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A series of air-stable, late transition, metal-based initiators with the structures ML2(CCR)2 (M=Pd and Ni; L=PPh3 and Pn-Bu3; R=Ph and CH2OH) for the polymerization of (dimethylamino)ethyl methylate (DMAEMA) were developed. Transition metal, phosphine, alkynyl, as well as solvents exhibited significant influence on the polymerization. Among them, Pd(CCPh)2(PPh3)2 (PPP) shows the highest activity in CHCl3 for DMAEMA polymerization. The PDMAEMA obtained is a syndiotactic polymer with high number-average molecular weight (Mn) of 20.2 × 104. A free radical polymerization mechanism with some ATRP characteristics was proposed for the present polymerization. 相似文献
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Jihong LU Danfeng ZHANG Qian CHEN Buwei YU 《Frontiers of Chemical Science and Engineering》2011,5(1):19
Two types of salicylaldiminato-based nickel complexes, mono-ligated Ni(II) complexes ([O-C6H4-o - C(H)=N-Ar]Ni(PPh3)(Ph) (5 ), [O-(3,5-Br2)C6H2-o -C(H)=N-Ar]Ni(PPh3)(Ph) (6 ), [O-(3-t -Bu)C6H3-o -C(H)=N-Ar]Ni(PPh3)(Ph) (7 )) and bis-ligated Ni(II) complexes ([O-(3,5-Br2)C6H2-o -C(H)=N-Ar]2Ni (8 ), [O-(3,5-Br2)C6H2-o -C(H)=N-2-C6H4(PhO)]2Ni (9 ), Ar=2,6-C6H3(i -Pr)2) were synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), mass spectrography (MS) and elemental analysis (EA). In the presence of methylaluminoxane (MAO) as cocatalyst, all the nickel complexes exhibited high activities for the polymerization of methyl methacrylate (MMA) and syndiotactic-rich poly(methyl methacrylate) (PMMA) was obtained. The complexes with less bulky substituents on salicylaldiminato framework possessed higher activities, while with the same salicylaldiminato, the mono-ligated nickel complexes showed higher catalytic activity than bis-ligated ones. 相似文献
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采用可编程的线性直流电源电解铁阳极产生Fe2+,以此引发过硫酸铵(APS)产生自由基,催化甲基丙烯酸甲酯(MMA)单体进行乳液聚合。在优化的聚合时间和引发剂浓度条件下,重点研究了电流强度对聚合物相对分子质量及分布的调控作用。结果表明:在0.10~0.18 A的电流范围内,随着电流强度的增大,聚合物的平均相对分子质量也有所增加。通过调节电流的大小,可以对聚合物的相对分子质量分布进行调控,当电流从0.10 A增大至0.12 A时,聚甲基丙烯酸甲酯(PMMA)相对分子质量分布指数(Mw/Mn)减小为1.461。 相似文献
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《国际聚合物材料杂志》2012,61(1-2):55-68
Abstract The synthesis of nickel/chromium hydrotalcite and zinc/iron Hydrotalcites are described. The compounds have been characterized by X-ray powder diffraction (XRD), Infrared spectroscopy (IR), and thermogravimetric analysis (TGA) techniques. The rate of polymerization of methyl methacrylate (MMA) in the presence of different hydrotalcites at various concentrations of initiator and different temperatures were studied. The activation energies of polymerization were calculated. 相似文献
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根据热电阻法测量原理,测量了甲基丙烯酸甲酯(MMA)本体聚合模拟体系的导热系数。研究了导热系数随转化率和温度的变化规律,并建立了相应的关联式。测量结果表明,相同转化率时,MMA本体聚合体系导热系数随温度的升高而减小;不同温度下其导热系数均随转化率的增大而逐渐增加。该关联式计算值与测量值的最大偏差为1.6%,可较好地预测MMA本体聚合体系导热系数。 相似文献
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研究了催化剂V2O5-P2O5/SiO2的制备,并对其结构、性能进行了表征。通过甲基丙烯酸甲酯的催化合成过程,对该催化剂的活性进行了考察。解释和分析了催化剂的制备、组成及反应条件等因素对其活性及甲基丙烯酸甲酯合成的影响。实验结果给出常压下气固相催化合成甲基丙烯酸甲酯效果较好的催化剂V2O5-P2O5/SiO2的制备条件:V/P摩尔比为1:2.8,活化温度为450℃,浸渍时间3h。实验结果还给出常压下催化剂V2O5-P2O5/SiO2催化合成甲基丙烯酸甲酯效果较优的反应条件:在空速1500h^-1,反应温度300℃,丙酸甲酯/甲缩醛摩尔比为1.6:1的条件下进行常压反应,所得甲缩醛转化率为86.7%,甲基丙烯酸甲酯的选择性为66.2%,收率为57.40%。 相似文献
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A series of supported intermetallic Pb-Pb catalysts were prepared with the impregnation method by changing the support (silica, molecular sieve or g-alumina ) and the pore size. The chemical states of the two metals were characterized by XPS analysis, the process for producing methyl methacrylate based on the direct oxidative esterification of methacrolein with methanol in the presence of oxygen was performed in a slurry reactor with the above-mentioned catalysts. The influence of the calcination temperature and the kinds of support as well as the pore size on catalytic activity had been extensively investigated. Under the conditions of temperature at 80℃, catalyst 3.8% (w) and the reaction time 2 h, the conversion rate of methacrolein reached 85%, the selectivity and the yield of methyl methacrylate were 90% and 76.5%, respectively. 相似文献
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基于均匀设计方法对甲基丙烯酸甲酯(MMA)的分散聚合反应进行了试验设计,并通过回归分析,建立了聚甲基丙烯酸甲酯(PMMA)粒子相关性能参数(PMMA相对分子质量、粒径大小及分布)和各变量(单体质量分数、稳定剂用量、引发剂用量和反应介质溶度参数)之间的回归方程。根据回归方程进行了分散聚合反应的配方优化,得到了约束条件下的MMA分散聚合反应配方,实测值与预测值比较结果表明,回归方程的预测值与优化配方制备的PMMA粒子的各项性能实测值之间的相对偏差在10%以内,对试验配方设计有指导作用。 相似文献
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合成了一种新的同双核钛茂金属催化剂[(CH3C5H4)TiCl2]2[C5H4CH2CH2OCH2CH2C5H4](A),用元素分析和1H-NMR进行了表征.在助催化剂的作用下,该催化剂体系可有效催化甲基丙烯酸甲酯(MMA)本体和溶液聚合.考察了助催化剂、反应温度和时间对聚合的影响.结果表明,Al(i-Bu)3催化性能优于Al(Et)3和甲基铝氧烷(MAO).以Al(i-Bu)3为助催化剂,本体聚合在MMA和A的摩尔比为1 500,Al(i-Bu)3和A的摩尔比为20,60 ℃,反应时间20 h条件下,单体转化率达98.6%,PMMA的粘均分子量为 7.87×105;溶液聚合在MMA和A的摩尔比为1 500,Al(i-Bu)3和A的摩尔比为20,80 ℃,反应时间15 h条件下,单体转化率77.3%,PMMA的粘均分子量3.24×105.聚合所得PMMA分子量分布为5.0~7.0. 相似文献
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《国际聚合物材料杂志》2012,61(5):353-369
The catalytic behavior of cobalt (II) phthalocyanine (CoPc) immobilized on bentonite clay, with different complex loadings ranging between 0.2 and 2.2 wt%, in the presence of n-butyl amine solvent, was investigated in bulk polymerization of methyl methacrylate without using an activator or cocatalyst. The interaction of CoPc molecules with a bentonite surface, encouraged by the amine, involved the inclined stacking model, i.e., interaction between N-atoms of the macro-ring system and OH's of the support. Two different mechanistic pathway regions could be suggested, depending on complex loadings. The first was in the range, 0.2?1.0 wt% CoPc, behaving in ionic fashion as the bare bentonite. Isolated oriented molecules probably activated bentonite through the exposure of new internal acid sites during intercalation. The second, in the range of 1.4?2.2 wt% CoPc, proceeded via combined mechanisms, ionic functioned by bentonite support and free radical functioned by complex packed oriented stacks, staggered in clay galleries to cover a fraction of internal active acid sites. The number of polymer chains formed per one CoPc center (reaction turnovers) was >2–~10 with diluted catalyst samples. With higher loadings, one chain was formed per active site. Such behaviors, without a detectable effect on polymer characteristics or enchainment sequence, were studied in light of intercalation, orientation and accessibility models. 相似文献
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Yosreya M. Abu-Ayana Ragia M. Mohsen 《Polymer-Plastics Technology and Engineering》2013,52(8-9):1503-1522
A laboratory reactor was designed and constructed to study the effect of both speed of agitation and a concentration of suspension stabilizer on particle size and particle size distribution during the suspension polymerization of methyl methacrylate. It was concluded that the average particle size of the prepared polymer powder is directly proportional to the speed of agitation and is inversely proportional to the stabilizer concentration. New empirical equations correlating the average particle size and the particle size distribution (PSD) were derived from the study. 相似文献
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2-乙烯基吡啶-甲基丙烯酸甲酯两嵌段共聚物的合成与表征 总被引:2,自引:2,他引:0
采用阴离子活性聚合方法合成了聚2-乙烯基吡啶(P2VP)-聚甲基丙烯酸甲酯(PMMA)两嵌段共聚物(P2VP-b-PMMA),并采用GPC、FT-IR、NMR等手段进行了结构表征.结果表明,聚合产物为数均分子量103166、多分散指数1.08的单分散P2VP-b-PMMA. 相似文献
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以SiO2纳米粒子为种子的甲基丙烯酸甲酯乳液聚合 总被引:8,自引:0,他引:8
本文采用SiO2纳米粒子作为种子进行了甲基丙烯酸甲酯的乳液聚合。初步探讨了此类种子乳液聚合的过程;也分析了SiO2的用量对所生成的残渣率的影响,SiO2在残渣中的实际含量均比在乳液聚合物中略高,这是由于总有一些单体转移到不含SiO2的自由胶束中进行聚合而造成的。所得的复合乳液聚合物的力学和热学性能测试结果表明材料的这两种性能均随SiO2含量的增加而降低。 相似文献
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对氯甲基苯乙烯共聚物引发甲基丙烯酸甲酯原子转移自由基聚合 总被引:1,自引:0,他引:1
通过偶氮二异丁氰(AIBN)引发苯乙烯(St)与对氯甲基苯乙烯(p-CMS)共聚,合成了二元共聚物P(St-co-CMS),在氯化亚铜/四甲基乙二胺(CuC l/TMEDA)催化下,以此二元共聚物为大分子引发剂引发甲基丙烯酸甲酯(MMA)的原子转移自由基聚合(ATRP),成功地合成了结构明晰的以聚苯乙烯为主链、聚甲基丙烯酸甲酯为支链的接枝共聚物P(S-g-MMA)。大分子引发剂和接枝共聚物的结构通过红外光谱(IR)、核磁共振氢谱(1HNMR)得到了确认,并测定了接枝共聚物的平均支链数目、平均支链长度、接枝率及接枝效率。结果表明,用这种方法制备的接枝共聚物相对分子质量分布较窄,支链数目及长度可控,接枝效率高达93.7%。 相似文献
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This study investigated the relationship between particle size, particle distribution, thermal, and optical properties of poly(methyl methacrylate) microbeads using dispersion polymerization under various methanol/water (MeOH/H2O) dispersion medium ratios and methyl methacrylate acid concentrations. The particle size of the poly(methyl methacrylate) microbeads increased when the medium solubility and monomer concentration increased simultaneously. In addition, the molecular weight and polydispersity of the poly(methyl methacrylate) microbeads were increased as the methanol ratio increased. The refractive index increased as the content of the poly(methyl methacrylate) microbeads increased with wavelengths of 546 and 589 nm. 相似文献