Optical properties of surface-modified Bi2O3 nanoparticles

Stearic acid coated Bi₂O₃ nanoparticles in the size range of 5-13 nm were synthesized by the microemulsion method. HRTEM showed that the morphology of Bi₂O₃ nanoparticles was ellipsoidal. The absorption edge of Bi₂O₃ nanoparticles showed a blue shift of ∼0.45 eV, comparing with that of the bulk Bi₂O₃. At room temperature, Bi₂O₃ nanoparticles also showed a strong luminescence at 397 and 420 nm, depending on the excitation wavelength.     

Probing organization and communication at layered interfaces

We have investigated the local organization intrinsic to a variety of interfacial structures, by both electrochemical and spectroscopic means. Our focus has been on the design and construction of biomimetic interfaces, where a lipid bilayer or a hybrid bilayer membrane can be bound to an interface. The goal of this work is ultimately to create an interface on a transducer surface that can support an enzyme in its active form. To this point, we have examined the extent of organization that is achievable in monolayers that will be used to bind bilayer structures to a transducer surface. Our electrochemical data point to the important role of the substrate surface in determining adlayer organization. We have also investigated the fluidity and structural heterogeneity of lipid bilayers using time-resolved and steady state fluorescence spectroscopy. Our data point to the highly interactive nature of lipid bilayer constituents, where perturbations introduced to one region have significant consequences on other regions of the bilayer. Such information is directly relevant to the existence and properties of lipid raft structures in both model and biological bilayers.     

CdS纳米粒子的表面修饰及其对光学性质的影响

用反胶束法合成了用表面活性剂分子磺基焉珀酸双－２－乙基已酯钠盐（ＡＯＴ）进行表面修饰的ＣｄＳ纳米粒子（记为ＣｄＳ／ＡＯＴ－ＳＯ３＾－）,研究了这种纳米粒子在正庚烷（ｈｅｐｔａｅ）和吡啶（Ｐｙ）溶剂中的荧肖及光解行为,发现其在正庚烷中荧光很强,而Ｐｙ却强烈地猝灭ＣｄＳ纳一子的荧光,用电荷转移猝灭机制进行了解释,这种解释为ＣｄＳ纳米粒子在Ｐｙ中光解实验进一步证实。     

硅烷偶联剂对SSBR/SiO_2混炼胶体系动态流变行为的影响

研究了高填充白炭黑(SiO2)补强溶液聚合丁苯橡胶(SSBR)混炼胶体系的动态流变特性,分别考察了在2个混炼温度(120℃、160℃)下添加3种不同偶联剂(TESPT、TESPD、NXT)对其体系中SiO2粒子表面改性的效果.结果表明,在较低混炼温度下添加偶联剂,不利于SiO2粒子表面改性.在较高混炼温度下,偶联剂TESPT、PESPD、NXT均对SiO2粒子表面有改性效果,但同时引起混炼胶不同程度的焦烧,其中以TESPT最明显.随SiO2粒子表面改性程度的提高,出现“Payne效应”的临界应变(γc)值以及低频率(ω)区域lgG′-lgω曲线的斜率值均增大,反映出偶联剂对SiO2与SSBR相互作用的促进以及SiO2粒子分散的改善.     

二氧化硅纳米粒子表面修饰及其表征

采用溶胶-凝胶法合成粒径在50—150nm范围内的二氧化硅（SiO2）纳米粒子。用甲基丙烯酸-3-（三甲氧基硅基）丙酯（MPS）对SiO2纳米粒子表面进行修饰，使其表面接枝能参与自由基聚合反应的碳碳双键基团。用元素分析、FTIR、^13C CP／MASNMR和^29Si CP／MASNMR等手段对修饰过的SiO2纳米粒子进行表征，以确证MPS接枝在SiO2纳米粒子上。分析修饰过的SiO2纳米粒子的^29Si CP／MASNMR和FTIR谱图，还可初步推断MPS接枝在SiO2纳米粒子表面的机理：MPS首先发生水解缩合反应形成低聚物，然后通过氢键作用吸附到SiO2纳米粒子表面，最后MPS低聚物中未缩合的硅羟基与SiO2纳米粒子表面的硅羟基发生缩合反应。     

Surface-Modified Superparamagnetic Iron-Oxide Nanoparticles

Summary. The generation of superparamagnetic iron-oxide nanoparticles bearing fluorescent ligands is described. γ-Fe₂O₃ nanoparticles (radius ∼4 and 8 nm) bearing octylamine or oleic acid as ligands were prepared by hydrothermal synthesis starting from Fe-cupferron and iron pentacarbonyl, respectively. Ligand exchange proceeds with 1,2-diols bearing ω-azido or ω-bromo ligands at elevated temperatures. Subsequent nucleophilic substitution reaction, followed by 1,3-dipolar cycloaddition reactions with 2,4,6-trinitro-1-O-propargyl-benzene yields superparamagnetic iron-oxide nanoparticles with a fluoresecent ligand on their surface.     

Synthesis of spherical submicron-sized magnetite/silica nanocomposite particles

This paper describes a method for fabricating spherical submicron-sized silica particles that contained magnetite nanoparticles (magnetite/silica composite particles). The magnetite nanoparticles with a size of ca. 10 nm were prepared according to the Massart method, and were surface-modified with carboxyethylsilanetriol. The fabrication of magnetite/silica composite particles was performed in water/ethanol solution of tetraethoxyorthosilicate with ammonia catalyst in the presence of the surface-modified magnetite nanoparticles. The magnetite/silica composite particles with a size of ca. 100 nm were successfully prepared at 0.05 M TEOS, 15 M water, and 0.8 M ammonia with injection of the magnetite nanoparticle colloid at 2 min after the initiation of hydrolysis reaction of TEOS. Magnetite concentration in the composite particles could be raised to 17.3 wt.% by adjustment of the injected amount of the magnetite colloid, which brought about the saturation magnetization of 7.5 emu/g for the magnetite/silica composite particles.     

Surface-modification in situ of nano-SiO2 and its structure and tribological properties

The preparation of a series of dispersible nano-SiO₂ by surface-modification in situ was described in this paper. It is found that some silane coupling agents can be combined with nano-SiO₂ by covalent bonds, which change the nanoparticle's surface properties and make nano-SiO₂ disperse well and steadily in many organic mediums. The structure of nanoparticles was characterized by transmission electron microscopy (TEM), infrared spectrum (IR), X-ray photoelectron spectra (XPS) and thermogravimetric analysis (TG). The dispersivity of these nanoparticles in organic solvents was measured by light transmittance. Considering such superior dispersion in oily solvents and very small size, we primarily investigated their tribological behaviors as additive in lubricant on wear testers. The results show that they can evidently increase anti-wear ability and reduce the friction coefficient of lubricant.     

热塑性聚氨酯生物材料的合成及表面改性进展

详细地综述了国内外聚氨酯生物材料的合成及表面改性研究的最新进展,分析了各种聚氨酯作为生物材料的优缺点及物理与化学特性,介绍了几种主要的表面改性途径。     

Effects of surface-modification with Bi2O3 on the thermal stability and photoinduced charge property of nanocrystalline anatase TiO2 and its enhanced photocatalytic activity

Bi₂O₃ surface-modified TiO₂ nanoparticle has been synthesized by sol-hydrothermal processes, followed by post-treatment with an appropriate amount of bismuth nitrate solution, and also characterized by XRD, Raman, BET, TEM, FT-IR, XPS, UV-vis DRS and SPS techniques. The effects of the surface-modification with Bi₂O₃ on the thermal stability, photoinduced charge separation and photocatalytic activity for degrading rhodamine B (or phenol) under ultraviolet (or visible) irradiation are investigated in detail, along with their relationships and the activity enhancement mechanisms are also suggested. The results show that the modification with Bi₂O₃ can improve the thermal stability of the as-prepared anatase crystallites, consequently enhancing the anatase crystallinity so as to promote the photoinduced charge separation. And the modification with Bi₂O₃ also extends the optical response range. It can be concluded that the activity enhancement of surface-modified TiO₂ is mainly attributed to the increase in the photoinduced charge separation rate and to the extent of the optical response range, compared with un-modified ones. Moreover, the inhibition phase transformation mechanism related to Bi₂O₃ is suggested.