半导体纳米粒子／聚合物复合材料及制备方法进展

半导体纳米粒子 /聚合物复合材料是一类新型功能材料。由于它有着特殊的光电物理特性 ,无论是从基础研究的角度或是就其潜在的应用价值而言 ,均引起了科学家们的极大关注。本文介绍了半导体纳米粒子 /聚合物复合材料的概念、结构性能 ,对其制备方法的进展进行了总结 ,并展望了其发展前景。     

聚合物热电复合材料的研究进展

本文综述了碳纳米材料/聚合物、半导体合金/聚合物、金属纳米粒子/聚合物以及聚合物/聚合物等热电复合材料的研究进展。简要分析了热电复合材料的性能提升机理及现有材料尚存在的问题,并指出了聚合物热电复合材料今后的发展方向。     

累托石/聚合物纳米复合材料的新进展

累托石是我国湖北省盛产的铝硅酸盐矿物, 其与蒙脱土极为相似, 但又具有它独特的结构特点, 近年来广泛用于聚合物/层状硅酸盐纳米复合材料的制备. 本文介绍了累托石的结构特性、表面修饰和累托石/聚合物纳米复合材料的结构及制备方法, 总结了累托石/壳聚糖基纳米复合材料及其作为抗菌剂、吸附剂、药物控释材料和基因载体等功能化应用方面的最新研究成果, 并提出了累托石/聚合物纳米复合材料未来的研究方向.     

碳量子点/BiPO_4纳米复合材料增强的可见光吸收和电荷分离

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO_4纳米复合材料的光催化性能。结果表明:在模拟太阳光或可见光的照射下,碳量子点/BiPO_4复合材料的光催化性能均优于单纯的BiPO_4。碳量子点/BiPO_4复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

黏土矿物基纳米复合阻燃材料的研究进展

聚合物纳米复合材料因具有质轻、耐腐蚀、电绝缘、易于加工等优异的性能而被广泛应用于国民生产生活的各个领域.然而,大多数聚合物材料都极易燃烧,这严重限制了其在诸多领域中的实际应用.因此,增强聚合物的阻燃性能具有重大意义.近年来,随着人们的环保和健康意识日益增强,以环境友好的方法制备高强度、高韧性、高抗氧化性和良好阻燃性的聚合物复合材料的研究受到越来越多国内外研究者的青睐,高效绿色阻燃剂将具有巨大的市场潜力.纳米黏土是天然、无毒、低成本、可生物降解且具有生物相容性的材料,常被用于合成各种聚合物纳米复合材料,由于其较大的比表面积、阻隔性和热稳定性,可有效改善聚合物材料的阻燃性和力学性能.本文总结了近几年天然黏土矿物增强聚合物纳米复合材料阻燃性和热稳定性的相关研究.根据不同来源,将聚合物材料分为天然聚合物材料和合成聚合物材料,分别探讨了添加黏土矿物对各种聚合物纳米复合材料阻燃性能的增强效果,并归纳了天然黏土矿物在聚合物纳米复合材料中的阻燃机理.与普通聚合物复合材料相比,天然黏土由于其独特的结构(纤维状、管状及层状),可以捕获易燃挥发物、阻隔热和质的传递.此外,天然黏土可以在聚合物表面形成强大的阻隔层,以延缓热和质的传输过程.最后,指出了目前纳米复合材料在阻燃研究中存在的问题.对当前文献的深入调查为实现聚合物/黏土纳米复合材料的高效利用提供有用的信息,并为设计新型高性能聚合物/黏土纳米复合材料提供理论指导.     

增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合材料（英文）

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO_4纳米复合材料的光催化性能。结果表明:在模拟太阳光或可见光的照射下,碳量子点/BiPO_4复合材料的光催化性能均优于单纯的BiPO_4。碳量子点/BiPO_4复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

增强可见光吸收和电荷分离的碳量子点/BiPO4纳米复合材料

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO₄纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO₄纳米复合材料的光催化性能。结果表明：在模拟太阳光或可见光的照射下,碳量子点/BiPO₄复合材料的光催化性能均优于单纯的BiPO₄。碳量子点/BiPO₄复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

纳米纤维素发光材料研究进展

纳米纤维素发光材料不仅具有发光基团特有的光物理或光化学性能,还具备纳米纤维素的可生物降解、生物相容、环境友好等特性,拓展了功能化纤维材料的应用领域.根据制备方法,纳米纤维素发光材料可分为三类:纳米纤维素/碳量子点复合发光材料、纤维素发光碳量子点和纳米纤维素/荧光染料复合发光材料.纳米纤维素发光材料具有独特的光学特性及结...     

减振阻尼材料纳米改性试验研究

聚合物混凝土是一种具有良好的耐久性(包括耐水、耐冻融、耐腐蚀等),力学性能(包括抗压、抗弯强度等)、阻尼特性的复合材料,广泛的应用于各个领域中。纳米粒子由于其尺寸非常的小,因此具有突出的表面效应、小尺寸效应和量子限域效应,具有异于普通材料的光、电、磁、热、力学、机械等性能,将纳米粒子成功的加入到聚合物混凝土中,在保证聚合物混凝土力学特性的前提下,大大提高聚合物混凝土的阻尼特性,改善聚合物混凝土的综合特性,形成减振降噪用纳米复合材料。     

功能纳米复合材料的研究现状与展望

近年来,国内外材料科学界对纳米复合材料的研究非常重视,已采用化学和物理方法成功地将具有量子限域效应的功能纳米粒子均匀地嵌入到玻璃、聚合物和液体等基质中,获得了明显增强的功能特性,改善２了材料的结构稳定性和可处理性,为新型功能材料的理论研究和实际应用奠定了基础。本文就国内外纳米复合材料的研究现状,并结合本实验室的研究成果对纳米复合材料展趋势作了一概述。     

Optical memory based on photo-activated fluorescence of core/shell CdSe/CdS quantum dots embedded in poly(butylmethacrylate)

This work presents the observation of a photo-activated fluorescence from core/shell quantum dots of CdSe/CdS incorporated in a poly(butylmethacrylate) matrix. Upon illumination with UV-light, the intensity of fluorescence from the quantum dots increases as seen by naked eyes at ambient conditions. This allows its utilization in optical memory media based on thin films of CdSe/CdS polymer nanocomposites suitable for practical application. The quantum dots are synthesized by the hot-injection method and embedded in poly(butylmethacrylate) matrix by radical polymerization with 1,1′-azobis-(cyclohexanecarbonitrile). The fluorescence of quantum dots quenched during the polymerization process, but appeared again after illumination of the nanocomposite material with UV-light. The fluorescence properties of quantum dots are governed by the presence of trioctylphosphine oxide in the matrix, which allows control of the optical memory effect.     

Polymer encapsulation of CdE (E = S, se) quantum dot ensembles via in-situ radical polymerization in miniemulsion

Cadmium sulfide and cadmium selenide/polymer nanocomposites were prepared via in-situ radical polymerization in miniemulsion. Organically capped CdE (E = S, Se) quantum dots (QDs) were used as the starting materials and ensembles of these dots were encapsulated with no need of further surface treatment. The use of two polymer matrices was investigated: polystyrene (PS) and poly(n-butyl acrylate) (PBA). In both cases, homogenous nanocomposites were obtained and their optical properties were investigated by visible absorption and photoluminescence spectroscopy. Quantum size effects were assigned to the nanocomposites, indicating the integrity of the individual QDs upon polymer encapsulation using the miniemulsion process.     

Preparation of optically active substituted polyacetylene@CdSe quantum dots composites and their application for low infrared emissivity

Optically active substituted polyacetylene@CdSe quantum dots (SPA@CdSe QDs) nanocomposites were fabricated by grafting helical SPA polymers onto the surface of semiconductor QDs through ester linkage. Optically active SPA polymer derived from chiral amino acids was copolymerized by a rhodium zwitterion catalyst and was evidently proved to adopt a predominately single-handed helical conformation. The SPA@QDs nanocomposites were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis. The results indicated that the organic SPA matrix exhibited an enhancement in thermal stability after the hybridization with CdSe QDs, while the blended QDs maintained their original crystalline structure during grafting. The infrared emissivity properties of the SPA@QDs nanocomposites at 8–14 μm were further investigated. The data demonstrated that the SPA@QDs-15 composite film possessed an infrared emissivity value of 0.501, which was much lower than pristine SPA and QDs. This might be attributed to the incorporation of optically active helical SPA and semiconductor QDs in a hybrid phase, which had great effect in enhancing their interfacial interactions.     

Optoelectronic and nonlinear optical processes in low dimensional semiconductors

Spatial confinement of quantum excitations on their characteristic wavelength scale in low dimensional materials offers unique possibilities to engineer the electronic structure and thereby control their physical properties by way of simple manipulation of geometrical parameters. This has led to an overwhelming interest in quasi-zero dimensional semiconductors or quantum dots as tunable materials for multitude of exciting applications in optoelectronic and nonlinear optical devices and quantum information processing. Large nonlinear optical response and high luminescence quantum yield expected in these systems is a consequence of huge enhancement of transition probabilities ensuing from quantum confinement. High quantum efficiency of photoluminescence, however, is not usually realized in the case of bare semiconductor nanoparticles owing to the presence of surface states. In this talk, I will focus on the role of quantum confinement and surface states in ascertaining nonlinear optical and optoelectronic properties of II–VI semiconductor quantum dots and their nanocomposites. I will also discuss the influence of nonlinear optical processes on their optoelectronic characteristics.     

Novel multifunctional nanocomposites from titanate nanosheets and semiconductor quantum dots

A novel synthesis for a titanate nanosheets loaded nanocomposite has been developed. On this basis, a multifunctional material for optical applications has been fabricated with tunable refractive index, improved processing behavior and luminescent properties imparted by the incorporation of semiconductor quantum dots.Titanate synthesis, host material choice and quantum dots functionalization have been here addressed to obtain films with good optical quality and stable photoluminescence.In order to assess the potential application of the obtained nanocomposites, imprinting lithography and aerosol-based deposition techniques have been applied with promising results.The obtained nanocomposites have been characterized by UV–Vis, photoluminescence and FT-IR spectroscopy, X-ray diffraction and Transmission Electron Microscopy. The optical properties of the nanocomposite film have been tested by spectroscopic ellipsometry and M-line technique.     

Electronic structure and optical property of semiconductor nanocrystallites

Semiconductor nanostructures show many special physical properties associated with quantum confinement effects, and have many applications in the opto-electronic and microelectronic fields. However, it is difficult to calculate their electronic states by the ordinary plane wave or linear combination of atomic orbital methods. In this paper, we review some of our works in this field, including semiconductor clusters, self-assembled quantum dots, and diluted magnetic semiconductor quantum dots. In semiconductor clusters we introduce energy bands and effective-mass Hamiltonian of wurtzite structure semiconductors, electronic structures and optical properties of spherical clusters, ellipsoidal clusters, and nanowires. In self-assembled quantum dots we introduce electronic structures and transport properties of quantum rings and quantum dots, and resonant tunneling of 3-dimensional quantum dots. In diluted magnetic semiconductor quantum dots we introduce magnetic-optical properties, and magnetic field tuning of the effective g factor in a diluted magnetic semiconductor quantum dot.     

半导体量子点玻璃的研究进展

介绍了半导体量子点材料禁阻类型,详细阐述了共熔法、溶胶-凝胶法、离子注入法等半导体量子点玻璃材料的制备方法,探讨了半导体量子点玻璃的尺寸效应、禁阻效应、库仑阻塞效应和非线性光学效应等特性及其未来应用前景.     

CdTe quantum dots and polymer nanocomposites for x-ray scintillation and imaging

Investigations are reported on the x-ray scintillation and imaging application of CdTe quantum dots (QDs) and their polymer nanocomposites. Aqueous CdTe QDs with emissions ranging between 510 and 680 nm were prepared and incorporated into polyvinyl alcohol or polymethyl methacrylate polymer matrices. The x-ray luminescent properties were evaluated and a resolution of 5 lines∕mm was obtained from the nanocomposite films. Additionally, the fast decay time, nonafterglow, and superior spectral match to conventional charge coupled devices, show that CdTe QD nanocomposites have high promise for x-ray imaging applications.     

硫化铜量子点的研究进展

硫化铜量子点作为一种p型半导体纳米晶,具有很强的表面等离子体共振效应、低的毒性以及独特的光学和电学性能,在光催化、生物技术、光电转换材料领域受到了极大关注。由于单分散的硫化铜量子点的制备过程复杂,效率较低,并且纯的硫化铜量子点电导率较低,这极大地限制了其在能量存储器件方面的应用。此外,由于硫化铜量子点复杂的能带结构和独特的p型半导体特性,针对硫化铜量子点的光学性能调控尚不成熟。基于此,本文综述了硫化铜量子点在制备方面的研究现状与取得的进展,介绍了硫化铜量子点的能带结构、晶体结构,及其在量子点敏化太阳能电池、光催化降解污染物、肿瘤细胞诊断与治疗等方面的研究进展,并对硫化铜量子点或Cu系量子点更进一步的研究、开发应用提出了几点建议。     

One-pot encapsulation of luminescent quantum dots synthesized in aqueous solution by amphiphilic polymers

A simple one-pot polymer encapsulation method is developed for group II-VI semiconductor quantum dots (QDs) synthesized in aqueous solution. The micelles of amphiphilic polymers, such as octadecylamine-modified poly(acrylic acid), capture and encapsulate the QDs when the original hydrophilic ligands, namely 3-mercaptopropionic acid (MPA), capped on the CdTe/CdS core/shell QDs are partially or fully exchanged by the hydrophobic ligands, 1-dodecanethiol. The molar ratio of the amphiphilic polymer to QDs plays a crucial role in determining the final morphology of the encapsulated structures, including the number of QDs encapsulated in one polymeric micelle. Importantly, the polymer coating significantly improves the optical properties of the QDs, which enhances the photoluminescence quantum yield by about 50%. Furthermore, the photostability of the amphiphilic polymer-coated QDs is much better than that of the synthesized QDs capped with MPA.