真空中加热衬底对ZnSe MIS二极管电致发光的影响

本文研究了在制备ZnSe MIS二极管的绝缘层时,为了改善IS间的界面接触,在真空中加热ZnSe衬底,其结果虽然使电致发光的均匀性有所改善,却使原来的蓝色电致发光变为红色。文中着重研究了红色电致发光的起源,在液氮温度下出现的二个峰值为5350Å和6320Å的谱带应分别归结为ZnSe晶体中的铜绿(Cu-G)和铜红(Cu-R)发光中心。文中指出,真空中加热的条件,使ZnSe晶体中残留的Cu杂质从非发光中心状态转变为发光中心状态。因此,要改善ZnSe晶体蓝色电致发光的性能,进一步提高ZnSe晶体的纯度是十分重要的。     

Facile synthesis of hollow polymer microspheres with movable cores with the aid of hydrogen-bonding interaction

Poly(divinylbenzene-co-acrylic acid) (poly(DVB-co-AA)) hollow microspheres with movable poly(DVB-co-AA) cores were prepared by a facile route. In this approach, poly(DVB-co-AA) microspheres were first used as templates to synthesize poly(DVB-co-AA)@PAA core-shell particles with a non-crosslinked PAA shell by distillation precipitation polymerization in acetonitrile. In situ polymerization to prepare poly(DVB-co-AA)@PAA@poly(DVB-co-AA) trilayer microspheres was then developed, in which the hydrogen-bonding interaction between the carboxylic acid groups played a key role as the driving force for the formation of monodisperse trilayer structure polymer microspheres. After removal of the non-crosslinked poly(acrylic acid) (PAA) midlayer of the poly(DVB-co-AA)@PAA@poly(DVB-co-AA) microspheres in ethanol under basic conditions, poly(DVB-co-AA) hollow microspheres with movable poly(DVB-co-AA) cores were obtained. Functional poly(DVB-co-AA) cores could be released successfully when the hollow structure was destroyed. The resultant core-shell, trilayer polymer microspheres and hollow polymer microspheres with movable cores were characterized by transmission electron microscopy (TEM), dynamic laser scattering (DLS), and Fourier transform infrared (FT-IR) spectra.     

Rattle-type microspheres as a support of tiny gold nanoparticles for highly efficient catalysis

SiO(2)/poly(ethyleneglycol dimethacrylate) (PEGDMA) rattle-type microspheres loaded with tiny sized gold nanoparticles (~2 nm) were prepared through a facile and novel method. Catalyzed reduction of 4-nitrophenol with NaBH(4) demonstrated that this rattle-type microsphere possessed high catalytic efficiency.     

A novel method for quantitative determination of tea polysaccharide by resonance light scattering

A new method for the determination of tea polysaccharide (TPS) in green tea (Camellia sinensis) leaves has been developed. The method was based on the enhancement of resonance light scattering (RLS) of TPS in the presence of cetylpyridinium chloride (CPC)-NaOH system. Under the optimum conditions, the RLS intensity of CPC was greatly enhanced by adding TPS. The maximum peak of the enhanced RLS spectra was located at 484.02 nm. The enhanced RLS intensity was proportional to the concentration of TPS in the range of 2.0-20 μg/ml. It showed that the new method and phenol-sulfuric acid method give some equivalent results by measuring the standard compounds. The recoveries of the two methods were 96.39-103.7% (novel method) and 100.15-103.65% (phenol-sulfuric acid method), respectively. However, it showed that the two methods were different to some extent. The new method offered a limit of detection (LOD) of 0.047 μg/ml, whereas the phenol-sulfuric acid method gives a LOD of 1.54 μg/ml. Interfered experiment demonstrated that the new method had highly selectivity, and was more suitable for the determination of TPS than phenol-sulfuric method. Stability test showed that new method had good stability. Moreover, the proposed method owns the advantages of easy operation, rapidity and practicability, which suggested that the proposed method could be satisfactorily applied to the determination of TPS in green tea.     

pH-Responsive hollow polymeric microspheres and concentric hollow silica microspheres from silica-polymer core-shell microspheres

Nearly monodispersed silica-poly(methacrylic acid) (SiO 2-PMAA) core-shell microspheres were synthesized by distillation-precipitation polymerization from 3-(trimethoxysilyl)propylmethacrylate-silica (SiO 2-MPS) particle templates. SiO 2-PMAA-SiO 2 trilayer hybrid microspheres were subsequently prepared by coating of an outer layer of SiO 2 on the SiO 2-PMAA core-shell microspheres in a sol-gel process. pH-Responsive PMAA hollow microspheres with flexible (deformable) shells were obtained after selective removal of the inorganic SiO 2 core from the SiO 2-PMAA core-shell microspheres by HF etching. The pH-responsive properties of the PMAA hollow microspheres were investigated by dynamic laser scattering (DLS). On the other hand, concentric and rigid hollow silica microspheres were prepared by selective removal of the PMAA interlayer from the SiO 2-PMAA-SiO 2 trilayer hybrid microspheres during calcination. The hybrid composite microspheres, pH-sensitive hollow microspheres, and concentric hollow silica microspheres were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray (EDX) analysis.     

Raspberry-like polymer/silica core-corona composite by self-assemble heterocoagulation based on a hydrogen-bonding interaction

Raspberry-like poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine)/silica (poly(EGDMA-co-VPy)/SiO₂) core-corona composite was prepared by a self-assemble heterocoagulation based on a hydrogen-bonding interaction between the pyridyl group of poly(EGDMA-co-VPy) core and the active hydroxyl group of silica corona. The raspberry-like composite was stable near the neutral environment with pH ranging from 5.0 to 8.0. The effects of the solvent and the mass ratio of silica to polymer microsphere on the coverage of the silica corona on poly(EGDMA-co-VPy) core were investigated in detail. The resultant core-corona heterocoagulates were characterized with scanning electron microscope and the nature of the interaction between the polymer core particle and silica corona particle was identified as hydrogen bonding with Fourier Transform Infrared spectroscopy.     

添加氢化钙合成高分子量聚对苯二甲酰对苯二胺的研究

研究使用氢化钙代替吡啶作为酸吸收剂合成高分子量聚对苯二甲酰对苯二胺(PPTA),并与以吡啶作酸吸收剂的聚合产物进行对比以评估该研究的应用前景.尝试以氢化钙代替吡啶,考察氢化钙的加入对TPC与PPD的聚合过程及聚合产物分子量和结构的影响.研究结果表明,添加氢化钙可以聚合出高分子量PPTA.元素分析、X-射线衍射及红外光谱分析结果表明,使用氢化钙和吡啶作为酸吸收剂合成的PPTA在元素含量和结构上均相同.热重分析结果表明,使用两种酸吸收剂得到的PPTA的热分解温度都在550℃左右.这些研究结果初步证明使用氢化钙代替吡啶进行高分子量PPTA工业聚合是可行的.     

Core-corona polymer composite particles by self-assembled heterocoagulation based on a hydrogen-bonding interaction

Poly(ethylene glycol dimethacrylate-co-acrylic acid) (poly(EGDMA-co-AA)) small microspheres were effectively self-assembled on poly(ethylene glycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-VPy)) surfaces to form a core-corona structure with a raspberry-like polymer composite by a hydrogen interaction mechanism through an affinity complex between the carboxylic acid group and pyridine group. The control of coverage of the poly(EGDMA-co-AA) corona on the surface of poly(EGDMA-co-VPy) was studied in detail via adjustment of the nature of the mass ratio between the core and corona. The effects of the pH and solvent used on the morphology of the self-assembled core-corona polymer composites were investigated. The nature of the interaction between the core and corona polymer particles was identified as hydrogen bonding with FT-IR spectroscopy.     

肝素功能化生物材料的研究进展

从物理吸附涂层、共价键连接和微载体控释等方面综述了肝素功能化生物材料的最新研究进展.大量研究表明这些肝素材料具有抗凝血和/或生长因子释放的功能,但未来的研究重点是构建各种控制释放肝素亲和性生长因子的系统.     

一种X-射线不透性聚氨酯显影材料的制备及性能研究

利用对碘苯胺对含有过量异氰酸根的聚氨酯分子进行封端,合成了一种新型的X-射线不透性聚氨酯显影材料.利用X-射线映射对不同封端量聚氨酯的显影效果进行评定;利用DSC和TGA对其热性能进行表征,并评估封端反应对聚氨酯热稳定性的影响;利用噻唑蓝(MTT)比色法测试了材料的细胞毒性;并对具有不同碘含量聚氨酯材料的显影效果、相对分子量及其分布、力学性能进行了对比研究.研究结果表明,当碘含量达到3.5wt%左右时聚氨酯材料即可达到同等厚度铝板相同的显影效果,而且在此条件下,聚氨酯材料依然保持较好的力学性能和热稳定性.MTT法测试表明对碘苯胺封端的聚氨酯材料不具有细胞毒性.