共查询到9条相似文献,搜索用时 0 毫秒
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《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):401-413
The polymerization of an ionic propargyl derivative, 4-dimethylamino-N-propargylpyridinium bromide (DMAPPB), was carried out by palladium, platinum, and ruthenium chlorides. The polymerization of DMAPPB by these transition metal catalysts proceeded well to give a relatively high polymer yield. The chemical structure of the resulting polymer was characterized by such instrumental methods as elemental analysis, infrared, NMR, UV–visible spectroscopies to have conjugated polymer backbone system bearing 4-dimethylamino-N-methylenepyridinium bromide. The polymer was soluble in DMF, DMSO, and formic acid, and found to be less hygroscopic than those of similar homologues having more smaller substituents. The resulting polymers were mostly black powders and showed the amorphous morphology. 相似文献
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SiO2负载的后过渡金属配合物/三乙基铝催化乙烯聚合研究 总被引:5,自引:0,他引:5
将后过渡金属配合物{[2,6-ArN=C(Me)2C5H3N]FeCl2} ( Ar=2,6-iPr2C6H3) Ⅰ负载于SiO2上, 并与三乙基铝(AlEt3)组成催化剂体系并催化乙烯聚合. 考察了Al/Fe比(AlEt3/催化剂摩尔比)、聚合温度对催化剂活性、聚乙烯(PE)分子量、熔融温度以及结晶度的影响. 在Al/Fe比为750、聚合温度为40 ℃时, 催化剂活性达到7.07×105g PE·(mol Fe·h)-1. 实验所得聚合物的分子量为1.05×105~2.33×105 g/mol, 熔融温度高达132 ℃左右,结晶度在44.2%~77.8%之间. 相似文献
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杯芳烃钕配合物均相体系催化丁二烯聚合 总被引:6,自引:0,他引:6
应用新型配体杯芳烃钕配合物与三异丁基铝以及添加Al(i-Bu)2Cl为第三组分构成二元、三元均相催化体系催化丁二烯聚合.研究结果表明,对于杯[6,8]芳烃钕(C[n]NdxCly)/Al(i-Bu)3/汽油体系,当n(Al)/n(Nd)=40~100,50℃时具有中等催化聚合活性,所制得聚丁二烯的粘均分子量为1×105~2×105,顺-1,4结构含量为89%左右,添加适量Al(i-Bu)2Cl能提高催化活性.杯芳烃钕(C[n]Nd)构成的三元体系在n(Al)/n(Nd)=30,n(Cl)/n(Nd)=1~3时不同杯芳烃的活性次序为:C6>C4>C8 相似文献
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用原子转移自由基聚合方法制备新型含有高分子金属配合物的无机-有机杂化材料 总被引:5,自引:3,他引:2
近年来,表面引发聚合制备聚合物刷,由于其能控制无机物表面性能,在材料科学方面有广泛的应用前景.在制备聚合物刷的一系列聚合方法中,“活性”/可控自由基聚合,尤其是原子转移自由基聚合(Atom Transfer Radical Polymerization,ATRP)得到广泛使用.它可获得分子量分布较窄的结构规整的聚合物,可将一些功能性的单体引入聚合物体系获得功能聚合物, 相似文献
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Cui Wang Christina Wegeberg Oliver S. Wenger 《Angewandte Chemie (International ed. in English)》2023,62(43):e202311470
Photosensitizers for sensitized triplet-triplet annihilation upconversion (sTTA-UC) often rely on precious heavy metals, whereas coordination complexes based on abundant first-row transition metals are less common. This is mainly because long-lived triplet excited states are more difficult to obtain for 3d metals, particularly when the d-subshell is only partially filled. Here, we report the first example of sTTA-UC based on a 3d6 metal photosensitizer yielding an upconversion performance competitive with precious metal-based analogues. Using a newly developed Cr0 photosensitizer featuring equally good photophysical properties as an OsII benchmark complex in combination with an acetylene-decorated anthracene annihilator, red-to-blue upconversion is achievable. The upconversion efficiency under optimized conditions is 1.8 %, and the excitation power density threshold to reach the strong annihilation limit is 5.9 W/cm2. These performance factors, along with high photostability, permit the initiation of acrylamide polymerization by red light, based on radiative energy transfer between delayed annihilator fluorescence and a blue light absorbing photo-initiator. Our study provides the proof-of-concept for photon upconversion with elusive first-row analogues of widely employed precious d6 metal photosensitizers, and for their application in photochemical reactions triggered by excitation wavelengths close to near-infrared. 相似文献
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A series of cationic rare‐earth aryloxide complexes, i.e., [LREOAr']+[B(C6F5)4]– (L = CH3C(NAr)CHC(CH3)(NCH(R)CH2PPh2); RE = Y, Lu; Ar' =2,6‐tBu2‐C6H3, 2,6‐(PhCMe2)2‐4‐Me‐C6H2; Ar = 2,6‐iPr2‐C6H3, 2,6‐(Ph2CH)2‐4‐iPr‐C6H2; R = H, CH3, iPr, Ph), were prepared and applied to the Lewis pair polymerization of methyl methacrylate (MMA). The stereoregularity of the resulting PMMA was significantly affected by the R substituent on the pendant arm of the tridentate NNP ligand, and was found to increase with increase in the steric hindrance of R. When using a Ph group as R, the Y complex produced a highly isotactic polymer with an mm value of 95% and a Tg of 54.6 oC. In contrast, the steric hindrance of the Ar and Ar' groups had no effect on the tacticity of the resulting polymer, presumably because these two substituents were situated such that they pointed outward from the cyclic intermediates. Kinetics studies demonstrated that the polymerization was a first‐order process with regard to the monomer concentration prior to catalyst deactivation. End group analysis indicated that the polymerization was accompanied by two possibly competing chain‐termination side reactions that proceeded via intramolecular backbiting cyclization. 相似文献