纳米SiO2/Al复合粒子的制备

利用在活化微米金属铝粉表面包覆纳米SiO2致密膜的方法，以对推进剂燃烧具有催化作用的纳米膜取代了铝粉表面本身的惰性氧化层。分析了纳米膜包覆的形成机理，并以此制备了纳米SiO2／A1复合粒子。通过检测分析，发现包覆前后颗粒粒度变化不明显，包覆膜的厚度在10nm左右，与铝粉本身的氧化层厚度相当；发现复合颗粒表面有Si-O-Si反对称伸缩振动峰及Si-O-Si弯曲振动吸收峰，表明包覆膜为SiO2。     

PC/ZnO-SiO2纳米复合材料的制备及注塑工艺探讨

采用正硅酸乙酯（TEOS）水解生成的SiO2对纳米ZnO进行表面包覆,制备了ZnO—SiO2纳米复合粒子,并用该复合粒子对聚碳酸酯（PC）进行改性处理。考察了纳米ZnO的表面包覆改性效果,研究了不同纳米复合粒子用量时复合材料的耐光氧老化性能,并探讨了纳米复合粒子对复合材料注塑工艺的影响。结果表明,SiO2成功包覆在纳米ZnO的表面,纳米复合粒子为球形,大小均匀,且在PC基体中分散均匀;纳米复合粒子的加入使复合材料的耐光氧老化性能明显提高,而加热温度、注塑压力和保压压力降低。     

包覆SiO2的硬脂酸相变储能材料的低热固相化学合成及其热性能

采用低热固相化学反应法,一步制备了表面包覆SiO2的硬脂酸相变储能纳米粒子.由红外光谱、X射线衍射和差示扫描量热法对表面包覆SiO2的硬脂酸纳米粒子进行了表征.利用动态光散射激光力度仪测定了材料的粒径分布,同时对材料表面包覆前后的接触角进行了测定.结果表明:硬脂酸纳米粒子表面成功包覆了SiO2层.包覆的硬脂酸纳米粒子为球状,粒径大约为110 nm.包覆的硬脂酸纳米粒子相转变温度为61.4℃,相变过程中的焓值为153.1 J/g,具有良好的蓄热能力,可用于太阳能利用等方面的储能蓄热.     

交联度对泪珠状SiO_2/PS复合粒子结构和形貌的影响

用硅烷偶联剂KH570对泪珠状SiO2纳米粒子的表面进行改性,并作为苯乙烯聚合反应中的种子,利用分散聚合法合成具有核壳结构的泪珠状SiO2/PS复合粒子。采用红外光谱研究了泪珠状SiO2纳米粒子与KH570、聚苯乙烯之间的相互作用;采用透射电子显微镜和扫描电子显微镜观察复合粒子的结构和形貌。结果表明,随着交联度的不同,SiO2/PS复合粒子具有不同的构型。润湿性测试结果表明,球形SiO2/PS复合粒子具有疏水性而泪珠状SiO2/PS复合粒子具有亲水性。     

交联度对泪珠状SiO_2/PS复合粒子结构和形貌的影响

用硅烷偶联剂KH570对泪珠状SiO2纳米粒子的表面进行改性,并作为苯乙烯聚合反应中的种子,利用分散聚合法合成具有核壳结构的泪珠状SiO2/PS复合粒子。采用红外光谱研究了泪珠状SiO2纳米粒子与KH570、聚苯乙烯之间的相互作用;采用透射电子显微镜和扫描电子显微镜观察复合粒子的结构和形貌。结果表明,随着交联度的不同,SiO2/PS复合粒子具有不同的构型。润湿性测试结果表明,球形SiO2/PS复合粒子具有疏水性而泪珠状SiO2/PS复合粒子具有亲水性。     

纳米银的制备、修饰及与鲱鱼精DNA的作用

采用氧化还原法制备了纳米银粒子,在乙醇溶剂中,纳米银粒子表面成功包覆上了SiO2层.利用透射电镜、紫外可见吸收光谱、荧光光谱对纳米银及包覆结构(Ag为核,SiO2为壳,Ag@SiO2)进行了表征.实验表明:氨水的加入顺序对Ag@SiO2核壳结构具有一定的影响;随着SiO2壳层的不断加厚,纳米银的特征吸收峰红移,吸收强度降低,在本实验中当厚度大于50nm时,特征吸收峰发生蓝移,吸收强度增大.纳米银的发射光谱表明SiO2壳层的包覆使纳米银的发射强度降低.另外,采用光谱法考察了Ag@SiO2纳米粒子与鲱鱼精DNA的相互作用,结果表明:鲱鱼精DNA的吸收光谱及Ag@SiO2的发射光谱无明显变化,初步证明Ag@SiO2纳米粒子具有较好的生物兼容性,这为Ag@SiO2纳米粒子的毒理及其在生物医学上应用提供了重要依据.     

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。     

纳米SiO_2表面接枝聚合改性及在PP中的分散

纳米SiO2粒子经硅烷偶联剂表面处理后,采用乳液聚合方法在纳米SiO2粒子表面接枝苯乙烯单体,实现了纳米SiO2表面的高分子包覆改性,制备了具有核壳结构的聚苯乙烯接枝SiO2复合纳米粒子.采用傅里叶变换红外光谱、透射电子显微镜对纳米SiO2粒子的表面结构及其在聚丙烯(PP)中的分散状况进行了表征.结果表明,接枝改性后纳米SiO2粒子能够在PP基体中均匀分散,明显改善了PP复合材料的力学性能.     

核-壳结构纳米CaCO_3/SiO_2复合粒子的制备

采用在氢氧化钙碳化过程中向体系中滴加硅酸钠溶液的方法来制备核-壳结构的纳米CaCO3/SiO2复合粒子。将超细碳酸钙的制备和表面包覆改性工艺融为一体,在碳化反应的末期加入硅酸盐水溶液,通过控制碳化末期的反应及硅酸盐水解反应的进程,有效地防止了碳酸钙粒子的团聚,同时在超细碳酸钙粒子表面成膜包覆二氧化硅薄层,获得核-壳结构的CaCO3/SiO2复合颗粒。用耐酸性测试、吸油值、TEM、IR等方法对复合粒子的包覆效果、粒径大小、形貌、化学组成等做了分析和表征。     

低热固相化学法合成脂肪酸相变材料及其表征

利用低热固相化学反应法,一步制备出表面包覆SiO2的十六酸相变储能微纳米粒子.表面包覆SiO2的十六酸微粒由红外光谱,X射线衍射和差示扫描量热法进行了表征.结果表明:十六酸表面成功包覆了SiO2层,包覆后的颗粒呈球状,粒径大约为200nm,相转变温度为51.9℃,相变过程中的焓值为131.03J/g,具有良好的蓄热能力,可用于太阳能利用等方面的储能蓄热.     

Preparation and Characterization of Silica/Polyamide-imide Nanocomposite Thin Films

The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant—cetyltrimethyl ammonium bromide (CTAB). The composite films were characterized by scanning electron microscope (SEM), thermo gravimetric analysis (TGA) and thermomechanical analysis (TMA). CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET) continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.     

Microgel/SiO2 hybrid colloids prepared using a water soluble silica precursor

In the present work we demonstrate that functional polymer microgels may act as smart self-catalyzing system inducing controlled formation of silica nanoparticles inside the polymer network and formation of hybrid colloids. We synthesized a water soluble silica precursor PEG-PEOS via post-modification of hyperbranched poly(ethoxysiloxane) (PEOS) with poly(ethylene glycol) monomethyl ether. We used poly(N-vinylcaprolactam)-based microgel functionalized with imidazole and β-diketone groups as a matrix for biomimetic deposition of silica. Composite microgel particles containing silica nanoparticles (up to 20 wt.-%) have been prepared by simultaneous PEG-PEOS conversion and silica deposition in the microgels. TEM studies indicate the infiltration of silica nanoparticles (～10 nm) inside the corona region of the microgels due to the strong acid–base interaction between the acidic silica and basic imidazole groups. The resulting composite particles were found to be colloidally stable and no aggregation was observed even after months of storage. The incorporation of silica nanoparticles increased the rigidity of the microgel particles and reduced their thermal sensitivity.     

Tribological and electrical properties of silica‐filled epoxy nanocomposites

The tribological and electrical properties of epoxy composites filled with nano‐sized silica particles are studied and discussed in this article. To enhance the interfacial interaction between the fillers and the matrix, nanoparticles were pretreated with silane coupling agent. Dry sliding wear tests were carried out with configuration of composite sample on a rotating steel disc. Electrical measurements such as AC breakdown voltage, at 50 Hz, high voltage‐low current arc resistance and wet tracking resistance were carried out. The results reveal the influence of nanosized silica loading on wear resistance of the epoxy. It is observed that 10 wt% loading of silica is very effective in reducing the wear loss. With further increase of silica filler loading, the nanoparticles agglomerated and resulted in increase of the specific wear rate. The influence of silica particles on the specific wear rate is more pronounced under sliding wear situation. The influence of silica particle loading on epoxy is evident in the results of electrical parameters like dielectric strength, arc resistance and tracking resistance. These parameters showed improvement with filler loading up to 15 wt% and beyond this value of filler loading noticeable deterioration was observed. The effects of electrical stresses in the morphologies of the surfaces of epoxy nanocomposites are discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

A facile approach to fabricate porous nylon 6 nanofibers using silica nanotemplate

Porous Nylon 6 nanofibers were prepared using silica nanoparticles as the template. Firstly, Nylon 6/silica composite nanofibers were prepared as precursors by electrospinning Nylon 6 solutions containing different contents of silica nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and the inner structure of composite nanofibers; where it was found that silica nanoparticles were distributed both inside and on the surface of nanofibers. Analytical techniques [Fourier transform infrared (FTIR), differential scanning calorimetry, thermal gravimetric analysis (TGA), and wide‐angle X‐ray diffraction) were used to study the structure and properties of these composite nanofibers. The glass transition, melting, and crystallization processes of the fibers were affected by the addition of silica nanoparticles. Secondly, porous Nylon 6 nanofibers were obtained by removing silica nanoparticles via hydrofluoric acid treatment. The removal of silica nanoparticles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of the porous structure in these nanofibers. After the formation of the porous structure, Brunauer–Emmett–Teller specific surface areas of nanofibers were increased as compared to solid Nylon 6 and composite nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高固含量聚硅酸钾基防火凝胶及其在复合防火玻璃中的应用

通过蒸发浓缩的方法制备了高固含量硅溶胶分散液,采用纳米粒度及Zeta电位分析仪研究了蒸发浓缩前后分散液中无机粒子粒径和Zeta电位的变化。进而,以高固含量硅溶胶分散液为原料,氢氧化钾溶液为固化剂,制备了高固含量聚硅酸钾基防火凝胶和复合防火玻璃,采用小型耐火试验炉、热重分析、扫描电子显微镜、红外光谱等测试手段,研究了复合防火玻璃的耐火性能及防火凝胶的热稳定性和耐火机理。结果表明:蒸发浓缩的方法对纳米粒子的粒径和分散稳定性几乎没有影响;分散液固含量的提高能够极大地提升复合防火玻璃的耐火隔热性,并一定程度上提升防火凝胶的热稳定性。     

Silica nanoparticles modified with vinyltriethoxysilane and their copolymerization with N,N′‐bismaleimide‐4,4′‐diphenylmethane

The synthesis and characterization of the vinyltriethoxysilane‐modified silica nanoparticles were investigated. It was shown that the vinyltriethoxysilane molecules had been successfully grafted onto the silica nanoparticles. The native and silane‐modified silica dispersions in N‐methyl‐2‐pyrrolidone with the total solids contents within the range 1–6 wt % exhibited dramatically different flow behaviors. The polymerization of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) initiated by barbituric acid in the presence of the native or vinyltriethoxysilane‐modified silica nanoparticles were then carried out in γ‐butyrolactone (total solids content = 20%). The higher the level of silica, the better the thermal stability of the BMI/silane/silica composite particles. The silane‐modified silica particles significantly improved their dispersion capability within the continuous BMI oligomer matrix. Furthermore, the degree of dispersion of the vinyltriethoxysilane‐modified silica particles in the BMI oligomer matrix decreased with the weight percentage of silica based on total solids increased from 20 to 40 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: Sci 103: 3600–3608, 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.     

微滴乳液聚合制备PDMS/SiO2纳米复合材料

采用超声分散的方法,以少量八甲基环四硅氧烷(D₄)对硅溶胶粒子进行表面接枝改性。然后在改性硅溶胶存在下,以十二烷基苯磺酸(DBSA)为乳化剂兼催化剂进行D₄的微滴乳液聚合,得到聚硅氧烷(PDMS)/二氧化硅(SiO₂)纳米复合乳液。采用FTIR、TGA、纳米粒度仪、TEM和拉力机分别对样品进行了表征。结果表明:采用超声分散的方法,能够有效地实现硅溶胶粒子的表面改性。通过微滴乳液聚合得到的复合乳胶粒是聚合物包覆二氧化硅粒子的核壳结构形态。SiO₂的引入提高了有机硅复合膜力学性能,增强了热稳定性。     

Improvement of Hardness and Wear Resistance of Glass Fiber-Reinforced Epoxy Composites by the Incorporation of Silica/Carbon Hybrid Nanofillers

The tribological performance of hybrid composite (epoxy reinforced with woven, nonwoven tissue glass fibers, silica and carbon black nanoparticles) was investigated. Two methods were used to ensure good dispersion of nanoparticles in epoxy resin which were ultrasonic processor and magnetic stirrer. The effect of silica and/or carbon black nanoparticle content on microindentation hardness and wear properties of the neat glass fiber-reinforced epoxy composites was investigated. The results from the wear test indicated that, under all applied loads, incorporation of silica and carbon black nanoparticles either single or combined significantly improved the wear resistance of neat glass fiber reinforced epoxy. A significant increase in hardness of the hybrid nanocomposite laminates was achieved. Analysis of variance was developed to study the optimal wear testing parameters on composite samples. The most significant parameter is the time, followed by nanoparticle (silica and carbon black) content.     

纳米SiO2增强TPS/PVA复合材料的研究

以甲酰胺／己内酰胺为复配增塑剂,添加纳米二氧化硅（SiO2）熔融制备了热塑性淀粉／聚乙烯醇／纳米二氧化硅（TPS／PVA／SiO2）复合材料,研究了复合材料的力学性能、流变性能和耐水性能。结果表明：添加1phr的表面改性SiO2,TPS／PVA的拉伸强度和断裂伸长率以及耐水性能均有所提高,但过量的纳米SiO2对材料的力学性能有损害;经KH560表面改性的纳米SiO2的团聚明显减少,因而对TPS／PVA性能的改善更明显;TPS／PVA／SiO2复合材料具有优良的加工性能,熔体表现出假塑性流体的特征。