Preparation and characterization of the transparent hybrids of silicone epoxy resin and titanium dioxide nanoparticles via sol-gel reactions

In order to prepare transparent hybrid films of high refractive index, nanoparticles of TiO2 were prepared and dispersed in a silicone epoxy (SE) resin synthesized from diphenyl silane diol and [2-(3,4-epoxycyclohexyl)ethyl] trimethoxysilane by sol-gel reactions. It was found that amorphous TiO2 nanoparticles of about 5 nm modified with hexahydro-4-methyl phthalic anhydride [HMPA] were dispersed in the SE resin without agglomerations. The refractive index of the hybrids increased linearly with increasing the TiO2 contents. The hybrid containing 30 wt% of the TiO2 particles showed light transmittance of 94% at 450 nm and refractive index of 1.63. The fine dispersion of the TiO2 nanoparticles was attributable to the sol-gel reactions between the SE resin and TiO2 nanoparticles and the modification of the TiO2 particles with HMPA.     

减反射可见光与反射近红外线双功能镀膜玻璃

采用溶胶-凝胶工艺,用提拉法在光伏玻璃上制备了玻璃/TiO2-SiO2/SnO2∶F/SiO2减反射可见光与反射近红外双功能膜。用拟合方法研究了TiO2掺量对TiO2-SiO2膜层折射率的影响、以及溶胶中水含量对SiO2膜层折射率的影响;研究了快速热处理温度对SnO2∶F膜结构和方块电阻的影响,用紫外-可见光谱(UV-Vis)测试了膜层的透射率,用扫描电镜(SEM)观察了膜层的表面形貌。结果表明,TiO2掺量可以使TiO2-SiO2膜层的折射率在1.49~1.97之间变化,SiO2溶胶中的水含量能够在膜面上形成微孔,降低SiO2膜层的折射率。通过优化工艺,制备出了在可见光范围平均透过率约为96%、1120nm波长近红外起始反射的双功能复合膜。对得到的结果进行了讨论。     

Preparation and optical properties of indium tin oxide/epoxy nanocomposites with polyglycidyl methacrylate grafted nanoparticles

Visibly highly transparent indium tin oxide (ITO)/epoxy nanocomposites were prepared by dispersing polyglycidyl methacrylate (PGMA) grafted ITO nanoparticles into a commercial epoxy resin. The oleic acid stabilized, highly crystalline, and near monodisperse ITO nanoparticles were synthesized via a nonaqueous synthetic route with multigram batch quantities. An azido-phosphate ligand was synthesized and used to exchange with oleic acid on the ITO surface. The azide terminal group allows for the grafting of epoxy resin compatible PGMA polymer chains via Cu(I) catalyzed alkyne-azide "click" chemistry. Transmission electron microscopy (TEM) observation shows that PGMA grafted ITO particles were homogeneously dispersed within the epoxy matrix. Optical properties of ITO/epoxy nanocomposites with different ITO concentrations were studied with an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrometer. All the ITO/epoxy nanocomposites show more than 90% optical transparency in the visible light range and absorption of UV light from 300 to 400 nm. In the near-infrared region, ITO/epoxy nanocomposites demonstrate low transmittance and the infrared (IR) transmission cutoff wavelength of the composites shifts toward the lower wavelength with increased ITO concentration. The ITO/epoxy nanocomposites were applied onto both glass and plastic substrates as visibly transparent and UV/IR opaque optical coatings.     

TiO2/环氧树脂纳米复合材料的研究

以纳米TiO₂作为增强材料,制备纳米复合材料,研究了不同的纳米 TiO₂含量对纳米复合材料性能的影响,采用透射电镜对纳米 TiO₂粒子的分布进行了表征,采用正电子湮没技术(PALS),测试了自由体积的尺寸及浓度。结果表明,纳米粒子均匀分散于环氧树脂中,使环氧树脂的拉伸强度、拉伸模量、冲击强度得以提高;也使环氧树脂的自由体积尺寸增大。     

高折光率环氧/ZrO2纳米杂化材料的制备

采用溶胶-凝胶法在环氧E51中原位生成无机纳米ZrO₂团簇,并利用有机环氧分子链上的侧羟基与无机纳米团簇间形成化学键,以增加有机无机组分间的相容性,并防止无机纳米团簇在体系中团聚。采用红外光谱、X射线衍射、扫描电镜、原子力显微镜和透射电镜等对其结构进行了表征,证明成功地在体系中原位生成了ZrO₂纳米粒子且分布均匀,所制备的薄膜材料具有很好的平整度。环氧/ZrO₂纳米杂化光学材料的折光率随着体系中无机纳米粒子含量的增加而呈线性增加,并实现折光率在1.512~1.749间连续可调;在可见光波长范围内,环氧/ZrO₂纳米杂化光学薄膜的透过率普遍维持在85%以上,当纳米粒子的含量增至25%后,透光率也能保持在80%以上。     

LED有机硅封装材料的研究进展

有机硅封装材料具有较好的绝缘性能、耐候性能、耐紫外线性能及较高的透光率和折射率等,其固化时应力较小,不易发生黄变,可有效延长LED的使用寿命,是较为理想的LED封装材料。综述了有机硅改性环氧树脂类封装材料和有机硅类封装材料的研究进展,并展望了其未来的研究方向。     

固化剂类型与固化条件对环氧/粘土纳米复合材料插层剥离行为的影响

本文作者选用了5种不同类型的胺类固化剂:二乙烯三胺(DETA),二氨基二苯基甲烷(DDM),2.4.6三(二甲氨基甲基)苯酚(DMP-30),增韧改性胺和低温固化改性胺。考察了固化剂类型,固化温度和时间对环氧树脂/粘土纳米复合材料插层剥离行为的影响。固化程度和粘土层间距分别采用FT-IR和XRD,TEM检测。结果表明:环氧/粘土的插层与剥离行为与所选用的五种固化剂类型关系不大,而主要取决于固化工艺参数。在合适的固化条件下,当环氧树脂在粘土层间的固化速度大于层外固化速度,达到基本固化时,就能实现粘土的剥离,得到环氧/粘土纳米复合材料。     

层间引发聚合法制备EA/α-ZrP光固化纳米复合材料及其结构表征

以4-溴甲基二苯甲酮与二甲基正十二胺反应合成的新型长链季铵盐光引发剂苯甲酰苄基二甲氨基十二烷基溴化铵(BDDB),进行插层修饰α-ZrP,通过层间引发聚合的方法光固化制备EA/α-ZrP纳米复合材料.XRD和TEM分析结果表明,α-ZrP片层在光固化复合材料中已得到插层和部分剥离;力学性能测试结果表明,EA/α-ZrP光固化纳米材料的拉伸强度、弹性模量及断裂伸长率得到了显著提高.     

Improvement of epoxy resin properties by incorporation of TiO2 nanoparticles surface modified with gallic acid esters

Epoxy resin/titanium dioxide (epoxy/TiO₂) nanocomposites were obtained by incorporation of TiO₂ nanoparticles surface modified with gallic acid esters in epoxy resin. TiO₂ nanoparticles were obtained by acid catalyzed hydrolysis of titanium isopropoxide and their structural characterization was performed by X-ray diffraction and transmission electron microscopy. Three gallic acid esters, having different hydrophobic part, were used for surface modification of the synthesized TiO₂ nanoparticles: propyl, hexyl and lauryl gallate. The gallate chemisorption onto surface of TiO₂ nanoparticles was confirmed by Fourier transform infrared and ultraviolet–visible spectroscopy, while the amount of surface-bonded gallates was determined using thermogravimetric analysis. The influence of the surface modified TiO₂ nanoparticles, as well as the length of hydrophobic part of the gallate used for surface modification of TiO₂ nanoparticles, on glass transition temperature, barrier, dielectric and anticorrosive properties of epoxy resin was investigated by differential scanning calorimetry, water vapor transmission test, dielectric spectroscopy, electrochemical impedance spectroscopy and polarization measurements. Incorporation of surface modified TiO₂ nanoparticles in epoxy resin caused increase of glass transition temperature and decrease of the water vapor permeability of epoxy resin. The water vapor transmission rate of epoxy/TiO₂ nanocomposites was reduced with increasing hydrophobic part chain length of gallate ligand. Dielectric constant of examined nanocomposites was influenced by gallate used for the modification of TiO₂ nanoparticles. The nanocomposites have better anticorrosive properties than pure epoxy resin, because the surface modified TiO₂ nanoparticles react as oxygen scavengers, which inhibit steel corrosion by cathodic mechanism.     

Optical and thermal properties in experimental Bis-GMA-based resins influenced by filler characteristics

The optical and thermal properties were examined in experimental 2,2-Bis-[4-(3-methacryloxy-2-hydroxypropoxy)phenel]propane (Bis-GMA)-based composite resin systems, each of which contained silica, silica-alumina and alumina filler particles. The filler particles were surface-treated by 1% -methacryloxypropyl trimethoxy silane and directly dispersed into the visible-light-cured Bis-GMA-based resin matrix. The average particle size was from 0.012 to 70 µm (silica filler), 2.4 to 8.4 µm (silica-alumina) and 0.02 µm (alumina). The analyses indicated that the filler-containing resin had a larger value of light transmittance when the difference in refractive index between comonomer and filler was smaller. In selected properties such as light transmittance, refractive index and depth of cure, the transmittance and the refractive index difference were important in the increased depth of cure in the Bis-GMA-based resins.     

纳米TiO_2对复合固化环氧树脂胶粘剂的改性研究

通过添加具有活性的纳米TiO_2对异佛尔酮二胺(IPD)与酰胺基胺树脂作为复合固化剂的环氧胶粘剂体系进行改性,实验结果表明:随着纳米TiO_2的适量加入,环氧胶粘剂体系的物理性能得到很大改善,当纳米TiO_2的加入量达到6%(Wt)时,达到最佳值,与纯树脂体系相比,弯曲强度提高96%,弯曲模量提高38%,冲击强度提高180%.而此时的环氧复合胶粘剂体系的粘接性能也比纯树脂均有所提高,剪切强度提高39%、剥离强度提高28%,以及玻璃化温度提高6%.可见,纳米TiO_2的加入对环氧胶粘剂体系具有明显的增强作用.     

聚乙烯亚胺改性TiO2及光催化性能研究

纳米TiO2经3-氨丙基三乙氧基硅烷(APTES)改性后,再通过聚乙烯亚胺(PEI)单体在APTES-TiO2表面进行原位化学氧化接枝聚合,制备了基于共价键结合的PEI/APTES-TiO2纳米复合光催化材料。以甲基橙(MO)为目标降解物,研究了所制备复合材料在紫外光下和太阳光作用下的光催化性能。通过红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等对所制备的复合材料进行了表征。结果表明,TiO2经过有机改性后复合材料在紫外光和太阳光下都出现了较强的吸收,光能的利用率和光生载流子的分离效率得到提高,复合材料表现出较高的光催化活性。     

TiO(2) nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO(2) nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO(2)/PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO(2) nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO(2) polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region.     

二维和零维纳米材料协同增强的高性能纳米复合材料

将二维蒙脱土和零维纳米TiO_2共同复合到环氧树脂中,成功地制备出一种高性能有机蒙脱土/纳米TiO_2/环氧树脂复合材料。力学性能测试和热分析显示,该复合材料在拉伸模量、拉伸强度、弯曲模量、弯曲强度、缺口冲击强度、玻璃化转变温度、热分解温度上都明显优于纯环氧树脂,也优于有机蒙脱土/环氧树脂复合材料和纳米TiO_2/环氧树脂复合材料。XRD检测和透射电子显微镜观察显示,在有机蒙脱土/纳米TiO_2/环氧树脂复合材料中,蒙脱土被完全剥离为纳米单片,和纳米TiO_2交错分布于环氧树脂中。选择适宜的两种维度的纳米材料复合于聚合物中,是制备新型高性能复合材料的成功思路。     

Mechanical and barrier properties of epoxy polymer filled with nanolayered silicate clay particles

The diglycidyl ether of bisphenol A (DGEBA) epoxy resin system filled with organo clay (OC) and unmodified clay (UC) were processed separately by two different curing agents. Triethylene tetramine (TETA) and Diaminodiphenyl methane (DDM) hardeners were used as curing agents. The nanocomposites were processed by shear mixing at different clay concentrations (1, 2, 3,5 and 10 wt%). The OC and UC were characterized by x-ray diffraction (XRD) technique. The morphology of the nanocomposites was obtained by XRD and Transmission Electron Microscopy (TEM). Bending and Impact tests conducted on these materials revealed that the organo clay filled epoxy resin showed good improvement in property over unmodified clay filled epoxy composites. The mass uptake of the nanocomposites was studied in the acid, base and water mediums. It is observed that the mass uptake in the acid medium is higher than in other mediums. The equilibrium mass uptake in all the mediums for nanocomposites was found to be lower compared to neat epoxy polymer system.     

Transparency and toughness characterization of epoxy resins modified with liquid chloroprene rubber

Transparent epoxy resins modified with liquid chloroprene rubber (LCR), containing in a category of rubber-toughened resin were found. Transparency and toughness characterization of the modified epoxy resins were investigated as a function of LCR content. Epoxy resins modified with 0–10 vol % LCR showed complete phase-separation microstructure. However, these modified resins were transparent, because the refractive index of LCR was compatible with that of the epoxy resin matrix at room temperature. On the other hand, it was observed that above 10 vol % LCR, a certain amount of LCR dissolved into the epoxy matrix. In this case, the glass transition temperature decreased with increasing LCR content. It was also found that the critical stress intensity factor, K _c, of the modified epoxy resins exhibited a maximum between 10 and 15 vol % LCR.     

Thermoplastic polymer nanocomposites for applications in optical devices

Polymer optical fibres (POF) have superior properties compared to glass fibres like e.g. high flexural strength, uncomplicated mechanical machining and inexpensive mass production. Dispersion of nanoscaled ceramic fillers in polymers allows the modification of the refractive index depending on the ceramic used and the aspired application. Current work deals with the development of a process chain to tailor the refractive index of PMMA using a UV-curable reactive resin and ceramic nanopowders as well as with the ageing behaviour of polymer nanocomposites. Improved dispersion techniques applying high shear forces to deagglomerate the ceramic powders lead to a refractive index shift depending on the ceramic fillers maintaining a transparency of resulting polymer nanocomposites sufficient for optical applications in the visible (633 nm) and in the infrared (1550 nm) regime. Optical devices were obtained using reaction moulding of the modified polymer nanocomposites as rapid prototyping method.     

环氧树脂改性水性聚氨酯的合成研究

采用甲苯二异氰酸酯(TDI-80)、聚醚二醇(N220)、二羟甲基丙酸(DMPA)、环氧树脂和丙烯酸羟丙酯(HPA),合成了环氧改性的双键封端水性聚氨酯乳液.乳液由于含有不饱和双键而具有感光性能,故此乳液可用作水性紫外光固化涂料或胶粘剂的预聚物.实验结果表明,随着环氧树脂用量的增大,涂膜的硬度、耐水性、耐溶剂性及力学性能增强,但乳液外观和稳定性变差,故适宜的环氧树脂添加量为4%～8%.通过傅立叶变换红外光谱、粒径分析仪、凝胶渗透色谱(GPC)和透射电镜(TEM)等对乳液进行了表征.粒径分析仪分析显示,加入环氧树脂后,水性聚氨酯(WPU)分散体粒径增大,粒径分布变宽.凝胶渗透色谱分析表明环氧树脂改性水性聚氨酯提高了聚氨酯的分子量.     

Size reduction of WO3 nanoparticles by ultrasound irradiation and its applications in structural nanocomposites

The porous WO₃ (pore size 2–5 nm) nanoparticles were synthesized using a high intensity ultrasound irradiation of commercially available WO₃ nanoparticles (80 nm) in ethanol. The high resolution transmission electron microscopic (HRTEM) and X-ray studies indicated that the 2–5 nm uniform pores have been created in commercially available WO₃ nanoparticles without much changing the initial WO₃ nanoparticles (80 nm) sizes. The nanocomposites of WO₃/SC-15 epoxy were prepared by infusion of 1 wt.%, 2 wt.% and 3 wt.% of porous WO₃ nanoparticles into SC-15 epoxy resin by using a non-contact (Thinky) mixing technique. Finally the neat epoxy and nanocomposites were cured at room temperature for about 24 h in a plastic rectangular mold. The cured epoxy samples were removed and precisely cut into required dimensions and tested for their thermal and mechanical properties. The HRTEM and SEM studies indicated that the sonochemically modified porous WO₃ nanoparticles dispersed more uniformly over the entire volume of the epoxy (without any settlement or agglomeration) as compared to the unmodified WO₃/epoxy nanocomposites.     

剥离型环氧树脂/蒙脱土纳米复合材料研究

采用阳离子交换的方法对蒙脱土进行了有机化处理,使蒙脱土由亲水性变成亲油性,并且使其层间距由原来的1.2nm扩大到2.2nm.采用X-射线衍射仪研究了有机蒙脱土在环氧树脂中的剥离行为,制备了环氧树脂/蒙脱土纳米复合材料并测试了其性能.实验结果表明,环氧树脂与有机蒙脱土的相容性好,蒙脱土在环氧树脂中完全剥离;环氧树脂/蒙脱土纳米复合材料的力学性能、热性能以及阻隔性能与纯环氧树脂固化物相比均有不同程度的提高和改善.