聚异丁烯丁二酰亚胺系列衍生物的合成及其对TiO2纳米粒子的分散性能研究

合成了含有确定长度的聚异丁烯链段与4种不同的乙烯胺链段（乙二胺、二乙烯三胺、三乙烯四胺和四乙烯五胺）组合的聚异丁烯丁二酰亚胺系列衍生物,并将它们用作TiO2纳米粒子在非极性溶剂中的分散剂.详细考察了亲水/亲油基团大小对分散性能的影响规律：当聚异丁烯链段的分子量为2000时,随着乙烯胺段链长的增加,TiO2粒子的粒径和Z...     

Effect of Side Chains and Sulfonic Groups on the Performance of Polycarboxylate-Type Superplasticizers in Concentrated Cement Suspensions

Polycarboxylate-type superplasticizers (PCs) containing different side chains and sulfonic groups have been synthesized, and the effect of side chains and sulfonic groups on their performance in cementitious systems has been intensively investigated by measuring zeta potential, thickness of absorption layer, paste fluidity, rheological properties as well as the setting time in this paper. Results show that the PC containing both short poly(ethylene oxide) (PEO) side chains and long PEO side chains with the molar ratio of 1:1 has a better dispersibility than the PC containing only short PEO side chains or only long PEO side chains in cement suspensions. The shorter the side chain of the PC, the longer the setting time of cement paste incorporating it. An appropriate increase of sulfonic group content is beneficial for the improvement of dispersibility for the PC and leads to no obvious change for the setting time. It also suggests that there is a geometrical balance between the PEO side chains and sulfonic groups for the performance of PC. This work is not only helpful for understanding the relationship of molecular structure of PCs and their performance, but also further designing optimum molecular structure of PC to meet the requirement in different concrete system.     

Synthesis of Nano‐Sized TiO2 Colloidal Sol and Its Optical Properties

Nano‐sized TiO₂ sol was prepared through a wet synthesis process. The synthesis procedure involved hydrolysis of TiCl₄, acid treatment, and a SiO₂ surface‐modifying process. Before surface modification, the TiO₂ suspension was treated with acid to remove Na ions, soluble TiO_2, and other impurities. The acid treatment of a TiO₂ suspension at a higher temperature was proved to be useful for effective SiO₂ modification. The colloidal sol provided high transparency in visible light as well as excellent UV‐shielding properties. Surface modification of TiO₂ particles with SiO₂ greatly improved both the dispersing stability in neutral pH and the photostability of TiO₂ colloidal sol.     

Design and Development of Oral Oil-in-Water Nanoemulsion Formulation Bearing Atorvastatin: In Vitro Assessment

The objective of the present investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of AT-Ca with minimum surfactant concentration that could improve its solubility as well as its oral bioavailability. The composition of optimized nanoemulsion formulation was Sefsol 218 and oleic acid (1:1) 10% w/w, as an oil phase, Tween-20 (19% w/w) as a surfactant, Carbitol (19% w/w) as a cosurfactant and distilled water (52% w/w) as an aqueous phase, containing 10 mg of AT. The optimized formulation showed higher% drug release (99.34%), lower droplet size (42.8 ± 0.42 nm) with low polydispersity index (0.237 ± 0.012), less viscosity (27.51 ± 1.01 cP) and infinite dilution capability. In vitro drug release from the nanoemulsion formulations was highly significant (p < 0.01) as compared to drug suspension.     

Preparation and applications of novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite nanocomposites

Novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite (HAp) nanocomposites were prepared by the reaction of calcium nitrate tetrahydrate and phosphoric acid in the presence of the corresponding oligomer. These fluorinated oligomer/HAp composites thus obtained are nanometer size‐controlled fine particles (83–173 nm), and were found to exhibit good dispersibility in methanol, ethanol, and isopropyl alcohol. These fluorinated HAp nanocomposites were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleophobic characteristics imparted by fluorine on their surface. In addition, the surface structural changes of the modified polyethylene terephtalate and PMMA films treated with these fluorinated nanocomposites before and after soaking in a simulated body fluid (SBF) were analyzed by using SEM, XRD, and EDX to observe the formation of spherical HAp deposits on the surface. Copyright © 2009 John Wiley & Sons, Ltd.     

改进黏度在线凝胶色谱的测定结果

黏度在线凝胶色谱是一种同时配备浓度和黏度检测器的凝胶色谱，由于其测定过程简单直接，被越来越多地广泛采用，但因为数据处理方式和仪器精度的问题，其数均分子量、重均分子量与分散度结果存在较大误差．实验表明，选择适当的谱峰叠加处理、改进普适校正曲线精度、调整标样进样方式以及选择合适的积分点等手段可以明显改善存在的问题，从而大幅度地提高数均分子量、重均分子量与分散度的结果准确性。     

Surface functionalization of multiwalled carbon nanotubes by the photo‐responsive strategy of π‐π stacking and azide‐grafting

In this communication, we report a new, simple, and eco‐friendly method to develop highly dispersible multiwalled carbon nanotubes (MWCNTs) by π‐π stacking and azide‐grafting. MWCNTs were functionalized via standard physisorption, followed by nitrene addition using azido compounds upon ultraviolet activation. The functionalized MWCNTs show excellent dispersibility without raising distinct damage, which can bear comparison with that of MWCNTs oxidized with mixture acids. This method allows for the improvement of the chemical compatibility of MWCNTs with specific polymers for application in nanotube‐based composites and opens a potential pathway for surface protection.     

柠檬酸根对纳米Fe3O4颗粒的生长及性能的影响

现代诊断学的发展使得超小超顺磁性的Fe₃O₄粒子在医学领域具有重要应用价值。实验中利用某些羧酸盐对铁氧化物晶粒成长的抑制作用，在共沉淀法中引入柠檬酸根，制备出平均粒径小于5 nm的Fe₃O₄纳米分散体系。研究了不同柠檬酸根浓度对生成粒子的大小、结晶和表面吸附情况的影响。对Fe₃O₄颗粒在不同条件下的磁性与胶体稳定性进行了讨论。     

Photografting of vinyl polymers onto ultrafine inorganic particles: Photopolymerization of vinyl monomers initiated by AZO groups introduced onto these surfaces

The photografting of polymers onto ultrafine inorganic particles, such as silica and titanium oxide, initiated by azo groups introduced onto these surfaces was investigated. The introduction of azo groups onto the particles was achieved by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with surface isocyanate groups, which were introduced by the treatment with tolylene 2,4-diisocyanate. It was found that the photopolymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and N-vinylcarbazole, is initiated by ultrafine particles having azo groups. The corresponding polymers were effectively grafted onto these surfaces through the propagation of the polymer from the surface radicals formed by the photodecomposition of the azo groups: e.g., the percentage of grafting of PMMA and polystyrene onto silica was reached to 112 and 176%, respectively. The percentage of grafting onto silica in the graft polymerization initiated by photodecomposition of surface azo groups was much larger than that initiated by thermal decomposition. Polymer-grafted ultrafine particles thus obtained gave a stable colloidal dispersion in good solvents for the grafted chain. © 1994 John Wiley & Sons, Inc.