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51.
Chih-Fen Hsing Peter Kovacic Issam A. Khoury 《Journal of polymer science. Part A, Polymer chemistry》1983,21(2):457-466
Biphenyl and biphenyl-d10 were coupled by aluminum chloride-cupric chloride. For the two systems, the yields of p-quaterphenyl, p-sexiphenyl, and sublimation residue were compared. The results, which have mechanistic significance, are similar to those reported earlier for benzene versus benzene-d6; that is, a decrease in DP for the deuterated substrate. p-Sexiphenyl, obtained from biphenyl or p-terphenyl and aluminum chloride-cupric chloride, displayed a concentration of 3 × 1017 spins/g in ESR. There was little or no change in spin density after sublimation or crystallization. Even after drastic purification by a variety of techniques the radical character persisted. Biphenyl was polymerized by aluminum chloride-cupric chloride at temperatures in the 50–155°C range. Processable polymers with m- and p-phenylene linkages were produced. When doped with AsF5, the highest conductivity obtained was 7.3 × 10?2 Ω?1 cm?1. 相似文献
52.
Chih-Fen Hsing Issam Khoury Massimo D. Bezoari Peter Kovacic 《Journal of polymer science. Part A, Polymer chemistry》1982,20(12):3313-3323
ESR data for poly(p-phenylene) (PPP) prepared from benzene and catalyst-oxidant systems were compared with data for PPP obtained by a variety of other methods. The results were similar, except for the Yamamoto preparation, and comparable to the spin densities for heterocyclic polymers of thiophene, pyrrole, and selenophene. Deuterated PPP from C6D6 showed significant differences in properties, in comparison to ordinary PPP, in relation to molecular weight, color, solubility, and spins/g in electron spin resonance (ESR). The implications are discussed with regard to the mechanism of benzene polymerization by AlCl3-CuCl2. 相似文献
53.
54.
Molecular weight (MW) determinations of polydiphenylsiloxane‐co‐polydimethylsiloxane (PDPS/PDMS), polydiphenylsiloxane‐co‐polymethylphenylsiloxane (PDPS/PMPS) and polydiphenylsiloxane‐co‐polymethyl(3,3,3‐trifluoropropyl)siloxane (PDPS/PMFPS) statistical copolymers by gel permeation chromatography (GPC), GPC coupled differential viscometer (GPC‐DV) and light scattering (LS) techniques have been compared and discussed. The MW obtained by GPC‐DV in the PDPS/PDMS and the PDPS/PMPS series agreed with that obtained by LS very well. In PDPS/PDMS copolymers, it was found that the MW obtained by GPC was much lower than that obtained by GPC‐DV and LS, as Ph2SiO) content is higher than 50 mol%. In PDPS/PMFPS copolymers, the MW obtained by GPC was far different from that obtained by GPC‐DV and the deviation decreased with increasing Ph2SiO) mol%. The α values of the copolymers can be explained by the structure of the polymer in tetrahydrofuran (THF). Based on the relatively soluble copolymers, not only the differential refractive index increments (dn/dc) of PMPS, PDMS and PMFPS homopolymers but also that of the PDPS homopolymer in THF could be calculated by their corresponding copolymers. 相似文献
55.
A convection–diffusion porous media model for moisture transport in polymer composites: Model development and validation 下载免费PDF全文
Liangbiao Chen Hsing‐Wei Chu Xuejun Fan 《Journal of Polymer Science.Polymer Physics》2015,53(20):1440-1449
Moisture may cause many detrimental effects to polymers and their composites, thus inhibiting the applications of polymeric materials in hot and humid environments. In this article, a convection–diffusion porous media model is derived to better characterize rapid moisture transport in polymer composites at high temperatures. The model considers both continuum diffusion in solid and high‐pressure convection taking place in the pore network. Coupling of convection and diffusion is achieved by combining the law of conservation of mass, Darcy's law, the liquid–vapor chemical equilibrium, and the ideal gas law. The presented model is validated by conducting experimental tests on an epoxy compound. It is found that the proposed convection–diffusion model is more effective than diffusion‐only and convection‐only models for interpreting rapid desorption tests at high temperatures. A numerical study is also performed to predict maximum vapor pressure during a rapid heating process. Vapor pressure is found to be as high as 6.5 MPa at a heating rate of 10 K/s. It is concluded that the convection–diffusion model is able to capture both vapor dynamics and diffusion mechanism in porous polymeric materials, and can be potentially used to further investigate polymer‐moisture interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1440–1449 相似文献
56.
The title compound rac-11-t-butoxy-l,4-dihydro-l,4-methanoanthracene(C19H20O,Mr = 264.35) has been synthesized and characterized by FT-IR,’H NMR,HRMS spectra and single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21/n,with a = 13.5240(10),b = 8.3453(6),c = 13.9604(9) ,β= 100.0190(10)°.The structure of the title compound comprises a norbomene unit with a t-butoxy group,having a naphthalene ring fused on one side.The naphthalene is essentially planar with a maximum deviation of 0.032(2) for atom C(3).In the crystal,inversion-related molecules are linked by pairs of C-H…O hydrogen bonds,forming a cyclic dimer with R22(16) graph-set motif.The C-H…πinteractions are also observed,linking the molecules into a continuous two-dimensional framework structure. 相似文献
57.
Robinson Anandakathir Taizoon Canteenwala Hsing‐Ling Wang 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1945-1954
Highly soluble hexadecaaniline (A16)‐grafted polyolefin derivatives poly(maleic acid‐hexadecaanilinamide‐alt‐1‐octadecene) (PMAO‐A16) in a comb‐like configuration with alternate linear hexadecane and A16 side‐chains were synthesized and characterized. The structure of PMAO‐A16 was substantiated by infrared and UV‐Vis spectra showing high intensity of characteristic absorption peaks corresponding to a high degree of A16 attachments. Covalent grafting of hexadecaanilines onto the polymer backbone of PMAO was confirmed by the detection of a new amide [–(C[dbnd]O)–NH–] absorption band appearing at 1661 cm?1 accompanied with the full disappearance of anhydride carbonyl absorptions. Based on the comparison between TGA profiles of PMAO‐A16 and hexadecaaniline, a 12.5% wt loss at 365–600°C was accounted for full elimination of aliphatic side‐chains that matches approximately with the weight percentage of total hexadecane arms (12.7%). The data revealed a nearly quantitative yield of A16 grafting on anhydride subunits leading to complete conversion of PMAO into PMAO‐A16. Furthermore, preliminary 1H‐NMR study of PMAO‐A16 indicated its capability to undergo molecular self‐assembly in DMSO where A16s were dispersed in the solvent phase with hexadecane side‐chains located in a phase‐separated domain. 相似文献
58.
Ye Feng Yu Alexander Y. Zhu Ramn Paniagua‐Domínguez Yuan Hsing Fu Boris Luk'yanchuk Arseniy I. Kuznetsov 《Laser \u0026amp; Photonics Reviews》2015,9(4):412-418
Recently, metasurfaces have received increasing attention due to their ability to locally manipulate the amplitude, phase and polarization of light with high spatial resolution. Transmissive metasurfaces based on high‐index dielectric materials are particularly interesting due to the low intrinsic losses and compatibility with standard industrial processes. Here, it is demonstrated numerically and experimentally that a uniform array of silicon nanodisks can exhibit close‐to‐unity transmission at resonance in the visible spectrum. A single‐layer gradient metasurface utilizing this concept is shown to achieve around 45% transmission into the desired order. These values represent an improvement over existing state‐of‐the‐art, and are the result of simultaneous excitation and mutual interference of magnetic and electric‐dipole resonances in the nanodisks, which enables directional forward scattering with a broad bandwidth. Due to CMOS compatibility and the relative ease of fabrication, this approach is promising for creation of novel flat optical devices.
59.
1,6‐Dinitroperylene Bisimide Dyes: Synthesis,Characterization and Photophysical Properties 下载免费PDF全文
1,6‐ and 1,7‐regioisomers of dinitro‐substituted perylene bisimides ( 1a — 1b and 2a — 2b ) were synthesized under mild condition in high yields. The 1,6‐ and 1,7‐regioisomers were successfully isolated from the regioisomeric mixture using conventional methods of separation and subsequently characterized by 500 MHz 1H NMR spectroscopy. This is the first time when 1,6‐dinitroperylene bisimides ( 1a — 1b ) are obtained in pure form. Furthermore, the photophysical and electrochemical properties of 1 and 2 were found to be almost the same. The nitro functionalities provide stability of n‐type charge carriers by lowering the LUMO to resist ambient oxidation, which may offer potential applications in air‐stable n‐type organic semiconductors. 相似文献
60.
Separation and Migration Behavior of Dichlorophenols in β‐Cyclodextrin‐Modified Capillary Zone Electrophoresis 下载免费PDF全文
Chih‐Yu Chen Yu‐Chih Liu I‐Chin Chien Chung‐Chuan Hsueh Chen‐Hsing Lin 《中国化学会会志》2014,61(9):1025-1030
The separation and migration behavior of six isomeric dichlorophenols (DCPs) in cyclodextrin‐modified capillary zone electrophoresis (CD‐CZE) using a phosphate‐borate buffer at alkaline pH with β‐CD and hydroxypropyl‐β‐CD (HP‐β‐CD) as electrolyte modifiers were investigated. The influence of buffer pH and the concentration of β‐cyclodextrins were examined. The results indicate that baseline separation of six isomeric DCPs can be achieved with addition of β‐CD concentration in the range of 2.0‐10 mM or HP‐β‐CD concentration in the range of 4.0‐10 mM at pH 10.0. Binding constants of DCPs to β‐CDs were evaluated for a better understanding of the interaction of DCPs with β‐CDs. 相似文献