功能化CdS纳米晶的制备

以氯化镉和硫化钠为原料,2-巯基乙醇(ME)为有机配体,成功制备了粒径可控的、表面富有羟基的CdS纳米晶.采用不同的ME/Cd2 及H2O/DMF比例以观察有机配体及溶剂对生成粒子尺寸的影响.透射电子显微图证实了球形CdS纳米粒子很好地分散在H2O/DMF溶液中,没有任何团聚现象发生.傅立叶变换红外谱图(FT-IR)显示了羟基基团成功地包覆在纳米晶的表面.X线衍射(XRD)测试揭示了功能化CdS纳米晶的晶形主要为立方晶.     

复合结构纳米晶CdS∶Cu/CdS的制备及光学特性

在非配位溶剂中合成了高质量的CdS纳米晶核,并利用Cu²⁺离子对其进行掺杂,制备了CdS∶Cu纳米晶.通过进一步采用连续离子层吸附反应的方法对CdS∶Cu纳米晶进行表面修饰,得到CdS∶Cu/CdS复合结构纳米晶.利用X射线衍射(XRD),透射电镜(TEM),紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)对其结构、形貌以及光学性质进行了表征和分析,结果表明:所制备的复合结构CdS∶Cu/CdS纳米晶为立方闪锌矿结构;与CdS纳米晶核相比,掺杂Cu²⁺可以使其表面态发光发生红移;在CdS∶Cu纳米晶中,通过改变掺杂Cu²⁺的浓度,可以实现表面态发光在570和620nm之间的连续调节.与未经包覆的CdS∶Cu纳米晶相比,包覆层CdS增强了纳米晶CdS∶Cu的稳定性.     

CdS纳米晶薄膜的制备及光电性能研究

利用化学浴沉积法,以N(CH2CH2OH)3为络合剂,Cd(CH3COO)2·2H2O和(NH2)2CS为前驱体溶液制备了CdS纳米晶薄膜,利用FESEM、XRD考察了前驱体浓度、络合剂浓度、前驱体溶液的pH值、反应温度等因素对CdS纳米晶薄膜的表面形貌、晶粒大小及晶体结构的影响,在最佳工艺条件下可以制得表面平整,结构致密的CdS纳米晶薄膜。UV-Vis光谱表明CdS在短波长区域有较强的吸收,符合作为窗口材料和过渡层的要求;光电性能测试表明CdS具有较好的光电响应,呈特征n型半导体特性。     

水相合成 CdS纳米晶标记牛血清白蛋白

利用水相中直接合成的CdS纳米晶，与牛血清白蛋白(BSA)进行偶连标记。通过分子筛层析对标记后的牛血清白蛋白进行纯化，在紫外灯下即可观察到标记蛋白的荧光。对CdS纳米晶标记后的牛血清白蛋白的荧光光谱的研究表明，标记蛋白后的CdS纳米晶其荧光无明显淬灭。     

CdS半导体纳米晶的生长及其光谱研究

用玻璃沉淀技术制备了含过饱和CdS的玻璃固溶体,在一定条件下晶化处理使其长出CdS量子点,并采用了X射线衍射、高分辨扫描电镜、光吸收谱和荧光发光光谱等测试手段分析其性能,结果表明经过晶化处理可以在玻璃中长出CdS量子点,尺寸大约为10～25nm,吸收谱中出现明显的红移现象,反映出量子点的量子限域效应,荧光发光图谱中可以看出量子点发光主要由带隙发光和表面缺陷态发光组成,提高热处理温度可以改善晶粒的完整性.     

硫代苯甲酸两步合成CdS纳米晶及表征

采用两步法,首次以硫代苯甲酸合成的Cd(SCOC6H5)2在十六胺(HAD)介质中于120℃热解合成了CdS纳米晶,并采用透射电子显微镜(TEM)、X射线衍射(xRD)、荧光分光光度计(PL)对其进行了表征.结果表明,纳米晶为晶形完美的六方状颗粒,并夹杂有小短棒,六方状颗粒边长约为5nm,小棒的长度为10～25nm.通过X射线衍射(XRD)进一步分析得知,其成分为CdS.选区电子衍射环为多晶环,荧光峰证明出现了蓝移现象,并解释了原因,探讨了形成机理.     

一种无水无氧制备CdS纳米晶的新方法

以醋酸镉和硫为原料,采用二硫化四乙基秋兰姆TETD和2,2-二硫代二苯并噻唑为成核剂,利用无水无氧系统在ODE的溶液中制备了尺寸可控、单分散、均一的半导体CdS纳米材料.采用XRD、粒度分析、SEM技术分别表征产物的结构、粒度和形貌.通过改变两种成核剂的使用量及反应时间可以得到不同粒径的CdS纳米晶.研究表明,在一定范围内,成核剂使用量增加或者反应时间延长都会导致产物的粒度变大,因此通过调节成核荆的使用量和反应时间从而实现对CdS纳米晶的可控生长.     

功能化纳米晶与聚醚的分子组装

以醋酸镉和硫脲为原料,巯基乙醇为有机配体,制备了粒径可控的,表面富有羟基的CdS纳米晶.表面的羟基与γ-(2,3-环氧丙氧)丙基三甲基硅烷发生缩合反应,得到功能化的CdS纳米晶粉末在双金属催化剂的存在下,与环氧丙烷进行开环聚合,制备出分子组装的CdS纳米晶/聚醚接枝共聚物.用TEM表征了CdS纳米晶的形貌,紫外-可见光吸收光谱测定了纳米晶的光学性能,FT-IR证实了有机物在纳米晶表面的接枝.     

聚苯乙烯/粘土纳米复合材料研究进展

介绍了采用各种插层荆插层处理蒙脱土并用插层聚合、熔融插层法制备聚苯乙烯／粘土纳米复合材料及其结构特性、性能的研究进展．并对乳液聚合法制备聚苯乙烯／粘土纳米复合材料及其性能进行了简单介绍。     

纳米SiO_2/交联聚苯乙烯复合材料的合成及性能

以气相纳米二氧化硅为填料,交联聚苯乙烯(CLPS)为基体,采用原位本体聚合法制备了不同二氧化硅含量的SiO_2/CLPS复合材料,并利用透射电镜、红外光谱、差示扫描量热分析、热重分析和动态力学分析等技术对材料微观结构、热性能和介电性能进行了研究。结果表明,SiO_2质量分数不超过2%时,SiO_2颗粒以5~7 nm的粒径均匀地分散于交联聚苯乙烯基体中,聚合物基体与SiO_2产生较强的界面作用,形成了介电性能优异的纳米复合材料,介电常数和介电损耗分别保持在2.48~2.50和(4~8)×10-4之间;随着SiO_2含量进一步增加,材料的介电损耗显著增大,复合材料动态储能模量和玻璃化转变温度随SiO_2含量增加呈先上升后下降的趋势,在SiO_2质量分数为2%时达到最高,复合材料的玻璃化转变温度较纯CLPS有明显提高。     

POSS/PS复合材料的制备及其热性能

单官能团3-氯丙基笼形倍半硅氧烷(POSS)与官能化的聚苯乙烯(PS)进行缩合反应,得到POSS/PS复合材料,其热性能得到明显改善。单官能团3-氯丙基POSS由顶端封角法制备;PS经过3步处理以引入醇钠基团：Friedel-Crafts酰基化反应将羰基引入到PS的苯基上,羰基被硼氢化钠还原为羟基,金属钠与羟基反应生成醇钠基团;单官能团3-氯丙基 POSS分子上的C—Cl与PS上的醇钠基团缩合从而制备POSS接枝的POSS/PS复合材料。利用1H NMR和FTIR技术表征中间产物和POSS/PS复合材料,结果表明POSS笼上的C—Cl与官能化后PS链上的醇钠官能团之间的缩合反应效率很高。XRD测试表明POSS具有良好的分散性。TGA、DSC分析结果表明,由于POSS的引入,POSS/PS复合材料比纯PS的初始分解温度提高69℃,玻璃化转变温度提高16℃。     

Preparation and characterization of KGM/CdS nanocomposite film with low infrared emissivity

In this research, novel organic-inorganic nanocomposite films of Konjac glucomannan (KGM) and CdS were prepared by one-step synthesis. As-prepared films were characterized by IR, TEM and SEM. The results indicated that hexagonal CdS nanoparticles with the sizes of 10 to 100 nm were well dispersed in KGM. The infrared emissivities of the films were characterized by IR-1 infrared emissivity instrument. As results showed, the KGM/CdS nanocomposite films had significantly lower infrared emissivity (8-14 μm), meanwhile when the size of KGM nanoparticles was between 10 and 20 nm and the mole ratio of CdS to KGM was 1.2:1, the film got the lowest infrared emissivity value of 0.011, which would be attributed to the strong synergism effect existing between KGM and CdS nanoparticles.     

纳米CdS/聚丙烯酸酯复合材料的制备

以自制的高固体分热固性丙烯酸树脂为基质,以醋酸镉、硫代乙酰胺等为原料,在丙酮和甲醇的水溶液中,一步法制备了平均粒径为7nm的在聚合物基体中单分散的CdS纳米粒子。CdS/聚丙烯酸酯复合材料用X射线粉末衍射(XRD),透射电镜(TEM),紫外可见光谱(UVVis)和荧光光谱(PL)进行了表征。研究结果表明:金属离子首先与聚合物的羧基络合,生成硫化物纳米微粒后,聚合物又包覆在纳米微粒的表面形成保护层。     

Surfactant-dependent photoluminescence of CdTe/CdS nanocrystals

ABSTRACT

The photoluminescence of aqueously synthesised core/shell CdTe/CdS quantum dots (QDs) was investigated. Two molar ratios (2.4 and 1.3) of thioglycolic acid (TGA) to Cd²⁺ were compared to determine the best synthesis conditions for high photoluminescent quantum yield (PLQY) and photostability. A difference in the PLQY of the CdTe/CdS QDs was observed when CdS shells were grown with different TGA/Cd²⁺ ratios. The difference in the observed PLQY was attributed to the quality of the passivation of the CdTe during the CdS shell growth. At TGA/Cd²⁺ ratio of 1.3, the CdS shell forms through homogeneous nucleation, which is limited by diffusion of growth material from the solution onto the QDs surface. Due to the lattice mismatch of CdTe and CdS, the core will experience coherence strain resulting in dislocation sites and surface defects between nucleation sites which can result in non-radiative trap states. When the TGA/Cd²⁺ ratio is 2.0, the CdS shell grows epitaxially, minimising the number of surface trap states. Finally, we observed that the fluorescence intermittency was supressed for CdTe QDs after UV light illumination, attributed to annealing of deep surface trap states by UV light.     

Synthesis and characterization of porous sphere-like ZnO with dendrite nanocrystals from layered inorganic-organic nanocomposite on titanium substrate

The porous sphere-like ZnO inorganic-organic nanocomposites have been prepared by self-assembly at the present of CTAB (cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N⁺(CH₃)₃Br⁻) surfactant on the titanium substrate. After high temperature oxidation, all the organic were removed and the porous sphere-like ZnO dendrite nanocrystals were obtained. The resultant products have been characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The XRD pattern shows that the as-synthesized porous sphere-like is multilayered inorganic-organic nanocomposite, and the sample calcined at 500 °C for 2 h has a hexagonal wurtzite crystal structure. FE-SEM and TEM images demonstrate that porous sphere-like ZnO dendrite nanocrystals are formed. A possible formation mechanism is preliminary proposed for the formation of the novel nanostructure.     

Synthesis and characterization of CdS nanocrystals and maleic anhydride octene-1 copolymer nanocomposite materials by the chemical in-situ technique

In the present work, in-situ chemical co-precipitation method was employed for the preparation of CdS nanocrystals in the copolymer matrix. The process has been carried out successfully and the nanocomposites have been obtained with excellent optical and structural properties. During the process it was determined that the grain size of nanoparticles depend on regulation of the reaction conditions and on the proportions of the precursors in this method. Also the results have shown that the sizes of the nanoparticles increase with the increase of temperature and this shifts revealed in measurements. Surface morphology and crystallinity have been studied by AFM and XRD techniques, respectively. The average size of nanocrystals was calculated 2–6 nm by AFM and XRD measurements. Consequently, it have been detected that elaborated CdS nanocrystals demonstrate new interesting structural and optical properties. A detailed optical property of the obtained CdS/MA-octene-1 nanocomposite material is done by characterizing UV–Vis, FT-IR and PL spectrophotometric methods.     

Chitosan nanocomposite films incorporating cellulose nanocrystals and grape pomace extracts

Chitosan nanocomposite films incorporating grape pomace extract (GPE), either Cabernet Franc (CF; a red variety) or Viognier (a white variety), and cellulose nanocrystal (CNC) were prepared using a solvent casting method. Mechanical properties, water vapour permeability, color and opacity, crystalline structure, thermal properties, total phenolic content, and antioxidant activity of the films were characterized. Incorporating CNC alone significantly (P < .05) increased tensile strength of the films and decreased their percent elongation at break and water vapour permeability. Grape pomace extract had an opposite effect on mechanical properties by decreasing tensile strength but increasing percent elongation at break. Film color was mainly influenced by the presence and type of GPE. Films containing CF extract exhibited the darkest appearance with increased reddish and bluish hues. Addition of CNC significantly increased film opacity and the alignment of chitosan chains, while the effect of GPE was not significant. Thermal analysis showed that chitosan and CNC were partially miscible and that the addition of CNC did not significantly change decomposition temperature of the films. Incorporation of GPE significantly (P < .05) increase total phenolic content and antioxidant activity. Films containing CF had higher DPPH? radical scavenging capacity than their counterparts with Viognier. Film incorporating both CNC and CF shows greater potential for food packaging application because of a combination of improved physical properties and high antioxidant activity.