聚丙烯酰胺/纳米SiO2复合凝胶的制备及初步研究

利用原位自由基聚合方法合成了聚丙烯酰胺/纳米SiO2复合凝胶,并用红外光谱测定了凝胶化过程中几个典型的反应阶段的红外光谱图,结果表明,复合材料在凝胶化过程中,不仅存在聚合交联反应,同时内部还可能有氢键的形成或其他一些化学作用.用光学显微镜观察了不同纳米粒子含量的复合凝胶的表面形貌,研究表明,纳米粒子在凝胶中并没有出现团聚,表面仍为均匀体系.     

紫外光引发聚合聚丙烯酰胺絮凝剂的研究与发展

聚丙烯酰胺是一种重要的高分子聚合物,它和它的衍生物常用作有效的絮凝剂、增稠剂等,在日常生活及工业生产中应用广泛。紫外光引发聚合技术是一种绿色环保的聚合技术,目前已经在生物医药材料、纳米材料等领域取得了良好的应用。在絮凝剂制备领域,由紫外光引发制备的聚丙烯酰胺絮凝剂具有能耗低、时间短、操作简单的优势。论文综述了2012至2016年紫外光引发聚丙烯酰胺的合成、表征及其应用。     

反相微乳液模板原位聚合制备纳米氯化银/聚甲基丙烯酸甲酯及其结构表征

用甲基丙烯酸甲酯 (MMA)作油相 ,反相胶束微乳液作为模板 ,制备了纳米氯化银 (AgCl)粒子 ,再进行原位聚合制备了纳米氯化银 /聚甲基丙烯酸甲酯 (AgCl/PMMA)复合材料 .透射电镜 (TEM )分析表明 ,纳米AgCl的尺寸为 2 0～ 80nm .扫描电镜 (SEM )测试表明纳米AgCl粒子均匀地存在于PMMA基材中 .红外分析证明 ,胶束中水和表面活性剂AOT的羰基在MMA聚合后微观环境发生变化 ,纳米粒子同聚合物之间有吸附行为 .动态力学 (DMTA)分析复合材料 ,发现纳米AgCl粒子与聚合物之间存在强烈相互作用 ,形成了中间相层 (interphaselayer) ,改变了聚合物的动态力学性能 .     

对赖氨酸和精氨酸具选择性响应特性的聚二炔酸纳米粒子分散液

通过“非共价键合胶束”的方法制备聚二炔酸纳米粒子分散液,将二炔酸单体的乙醇溶液滴加到水中,通过254 nm紫外光照射聚合获得分散液.对于18种水溶性天然氨基酸,该体系对赖氨酸和精氨酸具有选择性响应.     

纳米粒子的电容

纳米粒子的电容对由纳米点陈列所形成的单电子器件是一个十分重要的参数。基于少体理论,提出了计算纳米粒子量子点充电电容的理论模型,由此可以预测出室温下出现库仑台阶等单电子现象的最大纳米粒子粒径。采用简谐势模型计算模拟了ＣｄＳ、ＰｂＳ半导体纳米粒子的充电电容,发现ＣｄＳ、ＰｂＳ纳米粒子的尺寸上限为１１与５ｎｍ。理论计算结果与实验相吻合。     

L-B技术进展——一种半导体纳米粒子的组装技术

纳米粒子由于有量子尺寸效应,因此它的物理、化学特性既有别于单个分子、几个分子组成的多聚体,又有别于体相材料。在溶液中利用制备胶体的方法来制备半导体纳米粒子已经比较成熟。稳定溶液中纳米粒子的方法进展甚速,如离子修饰、胶束固定等,而且它们在能量     

溶胶-凝胶法制备Polyme/MS/SiO2(M=Pb,Cd)复合纳米材料

采用溶胶－凝胶结合水热结晶技术,可成功把高聚物引入MS－SiO2网络结构。合成一种新型的有机－无机硫化物即Polymer/MS/SiO2(M=Pb,Cd)复合纳米材料,其中聚甲基丙烯酸甲酯或聚丙烯酰胺等高聚物的引入将有效地防止无机粒子团聚,控制粒子尺寸,前者还能形成核－壳结构复合粒子。作者还详细讨论了该复合纳米材料的热分析,结果表明,聚合物的存在提高了原有MS－SiO2(M=Pb,Cd)材料的热稳定性。     

溶液电火花法制备Ag—TiO2纳米级复相超细粉及其光学性质

首次报道采用溶液电火花制备Ａｇ－ＴｉＯ２纳米级复相超细粉,ＸＲＤ和ＴＥＭ分析表明,所得产物可是金红石相也可是锐钛矿相,粒径分布均匀,一般在５￣２０ｎｍ内,超细粉经超声重新分散后所得纳米粒子的ＴＥＭ像指出,许多粒子是由金属Ａｇ粒子和ＴｉＯ２粒子互相粘连构成葫芦状混合复相纳米结构,显示有比涂层修饰粒子略有减弱的增强激光拉曼散射（ＳＥＲＳ）效应和相应的光学性质。讨论了含有Ａｇ涂层的复合ＴｉＯ２粒子与纯Ｔ     

高定向石墨表面金纳米粒子和金纳米线的研究

利用真空沉积方法在高定向石墨(HOPG)基底上直接制备了粒径分布较小的金纳米粒子.超高真空扫描隧道显微镜(STM)研究发现,在74℃退火后,表观直径为2.5?nm的金纳米粒子在HOPG基底上形成了排列均匀的准一维纳米粒子链,并且此金纳米粒子链结构稳定.在122℃退火后,不同粒径的金纳米粒子在HOPG基底表面上聚合长大形成了准一维金纳米线.这一发现为制备由金粒子组成的有序纳米结构开辟了探索途径.     

高定向石墨表面金纳米粒子和金纳米线的研究

利用真空沉积方法在高定向石墨(HOPG)基底上直接制备了粒径分布较小的金纳米粒子.超高真空扫描隧道显微镜(STM)研究发现,在74℃退火后,表观直径为2.5nm的金纳米粒子在HOPG基底上形成了排列均匀的准一维纳米粒子链,并且此金纳米粒子链结构稳定.在122℃退火后,不同粒径的金纳米粒子在HOPG基底表面上聚合长大形成了准一维金纳米线.这一发现为制备由金粒子组成的有序纳米结构开辟了探索途径.     

New phenomenon in the channels of mesoporous silicate CMI-1: quantum size effect and two-photon absorption of ZnO nanoparticles

Quantum size effect (QSE) and very efficient laser action were observed in ZnO-mesoporous CMI-1 silica nanocomposites prepared through the incorporation of ZnO nanoparticles inside the channels of a silica mesoporous material CMI-1. The incorporation was made by direct impregnation of the mesoporous material in a zinc nitrate aqueous solution followed by calcination. The PL spectrum of the nanocomposites presents a significant blue-shift corresponding to the enhancement of the semiconductor band gap. Being excited by incident photons with energy of 1.82 eV, the ZnO nanoparticles exhibit spontaneous emission due to the excitonic recombination. In our samples, spontaneous emission turns to stimulated emission when the pumping intensity reaches a threshold value. This effect implies a two-photon excitation which was never observed with ZnO nanoparticles. This paper deals with results about the characteristics of the matrix and the nanocomposites and the lasing effect. A two-photon excitation phenomenon has been observed. PACS 81.05.Zx; 78.45.+h; 78.55.-m; 78.30.Fs; 72.80.Tm; 61.43.Gt; 61.46.+w; 61.66.Fn     

表面结构对SnO2半导体纳米粒子荧光性质的影响

本文利用荧光光谱对ＳｎＯ２纳米粒子水溶胶及其有机溶胶的光学性质进行了研究。发现粒子的表面结构对其光学性质具有极大的影响。水溶胶的荧光发射是由氧空位控制的,其发射强度工;有机溶胶由于表面活性剂的作用,改变粒子的表面结构,得到较强的荧光发射。     

利用共价键镶嵌上转换纳米晶制备发光NaYF_4-PMMA纳米复合聚合物

在NaYF_4纳米晶表面修饰不饱和基团,与甲基丙烯酸甲酯单体共聚,制备了NaYF_4-PMMA发光纳米复合聚合物。采用共价键将纳米晶镶嵌在聚合物基质中,可实现纳米粒子均匀、稳定、高浓度的掺杂。所使用的纳米发光材料为NaYF_4∶20%Yb,2%Er和NaYF_4∶20%Yb,1.5%Tm。NaYF_4∶20%Yb,2%Er纳米晶的尺寸为9~14 nm,NaYF_4∶20%Yb,1.5%Tm纳米晶的尺寸为11~15 nm。在980 nm红外光的激发下,NaYF_4∶20%Yb,2%Er-PMMA发出明亮的黄光,NaYF_4∶20%Yb,1.5%Tm-PMMA发出明亮的蓝光,分别与其对应的发光纳米晶的发射光谱完全一致。实验结果表明:NaYF_4-PMMA材料透明性良好,稳定性高,上转换发光强度大。这种上转换发光纳米复合聚合物在显示领域,特别是在真三维显示方面具有潜在的应用前景。     

Synthesis and characterisation: Zinc oxide–sulfide nanocomposites

A novel synthesis method is presented for the preparation of nanosized-semiconductor zinc oxide–sulphide (ZnO/ZnS) core–shell nanocomposites, both formed sequentially from a single-source solid precursor. ZnO nanocrystals were synthesized by a simple co-precipitation method and ZnO/ZnS core–shell nanocomposites were successfully fabricated by sulfidation of ZnO nanocrystals via a facile chemical synthesis at room temperature. The as-obtained samples were characterized by X-ray diffraction and transmission electron microscopy. The results showed that the pure ZnO nanocrystals were hexagonal wurtzite crystal structures and the ZnS nanoparticles were sphalerite structure with the size of about 10 nm grown on the surface of the ZnO nanocrystals. Optical properties measured reveal that ZnO/ZnS core–shell nanocomposites have integrated the photoluminescent effect of ZnO and ZnS. Based on the results of the experiments, a possible formation mechanism of ZnO/ZnS core–shell nanocomposites was also suggested. This treatment is suggested to improve various properties of optoelectronically valuable ZnO/ZnS nanocomposites. These nanosized semiconductor nanocomposites can form a new class of luminescent materials for various applications.     

聚偏二氟乙烯/(Y0.97Eu0.03)2O3稀土氧化物纳米复合材料制备、形貌及发光性能

借助超声技术采用一种简便易行的共沉淀方法制备出聚偏二氟乙烯(PVDF) /钇铕稀土氧化物((Y0.97Eu0.03)2O3)纳米粒子发光纳米复合材料。复合材料的断面形貌和(Y0.97Eu0.03)2O3纳米粒子在PVDF基体中的分散状态通过扫描电子显微镜(SEM)进行了研究,其发光性质通过荧光光谱进行表征。SEM结果表明:当(Y0.97Eu0.03)2O3纳米粒子添加量在1% ～5%时,(Y0.97Eu0.03)2O3纳米粒子在PVDF基体中形成尺寸在50 nm～2μm的团聚体,其尺寸随(Y0.97Eu0.03)2O3添加量增加而增大;当(Y0.97Eu0.03)2O3添加量小于1%时, (Y0.97Eu0.03)2O3纳米粒子在PVDF基体中实现了较好分散。发光光谱结果表明制备的纳米复合材料具有明显的红光发射特征,对应于(Y0.97Eu0.03)2O3纳米粒子的本征发射。制备的高分子发光纳米复合材料将来有望在光学材料中获得应用。     

Synthesis and characterization of TiO2/Ag/polymer ternary nanoparticles via surface-initiated atom transfer radical polymerization

We report on the novel ternary hybrid materials consisting of semiconductor (TiO₂), metal (Ag) and polymer (poly(oxyethylene methacrylate) (POEM)). First, a hydrophilic polymer, i.e. POEM, was grafted from TiO₂ nanoparticles via the surface-initiated atom transfer radical polymerization (ATRP) technique. These TiO₂-POEM brush nanoparticles were used to template the formation of Ag nanoparticles by introduction of a AgCF₃SO₃ precursor and a NaBH₄ aqueous solution for reduction process. Successful grafting of polymeric chains from the surface of TiO₂ nanoparticles and the in situ formation of Ag nanoparticles within the polymeric chains were confirmed using transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FT-IR spectroscopy also revealed the specific interaction of Ag nanoparticles with the CO groups of POEM brushes. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the semiconductor, producing ternary hybrid inorganic-organic nanomaterials.     

Tuning of optical properties of CdS nanoparticles synthesized in a glass matrix

Attempts were made to provide the data concerning directed synthesis of semiconductor nanoparticles in a dielectric silica-based glass matrix. These attempts involve finding out the connections between the structure, size of CdS nanoparticles, and optical properties of the nanocomposites produced. High-resolution focused ion beam scanning electron microscopy images of CdS nanoparticles incorporated in glass and SAXS results confirm the formation of uniformly distributed spherical CdS nanoparticles with an average diameter of about 6.2 nm. UV–Vis measurements show that CdS composites possess a direct bandgap wider than 2.45 eV depending on the heat treatment conditions; thus, heat treatment can be used to control nanoparticle size in each selected composite. The emission spectra showed a maximum at about 603 nm and a red shift of about 100 nm with increasing annealing temperature that is associated with the presence of defect states in the nanoparticles. In addition, semiconductor phase concentration in the glass matrix was found by using optical absorption data for the first time, which allows understanding the effect of nanocomposite structure on luminescence properties.     

High UV-shielding Performance of Zinc Oxide/High-Density Polyethylene Nanocomposites

Zinc oxide/high-density polyethylene nanocomposites with high-UV-shielding efficiency were reported. Zinc oxide nanoparticles were synthesized by the homogeneous precipitation method and calcination of the precursor at different temperatures. Zinc oxide/high-density polyethylene nanocomposites were subsequently prepared from high-density polyethylene and as-prepared zinc oxide nanoparticles via melt mixing process. The structural properties of the as-prepared zinc oxide nanoparticles and nanocomposites were studied in detail using X-ray diffractometer, Fourier transform infrared spectrometer, thermogravimetry, differential scanning calorimeter, ultrasonic pulse echo technique, scanning electron microscopy, and transmission electron microscope. The optical properties of the obtained nanocomposites were shown to depend on zinc oxide particle size and content. The nanocomposite containing zinc oxide nanoparticles with an average particle size of 25.22 nm after calcination at 350°C was found to have the most optimal optical properties, namely high-visible light transparency and high-UV light shielding efficiency, which are desirable for many important applications.     

Nanoparticles in mesoporous films,a happy marriage for materials science

Mesoporous ordered materials, whose porosity is within the 2–50-nm range, are an ideal host for functional nanoparticles. Mesoporous thin films, in particular, offer a large variety of options for the fabrication of advanced materials and devices based on the host-guest combination of matrix nanoparticles. Nanocomposite mesoporous films embedding metal, oxide, and semiconductor nanoparticles have been prepared using as matrix oxides, mixed oxides, and organic-inorganic hybrids. The organization of the pores is an important peculiar property of mesoporous ordered films and allows producing nanocomposites whose nanoparticles follow a very specific array within the material. The main synthesis methods to obtain mesostructured films containing nanoparticles, together with their applications, are briefly introduced in the present review.