Tuning the morphology of amphiphilic copolymer aggregates by compound emulsifier via emulsion–solvent evaporation

A series of poly(4-vinylpyridine)-b-poly{6-[4-(4-butyloxyphenylazo)phenoxy]hexyl methacrylate} (P4VP-b-PAzoMA) were employed to fabricate aggregates via the emulsion–solvent evaporation method. The emulsion was stabilized by compound emulsifier composed of SDS and span60. By tuning the ratio of two emulsifiers, P4VP-b-PAzoMA could self-assemble into various morphologies including porous microspheres, tremella-like aggregates, bowl-like aggregates and wrinkled microspheres. The transformation of the morphologies could be ascribed to three major aspects: the stability of emulsified chloroform droplets, the permeation of water into chloroform and the dispersity of the interior water droplets with regard to different HLB values. Besides, the morphology could even be tuned by changing the block ratio and the concentration of P4VP-b-PAzoMA, and the HLB dependent morphology changing was also proved within other block ratio or different concentration. The study uncovers a convenient and effective technique to manipulate the morphology of amphiphilic copolymer aggregates.     

Facile fabrication of asphaltene-derived graphene-polyurethane sponges for efficient and selective oil-water separation

Based on the natural graphene-structure in the raw asphaltene material, a graphene-polyurethane sponge (GPU) oil-absorption material was prepared via a facile and inexpensive route of dip-coated sponge carbonization, which used low-value petroleum asphlatene as the dip-coating reagent and polyurethane sponges as the template. The GPU presents high hydrophobic and super oleophilic properties, as well as the excellent oil absorption performance. And its chloroform absorption capacity could reach 123 times its original mass, which is significantly higher than that of most reported oil absorbents. Furthermore, the GPU exhibits good recyclability. It has the promising applications in the pollution control of spilt oil.     

Determination of diastereoisomeric alkaloids in urine by capillary electrophoresis with electrochemiluminescence detection

A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomenc alkaloids（ephedrine and pseudoephedrine）.The limits of detection（S/N = 3） were 4.5×10^-8 mol/L for ephedrine and 5.2×10^-8 mol/L for pseudoephedrine,respectively.The RSDs of migration time and peak area were less than 1.3 and 2.5%（n = 5）,respectively.The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine,ephedrine in nasal drops,and the monitoring of pharmacokinetics for pseudoephedrine.     

Incorporation of carboxylation multiwalled carbon nanotubes into biodegradable poly(lactic-co-glycolic acid) for bone tissue engineering

Biodegradable poly(lactic-co-glycolic acid) (PLGA)/carboxyl-functionalized multi-walled carbon nanotube (c-MWCNT) nanocomposites were successfully prepared via solvent casting technique. Rat bone marrow-derived mesenchymal stem cells (MSCs) were employed to assess the biocompatibility of the nanocomposites in vitro. Scanning electron microscopy (SEM) observations revealed that c-MWCNTs gave a better dispersion than unmodified MWCNTs in the PLGA matrix. Surface properties were determined by means of static contact angle, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analysis. The presence of c-MWCNTs increased the mechanical properties of the nanocomposites. Seven-week period in vitro degradation test showed the addition of c-MWCNTs accelerated the hydrolytic degradation of PLGA. In addition, SEM proved that the cells could adhere to and spread on films via cytoplasmic processes. Compared with control groups, MSCs cultured onto PLGA/c-MWCNT nanocomposites exhibited better adhesion and viability and also displayed significantly higher production levels of alkaline phosphatase (ALP) over 21 days culture. These results demonstrated that c-MWCNTs modified PLGA films were beneficial for promoting cell growth and inducing MSCs to differentiate into osteoblasts. This work presented here had potential applications in the development of 3-D scaffolds for bone tissue engineering.     

Synthesis,structure, and DNA-binding properties of manganese(II) and zinc(II) complexes with tris(<Emphasis Type="Italic">N</Emphasis>-methylbenzimidazol-2-ylmethyl)amine ligand

Tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and its two complexes, [Mn(Mentb)(DMF)(H₂O)](pic)₂ 1 and [Zn(Mentb)(pic)](pic) 2 (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single crystal X-ray diffraction revealed that the two complexes have different structures. In complex 1, the coordination sphere around Mn(II) is distorted octahedral, whereas in complex 2 the coordination sphere around Zn(II) is distorted trigonal bipyramidal. The DNA-binding properties of the free ligand and its two complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the ligand and its two complexes bind to DNA via an intercalation binding mode, and their binding affinity for DNA follows the order 1 > 2 > ligand.     

An Ylide Transformation of Rhodium(I) Carbene: Enantioselective Three‐Component Reaction through Trapping of Rhodium(I)‐Associated Ammonium Ylides by β‐Nitroacrylates

The chiral Rh^I–diene‐catalyzed asymmetric three‐component reaction of aryldiazoacetates, aromatic amines, and β‐nitroacrylates was achieved to obtain γ‐nitro‐α‐amino‐succinates in good yields and with high diastereo‐ and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of Rh^I‐associated ammonium ylides by nitroacrylates. This new transformation represents the first example of Rh^I‐carbene‐induced ylide transformation.     

TiO2光催化降解4-氯苯酚过程中的电分析监测

采用循环伏安法和紫外光谱法对有机物的光催化降解进行机理研究和在线监测.以标准光催化剂DegussaP25在紫外光照射下催化降解4-氯苯酚,发现在降解过程中至少有两对氧化还原中间产物对苯二酚-苯醌和羟基氢醌-羟基苯醌.由4-氯苯酚及中间产物的电极响应,可以观测到它们在光催化降解过程中的含量变化,从而对整个过程实现在线监测,并由此全面了解光催化反应机理.从不同反应时间后测得的紫外光谱可以看到,苯环特征峰逐渐消失.这表明4-氯苯酚的苯环逐渐被打开,直至被彻底降解.     

设计非线性光学材料的新思路:质子转移增强光学非线性

从酸的电子给体HO-C₆H₄-CHCH-C₆H₄-NO₂(OSN)可以向碱的电子受体Me₂N-C₆H₄-CHCH-C₅H₄N(DAMS)发生质子转移,质子转移后形成的相应离子与其中性分子相比,光学非线性增强.采用ZINDO-SOS,FF/PM₃及CPHF/PM₃三种方法对其进行了系统的理论研究.三种方法研究结果均表明,质子转移后所产生的离子和相应的中性分子相比,其第一超极化率β和第二超极化率γ-都显著增强.     

聚谷氨酸苄酯-聚乙二醇嵌段共聚物的合成和表征

通过嵌段共聚技术,合成了聚γ－苄基L－谷氨酸（PBLG）作为疏水性链段－聚乙二醇（PEG）作为亲水性链段的嵌段共聚物。用对甲苯磺酸酯化－氨水皂化法合成带有端氨基的聚乙二醇（AT－PEG）,光气－甲苯液相法制备谷氨酸苄酯－N－羟酸酐（BLG－NCA）。用AT－PEG引发BLG－NCA聚合制备PBLG－PEG或PBLG－PEG－PBLG,通过不同的单体、引发剂浓度比调节聚合物分子量。用GPC、^1HNMR、IR对聚合物的结构进行了表征。结果表明,带有端氨基的聚乙二醇确实能引发BLG－NCA生成PBLG和PEG的嵌段共聚物,产物中几乎没有残存的PEG,共聚物的分子量可控。