端环氧基聚苯乙烯低聚物的合成与表征

在常压、惰性气体保护下,用正丁基锂(n-BuLi)引发苯乙烯阴离子聚合,在添加剂无水三氯化铝的存在下,用环氧氯丙烷(ECH)对聚苯乙烯阴离子进行封端反应,制得分子量约为5×103的末端带环氧基团的聚苯乙烯低聚物。用GPC、FT-IR1、H-NMR及盐酸-二氧六环银量法对低聚物进行了表征,并考察了添加剂、封端反应的温度和时间对环氧端基含量的影响。结果表明:加入添加剂和降低封端温度有利于环氧端基含量的提高,在0℃左右封端效率较高,封端反应时间以1.0 h为宜。     

负离子合成POSS端基官能化聚苯乙烯

以苯乙烯为单体、氯丙基七异丁基多面体低聚倍半硅氧烷(chloropropyllsobutyl POSS,POSS-Cl)为封端剂、正丁基锂(n-Bu Li)为引发剂、环己烷为溶剂、四氢呋喃(THF)为结构调节剂,采用阴离子聚合技术,合成了POSS端基官能化聚苯乙烯(PS-POSS).采用核磁共振仪(1~H-NMR、~(13)C-NMR)和凝胶渗透色谱仪(GPC)对PS-POSS的结构和分子量分布进行了表征,证明了POSS与聚苯环乙烯锂(PSLi)发生了封端反应生成PSPOSS;封端后分子量分布略有加宽,特别是相比传统有机封端剂,没有二聚等副产物生成.考察了引发剂种类、结构调节剂用量、POSS用量、PS分子量、封端反应温度和时间等因素对PS-POSS封端效率的影响.结果表明,在THF/n-BuLi摩尔比大于5、POSS/n-BuLi摩尔比等于1.1、反应温度为60℃、反应时间为30 min时,封端效率最高,达到80%以上;而随着PS数均分子量增加,封端效率逐渐降低.     

高效凝胶色谱研究甲基丙烯酸环氧丙酯封端聚苯乙烯大分子单体的活性

合成大分子单体的封端剂一般是含卤素原子的烯烃化合物、丙烯酰卤化合物、卤代环氧化合物及不饱和酸酐等四大类。甲基丙烯酸环氧丙酯(GMA)作为聚苯乙烯(PS)活性阴离子封端剂合成甲基丙烯酸环氧丙酯封端聚苯乙烯大分子单体(PS-GMA)是     

基于双锂法的炔基功能化热塑性弹性体的合成

苯乙烯-异戊二烯-苯乙烯三嵌段聚合物(SIS)是目前广泛使用的一种热塑性弹性体(TPE)材料, 建立高效、 精准、 普适的SIS功能化方法一直是提高TPE材料性能的关键. 首先, 利用双烯单体与单官能度引发剂的反应合成了双官能度的双锂引发剂; 然后采用双锂引发法, 以炔基功能化单体封端, 高效合成了α,ω-端炔基官能化SIS聚合物. 采用叔丁醇锂作为异戊二烯聚合段的调节剂, 叔丁醇钾作为苯乙烯聚合段的调节剂, 合成了低乙烯基结构含量(5.8%)、 窄分子量分布(<1.17)的SIS三嵌段聚合物; 再向SIS三嵌段聚合物中一步加入炔基官能化的1,1-二苯基乙烯(DPE)衍生物进行封端, 以高于90%的收率高效合成了α,ω-端炔基官能化SIS三嵌段模块聚合物, 借助炔基的高效点击反应, 实现了功能化及拓扑化TPE材料的制备.     

含苄氯端基β-蒎烯大分子引发剂及嵌段共聚物的合成

在 - 40℃下 ,CH2 Cl2 中以α 氯代乙苯为引发剂 ,Ti(OiPr) 4 TiCl4复合物 (摩尔比为 1 3)为Lewis酸活化剂、nBu4NCl存在下先进行 β 蒎烯的活性聚合 ,30min后当单体转化率接近 10 0 %时 ,加入苯乙烯引发其活性聚合 .在苯乙烯低转化率 (15 %左右 )下终止反应 ,得到由 3～ 5个苯乙烯链节封端带苄氯端基的聚 β 蒎烯大分子引发剂 .1 H NMR分析表明每个大分子引发剂所带的苄氯端基数接近 1(1 1) .大分子引发剂与Ti(OiPr) 4 TiCl4复合后 ,CH2 Cl2 中 - 40℃下能顺利引发苯乙烯阳离子聚合 ,获得 β 蒎烯 苯乙烯嵌段共聚物 ;与氯化亚铜(CuCl) 2 ,2′ 联二吡啶 (bipy)复合 ,组成原子转移自由基聚合 (ATRP)引发体系 ,在甲苯中 110℃引发甲基丙烯酸甲酯 (MMA)自由基聚合 ,得到 β 蒎烯 MMA嵌段共聚物 ,但此时大分子引发剂的引发效率小于 10 0 %     

三步法合成高封端率端氨基聚乳酸

叔丁氧羰基碳酸酐((Boc)2O)和氨基丙醇反应合成叔丁氧羰基氨基丙醇(Boc-氨基丙醇),以此为引发剂在辛酸亚锡的催化下,引发L-丙交酯开环聚合合成叔丁氧羰基氨基封端聚乳酸(BocNH-PLLA),叔丁氧羰基(Boc)经三氟乙酸处理脱除后得到端氨基聚乳酸(PLLA-NH2).以PLLA-NH2为大分子引发剂,引发ω-苄氧羰基L-赖氨酸-N-羧酸酐(ω-Z-L-Lysine-NCA)开环聚合,合成聚L-乳酸-聚ω-苄氧羰基L-赖氨酸两嵌段共聚物(P(LLA-LLz)).采用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)对聚合物结构进行了表征.结果表明:PLLA-NH2端基亲核性明显提高,可引发ω-Z-L-Lysine-NCA开环聚合制备嵌段共聚物,PLLA-NH2的合成方法简便,氨基封端率高,其分子量和单体与引发剂的摩尔比具有良好的线性关系.     

以角鲨烯为天然橡胶模型物合成ATRP引发剂

以角鲨烯作为天然橡胶的模型物合成了ATRP引发剂,即先通过双键的部分环氧化得到环氧化角鲨烯(ESq),ESq再与2-溴代异丁酸发生开环反应合成溴功能化角鲨烯(ESq-Br).采用FT-IR和1 H-NMR研究了ESq与ESq-Br的结构,并结合GC-MS和13C-NMR分析了环氧基、溴功能基等官能团的分布情况.结果表明:ESq中含有3种环氧结构,且环氧基是均匀分布的;环氧基开环的同时伴随着重排副反应,通过研究剩余环氧基的分布,可推测ESq-Br中溴功能化单元(即引发点)的分布也是均匀的.     

PEO-PPO-PEO改性聚醚在开孔树脂模具的应用研究

以三嵌段端羟基聚醚HO-PEO-PPO-PEO-H为原料,通过酯化封端和醚化封端改性,分别制备出酯化和醚化封端的三嵌段聚醚,并以此为乳化剂与乙烯基混合单体、聚合物树脂粉料、水和氧化-还原引发体系混合形成可浇注固化的悬浮多相乳液。研究了乳化剂封端酯化醚化结构、封端碳链C_(4~16)及CH_2=C(R1)COOCH(R2)CH_2(式中R1=H,CH_3;R2=H,CH_3)对含水乳液稳定性能的影响及固化形成的耐高压多孔树脂模具孔隙开闭孔性、孔隙率、孔径大小及其分布的影响。结果表明,长链烷基醚化封端改性的三嵌段聚醚具有良好的乳化稳定性能,成型模具最可几孔径范围为24~50μm,开孔孔隙率为25%(V/V)以上。     

丙烯酸/2-丙烯酰胺基-2-甲基丙磺酸高吸水树脂的反相悬浮聚合及其性能

采用反相悬浮聚合法,通过均匀实验设计,制备了聚(丙烯酸(AA)/2-丙烯酰胺基-2-甲基丙磺酸(AMPS)）(PAAMPS)高吸水树脂,探讨了单体摩尔分数及其中和度、引发剂及交联剂摩尔分数（相对于单体总量）对蒸馏水、质量分数0.9%NaCl水溶液中吸液性能的影响,并经实验数据拟合,得到了二次回归方程,比较了优化配方、单因素实验的模拟值和实验值,结果表明,模拟值与优化值基本接近,其优化工艺参数为：AMPS占单体的摩尔分数8%,中和度为75%,交联剂、引发剂用量与单体的摩尔分数分别为0.035%和0.17%,单体总质量浓度为30%,分散剂用量为单体质量分数的0.5%,反应温度70 ℃,反应时间1.5 h。 此条件下合成的PAAMPS在蒸馏水、0.9%NaCl水溶液中的吸液倍率分别为1.600和130 g/g。     

硅醚-有机铝体系引发氧化环己烯光开环聚合

<正> 环氧化合物的光开环聚合一般采用正离子光引发剂,常用的有重氮盐、硫鎓盐和碘鎓盐。它们在光照下产生Lewis酸引发环氧化合物开环聚合,由于Lewis酸对金属有强的腐蚀性,从而限制了它们在光固化涂料的应用。 近年,Hayase等报道了一种新型光引发剂,是由硅醚和有机铝组成,用它固化端基     

Gels from a semifluorinated n-alkane in fluorinated solvents as a probe for intermolecular interactions

Diblock semifluorinated n-alkanes can form aggregates and gels in fluorinated solvents. We have investigated the thermal behavior of binary mixtures comprising F(CF₂)₈(CH₂)₁₆H and fluorinated solvents. The solvents were perfluorohexane, perfluoroheptane, perfluorooctane, perfluorooctyl bromide, perfluorodecalin, and perfluorotributylamine. The phase diagrams were used to calculate the activity coefficients of the two components and the main excess thermodynamic functions. The solubility and self-assembly behavior of F₈H₁₆ in the fluorinated solvents are related to the different solute–solvent dispersion interactions that depend on the polarizabilities and ionization potentials of the interacting species, and on the structural properties of the solvent.     

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性;均苯四甲酸二酐;联苯四羧酸二酐;二羟基联苯胺;聚酰亚胺;聚苯并噁唑;耐热性     

Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH₄ solution does not exceed 55 nm. NaBH₄ is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.     

HCOO在Cu(110)、Ag(110)和Au(110)表面的吸附

采用密度泛函理论(DFT)以及广义梯度近似方法(GGA)计算了甲酸根(HCOO)在Cu(110)、Ag(110)和Au(110)表面的吸附. 计算结果表明, 短桥位是最稳定的吸附位置, 计算的几何参数与以前的实验和计算结果吻合. 吸附热顺序为Cu(110)(-116 kJ·mol-1)>Ag(110)(-57 kJ·mol-1)>Au(110)(-27 kJ·mol-1), 与实验上甲酸根的分解温度相一致. 电子态密度分析表明, 吸附热顺序可以用吸附分子与金属d-带之间的Pauli 排斥来关联, 即排斥作用越大, 吸附越弱. 另外还从计算的吸附热数据以及实验上HCOO的分解温度估算了反应CO2+1/2H2→HCOO的活化能, 其大小顺序为Au(110)>Ag(110)>Cu(110).     

Transition metal complexes of the tripodal ligand 4-(2′-pyridylmethyl)-4-azaheptane-1,7-diamine. Crystal structures of [CuLCl]ClO4 and [NiL(MeCN)2](ClO4)2

The tripodal ligand 4-(2′-pyridylmthyl)-4-azaheptane-1,7-diamine has been prepared by reaction of 2-aminemethyl pyridine with acrylonitrile, followed by the reduction of the nitrile groups. Copper(II), nickel(II), zinc(II), cobalt(III) and chromium(III) complexes of the ligand have been prepared and characterized and the crystal structures of the complexes [CuLCl]ClO₄ and [NiL(MeCN)₂](ClO₄)₂ determined. The copper complex is five coordinate with approximate square pyramidal stereochemistry with the apical position occupied by a primary amine donor. The nickel complex is octahedral with the pyridine nitrogen donor lying trans to an acetonitrile ligand.     

SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES WITH AMPICILLIN

Abstract

The reaction, in water, of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions with sodium ampicillinate at room temperature has allowed isolation of dimers with the following general formula [M(amp)Cl]₂ × nH₂O (n = 1.5?3.2). The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibilities and spectroscopic methods (IR, Raman, EPR and UV-Visible). A dinuclear structure based on octahedrally coordinated metal ions is proposed.     

Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Coordination compounds based on imidazole and benzimidazole substituted nitronyl nitroxide radicals with transition metal ions and trivalent lanthanide ions are described from the perspective of their magnetic properties.For the transition metal compounds the crystal structures show various metal-nitroxide dimensionalities including mononuclear (0D), one-dimensional (1D) and two-dimensional (2D) complexes. The mononuclear complexes were isolated with most metal ions of the first transition series. One copper(II) complex shows a copper(II)-radical ferromagnetic coupling (J = +75 cm⁻¹) while for the other mononuclear compounds, mainly with manganese(II), the metal-radical interactions are antiferromagnetic. The one-dimensional and two-dimensional complexes are manganese(II) compounds which show canting effects leading to weak ferromagnetism.For the trivalent lanthanide ions [La(III), Gd(III) and Eu(III)], three series of mononuclear complexes were obtained in which the metal center is bound to four, two or one nitroxide radicals depending on the counter ions and ancillary ligands. Unexpectedly, in most gadolinium(III) complexes, the Gd(III)-radical interactions were found to be antiferromagnetic in contradiction with other foundings and previous theoretical models. In support to the magnetic studies, the optical properties of the lantanide complexes have also been investigated and are briefly described.     

具有聚集诱导发光性质的近红外荧光染料

聚集诱导发光(AIE)现象的发现为解决传统有机荧光分子在高浓度和聚集形态下存在的荧光猝灭问题提供了最佳方案,并实现了在光电器件、化学传感、生物成像和靶向治疗等众多领域的广泛应用.随着对AIE 发光机理研究的不断深入,AIE 分子体系得到了极大的扩展.其中,一类具有给体-受体结构的AIE分子能够显著降低分子能隙,使发光分...     

Simple,Selective, and Sensitive Spectrophotometric Method for Determination of Trace Amounts of Nickel（Ⅱ）, Copper （Ⅱ）, Cobalt （Ⅱ）, and Iron （Ⅲ） with a Novel Reagent 2-Pyridine Carboxaldehyde Isonicotinyl Hydrazone

A selective and sensitive reagent of 2-pyridine carboxaldehyde isonicotinyl hydrazone（2-PYAINH） was synthesized and studied for the spectrophotometric determination of nickel, copper, cobalt, and iron in detail. At a pH value of 7.0, 9,0, 9.0, and 8.0, respectively, which greatly increased the selectivity; nickel, copper, cobalt, and iron reacted with 2-PYAINH to form a 1：2 yellow-orange, 1：2 yellow-green, 1：2 yellow and 1：1 yellow complexes, with absorption peaks at 363, 352, 346, and 359 nm, respectively. Under the optimal conditions, Beer＇s law was obeyed over the ranges of 0.01-1.4, 0.01-1.5, 0.01-2.7, and 0.01-5.4 mg/L respectively. The apparent molar absorptivity and Sandell＇s sensitivities were 8.4×10^4, 5.2×10^4, 7.1×10^4, and 3.9×10^4 L·mol^-l·cm^-1, respectively, and 0.00069, 0.0012, 0.00078, and 0.0014 μg·cm2, respectively. The detection limits were found to be 0.001, 0.002, 0.003, and 0.01 mg/L, respectively. The detailed study of various interfering ions to make the method more sensitive was carried out and selective and several real samples were analyzed with satisfactory results.     

New Complexes of Ditopic Ligands with “d” and/or “s” Metal Ions

Abstract

The asymmetric compartmental macrocycles containing one N₂O₂ or N₃O₂ Schiff base and one O₂O₃ or O₂O₄ crown-ether like chamber, have been obtained by condensation reaction of the formyl precursors 3,3′-(3-oxapentane-1, 5-diyldioxy) bis (2-hydroxybenzaldehyde) or 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)-bis(2-hydroxybenzaldehyde) with ethyl ethylenediamine (H₂L_A, H₂L_C), 1,5-diamino-3-azamethylpentane(H₂L_B, H₂L_D), also in the presence of metal ions as templating agents. These ditopic ligands, with dissimilar coordination sites, have been designed and used for the selective complexation of “d” and/or “s” metal ions, respectively into the Schiff base and the crown ether chamber. The selectivity of these processes strongly depends on the size and on the donor atom sets of the sites. The possibility to obtain mononuclear M(L)·nH₂O (M = Ni²⁺, Cu²⁺, Co²⁺), Mn(L)(CH₃COO)·nH₂O or Na(L) and hetero-dinuclear MNa(L)(CH₃COO) (M = Ni²⁺, Cu²⁺, Co²⁺) and MnNa(L)(CH₃COO)₂·nH₂O complexes has been successfully tested. The ligands and complexes have been characterized by ir, nmr, mass spectrometry and magnetic susceptibility measurements.

Two of the ligands used for the preparation of the solid samples, i.e., to H₂L_A and H₂L_B, have been employed to study complexation reactions of Co(II) and Na(I) in solution. In order to obtain information on the ligand preorganization effect toward the complex stabilities, a simpler open chain parent compound of H₂L_B (H₂L_E) has been also prepared and studied. FT-IR spectra show that H₂L_A is unable to complex Na⁺ in DMSO while the complexation reactions of Na⁺ by H₂L_B and of Co²⁺ by H₂L_A take place with slow kinetics. Therefore, thermodynamic data have been obtained only for the systems Co²⁺/H₂L_B and Co²⁺/H₂L_E. The thermodynamic parameters obtained for the complexation reactions show that the pre-organization of the donor atoms in H₂L_B does not add a significant contribution to the stabilities of the complexes. Both H₂L_B and H₂L_E form in DMSO 1:1, 1:2 and 1:3 = M:L complexes with very similar stabilities and almost equal enthalpies of formation. Physico-chemical studies suggest besides that the slow reaction of Na⁺ with H₂L_B is probably due to the formation of a 1:1 complex where the metal cation, initially occupying the O₃ cage of the ligand, slowly binds also the oxygens of the phenolic moieties. Spectral and calorimetric data on solutions containing H₂L_B and different Co²⁺: Na⁺ ratios evidence that in DMSO no stable heterodinuclear complexes form when the neutral ligand is considered.