From Water‐Soluble CdTe Nanocrystals to Fluorescent Nanocrystal–Polymer Transparent Composites Using Polymerizable Surfactants

Zhang, Hao; Cui, Zhanchen; Wang, Yao; Zhang, Kai; Ji, Xiulei; Lü, Changli; Yang, Bai; Gao, Mingyuan

doi:10.1002/adma.200304521

Cited by 296 publications

(234 citation statements)

References 34 publications

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“…6À9 Following this approach, material scientists have sought to develop novel composites using many polymer/nanoparticle composite systems. 10À15 Some examples are ZnO/ PMMA, 16,17 ZnO/poly(hydroxyethyl methacrylate), 18 Al 2 O 3 / polycarbonate, 19 TiO 2 /poly(vinyl alcohol), 20 CdS/PS, 10 CdS/ PMMA, 21 ZrO 2 /PMMA, 22 CdTe/PS, 23 and BaTiO 3 /polyimide. 24 However, the refractive indices (RIs) of polymers and inorganic particles are usually different.…”

Section: ' Introductionmentioning

confidence: 99%

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles

Parlak

Demir

2011

ACS Appl. Mater. Interfaces

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The association of transparent polymer and nanosized pigment particles offers attractive optical materials for various potential and existing applications. However, the particles embedded into polymers scatter light due to refractive index (RI) mismatch and reduce transparency of the resulting composite material. In this study, optical composites based on polystyrene (PS) matrix and poly(methyl methacrylate) (PMMA)-grafted CeO2 hybrid particles were prepared. CeO2 nanoparticles with an average diameter of 18 ± 8 nm were precipitated by treating Ce(NO3)·6H2O with urea in the presence of a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane. PMMA chains were grafted on the surface of the nanoparticles upon free radical in situ solution polymerization. While blending of unmodified CeO2 particles with PS resulted in opaque films, the transparency of the composite films was remarkably enhanced when prepared by PMMA-grafted CeO2 hybrid particles, particularly those having a PMMA thickness of 9 nm. The improvement in transparency is presumably due to the reduction in RI mismatch between CeO2 particles and the PS matrix when using PMMA chains at the interface.

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Section: ' Introductionmentioning

confidence: 99%

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles

Parlak

Demir

2011

ACS Appl. Mater. Interfaces

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“…11,20,21 Because the large absorption and emission bands of water-soluble CdSe nanocrystals remain poorly understood, there is little information about their size distribution. Exchange of the short-chain surface ligand for a long-chain ligand renders water-soluble CdSe QDs easily soluble in organic solvents, 22 as shown by Gégout et al 23 Obtaining nanocrystals that are compatible with organic solvents is vital for applications in optoelectronic devices. All these advantages have motivated research into watersoluble QDs in an attempt to increase the photoluminescence quantum yield (ɸ f ) of materials synthesized in aqueous medium and to promote surface modifications that will ensure desirable optical and electronic properties as well as good chemical stability.…”

Section: Introductionmentioning

confidence: 99%

“…On average, [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] emission spectra were collected for each CdSe QDs dispersion obtained at different synthesis time of reaction by varying the excitation wavelength by 5 nm. To include all the geometric characteristics of the emission spectrum, for each sample, the initial excitation wavelength was defined in such a way that recording of the emission spectra began between 50 and 60 nm before the emission increased sharply.…”

Section: Size Distribution Determination Of Cdse Qdsmentioning

confidence: 99%

Synthesis, Optical Characterization, and Size Distribution Determination by Curve Resolution Methods of Water-Soluble CdSe Quantum Dots

et al. 2016

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In this work a colloidal approach to synthesize water-soluble CdSe quantum dots (QDs) bearing a surface ligand, such as thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), glutathione (GSH), or thioglycerol (TGH) was applied. The synthesized material was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy (UV-Vis), and fluorescence spectroscopy (PL). Additionally, a comparative study of the optical properties of different CdSe QDs was performed, demonstrating how the surface ligand affected crystal growth. The particles sizes were calculated from a polynomial function that correlates the particle size with the maximum fluorescence position. Curve resolution methods (EFA and MCR-ALS) were employed to decompose a series of fluorescence spectra to investigate the CdSe QDs size distribution and determine the number of fraction with different particle size. The results for the MPA-capped CdSe sample showed only two main fraction with different particle sizes with maximum emission at 642 and 686 nm. The calculated diameters from these maximum emission were, respectively, 2.74 and 3.05 nm.

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“…35,36 Por essa razão, têm-se estudado, recentemente, algumas alternativas para tornar essa distribuição de tamanhos mais estreita e aumentar a eficiência quântica desses materiais sintetizados em meio aquoso.…”

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O estado da arte da síntese de semicondutores nanocristalinos coloidais

et al. 2010

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, 74, 36301-160 São João del-Rei -MG, Brasil Recebido em 8/11/09; aceito em 21/4/10; publicado na web em 24/8/10 THE STATE OF THE ART IN THE SYNTHESIS OF COLLOIDAL SEMICONDUCTOR NANOCRYSTALS. Colloidal semiconductor nanocrystals, also known as quantum dots, have attracted great attention since they have interesting size-dependent properties due to the quantum confinement effect. These nanoparticles are highly luminescent and have potential applications in different technological areas, including biological labeling, light-emitting diodes and photovoltaic devices. The synthetic methods of semiconductor nanocrystals have progressed in the last 30 years, and several protocols were developed to synthesize monodisperse nanocrystals with good optical properties, different compositions and morphologies. This review describes the main methods used to synthesize nanocrystals in the II-VI and III-V systems, and the recent approaches in this field of research.Keywords: semiconductor nanocrystals; quantum dots; colloidal synthesis. INTRODUÇÃOA síntese de nanocristais, partículas cristalinas com tamanhos de 1 a 100 nm, tem sido o objeto de inúmeros trabalhos científicos no mundo todo, devido às suas intrigantes propriedades ópticas. Dentre os materiais nanométricos, têm-se os semicondutores nanocristalinos coloidais, também chamados de pontos quânticos, os quais apresentam os portadores de carga (buracos e elétrons) em um estado de forte confinamento quântico, o que faz com que estes materiais possuam propriedades ópticas que podem ser alteradas modificando-se apenas o tamanho das nanopartículas. Uma das propriedades ópticas mais interessantes destes nanocristais, do ponto de vista da aplicação tecnológica, é a forte intensidade de luminescência que apresentam, permitindo que sejam utilizados em dispositivos optoeletrônicos, fotovoltaicos e biomédicos, dentre outros. 1,2A Figura 1 apresenta imagens de dispersões coloidais aquosas de nanocristais de telureto de cádmio (CdTe) com diferentes cores de emissão, em função do tamanho das nanopartículas, bem como os espectros de absorção óptica (UV-Vis) e de fotoluminescência (PL) dessas amostras.3 Na Figura 1b é possível observar um deslocamento da banda de absorção óptica fundamental de 480 para 556 nm (red shift), devido à formação de partículas maiores ao longo da evolução da síntese. De maneira semelhante, na Figura 1c, fica evidente um deslocamento das bandas de emissão em direção a comprimentos de ondas maiores, de 507 nm da primeira amostra para 592 nm na última amostra, o que corresponde a uma variação nas cores de emissão, como mostrado na Figura 1a.Os semicondutores nanocristalinos podem ser divididos em diferentes grupos da tabela periódica, tais como II-VI, III-V e IV-VI, sendo que, nesta revisão, são abordados, principalmente, os métodos experimentais de síntese para produção dos semicondutores dos grupos II-VI e III-V, embora esse último grupo seja ainda muito menos estudado. As sínteses destes materiais podem ser realizadas pelo método top-down, que utiliza técnicas ...

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From Water‐Soluble CdTe Nanocrystals to Fluorescent Nanocrystal–Polymer Transparent Composites Using Polymerizable Surfactants

Cited by 296 publications

References 34 publications

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles

Synthesis, Optical Characterization, and Size Distribution Determination by Curve Resolution Methods of Water-Soluble CdSe Quantum Dots

O estado da arte da síntese de semicondutores nanocristalinos coloidais

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From Water‐Soluble CdTe Nanocrystals to Fluorescent Nanocrystal–Polymer Transparent Composites Using Polymerizable Surfactants

Cited by 296 publications

References 34 publications

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO2 Nanoparticles

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO2 Nanoparticles

Synthesis, Optical Characterization, and Size Distribution Determination by Curve Resolution Methods of Water-Soluble CdSe Quantum Dots

O estado da arte da síntese de semicondutores nanocristalinos coloidais

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Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles

Toward Transparent Nanocomposites Based on Polystyrene Matrix and PMMA-Grafted CeO₂ Nanoparticles