Au-SiO2复合纳米微球的制备与表征

采用溶胶-凝胶法制备SiO2纳米微球,以KH-550为粘结剂,利用简单的化学还原法,成功制备出Au-SiO2复合纳米微球,并通过扫描电子显微镜,透射电子显微镜,X射线衍射仪,紫外-可见分光光度计和多功能成像光电子能谱仪对其进行表征.结果表明,Au-SiO2复合纳米微球粒径约130 ～ 160 nm,且颗粒较均匀、分散性较好.样品中金纳米粒子均匀分散于SiO2纳米微球表面,粒径约4～9 nm,具有良好的面心立方结构,晶型良好,且Au物种主要以零价金属态存在.     

聚合物-纳米无机粒子复合微球研究新进展

近年来,聚合物-纳米无机粒子复合微球相关的设计、制备、以及应用研究得到了科学界众多学者的广泛关注与探索。本文论述了单体聚合法制备聚合物-纳米无机粒子复合微球的研究近况,主要介绍了悬浮聚合、乳液聚合(微乳液聚合、Pickering乳液聚合、细乳液聚合、反相乳液聚合、无皂乳液聚合)、分散聚合及溶液聚合的制备方法。概述了聚合物-纳米无机粒子复合微球在生物医药、光电材料、保护涂层、催化等方面的应用,展望了聚合物-纳米无机粒子复合微球的发展趋势。     

在PVDF-SiO2复合微球上的脂肪酶固定化

采用相转移法制备了包裹SiO2的聚偏氟乙烯(PVDF)复合微球,用其固定化假丝酵母脂肪酶(CRL). 结果表明,纯PVDF球、PVD-SiO2复合球用作酶固定化载体,对CRL的吸附量都较大. 随着PVDF-SiO2复合球中SiO2含量增多,其酶吸附量和活力回收率都有提高. PVDF与SiO2质量比为1:1的复合球的酶活力回收率最高,可达50.98%. 固定化CRL后,PVDF-SiO2复合球比SiO2更易实现固液分离,且对底物溶液无污染.     

二氧化硅形态对有机-无机复合弹性乳液涂膜性能的影响

采用预乳化、半连续种子乳液聚合法为聚合工艺,利用无机二氧化硅改性纯丙烯酸酯弹性乳液,使之兼有有机相和无机相的优点,制备有机-无机复合弹性乳液。分别选用3种不同形态的二氧化硅(纳米二氧化硅粉体、硅溶胶、正硅酸乙酯和A-151)进行对比试验,考察了二氧化硅形态对聚合物膜力学性能、吸水率、光学性能、耐热性等性能的影响。结果表明:二氧化硅形态对有机-无机复合弹性乳液涂膜性能有较大影响,二氧化硅以正硅酸乙酯和A-151的加入方式为最佳。     

多孔Fe2O3/SiO2复合磁性微球的合成

采用分散聚合法制备了单分散脲醛树脂／Fe2O3／SiO2的复合微球,研究了不同的反应条件对于复合微球的分散状况和粒径大小的影响。该微球在马弗炉内灼烧后,脲醛树脂成分被除去,得到Fe2O3／SiO2的复合微球,其中的Fe2O3组分一部分转化为磁性γ—Fe2O3。由脲醛树脂／Fe2O3／SiO2复合微球的电镜(SEM)图、Fe2O3／SiO2复合微球的XRD衍射图得知该微球为多孔的磁性复合微球,且具有单分散性。     

有机无机复合涂料

提高了亲油性和润滑性的低摩擦系数有机-无机杂合涂料及其制备；无机陶瓷涂料组合物及其涂装工艺；[编者按]     

用于化妆品的SiO2/TiO2复合微球的制备及表征

通过溶胶凝胶法在微米级的二氧化硅(SiO2)微球上包覆一层纳米级的二氧化钛(TiO2)粒子,将制备出的复合微粒表面接枝聚合改性,改性前后的复合颗粒用FT-IR、XRD表征,并用扫描电镜观察了微粒的形貌,用紫外分光光度计扫描了添加改性后复合微粒的自制防晒液的紫外吸收谱图,发现经复合后的纳米TiO2粒子的分散性能得到明显改善,复合处理后TiO2粒子的紫外吸收能力较纯TiO2增强80%,且光催化能力得到很大抑制,TiO2作为防晒剂安全性能大大提高,并讨论了该复合粒子在化妆品中的应用。     

MoO2/PSt核壳式纳米复合微球的合成与表征

结合了微乳液和γ-射线辐照法的优点,用微乳液控制产物的形貌,用γ-射线辐照法实现了在常温常压下制备出预期的核壳式无机-有机纳米复合微球。以七钼酸铵为无机盐原料,以苯乙烯为有机单体,用OP-10和OP-4作乳化剂,与水、煤油组成反相微乳液。用γ-射线辐射反相微乳液制备了二氧化钼/聚苯乙烯(MoO2/PSt)核壳结构的纳米复合微球。通过改变七钼酸铵的浓度和苯乙烯用量,观察产物形貌的变化。在七钼酸铵浓度为0.05 mol/L,苯乙烯用量为2 mL时,微球核壳结构明显,粒径均匀。     

有机-无机纳米复合功能材料的研制

将经过表面化学修饰的纳米粒子引入聚合胶体，制备了一系列具有特殊功能的有机-无机纳米复合薄膜材料. 聚合胶体通过控制硅氧烷前驱物的水解-聚合过程制备，纳米粒子包括ZrO2, SiC, AlOOH和ZnO等. 纳米粒子经过溶胶-凝胶过程对其进行表面改性，以改善其分散性能、优化界面结合或防止体系中有机组份的老化. 纳米粒子的作用主要是赋予传统的有机-无机杂化材料“第三功能”，如耐擦伤、耐腐蚀、抗紫外线等性能.     

Nonionic surfactant-stabilized raspberry-like polymer/silica nanoparticles latex with film formability

Raspberry-like P(St-BA)/SiO₂ nanoparticle latexes were prepared via miniemulsion polymerization of styrene (St) and butyl acrylate (BA) in the presence of 20 nm glycerol-modified SiO₂ sol as a Pickering emulsifier and octaphenyl polyoxyethylene (CA-897) as a nonionic surfactant, using 2,2-azobis (isobutyronitrile) (AIBN) as an initiator. 2-(Methacryloyl) ethyltrimethylammonium chloride (MTC) was introduced to act as an auxiliary monomer to enhance the attraction of SiO₂ sol onto latex nanoparticles (NPs) via increasing their electrostatic interaction with negative-charged SiO₂ sol. The average particle sizes of the latex particles can be well controlled from 200 to 360 nm by variation of the SiO₂ sol content as well as soft monomer BA component. The latex NPs displayed a good colloidal stability with excellent resistance to both strong acidic and basic environment. Furthermore, the nanosized latexes exhibited good film formability. The influence of reaction parameters, e.g., the initial silica amount and soft monomer BA content was systematically investigated on the film performances, such as hardness, abrasive resistance, water absorption, gloss. The results indicated that the increase of SiO₂ sol content can contribute to the increase of the film hardness and water absorption ability, while increasing BA component is beneficial to the improvement of the film gloss.     

One-pot fabrication of fluoride-silica@silica raspberry-like nanoparticles for superhydrophobic coating

A facile and effective method to fabricate raspberry-like nanoparticles is reported in a one-pot reaction. This method consists of two steps: preparation of silica nanoparticle precursors dispersion via the Stober process and growth of the tiny functional fluoride-silica nanoparticles on the surface of silica nanoparticle precursors via the hydrolysis-condensation reaction of tetraethoxysilane (TEOS) and 1H,1H,2H,2H-Perfluorodecyl triethoxysilane (HDFTES). The obtained raspberry-like nanoparticle dispersion could be spray coated onto different substrates directly with the water contact angle greater than 150° and water roll-off angle less than 4°. And the prepared coatings maintained water resistance after water jetting, sand abrasion. This method can be an effective strategy for fabricating superhydrophobic surfaces for practical industrial applications.     

还原法制备二氧化硅/银复合粒子

以球形纳米二氧化硅、硝酸银为原料,通过化学还原法制备了二氧化硅/银复合粒子。探讨了还原剂、硝酸银添加量、反应时间、反应温度等对二氧化硅载银粒子载银量的影响规律。采用原子吸收光谱测定法（AAS）和X射线衍射（XRD）分析,对产物的含银量、晶型及平均粒径进行表征。结果表明：取0.5 g球形纳米二氧化硅,在硝酸银浓度为3×10-2 mol/L、硝酸银乙醇溶液添加量为20 mL、反应温度为30 ℃、反应时间为2 h、乙醛为还原剂的条件下,获得的二氧化硅载银粒子的载银量为10.6%（质量分数）。     

PVAc/SiO2纳米复合乳液的性能研究

采用原位乳液聚合法制备了PVAc／纳米SiO2复合乳液,研究了纳米粒子对PVAc粘接强度和耐水性能的影响,并基于纳米压痕试验,分析了PVAc／纳米SiO2复合乳液的力学性能。研究表明,适量的纳米SiO2能显著改善PVAc胶层的粘接强度和耐水性能,并能明显提高PVAc薄膜的弹性模量、硬度及抗蠕变能力。     

Synthesis of TiO2/PAA nanocomposite by RAFT polymerization

Due to the strong tendency of nanoparticles such as metal oxides to agglomerate, homogeneous dispersion of these materials in a polymeric matrix is extremely challenging. In order to overcome this problem and to enhance the filler-polymer interaction, this study focused on living polymerization that was initialized from the surface of titania nanofillers. A new method for synthesizing TiO₂/polymer nanocomposites was found with a good dispersion of the nanofillers by using the bifunctional RAFT agent, 2-{[(butylsulfanyl)carbonothioyl]sulfanyl}propanoic acid). This RAFT agent has an available carboxyl group to anchor onto TiO₂ nanoparticles, and an SC(SC₄H₉) moiety for subsequent RAFT polymerization of acrylic acid (AA) to form n-TiO₂/PAA nanocomposites. The functionalization of n-TiO₂ was determined by FTIR and partitioning studies, the livingness of the polymerization was verified using GPC and NMR, while the dispersion of the inorganic filler in the polymer was studied using electron microscopy, FTIR and thermal analysis.     

Performance of EP/PpPDA and EP/PpPDA/SiO2 nanocomposite on corrosion inhibition of steel in hydrochloric acid solution

Epoxy-poly p-phenylendiamine (EP/PpPDA) and its nanocomposite with SiO₂ nanoparticles (EP/PpPDA/SiO₂) were synthesized and tested as potential corrosion inhibitors of steel in 1 M HCl solution. Performance of EP/PpPDA/SiO₂ and EP/PpPDA coatings on protection of steel against corrosion was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Atomic force microscopy (AFM) and at various temperatures between 298 and 328 K. Changes in the coating resistance and charge-transfer resistance with temperature were analyzed to determine the activation energies of the processes involved. The determined values of activation energy showed that the EP/PpPDA/SiO₂ coating has better anti-corrosion effect than EP/PpPDA. The thermodynamic functions of dissolution processes were also calculated and discussed. The results from AFM observations indicated that the presence of SiO₂ nanoparticles increased the roughness of Epoxy-poly p-phenylendiamine/SiO₂ nanocomposite (EP/PpPDA/SiO₂). It was finally concluded that the presence of silica nanoparticles enhance the protection properties of EP/PpPDA coating as a novel potential corrosion inhibitor for steel.     

Preparation and characterization of UV-curable epoxy/silica nanocomposite coatings

To enhance the interfacial interaction in silica nanoparticles filled polymer composites, the silica surface was firstly treated with glycidoxypropyl trimethoxysilane (GPTMS), and its structure was analyzed by ¹³C NMR and FTIR spectrophotometry. Then a series of GPTMS-modified silica/cycloaliphatic epoxy nanocomposite coatings with 0–6 wt% silica content were prepared by UV-induced cationic polymerization in the presence of a diaryliodonium photoinitiator and thioxanthone photosensitizer. The physical and mechanical properties such as hardness, adhesion, gloss, impact as well as tensile strength were examined. As a result, these composites demonstrated superior tensile strength and tensile modulus with increasing proportion of modified silica up to a certain level. An increase in abrasion resistance of nanocomposites with the addition of modified silica was observed. The thermal stability of nanocomposites was not enhanced with the addition of silica particles. SEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.     

Preparation and property of raspberry‐like AS/SiO2 nanocomposite particles

Surfactant‐free poly(acrylonitrile‐co‐styrene)/silica (AS/SiO₂) nanocomposite particles was synthesized in the presence of cheap, commercially amorphous aqueous silica sol at ambient temperature. Thermogravimetric analysis (TGA) indicated silica contents ranging from 5 wt % to 29 wt %, depending on reaction conditions. Particle size distributions and morphologies were studied using dynamic light scattering (DLS) and transmission electron microscopy (TEM), which clearly showed that most of the colloidal nanocomposites comprised approximately spherical particle with raspberry‐like morphology and relatively narrow size distributions. The optical clarity of solution‐cast nanocomposite films was assessed using UV–vis spectrometer, with high transmission being obtained over the whole visible spectrum. Differential scanning calorimetry (DSC) studies showed that the glass transition temperature of AS/SiO₂ nanocomposites can be higher than the corresponding pure AS, resulting from the hydrophilicity of the nanometer silica. The robustness and simplicity of this method may make large‐scale manufacture of this nanocomposite possible. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 415–421, 2007     

Preparation of acrylate polymer/silica nanocomposite particles with high silica encapsulation efficiency via miniemulsion polymerization

Acrylate polymer/silica nanocomposite particles were prepared through miniemulsion polymerization by using methyl methacrylate/butyl acrylate mixture containing the well-dispersed nano-sized silica particles coupling treated with 3-(trimethoxysilyl)propyl methacrylate (MPS). The encapsulation efficiency of silica particles was determined through the elution and hydrofluoride acid etching experiments, and the size distribution and the morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron microscopy. The coupling treatment of silica with MPS can improve the encapsulation efficiency of silica and the degree of grafting of polymer onto silica. When 0.10 g MPS/g silica was used to modify silica, the encapsulation efficiency of silica was greater than 95%, and the degree of grafting of acrylate polymer onto silica was about 60%. Although the average size and the size distribution index of the composite latex particles increased as the weight fraction of silica increased, the stable latex containing the ‘guava-like’ composite particles was obtained. The grafting of polymer onto silica particles improved the dispersion of silica particles in the solvents for acrylate polymer and in the polymer matrix.     

Synthesis and properties of HA/ZnO/CNT nanocomposite

The goal of this study was to examine the tribomechanical properties of hydroxyapatite (HA)/ZnO and HA/ZnO/CNT composite ceramics (carbon nanotubes; with different ratios 0.5?wt%, 1.0?wt%, and 1.5?wt%). The composites were synthesized using the hydrothermal method in an autoclave. The structure and morphology of the composites were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The consolidation process was performed by sintering the compounds at 1150?°C under an argon gas atmosphere. The effects of ZnO and CNT on the mechanical properties and wear resistance of the HA-nanoparticle-based ceramic composites were investigated using a Vickers hardness tester, nanoindentation, and reciprocating wear tester equipment. The nanohardness and elastic modulus of the sintered samples increased and the friction coefficient of the sintered samples decreased as the fraction of CNTs increased compared to the pure HA and HA/ZnO compounds. Furthermore, the wear loss of HA/ZnO/CNT composites decreased with the increase in the CNT content compared to the HA and HA/ZnO samples.