纳米二氧化硅粉体的表面改性研究进展

简介了纳米二氧化硅的表面改性方法；重点介绍了国内外纳米二氧化硅的表面改性方法及其对材料性能的影响；指出了纳米二氧化硅在聚合物基复合材料中的应用；展望了其发展前景。     

气相法改性纳米二氧化硅表面

采用硅烷偶联剂A-151处理的纳米二氧化硅粒子，具有良好的疏水性，并且反应副产物没有腐蚀性，有利于保护设备和环境保护。分别用表面羟基数、亲油化度等性能来表征改性纳米二氧化硅的效果。红外光谱分析表明A-151确实已经和纳米二氧化硅表明的羟基发生了化学反应，通过透射电镜研究发现改性后纳米二氧化硅在乙醇中达到纳米级的分散。     

纳米二氧化硅的表面改性研究

采用改性剂A、B、C分别对纳米二氧化硅表面进行改性,考察了改性剂剂量和搅拌方式对改性效果的影响.结果发现,改性剂A、B、C的剂量分别在1.3%、0.9%、1.5%时改性效果达到最好,而改性剂C改性效果随剂量的增加越来越好;超声波振荡的改性效果明显优于电动搅拌.     

纳米SiO_2的表面改性

分别用吐温-80、油酸、十二烷基苯磺酸钠、硅烷偶联3-氨丙基三乙氧基硅烷(KH550)和硅烷偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)处理纳米二氧化硅,用沉降体积和亲油化度来对比改性效果,结果表明KH570改性效果最好,其最佳工艺条件为:KH570用量为8%,反应温度为70℃,反应时间为2 h,反应pH为5.5。对KH570改性前后的纳米粉体进行了红外光谱分析、热重分析、紫外-可见光谱分析、扫描电镜分析等表征。结果表明,硅烷偶联剂与纳米二氧化硅之间形成了化学结合,改性后的纳米SiO_2分散性提高,从而更好地应用于聚合物材料中。     

纳米SiO_2的表面改性

分别用吐温-80、油酸、十二烷基苯磺酸钠、硅烷偶联3-氨丙基三乙氧基硅烷(KH550)和硅烷偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)处理纳米二氧化硅,用沉降体积和亲油化度来对比改性效果,结果表明KH570改性效果最好,其最佳工艺条件为:KH570用量为8%,反应温度为70℃,反应时间为2 h,反应pH为5.5。对KH570改性前后的纳米粉体进行了红外光谱分析、热重分析、紫外-可见光谱分析、扫描电镜分析等表征。结果表明,硅烷偶联剂与纳米二氧化硅之间形成了化学结合,改性后的纳米SiO_2分散性提高,从而更好地应用于聚合物材料中。     

纳米二氧化硅的制备、表面改性和应用前景

介绍了纳米二氧化硅的制备方法,表面改性技术以及在橡胶、塑料等领域中的应用情况,指出了其今后的发展前景。     

纳米二氧化硅表面接枝聚合改性研究进展

综述了纳米二氧化硅(Nano-SiO2)微粒表面接枝聚合改性的基本方法,分析了各种表面接枝聚合改性方法的特点,以及接枝聚合改性的研究进展。     

纳米颗粒强化相变流体传热性能的研究进展

相变流体是一种具有高载热密度的传热工质,但传热性能有待进一步提高.在相变流体中引入能显著提高流体传热性能的纳米颗粒是近年来兴起的研究课题.综述了纳米颗粒在微胶囊相变流体中强化传热性能的研究进展.结合笔者所在实验室的研究成果,介绍了纳米颗粒在相变乳状液方面的传热强化效果,最后提出了下一步工作的重点.     

纳米二氧化硅的表面改性及其应用进展

综述了国内外纳米二氧化硅的表面改性方法，并分类介绍了粉体纳米二氧化硅和胶体纳米二氧化硅的表面改性方法及其对材料性能的影响，分析讨论了纳米二氧化硅与有机聚合物的反应机理及其在聚合物基复合材料中的应用，展望了其发展前景。     

纳米流体在热管中的换热特性实验研究

在分析热管散热原理的基础上自制一套CPU热管散热系统,研究在不同纳米流体浓度下热管散热性能的变化情况。通过实验比较和分析,得到热管的最佳纳米流体浓度,从而最大限度地提高热管的实际散热能力。通过实验制备出CuO-水纳米流体,将其作为热管工质,建立一套热管换热性能的测试实验装置,使用装置并对热管进行换热性能测试。实验的各种参数：充液率为50%;纳米流体质量分数（ω）分别为1%、1.2%、1.4%。并与以水为工质的热管进行换热性能的对比,通过对不同CuO纳米颗粒浓度的CuO-水纳米流体热管实验结果分析发现:热管内CuO-水纳米流体的热传输具有一定的特殊性,通过多组实验掌握这种特殊性的规律,可以在一定条件下使得纳米流体在热管中起到强化传热的作用。     

Application of functionalized nanofluid in thermosyphon

A water-based functionalized nanofluid was made by surface functionalizing the ordinary silica nanoparticles. The functionalized nanofluid can keep long-term stability. and no sedimentation was observed. The functionalized nanofluid as the working fluid is applied in a thermosyphon to understand the effect of this special nanofluid on the thermal performance of the thermosyphon. The experiment was carried out under steady operating pressures. The same work was also explored for traditional nanofluid (consisting of water and the same silica nanoparticles without functionalization) for comparison. Results indicate that a porous deposition layer exists on the heated surface of the evaporator during the operating process using traditional nanofluid; however, no coating layer exists for functionalized nanofluid. Functionalized nanofluid can enhance the evaporating heat transfer coefficient, while it has generally no effect on the maximum heat flux. Traditional nanofluid deteriorates the evaporating heat transfer coefficient but enhances the maximum heat flux. The existence of the deposition layer affects mainly the thermal performance, and no meaningful nanofluid effect is found in the present study.     

Mesoporous silica nanoparticles functionalized with a redox-responsive biopolymer

A redox-responsive delivery system has been formulated for cancer therapy using mesoporous silica nanoparticles (MSNs). The silica surface is modified with carboxylic acid groups prior to loading with 5-fluorouracil (5-FU). Subsequently, the pores of the MSNs are sealed by reacting cystamine-modified carboxymethyl cellulose (CMC), which contains disulfide bonds, with the surface of the MSNs via carbodiimide chemistry. Because these bonds are the sites of cleavage, cells overexpressing reducing agents should be able to cleave Cystamine-modified CMC and release the encapsulated drug. Characterization of the resulting nanoparticles shows a decrease in surface area and pore volume, which suggests that the pores of MSNs has been sealed by the attachment of Cystamine-modified CMC. Transmission electron microscopy confirms these results and shows a coating of Cystamine-modified CMC on the surface of the MSNs. The release of 5-FU can be triggered in the presence of dithiothreitol (DDT), a reducing agent. The breast cancer cells (MCF-7) show the positive uptake of Redox-responsive MSNs Moreover, these nanoparticles exhibit higher cytotoxicity when the breast cancer cells are preincubated with DTT compared to the control nanoparticles or 5-FU loaded MSNs in the absence of DTT. These results show that MSNs crosslinked with Cystamine-modified CMC are redox-responsive and can be developed further for cancer therapy.     

一种离子液体为介质主体的纳米流体的制备

制备了一种以离子液体BMImBr作为介质主体,阿拉伯胶为分散剂,单臂碳纳米管(SWCNTs)为纳米粒子的纳米流体。考察了分散剂含量、超声时间、超声功率等因素对纳米流体稳定性和分散效果的影响。最佳工艺条件:2 000 0 g BMImBr中加入65.0 mg质量分数为15.38%的阿拉伯树胶水溶液,溶解后加入0.4 mg SWCNTs,在100 W功率下超声分散24 h,然后静置24 h,制备出了一种以离子液体为主体的新型的混合介质的纳米流体。通过电子显微镜对流体的形貌进行了表征,结果表明,SWCNTs均匀的分散于介质中。     

Microfluidics for selective concentration of nanofluid streams containing magnetic nanoparticles

Microfluidics is well-known for many Lab-on-a-Chip applications including sensing, cell sorting, separation, chemical reaction, emulsification, de-emulsification, droplet generation, energy generation and similar applications. The current research scenario in the field of interfacial science and colloidal technology has facilitated the advancement of microfluidics as a miniaturized option for many targeted tasks. Here we show how the microfluidics offers a low-cost solution for concentrating the dispersion of magnetic nanoparticles. The synthesized nanofluids were fed to the microchannels subjected to magnetic field. It has been found that the feed flow rate is one of the very crucial factors which affect the control of concentration of the nanofluids.     

Role of nanoparticles on nanofluid boiling phenomenon: Nanoparticle deposition

Suspended nanoparticles inside the nanofluids can modify the characteristics of heated surfaces and the physical properties of the base liquids, offering a great opportunity to optimize boiling heat transfer. This paper reviews the mechanisms of nanoparticle deposition and the effects induced by deposited nanoparticles on surface roughness, force balance at the triple line, surface wettability, active nucleation site density, receding and advancing contact angles, boiling heat transfer coefficient and critical heat flux. Both enhancement and deterioration effects on boiling heat transfer coefficient and critical heat flux have been discussed. Most of the existing experimental data confirms the enhancement of critical heat flux using alumina nanofluid, however there is no consistency about its boiling heat transfer coefficient.     

能使细胞内组织再生的蛋白质--EPM的开发及在生发剂中的应用

在日本FRAGRANCEJOURNAL2003年第一期刊登的关于生发剂展望的综述论文中 ,出现了一个生僻的日语单词“エピモルフイン” ,(略称为 :EPM)。查遍了现有辞典 ,没有此词。后来 ,从日本雅虎(www yahoo co jp)上搜索到此词的含义 ,非同小可 ,竟然是一种最近才开发的 ,能使细胞内组织再生的蛋白质 ,并已开始用于生发剂的配方。此种蛋白质能促使毛包中细胞内组织的再生。椐称 ,还能用于血管和内脏器官的再生医疗。日本住友电工素以研究电线和电缆的有机包覆材料而闻名。自20世纪80年代初开始进行生物化学工程的技术和材料的开发研究 ,于1992…     

Efficient removal of Cu(II) using amino‐functionalized superparamagnetic nanoparticles prepared via SI‐ATRP

An amino‐functionalized nano‐adsorbent (DETA‐MNPs) was prepared by a process involving: (1) synthesis of superparamagnetic Fe₃O₄ nanoparticles; (2) introduction of amino groups after which ATRP initiator was anchored; (3) grafting of glycidyl methacrylate (GMA) via SI‐ATRP; and (4) ring‐opening reaction of epoxy groups with diethylenetriamine (DETA). The nano‐adsorbent was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) and applied to remove Cu(II) in batch experiments. The effects of pH, Cu(II) concentrations, solution ionic strength, and contact time were investigated. The results show that the DETA‐MNPs are spherical with cubic spine structure, high saturation magnetization (41.9 emu g^?1), and an average diameter of 10 nm. The maximum Cu(II) adsorption capacity achieves 83.33 mg g^?1 at pH 5.0 by Langmuir model. The adsorption process is highly pH‐dependent and reaches equilibrium within 20 min. Furthermore, the DETA‐MNPs exhibit excellent dispersibility and reusability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42859.     

Immobilization of cellulase on functionalized cobalt ferrite nanoparticles

Amine functionalized cobalt ferrite (AF-CoFe₂O₄) magnetic nanoparticles (MNPs) were used for immobilization of cellulase enzyme via 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDS) and N-hydroxy-succinimide (NHS) coupling reaction. The structural, morphological and magnetic properties of AF-CoFe₂O₄ were determined. TEM micrograph revealed a mean diameter of ～8 nm and showed that the AF-CoFe₂O₄ remain distinct with no significant change in size after binding with cellulase. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of cellulase to AF-CoFe₂O₄. The properties of immobilized cellulase were investigated by optimizing binding efficiency, pH, temperature and reusability. The results showed that the immobilized cellulase has higher thermal stability than free cellulase, which might be due to covalent interaction between cellulase and AF-CoFe₂O₄ surface. The immobilized cellulase also showed good reusability after recovery. Therefore, AF-CoFe₂O₄ MNPs can be considered as promising candidate for enzyme immobilization.     

一种新的湿排粉煤灰活化处理方法

纳米技术和纳米材料的科学价值已逐渐被人们所认识，利用纳米技术对粉煤灰表面进行化学处理，使粉煤灰表面形成纳米、微米尺寸的活化腐蚀层。采用这种方法可大大提高粉煤灰水泥早期强度和后期强度，提高粉煤灰掺量。经处理的活化粉煤灰具有早强、减水效果，可用于砼掺和料，掺量可达30％～50％，具有较大的应用和推广价值。     

A new kind of ternary copolymer for ionic conduction

Two novel ternary copolymers, MNEC-TPC-LDABS and MMEC-TPC-LDABS, were synthesized by condensation copolymerization of mannitol-containing oligomeric side chains (MNEC) or melamine-containing oligomeric side chains (MMEC) with terephthaloyl chloride (TPC) and lithium 2,5-diaminobenzene sulfonate (LDABS), respectively, to become thermally stable and mechanically strong ionic conductors. Incorporating anionic groups (SO) into the structure of copolymers increases mobile cation concentration and introducing MNEC and MMEC enhances ionic conductivity via flexible chain motion assistance. The conductivity (ς) of MNEC-TPC-LDABS is 7.82 × 10⁻⁵ S/cm and of MMEC-TPC-LDABS is 9.17 × 10⁻⁵ S/cm, both measured at 25°C. The crystallinity and T_g of the copolymers were greatly decreased by the incorporation of dendritic macromolecule units of MNEC or MMEC. The temperature dependencies of the ionic conductivity for two polymers show curved Arrhenius plots, which suggest that ionic conduction is closely associated with segmental motion of the polymer hosts. The conductivity of the polymer electrolytes obeys the Williams–Landel–Ferry (WLF) and Vogel–Tammann–Fulcher (VTF) equation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 953–959, 1999