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将五甲基茂基三苄氧基钛 (Cp Ti(OBz) 3) 改性甲基铝氧烷 (mMAO)催化体系以顺序加料溶液法合成的乙烯与苯乙烯嵌段共聚反应产物进行沸丁酮、沸四氢呋喃 (THF)和沸氯仿等溶剂连续抽提分离 ,发现嵌段共聚物主要存在于THF和CHCl3的可溶级分中 ,嵌段共聚物的总含量占共聚产物的 2 2 8wt%~ 38 2wt% ,对THF和CHCl3可溶级分分别用 1 3C NMR、WAXD、DSC和GPC等手段进行表征 .1 3C NMR谱显示出含有支化聚乙烯链段和间规聚苯乙烯链段的嵌段共聚物特殊结构 ,WAXD谱表明嵌段共聚物因两链段的相互缠结使各自结晶度显著较低 ,由于嵌段共聚物苯乙烯链段较长、乙烯链段较短 ,DSC图谱只显示苯乙烯链段的结晶熔融峰 ,GPC曲线表明 ,单茂钛催化体系催化乙烯 苯乙烯嵌段共聚合的单一活性中心特征 .由此对Cp Ti(OBz) 3 mMAO催化体系的苯乙烯 乙烯嵌段共聚合机理进行初探 相似文献
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先用五甲基茂基三苄氧基钛 /甲基铝氧烷催化苯乙烯预聚 ,再与丁二烯进行嵌段共聚合。考察预聚时间、催化剂浓度、苯乙烯浓度等条件对嵌段共聚合反应的影响。共聚产物经沸丁酮、沸甲苯、沸四氢呋喃、沸氯仿连续抽提后 ,嵌段共聚物主要存在于氯仿的可溶级分中。随着预聚时间的增加 ,共聚反应催化效率增加 ,共聚产物中丁二烯含量下降 ;随着催化剂浓度增加 ,共聚催化效率增加 ,[Ti]为 2 .0× 1 0 -4 mol/L时 ,共聚活性达到最大值 ( 1 7.78× 1 0 3 gP/gTi) ,随着催化剂浓度进一步增加 ,共聚催化效率下降 ,共聚产物中丁二烯含量变化亦存在峰值。 相似文献
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甲基丙烯酸甲酯和长链烷基酯的嵌段共聚戴李宗*邹友思郭金泉潘容华(厦门大学化学系厦门361005)关键词阴离子聚合,甲基丙烯酸酯,嵌段共聚合,表征1996-08-07收稿,1996-11-18修回国家自然科学基金资助项目嵌段共聚合能得到具微相体系的共聚... 相似文献
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以α-甲基萘钾为引发剂,按顺序加入丁二烯,八甲基环四硅氧烷(D4)在THF中进行负离了嵌段共聚,制备了聚丁二烯-聚二甲基硅氧烷嵌段共聚物,讨论了聚合条件对嵌段共聚合过程的影响。考察聚丁二烯活性链引发D4进行嵌段共聚的反应动力学,求得在THF中30℃时D4,开环链增长的表观速率为10kg/mol.h表观活化能为28.3kJ/mol。 相似文献
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以α-甲基萘钾为引发剂,按顺序加入丁二烯、八甲基环四硅氧烷(D4)在THF中进行负离子嵌段共聚,制备了聚了二烯-聚二甲基硅氧烷嵌段共聚物.讨论了聚合条件对嵌段共聚合过程的影响.考察了聚了二烯活性链引发D4进行嵌段共聚的反应动力学,求得在THF中30℃时D4开环链增长的表观速率为10kg/mol.h、表观活化能为28.3kJ/mol. 相似文献
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报道用稀土化合物改性的钛系载体催化剂(SN催化剂)进行苯乙烯和丙烯顺序嵌段共聚合(Sequential block copolymerization) 的研究。通过对初生嵌段共聚产物进行溶剂萃取与分级,并用^13C-NMR、WAXD、DSC、DMA和电子显微镜进行表征,推断共聚物为具有等规聚苯乙烯链和等规聚丙烯链段的A-B型二嵌段共聚物,且各段均能结晶。发现嵌段共聚物比相应的均聚物具有较好的综合力学性能和热性能,而且对iPS/iPP共混具有良好的增容作用。 相似文献
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本文研究了以正丁基锂为引发剂、四氢呋喃为极性添加剂,在环己烷中进行α-甲基苯乙烯与苯乙烯阴离子共聚合。通过共聚组成及聚合活性种研究,由反应机理推导了该体系的共聚组成方程,求得了不同[THF]下的表观竞聚率值(?)和(?)。 相似文献
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Jianhui Wang Yinghuai Zhu Shoujian Li Chong Zheng John A. Maguire Narayan S. Hosmane 《Journal of organometallic chemistry》2003,680(1-2):173-181
The reactions of RNHSi(Me)2Cl (1, R=t-Bu; 2, R=2,6-(Me2CH)2C6H3) with the carborane ligands, nido-1-Na(C4H8O)-2,3-(SiMe3)2-2,3-C2B4H5 (3) and Li[closo-1-R′-1,2-C2B10H10] (4), produced two kinds of neutral ligand precursors, nido-5-[Si(Me)2N(H)R]-2,3-(SiMe3)2-2,3-C2B4H5, (5, R=t-Bu) and closo-1-R′-2-[Si(Me)2N(H)R]-1,2-C2B10H10 (6, R=t-Bu, R′=Ph; 7, R=2,6-(Me2CH)2C6H3, R′=H), in 85, 92, and 95% yields, respectively. Treatment of closo-2-[Si(Me)2NH(2,6-(Me2CH)2C6H3)]-1,2-C2B10H11 (7) with three equivalents of freshly cut sodium metal in the presence of naphthalene produced the corresponding cage-opened sodium salt of the “carbons apart” carborane trianion, [nido-3-{Si(Me)2N(2,6-(Me2CH)2C6H3)}-1,3-C2B10H11]3− (8) in almost quantitative yield. The reaction of the trianion, 8, with anhydrous MCl4 (M=Ti and Zr) in 1:1 molar ratio in dry tetrahydrofuran (THF) at −78 °C, resulted in the formation of the corresponding half-sandwich neutral d0-metallacarborane, closo-1-M[(Cl)(THF)n]-2-[1′-η1σ-N(2,6-(Me2CH)2C6H3)(Me)2Si]-2,4-η6-C2B10H11 (M=Ti (9), n=0; M=Zr (10), n=1) in 47 and 36% yields, respectively. All compounds were characterized by elemental analysis, 1H-, 11B-, and 13C-NMR spectra and IR spectra. The carborane ligand, 7, was also characterized by single crystal X-ray diffraction. Compound 7 crystallizes in the monoclinic space group P21/c with a=8.2357(19) Å, b=28.686(7) Å, c=9.921(2) Å; β=93.482(4)°; V=2339.5(9) Å3, and Z=4. The final refinements of 7 converged at R=0.0736; wR=0.1494; GOF=1.372 for observed reflections. 相似文献
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用表面张力法研究了阳离子gemini表面活性剂乙基-1, 2-双(十二烷基二甲基溴化铵)(简写为12-2-12)和非离子表面活性剂十二烷基聚氧乙烯醚(C12En,其中n = 4, 10, 23)混合体系在气液界面上的吸附行为;用扩张流变技术研究了吸附膜的扩张粘弹行为,实验数据用Lucassen-van den Tempel (LVT)模型进行拟合并根据模型得到了极限弹性值.最后研究了混合体系的泡沫行为,用泡沫塌陷到初始高度一半所对应的时间(t1/2)来表征泡沫的稳定性.结果表明,所有的非离子表面活性剂C12En均与12-2-12产生了吸引作用.在12-2-12浓度相同的情况下,混合吸附层中吸附分子的最小分子占据面积的顺序为12-2-12/C12E23 > 12-2-12/C12E10 > 12-2-12/C12E4,而极限弹性的顺序为ε0, fit(12-2-12/C12E4) > ε0, fit(12-2-12/C12E10) > ε0, fit(12-2-12/C12E23).与单组分12-2-12形成的吸附膜相比,只有12-2-12/C12E4形成更加紧密的结构.具有较小亲水头基的非离子表面活性剂C12E4的加入,可增强12-2-12吸附膜的弹性,进而增强了对应体系泡沫的稳定性. 相似文献
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The kinetics of the decomposition of cyclohexyl hydroperoxide(CHHP) in benzene catalyzed by vanadyl dibenzoylmethane[V0(DBM).,] has been studied.It was found that the products of decomposition of CHHP were cyclohexanol and cyclohexanone,which are produced in about equimolar amount,and the product cyclohexanol obviously inhibited the decomposition of CHHP.The kinetics data can be satisfactorily described by the following equation (with [CHHP]0>>[VO(DBM)2]0)R0=kK[CHHP]0[VO(DBM)2]0/(1+k[CHHP]0)This is the kinetic evidence for the formation of a catalyst-hydro-peroxide intermediate.In the equation K is the stability constant of the catalyst-hydroperoxide intermediate complex;k is the rate constant for the decomposition of the complex.The rate constant K at 500℃ may be expressed as follows:k=1.9×108exp(-53.7×103/RT)S-1 with the activation energy Ea=53.7kJ mol-1 相似文献
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Zhu Yinghuai Shirley Lo Pei Sia Fethi Kooli Keith Carpenter Richard A. Kemp 《Journal of organometallic chemistry》2005,690(26):6284-6291
In situ reaction of Li[closo-1-Ph-1,2-C2B10H10] with 7-azabicyclo [4.1.0] heptane results in the formation of the disubstituted carborane, closo-1-Ph-2-(2′-aminocyclohexyl)-1,2-C2B10H10 (1), in 63% yield. Decapitation of (1) with potassium hydroxide in refluxing ethanol produces the cage-opened nido-carborane, K[nido-7-Ph-8-(2′-aminocyclohexyl)-7,8-C2B9H10]− (2), in 80% yield. Deprotonation of the above monoanion with two equivalents of n-butyllithium followed by reaction with anhydrous MCl4 · 2THF (M = Zr, Ti) provides d0-half-sandwich metallocarboranes, closo-1-M(Cl)-2-Ph-3-(2′-σ-(H)N-cyclohexyl)-2,3-η5-C2B9H9 (3 M = Zr; 4 M = Ti) in 53% and 42% yields, respectively. The reaction of Li[closo-1,2-C2B10H11] with 7-azabicyclo [4.1.0] heptane in THF affords closo-1-(2′-aminocyclohexyl)-1,2-C2B10H10 (5) in 59% yield. Immobilization of the carboranyl amino ligand (1) to an organic support, Merrifield’s peptide resin (1%), has been achieved by the reaction of the sodium salt of (5) with polystyryl chloride in THF to produce closo-1-(2′-aminocyclohexyl)-2-polystyryl-1,2-C2B10H10 (6) in 87% yield. Further reaction of the dianion derived from (6) with anhydrous ZrCl4 · 2THF led to the formation of the organic polystyryl supported d0-half-sandwich metallocarborane, closo-1-Zr(Cl)-2-(2′-σ-(H)N-cyclohexyl)-3-polystyryl-2,3-η5-C2B9H9 (7), in 38% yield. These new compounds have been characterized by elemental analyses, NMR, and IR spectra. Polymerizations of both ethylene and vinyl chloride with (3) and (7) have been performed in toluene using MMAO-7 (13% ISOPAR-E) as the co-catalyst. Molecular weights up to 32.8 × 103 (Mw/Mn = 1.8) and 9.5 × 103 (Mw/Mn = 2.1) were obtained for PE and PVC, respectively. 相似文献
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Martina Dotzler Astrid Schmidt Jochen Ellermann Falk A. Knoch Matthias Moll Walter Bauer 《Polyhedron》1996,15(24):4425-4433
BiBr3 or SbI3 react at 20°C with LiN(PPh2)2 (1) to give elementary Bi or Sb and the P---P coupled phosphazene ligand Ph2P---N=PPh2---PPh2=N---PPh2 (2). The reaction of AsI3 with 1 at room temperature formed yellow needles of the eight-membered heterocycle
(3), whereas AsI3 interacted at 80°C with 1 in the molar ratio of 1:3 to give elementary arsenic and 2. Treatment of AsI3 and 1 at 20°C in a 1:2 stoichiometry yielded the seven-membered, cyclic arsenium(I) salt I·4THF (5·4THF), which was characterized by elemental analysis, conductivity, mass, IR and NMR spectroscopy and single-crystal X-ray structural analysis. 相似文献
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The electrochemical properties of CeCl3, dissolved in LiCI-KCI eutectic melt, were investigated by electrochemical techniques, such as cyclic voltammetry and square wave voltammetry on Mo electrode. It was shown that Ce(Ⅲ) is reduced to Ce(0) based on a three-step mechanism. In a temperature range of 833-923 K, the diffusion coefficient of Ce(Ⅲ) is lgDceoH)=-2.49-1704/T determined by means of the Berzins-Delahay equation with two different expressions under reversible and irreversible conditions. The apparent standard potential of a Ce(Ⅲ)/Ce(0) redox system is ECE^3+0^*/Ce^0 =3.551+0.0006132T(K) vs. Cl2/Cl^-. Some thermochemical properties of CeCl3 solutions were also derived from the electrochemical measurements, such as the enthalpy, entropy, Gibbs free energies and the activity coefficients of Ce(Ⅲ). The Gibbs free energy of a dilute solution of CeCl3 in this system was determined to be △G^0CeCl3/(kJ·mol^-1)=-1027.9+0.178T(K) And the activity coefficients, γCeCl3 , range between (7.78-9.14)×10^-3. Furthermore, the standard rate constant of kinetic reaction was calculated to be (4.94-9.72)× 10^-3 cmZ/s and the reaction was regarded as a quasi-reversible reaction under the present experimental conditions at 833 K. 相似文献
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Abstract— The extinction coefficient εT , of triplet benzophenone in benzene has been directly determined by absolute measurements of absorbed energy and triplet absorbance, Δ D 0 T , under demonstrably linear conditions where incident excitation energy, E 0 , and ground state absorbance, A 0 , are both extrapolated to zero. The result, 7220 ± 320 M -1 cm-1 at 530 nm, validates and slightly corrects many measurements relative to benzophenone of triplet extinction coefficients made by the energy transfer technique, and of triplet yields obtained by the comparative method.
As E0 and A 0 both decrease, Δ D 0 T becomes proportional to their product. In this situation, the ratio R = (1/ A 0 )(dΔ D 0 T /d E 0 ) = (εT - εG )φT . Measurements of R , referred to benzophenone, give (εT - εG )φT for any substance, without necessity for absolute energy calibration.
Both absolute and relative laser flash measurements on zinc tetraphenyl porphyrin (εT - εG at 470 nm = 7.3 × 104 M -1 cm-1 ) give φT = 0.83 ± 0.04. 相似文献
As E
Both absolute and relative laser flash measurements on zinc tetraphenyl porphyrin (ε
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Hervine Miller 《Polyhedron》1986,5(12):1965-1968
There is kinetic evidence of the formation of [Co(NH3)5NCSAg3]5+ in the interaction of [Co(NH3]5NCS]2+ with Ag+ in aqueous solution, with pseudo-first-order formation rate constant k = 0.158 s−1 for the forward reaction in the following equation at 25°C and [Ag+] in the range of 1.23–5.0 × 10−2 mol dm−3 and 0.10 ionic strength (NaClO4): Additionally, the formation constant, β2, for [Co(NH3)5NCSAg2]4+ has been determined to be log β2 = 4.717. For the [Rh(NH3)5I]2+-Ag+ reaction there is evidence of an outer-sphere interaction with rate constants of k2 = 670 dm3 mol−1 s−1 at 25°C and 0.10 ionic strength. This outer-sphere species undergoes further reaction to give the silver ion containing intermediates of the aquation reactions. 相似文献
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四氮杂-18-冠-6的锌/铜(Ⅱ)配合物的合成与结构 总被引:1,自引:0,他引:1
合成了1,10-二氧-4,7,13,16-四氮杂-18-C-6(以下用L代表)的硝酸锌和硝酸铜(Ⅱ)配合物.配合物Cu(L)(NO3)2晶体属正交晶系,Pbca空间群,晶胞参数如下:a=1.5744(6)nm,b=1.2676(4)nm,c=1.8983(6)nm,V=3.789(2)nm3,Z=8,最终偏离因子R1=0.0431,wR2=0.0904.配合物Zn(L)(NO3)2晶体属正交晶系,Pnna空间群,晶胞参数a=1.61356(10)nm,b=1.32871(11)nm,c=0.86260(5)nm,V=1.8494(2)nm3,Z=4,最终偏离因子R1=0.0718,wR2=0.1950.冠醚环上的4个氮原子和2个氧原子都参与了配位,NO3-未参与配位,中心金属离子的配位数为6.红外光谱、1H NMR和EPR谱等研究佐证了上述测定结果.Cu(L)(NO3)2循环伏安实验表明该配合物在-1.0~0V电压范围内,只发生Cu(Ⅱ)→Cu(Ⅰ)的还原反应,而在-1.6~0V电压范围内,发生Cu(Ⅰ)→Cu(0)的反应. 相似文献