties are attached to the side chain of a polymethacrylate (PMA) backbone. Polymer monolayers were successfully transferred onto hydrophilic glass substrates using a moving-wall type LB trough. The LB films were characterized by pressure-area isotherms, polarized ultraviolet visible spectra, ellipsometry, and second harmonic generation measurements. The characterization shows that NLO moieties in the side chain are inclined at a shallow angle to the plane of the substrate. The second-order nonlinear optical coefficient and molecular hyperpolarizability were also calculated. © 1993 John Wiley & Sons, Inc. 相似文献
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[reaction: see text] Synthetic strategies for preparing N,N'-bridged oligomeric guanidines bearing peptide side chains both on solid support and in solution are presented. Monomers are prepared from common alpha-amino acids and therefore contain conventionally protected peptide side chains. The side chains include alkyl, aromatic, hydroxyl, amino, carboxylic acid, and amide functional groups. Oligomer elongation utilizes acid-sensitive sulfonyl activated thiourea through the formation of carbodiimide intermediate. With proper preparation of monomers, synthesis of oligomer can be performed in two directions (equivalent to N to C terminal or C to N terminal in a peptide sequence) with excellent efficiency. 相似文献
17.
A. Riga D. Young G. Mlachak P. Kovach 《Journal of Thermal Analysis and Calorimetry》1997,49(1):425-435
A commercial set of polymers has been characterized by TG-DTA, DSC, TMA, FTIR spectroscopy and X-ray diffraction analysis (XRD). Thermal and mechanical stability, as well as the polymer glass transition temperature,T
g, and melt temperature,T
m, have been documented. There is a good correlation between measuredT
g andT
m values and published data. The degree of polymer crystallinity for polyethylene has been verified by XRD. The credibility and stability of these reference polymers is based on a comparison of their thermal properties, over a wide range of temperatures from two versions of a reference set, published in 1979 (A) and 1994 (B). The thermal properties and crystallinity of these polymers have stood the test of time and are reliable, readily available and consistent. 相似文献
18.
N. V. Orlov 《Russian Chemical Bulletin》2016,65(6):1418-1440
The review summarizes recent advances in the selective synthesis of complex molecular systems starting from simple readily available precursors. Such systems have a great potential for application in pharmacology, medicine, and materials science. The efficiency of the application of catalysis and structural studies for the development of new methods of synthesis is demonstrated. 相似文献
19.
Fabienne Poncin‐Epaillard Johann Beunet A. Bulou Jean‐Franois Bardeau 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3052-3061
Azobenzene, a photosensitive chromophore that undergoes photoinduced and thermal cis–trans isomerization, can be applied in a nonlinear optical field. {4′‐[(Hydroxy)ethyl]amino}‐4‐nitroazobenzene (disperse red 1) corresponds to one of these azo compounds, which can be grafted to a polymer chain as a part of the main chain, as a dangling group, or onto the polymer surface. In the last case, disperse red 1 is transformed into an acrylic monomer and then grafted onto a polypropylene surface modified with a cold carbon dioxide‐plasma treatment. A method is proposed for quantifying the radicals formed during the plasma treatment and, consequently, for optimizing the grafting reaction. The best conditions (the nature of the solvent, temperature, monomer concentration, and duration) are given. Both IR and Raman spectroscopies were used as efficient techniques for grafting characterization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3052–3061, 2001 相似文献
20.
Jiefeng Hai Enwei Zhu Linyi Bian Jin Wang Zixuan Wang Yang Li Liangming Yin Fujun Zhang Weihua Tang 《European Polymer Journal》2013
Two-dimensional poly[fluorene-alt-bithiophene] backboned copolymers were prepared by introducing phenylvinyl bridged accepting side chain containing malononitrile, 1,3-indanedione, or 4-nitrophenyl acetonitrile accepting moiety. The structural, optical, electroluminescent, electrochemical properties of these polymers were studied in details. These polymers possess good thermal stability and low highest occupied molecular orbital (HOMO) level (−5.59 to 5.67 eV). Results show that the introduction of π-conjugated accepting side chains can effectively adjust the optical and electrochemical properties of the resulting polymers. These new alternating copolymers may be promising electroluminescent materials. 相似文献