Superhydrophobic and luminescent methylsilicone resin film

The europium complex, Eu(BA)₃Phen was introduced to the methylsilicone resin film, the investigation showed that the variation of the morphology and surface components of the film was not obvious comparing to methylsilicone resin film, and the superhydrophobicity of the as-prepared film was still retained. Furthermore, the film showed excellent luminescent property, the red light can be observed.     

Assemblies, characterization, and luminescent enhancement of organized molecular films based on rare earth complexes

Langmuir-Blodgett (LB) films of different molar percentages of Eu(TTA)₃Phen (TTA=2-thenoyltrifluoroacetone; Phen=1,10-phenanthroline) with Gd(TTA)₃Phen coexisting with arachidic acid (AA) (complexes:AA=1:l, in molar ratio) were fabricated and the luminescence enhancement of Eu(III) in the films was studied in this investigation. The monolayers and LB films were characterized by π-A isotherms, fluorescence microscopy, UV-vis spectroscopy and low-angle X-ray diffraction. High-quality LB films and strongly luminescent films were obtained. It was learned from the present study that an efficient intermolecular energy transfer occurred from Gd(TTA)₃Phen to Eu(TTA)₃Phen in the films, which resulted in the luminescence enhancement effect. According to the proposed model of the “active enhancement circle” the distance of energy transfer from Gd-, Tb-, La-, and Y-complex to Eu-complex were calculated to be 1.2, 1.2, 0.7 and 1.0 nm, respectively.     

Luminescent properties of encapsulation of europium complex into meso-structured silica monoliths

Meso-structured silica monoliths using PEG (PEG=polyethylene glycol) as a low-cost template and synthesized via sol-gel methods were used as host materials for incorporation of europium complexes Eu(BA)₃Phen (BA=benzoic acid and Phen=1,10-phenanthroline). The meso-structured silica was silylated by 3-aminopropyltriethoxysilane (APTES) or 3-glycidoxypropyltrimethoxysilane (GPTMS) before wet impregnation. Samples were characterized by BET, diffuse reflectance (DR) spectroscopy, infrared spectroscopy and fluorescence measurements. The results showed that the emission quantum efficiency of GPTMS silylated meso-structured silica with larger pore size was up to 44.6%. Also, the lifetime measurement showed the complex encapsulated in this rigid matrix had longer lifetime than the pure complex in solid or liquid.     

Morphologies of diblock copolymer thin films before and after crystallization

Spin-coated thin films of about 100nm of low-molecular-weight hydrogenated poly(butadiene-b- ethyleneoxide) (PB_h-PEO) diblock copolymers have been crystallized at various constant temperatures. Crystallization has been observed in real time by light microscopy. Detailed structural information was obtained by atomic force microscopy, mainly enabled by the large viscoelastic contrast between amorphous and crystalline regions. The behavior in thin films is compared to the bulk properties of the polymer. Crystallization started from an annealed microphase separated melt where optical microscopy indicated a lamellar orientation parallel to the substrate. A small difference in the length of the crystallizable block produced significantly different crystallization behavior, both in the bulk and in thin films. For thin films of the shortest diblock copolymer (45% PEO content) and for an undercooling larger than about 10 degrees, crystallization created vertically oriented lamellae. These vertical lamellae could be preferentially aligned over several micrometers when crystallization occurred close to a three-phase contact line. Annealing at temperatures closer to the melting point or keeping the sample at room temperature for several months allowed the formation of a lamellar structure parallel to the substrate. A tentative interpretation based on kinetically caused chain folding and relaxation within the crystalline state, with implications on general aspects of polymer crystallization, is presented. Received 19 March 1999 and Received in final form 14 December 1999     

沉积法自组装三维有序的Eu(DBM)3Phen/SiO2胶体球

采用修饰的St ber法合成了300 nm的Eu(DBM)3Phen/SiO2胶体杂化球,并通过沉积法将这种胶体杂化球组装成厚度为5 mm,面积为12 cm2的三维有序结构。通过扫描电子显微镜观察发现这些胶体球在垂直于烧杯底面的所有层面中都显示了立方密堆积的结构。元素分析进一步证实了荧光分子被包埋在SiO2胶体球中。在355 nm的激发下,这种三维有序结构具有铕离子的特征发射。     

Factors affecting phase and height contrast of diblock copolymer PS-b-PEO thin films in dynamic force mode atomic force microscopy

Asymmetric PS-b-PEO block copolymer exhibits well-ordered cylindrical morphology with nanoscale domain sizes due to microphase separation. Since the PS and PEO blocks have large stiffness difference, this polymer system represents an ideal candidate for studies of the phase contrast behavior in atomic force microscopy (AFM). In this paper, PS-b-PEO films are investigated under different scanning conditions using two different atomic force microscopes. It is found that the phase contrast of the film can be well described in terms of energy dissipation, though the exact phase image may also depend on the scanning parameters (e.g., the repulsive versus attractive regimes) as well as the settings of the microscope. Height variation on sample surface does not have significant effect on phase contrast. However, in order to obtain true topography of the polymer film, care has to be taken to avoid damage to the sample by AFM. Under certain conditions, true topography can be obtained during the first scan in spite of the surface-damaging forces are used.     

Luminescent Properties of a Polymer Photoluminescent Composite Containing the Binuclear (EU,TB) Complex as an Emitter

Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu³⁺) to terbium (III) (Tb³⁺) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA)₃Phen and Eu_0.5Tb_0.5(AA)₃Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA)₃Phen and TCA/Eu_0.5Tb_0.5(AA)₃Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu_0.5Tb_0.5(AA)₃Phen composites the introduced Tb³⁺ ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb³⁺ion→Eu³⁺ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu_0.5Tb_0.5(AA)₃Phen composites was noticeably stronger than that of the TCA/Eu(AA)₃Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu_0.5Tb_0.5(AA)₃Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials.     

Synthesis and luminescent properties of complexes of Eu(III) with 2-thienyltrifluoroacetonate, terephthalic acid and phenanthroline

This work reports the synthesis and luminescent properties of complexes of europium(III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen), in the solid state. The new complexes were characterized by elemental analysis, infrared (IR) spectroscopy, scanning electronic microscopy (SEM) and thermal stability analysis. Both binuclear complex Eu₂(TPA)(TTA)₄Phen₂ and polynuclear complex Eu(TPA)(TTA)Phen present better thermal stability than the mononuclear complex Eu(TTA)₃Phen does. The formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra show narrow emission bands that arise from the ⁵D₀→⁷F_J (J=0-4) transition of the Eu³⁺ ion. The spectral data of the complexes Eu(TPA)(TTA)Phen and Eu₂(TPA)(TTA)₄Phen₂ present only one sharp peak in the region of the ⁵D₀→⁷F₀ transition indicating that only one Eu³⁺ ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)Phen and Eu₂(TPA)(TTA)₄Phen₂ fit a single-exponential decay law. The values of quantum efficiencies of the emitting ⁵D₀ level for the complexes Eu(TPA)(TTA)Phen and Eu₂(TPA)(TTA)₄Phen₂ are 29% and 28%, respectively.     

Spectroscopic studies on the luminescence properties of ternary europium complexes with different ligands

In this paper, ligand effect of several bi-dental oxygen (O) and nitrogen (N) ligands on the red luminescence properties of europium ion (Eu³⁺) was studied comprehensively. Absorption, emission, and excitation spectral properties of ternary europium complexes with different combinations of ligands including thenoyl trifluoroacetone (TTA), naphthyl trifluoroacetone (NTA), 2,2′-bipyridyl (bpy) and phenanthroline (Phen) were investigated. Efficient Eu³⁺ red emission was observed with all the combinations of the above mentioned ligands. The most intense emission was found with the all nitrogen coordinated complex Eu(bpy)₂(Phen)₂ while the longest wavelength excitation band was recorded with oxygen-nitrogen mixed NTA-bpy complex Eu(NTA)₁(bpy)₃. With change of the ligands combination and ratio, the Eu³⁺ emission peak changes slightly from 612 to 618 nm. The absorption and excitation spectra of the europium complexes were compared and analyzed referring to the individual absorption spectral properties of the ligands. The relation between ligand-to-metal charge transfer states and luminescence intensities for different complexes was studied.     

Study of temperature dependence of crystallisation transitions of a symmetric PEO-PCL diblock copolymer using simultaneous SAXS and WAXS measurements with synchrotron radiation

The reversible transitions of the lamellae of a crystalline-crystalline diblock copolymer from the melt to crystallites were studied using simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements with synchrotron radiation. A symmetric poly(ethylene oxide)-poly( -caprolactone) diblock copolymer was chosen for this study. We showed in the course of the block copolymer crystallisation that the time-resolved integrated intensity I _int was proportional to the product of the volume fractions of the PEO and PCL phases and the scattering contrast due to the electron density difference. These results demonstrated that simultaneous SAXS/WAXS measurements could be used to monitor the crystallisation process in two domains of different sizes at the same time.     

Electrical conductivity and luminescence of metal-organic nanocomposites

We presented the results of experimental study of electrical and luminescence properties of planar nanocomposites based on gold island films and layers of efficient organic luminophores — aluminum (III) 8-hydroxyquinolinate (Alq₃) and europium β-diketonates [Eu(DBM)₃ bath, Eu(DBM)₃ phen, and Eu(DBM)₃]. The mechanisms of electroluminescence of such hybrid systems are discussed and the processes of luminescence excitation in the organic component of nanocomposites are considered in detail. It is shown that the spectral characteristics of europium β-diketonates are controlled by the Eu³⁺ ion fluorescence. The proposed mechanisms of nanocomposite electroluminescence are confirmed by the results of measurements of cathodoluminescence spectra of organic luminophores.     

Tuning surface interactions to control shape and array behavior of diblock copolymer micelles on a silicon substrate

The micellar shape of liquid crystalline diblock copolymers, PEO_m-b-PMA(Az)_n, consisting of high surface energy components was controlled by tuning surface interactions. On a fluorinated surface, the diblock copolymers formed ordered arrays of spherical micelles consisting of PEO cores surrounded by PMA(Az) coronas. Gold ions could be doped into the PEO cores by immersion in a solution of the gold ion. The Au³⁺-doped micelles were subsequently etched and reduced by VUV radiation to form hexagonally ordered gold nanodots.     

Crystallization Behavior of PEO in Nano‐Structured PEO‐b‐PS/PPO Blends

Blends of poly (ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) diblock copolymer and poly (2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) homopolymer were obtained by solution blending, and the morphologies of PEO dispersed nanoparticles in PPO/PS matrix were observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The isothermal crystallization kinetics was studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Nonisothermal crystallization kinetics was studied using DSC. The results showed that PEO segments were easier to crystallize in the blend than in the copolymer probably due to the interfaces of PPO acting as nucleation sites to promote the crystallization of PEO. The crystallization of PEO blocks destroyed the pre‐existing microdomain structure even though the glass transition temperature of the matrix was much higher than the crystallization temperature.     

铕-苯甲酸-邻菲咯啉掺杂配合物体系的合成与荧光性能研究

合成了Eu_1-xLn_x(BA)₃ Phen(Ln： Gd,La,Y;BA： 苯甲酸;Phen： 1,10-邻菲咯啉)系列固体粉末配合物。红外光谱的研究表明该系列配合物具有相似的结构;荧光光谱表明该类配合物均能发出强的铕离子的特征荧光,并且掺杂元素能增强配合物的发光性能,起到共发荧光作用。     

Effect of added homopolymer on structures of thin films of PS-b-PDMS/PS mixture under solvent vapor annealing

Self assembly of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) followed by reactive ion etching technique is a promising method for fabricating periodical silica nanopatterns and can be applicable for device fabrication on nanoscale. We demonstrated a technologically useful way to control the inorganic silica nanostructures in thin films by directly mixing asymmetric (PS-b-PDMS) diblock copolymer with homopolymers of majority component, polystyrene (PS) under solvent vapor annealing followed by UV/O₃ treatment. The effects of molecular weight and volume fraction of added homopolymer (PS) on morphology and size of the nanostructure of blends have been carefully investigated by atomic force microscopy. Different morphology transitions observed on the ordering film surface by atomic force microscopy (AFM) are associated with kinetics of phase evolution with respect to homo-PS with different molecular weight. The periodic spacings and dimensions of the microdomains were readily tuned at the same time, just by adjusting the molecular weight and volume fraction of the blended homopolymer.     

共溅射和离子注入制备的SiO2(Eu)薄膜中Eu3+到Eu2+的转变

采用共溅射方法和Eu离子注入热生长的SiO₂方法得到SiO₂(Eu)薄膜,Eu离子的浓度为4%和0.5%.对样品X射线吸收近边结构(XANES)的研究和分析表明,在高温氮气中发生了Eu³⁺向Eu²⁺的转变.SiO₂(Eu)薄膜高温氮气退火下蓝光的发射证明了这一结论 关键词： 2(Eu)薄膜')" href="#">SiO₂(Eu)薄膜 XANES     

Reversible sphere-to-lamellar wetting transition at the interface of a diblock copolymer system

We use ellipsometry to investigate a transition in the morphology of a sphere-forming diblock copolymer thin-film system. At an interface the diblock morphology may differ from the bulk when the interfacial tension favours wetting of the minority domain, thereby inducing a sphere-to-lamella transition. In a small, favourable window in energetics, one may observe this transition simply by adjusting the temperature. Ellipsometry is ideally suited to the study of the transition because the additional interface created by the wetting layer affects the polarisation of light reflected from the sample. Here we study thin films of poly(butadiene-ethylene oxide) (PB-PEO), which order to form PEO minority spheres in a PB matrix. As temperature is varied, the reversible transition from a partially wetting layer of PEO spheres to a full wetting layer at the substrate is investigated.     

Development of electroluminescence cell using a Eu0.5Y0.5(TTA)3Phen organic luminescent complex

Novel red emitting organic luminescent complexes, namely Eu_0.5Ln_0.5(TTA)₃ Phen (Eu: europium, Ln: Y/Tb, Y: yttrium, Tb: terbium, TTA: thenoyl tri fluoro acetone, Phen: phenanthroline) were synthesized by solution technique, maintaining stoichiometric ratio. These complexes were characterized by various techniques such as XRD, optical absorption and photoluminescence (PL) spectra. Electroluminescence cells were designed by sandwiching Eu_0.5Ln_0.5(TTA)₃Phen between indium tin oxide (ITO) and aluminum (Al). Voltage?current characteristics and voltage?brightness characteristics of the developed electroluminescent cell were carried out. Turn on voltage of both the devices was found to be 9 V. These devices emit intense red emission at 611 nm, proving their potential applications as organic light emitting diodes and displays.     

Influence of ligands on the photoluminescent properties of Eu in europium β-diketonate/PMMA-doped systems

Three kinds of europium β-diketonates Eu(DBM)₃, Eu(BA)₃ and Eu(TTA)₃ (DBM: Dibenzoylmethane; BA: 1-Benzoylacetone; TTA: Thenoyltrifluoroacetone) were doped in poly(methyl methacrylate) (PMMA) matrix. The doped systems were studied by using photoluminescent (PL) spectroscopy, emission decay experiments and X-ray diffractometry. Eu(III) ions in the doped Eu(DBM)₃/PMMA systems have two distinct symmetric sites and the emission band changes greatly with the compositions. Eu(III) in the Eu(BA)₃/PMMA systems gives only one symmetric site in the doped systems and the emission band changes slightly with the compositions. Although two distinct symmetric sites of Eu(III) can be distinguished in the doped systems of Eu(TTA)₃/PMMA, the two sites have similar ⁵D₀ lifetimes and the luminescent spectra almost do not change with the compositions. XRD reveals that crystallites were formed in the doped Eu(DBM)₃/PMMA systems that have different crystalline structure from that of the chelate, and Eu(BA)₃ and Eu(TTA)₃ exist in amorphous state in the doped systems. The difference between the PL properties and structures of the doped systems for the three kinds of chelates should be attributed to different interactions between the chelate molecules and between the chelate and PMMA.     

Self-assembled block polymer templates as high resolution lithographic masks

Diblock copolymer thin films have recently received more attention due to their ability to organize into nanometric structures under thermal annealing. This phenomenon was studied for an asymmetric poly(styrene-block-methyl methacrylate) (PS-b-PMMA) diblock copolymer with PMMA weight fraction of 0.3 and MW = 67,100 g mol⁻¹. First, the surface chemistry of the substrate was modified to favor the formation of vertical PMMA cylinders surrounded by a PS matrix. We have also found that the mean pore area of cylinders increases with their coordination number. Finally, these films were used as a deposition or etching mask to produce well-organized arrays of holes, dots and nanopillars.