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1.
异丙醇铝改进的原子转移自由基聚合催化体系 总被引:5,自引:1,他引:4
以α 溴代异丁酸乙酯[2 (EiB) Br] 为引发剂,溴化亚铜(CuBr)/ 联二吡啶(bpy)/ 异丙醇铝[Al(OiPr)3] 为复合催化剂,在环己酮溶液中进行了甲基丙烯酸正丁酯(BMA) 的原子转移自由基聚合(ATRP) .研究了异丙醇铝对聚合速率及产物分子量分布的影响.异丙醇铝可与引发剂和聚合物中的羰基配位,使相邻的C—Br 键活化,ATRP 反应可以在较低温度下进行.适量溴化铜的加入,可调节ATRP 活性,可得到分子量可控且分子量分布窄的PBMA( MWD= 1-3 ~1-5) . 相似文献
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a—溴砼丁酸乙酯/CuBr/联吡啶体系引发的活性自由基聚合反应 总被引:6,自引:0,他引:6
用a-溴代丁酸乙酯为引发剂,CuBr和2,2’-联吡啶为催化剂,研究了MMA、St、MA在80℃下,MMA在室温下(20℃)的自由基活性聚合机理。 相似文献
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新型高活性催化剂乙烯气相聚合的研究(I):气相均聚和共聚… 总被引:3,自引:2,他引:3
研究了新型高活性乙烯气相聚合催化剂TiCl4/MgCl2/ZnCl2/SiCl4/醇/Al(i-Bu)3体系中钛和醇组分含量对聚合反应和产物颗粒形态的影响。测定了乙烯气相聚合反应动力学曲线,确定了聚合动力学方程。用SEM,DSC,WAXD,^1^3CNMR对催化剂及聚合物的形态,结构和性能进行了分析和表征。 相似文献
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IntroductionAtomtransferradicalpolymerization(ATRP),basedoncuproushalides(CuX)/2,2-bypyridine(bpy)/alkylhalides(RX)ascatalyst/initiatorsystem,isanewmethodtocontroltheradicalpolymerizationofstyreneand(methyl)methacrylate(MMA)[1,2].BecausetheCuCl/1,10… 相似文献
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新型高活性催化剂乙烯气相聚合的研究(Ⅵ):锌化合物对催化… 总被引:3,自引:1,他引:3
研究了新型高活性乙烯气相聚合催化剂TiCl4、Ti(OBu)4/MgCl2、SiO2和ZnCl2/醇/AlR3体系中ZnCl2-AlEt3/SiO2重量比和锌化合物含量对气相均聚合的影响,比较了2种不同催化剂Cat#A和Cat#B的聚合反应力学及性能差异。d f cltip 相似文献
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分别以Cu0/2 ,2′联吡啶(Bpy) 和CuCl2/Bpy 配合物为催化剂,CCl4 和偶氮二异丁腈(AIBN) 为引发剂,较为详细地研究了苯乙烯的原子转移自由基乳液聚合规律.结果表明:其乳液聚合体系均显示出了“活性”聚合的基本特征,即数均分子量与转化率呈线性关系,但聚合反应一经引发,聚合物的分子量就达数万,且分子量约为理论值的5 至20 倍;Cu0/Bpy/CCl4 体系的MWD 与本体聚合相当,而CuCl2/Bpy/AIBN 体系的MWD 比其本体聚合体系大,最小为1-64 ;研究Cu0/Bpy/CCl4 体系发现,乳液聚合与悬浮聚合在“活性”特征上没有本质的区别,但两者在动力学上有些差异;跟踪乳液聚合过程中的pH 值发现,体系中的pH 值随反应时间的延长呈下降趋势,并可能影响聚合速率. 相似文献
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Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated. 相似文献
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Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes
K. Hashimoto Y. Yamada T. Omori K. Yoshihara 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(3):187-197
Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/2, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of99Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/3, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material. 相似文献
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The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is and a unit cell contains eight formula units. The unit cell dimensions of are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO6 octahedra. The hydrogen bonding scheme is given. 相似文献
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Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO2(DH-CO2) reactions in the presence and absence of the CrOx/SiO2 catalyst have been studied between 673 and 873 K. It was found that the CrOx/SiO2 catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the
dehydrogenation of propane to propene in the presence of CO2on CrOx/SiO2can be facilitated by the RWGS reaction.</o:p> 相似文献
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Summary CexTi1-xO2 and H3PW12O40/CexTi1-xO2 catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and
carbon dioxide. H3PW12O40/CexTi1-xO2 showed a better catalytic performance than the corresponding CexTi1-xO2, due to the bifunctional catalysis of Br?nsted acid sites (provided by H3PW12O40) and base sites (provided by CexTi1-xO2). H3PW12O40/Ce0.1Ti0.9O2 showed the highest catalytic performance among the H3PW12O40/CexTi1-xO2 catalysts. 相似文献
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Ninh Nguyen Jacques Choisnet Maryvonne Hervieu Bernard Raveau 《Journal of solid state chemistry》1981,39(1):120-127
Oxygen defect K2NiF4-type oxides have been synthesized for a wide composition range: 0 ≤ x ≤ 1.34. From the X-ray and electron diffraction study three domains have been characterized: orthorhombic compounds with La2CuO4 structure for 0 ≤ x < 0.10, tetragonal oxides similar to LaSrCuO4 for 0.10 ≤ x < 1 and several superstructures derived from the tetragonal cell ( with n = 3, 4, 4.5, 5, 6) for 1 ≤ x ≤ 1.34. The compounds corresponding to 0 < x < 1 differ from the other oxides in that they are characterized by the presence of copper with two oxidation states: + 2 and + 3. A model structure for La0.8Sr1.2CuλO3.4, in which copper has only the + 2 oxidation state, and for which the actual cell is tegragonal—a = 18.804 Å and c = 12.94 Å—has been established. The particular structural evolution of these compounds is discussed in terms of a competition between the capability of Cu(II) to be oxidized to Cu(III) and the ordering of oxygen vacancies. 相似文献
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Grisel Corro Odilón Vázquez-Cuchillo Fortino Ba?uelos 《Reaction Kinetics and Catalysis Letters》2005,87(1):171-175
Summary A strong promoting effect of the presence of C3H8or C3H6was determined for the combustion of CH4in excess oxygen, over pre-sulfated 1%Pt/g-Al2O3and pre-sulfated 1%Pt-2%Sn/g-Al2O3catalysts.</o:p> 相似文献
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P.P. Edwards R.G. Egdell I. Fragala J.B. Goodenough M.R. Harrison A.F. Orchard E.G. Scott 《Journal of solid state chemistry》1984,54(2):127-135
HeI-excited valence-band ultraviolet photoelectron spectra and MgKα-excited Ti-2p X-ray photoelectron spectra are reported for the spinel materials LiTi2O4 and . The presence of a Fermi edge in the ultraviolet photoelectron spectrum of LiTi2O4 confirms the metallic nature of this material, although the measured density of states at the Fermi energy is much lower than that expected from an independent-electron interpretation of the magnetic susceptibility. This difference is attributed to a strong interaction of the conduction electrons with the lattice vibrations. The localization of conduction electrons that occurs in the final state in the Ti-2p X-ray photoelectron spectrum of LiTi2O4 is attributed to a Coulomb interaction with a core hole. 相似文献
19.
Mónica Martos Beatriz Julián Eloisa Cordoncillo 《Journal of solid state chemistry》2007,180(2):679-687
Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti1−2xNbxNixO2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni2+ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO2 powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO2-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.). 相似文献
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A series of single-phase LixNi0.8-yCo0.2ZnyOp(0.96 ≤x≤ 1.10, 0 ≤y≤ 0.05, 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method, in which LiOH·H2O, Zn-doped spherical Ni(OH)2 and Co2O3 were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD, SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine, narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity, but also a better cycling stability characterization than the un-doped one. The Li1.06Ni0.75Co0.22Zn0.03O2.03 material has an initial reversible capacity as high as 160.5mAh·g-1; and a first discharge efficiency 89.2%, and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles. 相似文献