固载化ZnCl2催化合成3-甲基-3-丁烯-1-醇

采用碾磨-活化法制备了SiO₂-ZnCl₂(Silzic)催化剂,并将其用于异丁烯与甲醛Prins缩合合成3-甲基-3-丁烯-1-醇(MBOH)。系统研究了温度、物料比、时间和催化剂的组成及用量对该反应的影响。结果表明,在不同的条件下,甲醛都保持着99%以上的高转化率;然而,不同的条件对MBOH的选择性和收率的影响程度不同,其中,反应温度、催化剂的酸量是影响该反应的关键因素;物料比和反应时间对MBOH的选择性和收率的影响相对较小。实验得到最佳的反应条件为,反应温度210 ℃、二氧六环8 g、三聚甲醛1.5 g、n(异丁烯)/n(三聚甲醛)=7:1、30 mg 1 mmol/g Silzic 和反应时间2 h,在此条件下MBOH的选择性和收率可分别达到93.8%和93.4%。当催化剂循环使用五次时,MBOH的收率降为85.2%,表明该催化剂具有一定的重复使用性。     

Tracking of the effects of the plasticizer on the water uptake and free volume changes of methylcellulose

The structural changes in methylcellulose containing poly(ethylene glycol) (PEG 400) as plasticizer caused by water absorption during storage were evaluated. In order to elucidate the structural changes in the polymer, water‐uptake measurements and positron annihilation lifetime spectroscopy (PALS) were utilized. The PEG concentrations relative to the total polymer content were varied within the range 0–75% w/w. The Doppler‐spectra were characterized by means of the conventional parameters S and W. A transition from a single phase to two phases was found in the methylcellulose films above PEG; a content of 33% w/w. The first step of ageing is merely a conformational change, after which the electron structure remains more or less the same, while both S and W indicate significant changes during the second slow step of ageing. Accurate determination of the plasticizer concentration relating to the single‐phase to two‐phase transition of Metolose‐PEG films has a great impact from the aspect of the application of a stable composition for coating of solid dosage forms. Copyright © 2007 John Wiley & Sons, Ltd.     

Crystallization behavior and biodegradation of poly(3-hydroxybutyrate) and poly(ethylene glycol) multiblock copolymers

Block copolymerization by using isocyanates is an effective method for incorporating PHB and PEG because it can prepare copolymers with good properties, such as toughness, strength, and so on. In this study, we adopted soil suspension system to estimate the biodegradability of a series of PHB/PEG multiblock copolymers with different compositions and block lengths. In the degradation process, the changes in weight loss, molecular weight, and tensile strength were periodically measured to determine the biodegradability, and the surface morphology was also observed by SEM. In contrast to pure PHB, the weight loss of the copolymer was relatively lower. On the other hand, the tensile strength and molecular weight experienced apparent decrease, and for BHG1000-3-1, they reached 46.7% and 77.7% of the initial value, respectively. SEM observation showed that the surface was covered with numerous erosion pits. All these indicate that the degradation indeed took place and long-chain molecules have been hydrolyzed into shorter ones. The crystallization behavior was also investigated by DSC and WAXD. The results showed that both the segments, PEG and PHB, can form crystalline phases at lower PHB contents ranging from 29% to 44%, and when PHB component was more than 60%, only PHB phase can crystallize.     

Plasma-Induced Graft Polymerization of Poly(ethylene glycol) Methyl Ether Methacrylate on Si(100) Surfaces for Reduction in Protein Adsorption and Platelet Adhesion

Argon plasma-induced graft polymerization of a solution-coated macromonomer, poly(ethylene glycol) methyl ether methacrylate (PEGMA), on the Si(100) surface was carried out to impart anti-fouling properties to the Si(100) surface. The surface composition and microstructure of the PEGMA graft-polymerized Si(100) surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) measurements. The extent of crosslinking in the plasma-graft polymerized PEGMA (pp-PEGMA) was estimated by gel fraction determination. In general, an appropriate RF power of about 15 W and a PEGMA macromonomer concentration of about 1 wt% in the coating solution for plasma polymerization produced a high graft yield of pp-PEGMA on the Si(100) surface (the pp-PEGMA-g-Si surface). The Si(100) surface with a high concentration of the grafted pp-PEGMA was effective in preventing bovine serum albumin (BSA) adsorption and platelet adhesion.     

Effect of poly(ethylene glycol) 200 on the formation of a polyetherimide asymmetric membrane and its performance in aqueous solvent mixture permeation

To investigate the effect of poly(ethylene glycol) (PEG) 200 on membrane performance, asymmetric polyetherimide (PEI) membranes with a small pore size were prepared by dry/wet-phase inversion from the casting solution containing N-methyl-2-pyrrolidone as a solvent and poly(ethylene glycol) 200 as an additive. Our experiment revealed that the addition of PEG 200 has an influence on the casting solution properties, permeation properties, and resulting membrane structures. Moreover, a drying process also affects the formation of a dense skin layer. Increasing the amount of PEG 200 drastically improved the solute rejection rate. The drying process improved the rejection rate. We also observed the effect of the mixed solvent (water/ethanol) on permeation through the membranes with various pore sizes. In the case of the membrane with a dense skin layer, the solvent permeation showed relationships with solution viscosity, surface tension, and membrane-solvent interaction.     

双金属改性MCM-41催化甲醛与异丁烯Prins缩合反应

通过研磨法制备了一系列不同金属负载的MCM-41催化剂,考察了单一金属及双金属负载催化剂对甲醛与异丁烯Prins缩合制备3-甲基-3-丁烯-1-醇(MBO)反应性能的影响,筛选出最佳的双金属Cu-Al负载催化剂.利用XRD、 NH_3-TPD、 N_2吸附、 UV-vis等表征手段对双金属改性前后催化剂的结构和酸性进行了深入分析,探究了其物质的量比例和协同作用对Prins反应性能的影响.结果表明,在温度200℃, n(异丁烯)/n(甲醛)=7,反应4 h的适宜条件下, Cu-Al(1∶1)/MCM-41对甲醛的转化率为100%, MBO产率高达98%,高于单一金属负载的催化剂. NH_3-TPD表征发现Cu-Al双金属负载催化剂具有适当的酸量和适宜的酸强度,可以提高MBO的产率.Cu-Al(1∶1)/MCM-41催化剂具有一定的再生性能,连续3次再生后催化剂的比表面积和孔容明显降低,催化剂活性中心聚集导致酸量尤其是中强酸和强酸量减少是反应活性下降的主要原因.     

手性酒石酸酯对不对称环氧化反应动力学拆分DL-1-十四烯-3-醇的催化选择性

利用Sharpless不对称环氧化反应动力学拆分二级烯丙醇DL-1-十四烯-3-醇,研究了不同手性酒石酸酯催化剂[酒石酸乙酯(DET)、酒石酸异丙酯(DIPT)、酒石酸环己酯(DCHT)以及酒石酸环十二酯(DCDT)]对该反应的催化选择性,拆分所得的烯丙醇的光学纯度有一定差异,从90%到99?.     

Li1.5Al0.5Ge1.5(PO4)3基固体复合电解质的制备及锂离子导电行为

将聚氧化乙烯(PEO)和二(三氟甲基磺酰)亚胺锂(LiTFSI)混合(固定EO/Li摩尔比为13)后, 采用溶液浇注法制备了一系列不同Li_1.5Al_0.5Ge_1.5(PO₄)₃(LAGP)与PEO质量比的LAGP-PEO(LiTFSI)固体复合电解质体系. 结合电化学阻抗法、 表面形貌表征以及与惰性陶瓷填料(SiO₂, Al₂O₃) 性能的对比分析, 探讨了LAGP在固体复合电解质中的作用机理以及锂离子的导电行为. 结果表明, 在以LAGP为主相的固体复合电解质中, PEO主要处于无定形态, 整个体系主要为PEO与LiTFSI的络合相、 LAGP与PEO(LiTFSI)相互作用形成的过渡相和LAGP晶相. 其中LAGP作为主要的导电基体不仅起到降低PEO结晶度、 改善两相导电界面的作用; 同时自身也可以作为离子传输的通道, 降低锂离子迁移的活化能, 从而使离子电导率得到提高. 当LAGP与PEO的质量比为6:4时, 固体复合电解质的成膜性能最好, 离子电导率最高, 在30 ℃时为2.57×10^-5 S/cm, 接近LAGP的水平, 电化学稳定窗口超过5 V.     

Traceless liquid-phase synthesis of 3-alkylamino-4,5-disubstituted-1,2,4-triazoles on polyethylene glycol (PEG)

A liquid-phase route to 3-alkylamino-4,5-disubstituted-1,2,4-triazoles has been developed, which permits the incorporation of three elements of diversity. The heterocycle was constructed upon PEG6000 (soluble polymer) modified by 4-hydroxy-2-methoxybenzaldehyde, from which a traceless cleavage could be realized with TFA/CH₂Cl₂. This method provided a library of 3-alkylamino-4,5-disubstituted-1,2,4-triazoles with reasonable yields and excellent purity.     

Synthesis of 3-hydroxy-1-methyl-2-(methylthio) pyrrole from methyl isothiocyanate and prop-2-yn-1-ol

A methylated adduct of lithiated 1-(1-ethoxyethoxy)allene and methyl isothiocyanate undergoes intramolecular cyclization in the presence of CuBr to give 3-(1-ethoxyethoxy)-1-methyl-2-(methylthio)pyrrole. The methanolysis of the latter affords 3-hydroxy-1-methyl-2-(methylthio)pyrrole. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1645–1647, September, 2000.     

Studies on hydroxy inclusion complexes. I. Host-guest interaction of the molecular complexes of 9-hydroxy-9-(1-propynyl) fluorene and 1,1-Bis (2,4-dimethylphenyl)-2-butyn-1-ol with water,methanol, ethanol,andn-propanol

Molecular inclusion by hydroxy host systems (9-hydroxy-9-(1-propynyl)fluorene+guest and 1,1-bis(2,4-dimethylphenyl)-2-butyn-1-ol+guest) has been investigated by using an empirical potential function. Water, methanol, ethanol, andn-propanol have been employed as guest molecules and their relative stabilities are considered. Alcohol is found to be more suitable than water as a guest molecule in the two tested host molecules. It is also found that the nonbonded interaction is the most important factor in determining the relative stabilities of hydroxy host systems.     

Photoluminescence Study on Charge Transfer Behavior of Poly(3‐hexylthiophene) and PCBM Blends

Charge transfer behavior of Poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C₆₁‐butyric acid methyl eser (PCBM) in solutions and in films were examined by photoluminescence (PL) spectroscopy. PL study in solutions indicated that separation distance between P3HT and PCBM affected charge transfer efficiency more seriously than the interface area issue between P3HT and PCBM. P3HT/PCBM film showed very effective photo‐induced charge transfer before post‐thermal annealing on the bi‐layer P3HT/PCBM film. Charge transfer efficiency was gradually diminished by the annealing‐induced phase separation between P3HT and PCBM as revealed by increasing PL emission intensity of P3HT.     

Effect of nano-filler dispersion on the thermal, mechanical and water sorption properties of green environmental polymer

Partially exfoliated nanocomposite（2） has been synthesized by intercalation of poly（propylene carbonate）（PPC） into commercial clay,Cloisite 20B（PPC/C-20B）.Nanocomposite 2 was characterized phiso-chemically and exhibited high thermal,mechanical and anti-water sorption properties as compared to PPC and intercalated nanocomposite（1） of PPC/C-20B having same amount of clay.TGA results revealed that the thermal decomposition temperature(T_d,50%) of 2 increased significantly,being 40 K and 17 K higher than that of pure PPC and 1,respectively,while DSC measurements indicated that the nano-filler dispersion of 2 increased the glass transition temperature from 21℃to 31℃.Accordingly,2 showed high elastic modulus,hardness and anti-water absorption capacity.These thermal,mechanical and anti-water absorption improvements are of great importance for the application of PPC as packaging and biomaterials.     

Effect of ethylene glycol on the end group structure of poly(3-hydroxybutyrate)

Ralstonia eutropha was cultivated in a culture medium supplemented with ethylene glycol (EG), which is known to act as a chain transfer agent in the production of poly(3-hydroxybutyrate) (PHB). The PHB extracted from the bacterial cells was analyzed by ¹H and ³¹P NMR spectroscopies and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The addition of EG exerted a remarkable influence on the mass of production and molecular weight of PHB, and then was found to result in chain transfer and termination reactions. MALDI-TOF MS of the partially hydrolyzed PHB revealed that either succinate or glutarate combined with the hydroxyl terminals of PHB as polymerization starters. From ³¹P NMR analysis, the carboxyl groups of the succinyls and glutaryls held in the terminals of the isolated PHB were found to be capped with EG, giving the telechelic polyester with hydroxy functionalities. Based on these results, we propose a plausible mechanism of enzymatic polymerization in the microbial PHB synthesis in the presence of EG.     

Iodobenzene‐Catalyzed Synthesis of α‐Azidoketones and α‐Thiocyanatoketones from Aryl Ketones with MCPBA as a Cooxidant

Iodobenzene‐catalyzed synthesis of α‐azidoketones and α‐thiocyanatoketones from aryl ketones with MCPBA as a cooxidant is described. The method is simple, rapid and practical, generating α‐azidoketones and α‐thiocyanatoketones from the aryl ketone without isolation of α‐tosyloxyketones in good to excellent yields.     

Swelling behaviour of crosslinked hydrogels based on (2-hydroxyethyl methacrylate) with a zwitterionic comonomer (1-3-sulfopropyl-2-vinyl-pyridinium-betaine)

Copolymeric hydrogels were prepared by the chemically initiated free radical copolymerization in aqueous solution of mixtures of [1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (SPV) and (2-hydroxyethyl methacrylate) (HEMA) in the presence of a crosslinking agent N,N′-methylene-bis-acrylamide (MBA). The hydrogels were swollen to equilibrium in water and aqueous KSCN at 298 K and their swelling behaviour has been investigated using gravimetric measurements. The effects of the concentration of KSCN and the mole fraction of SPV in the feed (F_s) have been noted and discussed. The main findings are:(a) In water, the water content (W₁) of copolymeric hydrogels is insensitive to SPV content at F_s ? 0.45. In contrast, W₁ decreases sharply with decreasing F_s within the range of 0 < F_s < 0.45. (b) In aq. KSCN, the degree of total swelling (W) exceeds the value in pure water, the enhancement in swelling being most marked at low values of [KSCN]. The content of water within the hydrogel increases with KSCN concentration in the swelling medium for low values of [KSCN], but thereafter falls with further increase in salt concentration. In contrast, the salt content within the swollen hydrogel displays a continuous increase with increasing [KSCN]. All these results of item (b) are for copolymeric hydrogels within the full range of F_s (0 < F_s < 1). (c) at a fixed aq. KSCN concentration, both W and W₁ increase sharply with increasing F_s over the entire range of copolymer composition.     

锂离子电池正极材料LixNi1/3Mn1/3Co1/3O2的合成及电化学性能研究

应用以氢氧化物共沉淀为前驱体的高温固相烧结法合成L iN i1/3Mn1/3Co1/3O2正极材料,研究了沉淀温度及烧结过程锂盐投入量对该材料的结构和电化学性能的影响.结果表明,以室温(~20℃)下合成的氢氧化物为前驱体制备的L iN i1/3Mn1/3Co1/3O2具有较好的电化学性能.高温固相烧结会导致部分L iOH损失,因而在合成过程中需加入过量的氢氧化锂,实验表明L i1.08N i1/3Mn1/3Co1/3O2材料的电化学性能最优.     

Supramolecular Network Based on the Self‐Assembly of γ‐Cyclodextrin with Poly(ethylene glycol) and its Shape Memory Effect

A novel supramolecular network has been prepared based on the formation of inclusion complexes between γ‐cyclodextrin and poly(ethylene glycol), in which the PEG chains are interlocked by γ‐CD rings. This PEG/γ‐CD network exhibits good shape memory behavior because of the crosslinked structure. The crosslinked PEG/γ‐CD inclusion complexes and PEG crystallites account for the fixing phase and reversible phase, respectively. The characteristics of the materials have been investigated by ¹H NMR spectroscopy, XRD, DSC, DMA, viscosity tests, and swelling measurements.

     

CCl_2(A~1B_1,a~3B_1)自由基被烷烃类分子猝灭动力学

用放电- LIF实验装置 ,对 CCl4/Ar混合气体放电产生 CCl_2自由基 ,再用 541.52 nm激光将电子基态 CCl_2激励到激发态 A~B_1(0,4,0)振动能级上 ,通过检测激发态 CCl_2时间分辨荧光信号 ,测得室温下 CCl_2(A~B_1)被烷烃类分子猝灭的实验结果 ,用我们提出的三能级模型分析处理实验数据 ,获得 CCl_2(A~1B_1)态和 CCl_2(a~3B_1)态的碰撞猝灭速率常数 k_A和 k_a值 .