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Dong-heng Zhang Su-yun Jie Hai-jian Yang Fei Chang Wen-hua Sun Key Laboratory of Engineering Plastics Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2005,23(6)
A series of salicylaldimines,synthesized in high yield via microwave-assisted condensation of salicylaldehyde and 2-alkoxyaniline were allowed to react with nickel chloride to form six-coordinated nickel complexes.These nickel complexes were carefully characterized,and the solid structure of la was elucidated by X-Ray diffraction.Activated with MAO,the nickel complexes showed good activity for homopolymerization of norbornene.Reaction parameters,such as the ratio of nickel precursor to MAO,monomer concentration,reaction time and the reaction temperature,as well as the nature of the ligands were found to have significant effects on the catalytic activity and some properties of the resulting polynorbornene. 相似文献
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In this study the stability of the NO spin-trapping complex, (dithiocarbamate)2Fe2+NO and its interaction with rat peritoneal macrophages was investigated. The stability experiments showed that DTCS (dithiocarboxy sarcosine) trapping complex was more stable than that of MGD (N-methyl-D-glucamine-dithiocarbamate) in macrophages activated by PMA (phorbol-1,2-myristate-1,3-acetate) and L-arginine. Free radical species, O2
- and NO, generated in macrophages respiratory burst were causative for the instability of the NO trapping complex. Addition of more dithiocarbamate and ferrous salt could increase the stability of the trapping complex in the system. Dithiocarbamate and ferrous salt did not impair the oxygen consumption of macrophages. The increasing effects of dithiocarbamate derivatives and ferrous salt on the stability of the trapping complex may be due to their scavenging effects on the free radicals generated by macrophages and their ability to inhibit the oxidation of ferrous ion in the (dithiocarbamate)2Fe2+NO complex. 相似文献
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AndreaR.Szkurhan MichaelK.Georges 《高分子科学》2004,(4):309-312
An overview of aqueous polymerizations, which include emulsion, miniemulsion and suspension polymerizations, under stable free radical polymerization (SFRP) conditions is presented. The success of miniemulsion and suspension SFRP polymerizations is contrasted with the difficulties associated with obtaining a stable emulsion polymerization. A recently developed unique microprecipitation technique is referenced as a means of making submicron sized particles that can be used to achieve a stable emulsion SFRP process. 相似文献
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Galina Temtsin-Krayz Alexander I. Shames Shmuel Bittner 《Research on Chemical Intermediates》2003,29(3):325-333
EPR spectroscopy was used to assess the radicals produced upon basic decomposition of N,N-bis-(3-chloro-1,4-naphthoquinon-2-yl) amine (BClNQA). Three radicals have been trapped and identified: N-bis(3-chloro-1,4-naphthoquinone) hydrazine radical (6), 2-hydroxy-3-chloro-1,4-naphthoquinone anion radical (9) and 2-amino-3-chloro-1,4-naphthoquinone radical (8). The probable reaction mechanism, the structure of intermediates as well as the reaction profile are discussed. 相似文献
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ATOM TRANSFER RADICAL POLYMERIZATION OF 2,5-BIS[(4-HEXYLOXYPHENYL)OXYCARBONYL]STYRENE 总被引:2,自引:0,他引:2
A side-on liquid crystalline monomer, 2,5-bis[(4-hexyloxyphenyl)oxycarbonyl]styrene) (HPCS), was successfully polymerized via atom transfer radical polymerization (ATRP). The polymerization was catalyzed by CuBr/PMDETA in chlorobenzene at 90℃ with (1-bromoethyl)benzene as the initiator. The polymers have narrow MWD. It is the second example of mesogen-jacketed liquid crystalline polymer (MJLCP) prepared by ATRP. 相似文献
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The ring-opening polymerization of 1,4-dioxan-2-one (PDO) was carried out by lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(OAr)3) as novel single component initiator. The influences of polymerization reaction temperature and the molar ratio of monomer to initiator on the monomer conversion and molecular weight of poly(1,4-dioxan-2-one) (PPDO) were explored. PPDO with high viscosity average molecular weight of 1.95 × 105 can be prepared at 40℃ when [PDO]/ [La(OAr)3] molar ratio was 800. Mechanism investigation shows that the polymerization proceeds through a "coordinationinsertion" mechanism with selective rupture of acyl-oxygen bond of PDO. 相似文献