A New Application for Microgels:  Novel Method for the Synthesis of Spherical Particles of the Y<sub>2</sub>O<sub>3</sub>:Eu Phosphor Using a Copolymer Microgel of NIPAM and Acrylic Acid

Martinez‐Rubio, M. I.; Ireland, Terry G.; Fern, George R.; Silver, Jack; Snowden, Martin J.

doi:10.1021/la0105883

Cited by 130 publications

(96 citation statements)

References 19 publications

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“…9 The demand for high resolution and increased efficiency in phosphors for FEDs has promoted the development of phosphors that perform at low voltages. [10][11][12][13][14] Many efficient sulfide-based phosphors, such as Y 2 O 2 S:Eu, Gd 2 O 2 S:Tb, SrGa 2 S 4 :Eu, Zn͑Cd͒S:Cu,Al, ZnS:Ag,Cl, etc., have been explored as possible low voltage phosphors. [15][16][17][18] Unfortunately, sulfide phosphors are easy to decompose and to emit sulfide gases under the electron excitation, subsequently causing the cathodes to deteriorate, thus lowering the lifetime and luminous efficiency of phosphors.…”

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confidence: 99%

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Liu

Zou

2010

J. Electrochem. Soc.

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Nanocrystalline Tb 3+ -doped La 2 O 3 phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction ͑XRD͒, field-emission-scanning electron microscopy ͑FESEM͒, photoluminescence, cathodoluminescence ͑CL͒ spectra, and lifetimes were utilized to characterize the synthesized phosphors. The XRD results revealed that a pure La 2 O 3 phase can be obtained at 700°C. FESEM images indicated that the La 2 O 3 :Tb 3+ phosphors are composed of aggregated spherical particles with sizes ranging from 60 to 100 nm. Under the excitation of UV light and low voltage electron beams ͑0. Although LCDs hold almost more than 50% of the market for flat panel displays, in demanding applications found in military applications, medical instruments, vehicles, and dusty environments, the weaknesses of LCDs are severe, viz., small viewing angle, limited operation temperature, relatively low brightness, and sensitivity for constant movement.2-4 Therefore, a considerable amount of research has been focused on the development of emissive flat panels. Among the emissive display technologies, field-emission displays ͑FEDs͒ have been developed as one of the most promising flat panel displays due to its potential to provide displays with thin panel thickness, self-emission, wide viewing, quick response, high brightness, high contrast ratio, light weight, and low power consumption. 5,6 Monocolor Spindt-type FEDs have been supplied to the market, and they have proven good reliability and performance since 7 years ago, 7 and preparation for mass production of color FEDs had started in recent years. Fundamentally, FEDs are constructed by three elemental parts, such as micro or nanofabrication of emitters, vacuum packaging, and phosphor anodes. Each of the three elements is essential to realize FEDs with interrelationship. 7,8 FEDs must operate at significantly lower excitation voltages ͑Յ5 kV͒ and higher current densities ͑10-100 A/cm 2 ͒ than CRTs. Thus phosphors for FEDs are required to have a high efficiency at low voltages, high resistance to current saturation, long service time, and equal or better chromaticity than CRT phosphors. 9The demand for high resolution and increased efficiency in phosphors for FEDs has promoted the development of phosphors that perform at low voltages.10-14 Many efficient sulfide-based phosphors, such as Y 2 O 2 S:Eu, Gd 2 O 2 S:Tb, SrGa 2 S 4 :Eu, Zn͑Cd͒S:Cu,Al, ZnS:Ag,Cl, etc., have been explored as possible low voltage phosphors.15-18 Unfortunately, sulfide phosphors are easy to decompose and to emit sulfide gases under the electron excitation, subsequently causing the cathodes to deteriorate, thus lowering the lifetime and luminous efficiency of phosphors. 19,20 Oxide-based phosphors are more stable and environmental friendly in comparison with sulfides. Therefore, rare-earth-doped oxide-based phosphors for FEDs have been of great interest due to their excellent light output, color rendering properties, and superior stability under electron bombardment. [21][22][23] One of the promising candidate...

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confidence: 99%

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Liu

Zou

2010

J. Electrochem. Soc.

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“…The effects of the microgel cross-link density and of the concentration of functional groups were investigated and related to the percentage of microgels containing metalnanoparticles. Subsequent studies involved the metallation of microgels comprising a minor fraction of the metalbinding functional groups and a major fraction of nonfunctional moieties [46][47][48][49]. Kumacheva and coworkers have reported using a single class of P(NIPAM-co-AA) microgel template for the in situ production of different types of nanoparticles (semiconductor, metal, and magnetic) and/or nanorods that have lead to nanocomposites with unique properties and high structural hierarchy [50][51][52].…”

Section: Introductionmentioning

confidence: 99%

Metal Nanocrystals Embedded within Polymeric Nanostructures: Effect of Polymer-Metal Compound Interactions

et al. 2009

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pH-responsive PDEAEMA-b-PHEGMA amphiphilic block copolymers and random polymer networks have been used as matrices for the incorporation of metal species and the nucleation and growth of metal nanoparticles with sizes in the range of a few nanometers. The polymer characteristics and polymer-metal interactions upon metal incorporation and after metal reduction were investigated. Two different synthetic procedures were followed for the preparation of Pt nanoparticles within the block copolymers; addition of the metal precursor in a molecular copolymer solution at low pH led to a polymermetal charge neutralization process and the formation of micelles with compact non-hydrated cores, while the incorporation of H 2 PtCl 6 in a micellar copolymer solution at high pH led to polymer aggregation. The impregnation of K 2 PtCl 6 in a micellar copolymer solution at high pH was unsuccessful suggesting the lack of coordination of the neutral amine groups to the metal precursor. The effect of the metal precursor impregnation and the metal nanoparticle formation on the degree of swelling of random networks carrying different functionalities was also examined and the metal content of the hybrid materials was assessed. The equilibrium degrees of swelling of the networks were determined by two opposing effects: the degree of ionization, which caused the network to swell, and the polymer-metal complexation, which increased the effective cross-link density and caused the network to shrink. The metal content of the network was dictated by the polymermetal interactions and the degree of swelling of the network in the solvent medium. These hybrid materials are proposed for use as advanced catalysts in the synthesis of high-value cosmetics and pharmaceuticals.

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“…3 These microgels can be defined as crosslinked, and, stable colloidal particles ranging in diameter from 10 to 1000 nm and can undergo a reversible phase transition in media in response to subtle changes in pH and temperature. 4 Various methods, including free-radical emulsion copolymerization, 5,6 surfactant-free emulsion polymerization (SFEP), 7 reverse emulsion polymerization, 8 dispersion polymerization, 9 block copolymerization, 10 and interpenetration networks, 11,12 have been reported for the preparation of pH-sensitive and temperaturesensitive microgels, among which microgels based on the emulsion copolymerization (with or without surfactant) of N-isopropylacrylamide (NIPAM) with a pH-sensitive vinyl monomer such as acrylic acid, [13][14][15][16][17] methacrylic acid (MAA), 18,19 or vinyl acetic acid 20 have been extensively studied.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of novel, temperature‐sensitive microgels based on N‐isopropylacrylamide and tert‐butyl acrylate

Zhang

Zha

et al. 2006

J of Applied Polymer Sci

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A series of temperature-sensitive microgels based on N-isopropylacrylamide as the main monomer, tert-butyl acrylate (tBA) as the comonomer, and N,N 0 -methylene-bis(acrylamide) as the crosslinker were synthesized with a modified surfactant-free emulsion polymerization method. The chemical structure and global shape with an excellent monodispersity of the microgels were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The temperature-sensitive behavior of the microgels was investigated by dynamic light scattering and ultraviolet-visible spectrophotometric analysis. The results show that the volume phase-transition temperature of the poly(N-isopropylacrylamide-co-tert-butyl acrylate) [poly(NIPAM-co-tBA)] microgels were tuned over a broad range by the incorporated amount of tBA comonomer and their temperature sensitivity decreased with increasing content of tBA units incorporated into the microgel network. Furthermore, the swelling ratios of the poly (NIPAM-co-tBA) microgels were lowered gradually with increasing tBA unit content within the microgel network.

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A New Application for Microgels: Novel Method for the Synthesis of Spherical Particles of the Y₂O₃:Eu Phosphor Using a Copolymer Microgel of NIPAM and Acrylic Acid

Cited by 130 publications

References 19 publications

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Metal Nanocrystals Embedded within Polymeric Nanostructures: Effect of Polymer-Metal Compound Interactions

Synthesis and characterization of novel, temperature‐sensitive microgels based on N‐isopropylacrylamide and tert‐butyl acrylate

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A New Application for Microgels: Novel Method for the Synthesis of Spherical Particles of the Y2O3:Eu Phosphor Using a Copolymer Microgel of NIPAM and Acrylic Acid

Cited by 130 publications

References 19 publications

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Metal Nanocrystals Embedded within Polymeric Nanostructures: Effect of Polymer-Metal Compound Interactions

Synthesis and characterization of novel, temperature‐sensitive microgels based on N‐isopropylacrylamide and tert‐butyl acrylate

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A New Application for Microgels: Novel Method for the Synthesis of Spherical Particles of the Y₂O₃:Eu Phosphor Using a Copolymer Microgel of NIPAM and Acrylic Acid