Preparation and properties of polymer and quantum dot composites

Quantum dots (QDs) were prepared in an organic system through a simple and low-cost wet chemistry method. Polymer beads with a diameter of 60–70 nm and specific functional groups were synthesized by a particular seeded emulsion polymerization technique. QDs were embedded in the polymer beads with the specific functional groups through dissolving and swelling method, which provided the condition for the conjunction of biomolecules and QDs as fluorescent probes. The prepared composites were characterized with UV-Vis, PL, TEM, FTIR, CLSM and conductance titration etc. The results show that QDs are successfully embedded in polymer beads, which breaks the limitation that the conjunction of biomolecules and QDs can be achieved only for those synthesized in aqueous system. __________ Translated from Journal of Shanghai Jiaotong University, 2005, 39(1) (in Chinese)     

COMPUTER SIMULATION OF A SINGLE POLYMER CHAIN IN DIFFERENT SOLVENTS

In the present paper, the behavior of a single polymer chain under various solvent conditions was modeled by self-avoiding walks (SAW) with nearest neighbors attraction Δε on a simple cubic lattice. Determination of the θ-condition wasbased on the numerical results of the mean square radius of gyration and end-to-end distance. It was found that at the θtemperatue Δε/kT equals -0.27. The exponents a in the Mark-Houwink equation with different interaction parameters areconsistent with the results of experiments: under θ-condition, a = 0.5, and for a good solvent α= 0.74-0.84, respectively.     

双显色剂高灵敏协同显色反应的研究——钴(Ⅲ)-亚硝基R盐-结晶紫体系

在水溶液中钴(Ⅱ)与亚硝基R盐所形成的配合阴离子可以与有机碱阳离子(结晶紫)缔合形成中性缔合分子。在聚乙烯醇存在下,配合物可稳定存在于水溶液中。钴(Ⅲ)-亚硝基R盐-结晶紫配合物在510nm处有一最大吸收,摩尔吸光系数ε_(510)=1.47×l0~5L·mol~(-1)·cm(-1)。配合物中各组分的摩尔比为:Co:R:CV=1:3:6。反应具有较高的选择性,采用双峰双波长法测定钴可使灵敏度得到进一步提高,相应的摩尔吸光系数ε_(510-640)=4.09×10~5L·mol~(-1)·cm~(-1)。方法用于合成试样中钴的测定,结果满意。     

Effect of Pluronic F127 on the pore structure of macrocellular biodegradable polylactide foams

Thermally induced phase separation technique was utilized to fabricate biodegradable poly(l ‐lactic acid) (PLLA) macrocellular foams which were capable of being applied in tissue engineering. The block copolymer Pluronic F127 composed of (polyethyleneoxide)‐(polypropyleneoxide)‐(polyethyleneoxide) [(PEO)‐(PPO)‐(PEO)] was used as a porogen. Water/dioxane mixtures with different volume ratios were used as solvents. The addition of Pluronic F127 could induce an appearance of large pores (50–200 μm) besides small pores (10–20 μm) or a change from a solid–liquid phase separation to a liquid–liquid phase separation. The role of Pluronic F127 depends on the water/dioxane ratios in the PLLA/dioxane/water system. The X‐ray diffraction patterns and porosity measurement results showed that Pluronic F127 was crystallized and existed on the pore wall. The effect of Pluronic F127 on changing pore structure is attributed to the occurrence of the interaction of the lipophilic PPO blocks in Pluronic F127 with PLLA clews, consequently, this results in PLLA aggregation and early phase separation on cooling. Copyright © 2004 John Wiley & Sons, Ltd.     

钆铁磁－顺磁相变的正电子寿命研究

通过测量金属钆在居里点附近的正电子湮没寿命谱随温度变化的关系，发现钆的正电子湮没寿命在居里点近邻Ｔ＜ＴＣ一侧随温度有显著变化，而在此温区以外几乎不随温度变化     

活性碳分离碳－60和碳－70

活性碳用苯胺处理后，可以减少对Ｃ＿（６０）和Ｃ＿（７０）的不可逆吸附，从而增加Ｃ＿（６０）和Ｃ＿（７０）的分离收率，同时提高了Ｃ＿（７０）的纯度。     

Polymer bound glutamic acid salicylaldehyde Schiff‐base complex ­catalyst for oxidation of olefins with ­dioxygen

The polymer bound Schiff‐base ligand (PS‐SalGlu) has been prepared from polystyrene bound salicylaldehyde and glutamic acid, and its complex (PS‐SalGlu‐Co) has also been synthesized. The polymer ligand and its complex were characterized by infrared spectroscopy, small area X‐ray photoelectron spectroscopy, and inductively coupled plasma‐atomic emission spectro (ICP‐AFS). In the presence of the complex, cyclohexene can be effectively oxidized by molecular oxygen without reductant. The long‐chain linear aliphatic olefins, such as 1‐octene, 1‐decene, 1‐dodecene and 1‐tetradecene, can be directly oxidized by molecular oxygen catalyzed by PS‐SalGlu‐Co, which affords the 1,2‐epoxy alkane. Copyright © 2001 John Wiley & Sons, Ltd.     

2,4-二氧代-1,3,2-苯并二氮磷杂环己烷与■C=C■及CS_2加成反应的研究

本文研究了2,4-二氧代-1,3,2-苯并二氮磷杂环己烷的磷氢键对β-硝基苯乙烯、丙烯酸酯、丙烯腈及二硫化碳的加成反应,共合成了18个新的加成产物.发现通过选用不同的碱或控制碱的用量.可选择性的进行加成或开环反应.由X衍射证实:在加成产物的结构中,环外P-C键构象因受磷杂环船式构象影响,以邻位交叉式(A)为主.     

A novel approach to carbon hollow spheres and vessels from CCl4 at low temperatures

Carbon hollow spheres (400-600 nm) and vessels (400 nm x 3000 nm) have been synthesized from sp3-CCl4 at 190 and 230 degrees C, respectively. The HRTEM images and Raman spectra reveal the sp2 nature of the as-obtained products, indicating that the transformation from carbon sp3 to sp2 occurs in the reactions. The possible mechanism has also been proposed.