Assembly of side-functional monomers with inorganic nanometer particles

Monomers of methacrylate with various pi -conjugated pendants were designed and prepared in our laboratory, The monomer with suitable end-group was successfully assembled with nano-scale inorganic particles to form an orderly-aligned structure that showed special optical properties, both absorption and emission band were much red-shifted compared with the monomer, A new type of organic/inorganic hybrid materials was obtained by in situ polymerization of the assembly, The hybrid materials could also show special optical properties as the assembly, This might open a new route to tune the emission color.

骨固定用聚乳酸/无机纳米粒子复合材料

本论文针对目前用于骨固定和骨修复的聚乳酸／无机纳米粒子复合材料的界面强度低、粒子分散不均匀以及所采用生物活性无机填料粒径较大等缺点，对轻基磷灰石及生物活性玻璃无机纳米粒子的制备、界面改性、粒子的分散、以及复合材料的制备进行了较详细的论述。另外，对材料的力学性能、结晶性能和生物相容性进行了较细统的测试和研究。（1）以磷酸和氢氧化钙为原料在40-80℃的反应条件下制备出了米粒状和棒状的HAP粒子，然后在-50℃的冷冻干燥机中干燥48h，得到白色的HAP粉末。用TEM、SEM、WAXD、FTIR等对所得产物进行了表征。研究结果表明，提高反应温度有利于生成高结晶度的长棒状HAP颗粒。此外，锻烧温度对粒子的形貌和结晶度也有很大的影响，锻烧温度越高，粒子的结晶度就越高，并且，当锻烧温度提高到900℃以上时，HAP粒子的形貌会由长棒形逐渐变成球形。（2）在高纯氢气气氛中，以辛酸亚锡为催化剂的反应条件下使左旋丙交酷开环聚合，直接接枝到HAP的表面，使HAP的粒子表面覆盖一层聚乳酸分子，使HAP的亲油性能得到提高。对表面接枝的轻基磷灰石（g-HAP）用31PMAS-NMR、FTIR、TGA、TEM、SEM和GPC进行了表征。结果表明，用此方法可在HAP表面接枝6％的PLLA。（3）用溶剂法制备了PLLA/g-HAP复合材料，并对其机械性能、结晶性能和生物相容性进行了表征。试验结果表明：与纯HAP相比，g-HAP粒子更容易均匀分散到PLLA基体中，当填料含量达到4％时，PLLAg-HAP复合材料的力学性能达到最好。由Dsc和PoM的实验结果表明，g-HAP粒子在聚合物基体中可以起到异相成核剂的作用。细胞实验结果表明，PLL刀g-HAP复合材料的细胞相容性明显优于纯的PLLA和PLLA/HAP复合材料。（4）以正硅酸乙酷（TEOS）、硝酸钙（Ca(NO3）2）和磷酸氢二按（（NH4）ZHPO4）为原料，利用在酸性溶液中水解，碱性溶液中缩聚沉淀，然后将反应液离心分离，冷冻干燥，最后在马弗炉中锻烧的方法，得到白色的5102-coo-PZos三元生物活性玻璃粉末。SEM和TEM分析结果表明，所得到生物活性玻璃是粒径在40nln左右的球形颗粒，且粒径分布非常均匀。（5）以正硅酸乙酷（TEoS）和硝酸钙（Ca（NO3）2）为原料，利用在酸性溶液中水解，碱性溶液中缩聚沉淀，然后将反应液离心分离，冷冻干燥，最后在马弗炉中锻烧的方法，得到粒径为200nm左右的球形SiO2-CaO二元生物活性玻璃粉末。

Characterization of Y2O3 : Eu coated with polystyrene

The core-shell Y2O3:Eu3+/polystyrene particles was prepared by surface modification with citric acid and emulsion polymerization method of styrene. The DTA curve of coated particles exhibits a small and wide exothermic peak of organic compound around 387 degreesC. The carbonyl stretching vibration band was shifted to low wavenumber in FTIR spectrum and the binding energy of Y3d5/2 was shifted to high-energy band in XPS spectrum. The results of FTIR and XPS show that citric acid was coupled to the particles surface. The hydrophilic surface became amphiphilic by modification of citric acid. So styrene could adsorb on particles surface to form emulsion structure which inorganic core was inside. EDS spectra show that Y2O3:Eu3+ particles were coated uniformly with polystyrene.

Photorefractive performance of a novel multifunctional inorganic-organic hybridized nanocomposite sensitized by CdS nanoparticles

A novel multifunctional inorganic-organic photorefractive (PR) poly(N-vinyl)-3-[p-nitrophenylazolcarbazolyl-CdS nanocomposites with different molar ratios of US to poly(N-vinyl)-3-[p-nitrophenylazo]carbazolyl (PVNPAK) were synthesized via a postazo-coupling reaction and chemically hybridized approach, respectively. The nanocomposites are highly soluble and could be obtained as film-forming materials with appreciably high molecular weights and low glass transition temperature (T,) due to the flexible spacers. The PVNPAK matrix possesses a highest-occupied molecular orbital value of about -5.36 eV determined from cyclic voltammetry. Second harmonic generation (SHG) could be observed in PVNPAK film without any poling procedure and 4.7 pm/V of effective second-order nonlinear optical susceptibility is obtained. The US particles as photosensitizers had a nanoscale size in PVNPAK adopting transmission electron microscopy. The improvement of interface quality between US and polymer matrix is responsible for efficient photoinduced charge generation efficiency in the nanocomposites. An asymmetric optical energy exchange between two beams on the polymer composites PVNPAK-CdS/ECZ has been found even without an external field in two-beam coupling (TBC) experiment, and the TBC gain and diffraction efficiency of 14.26 cm(-1) and 3.4% for PVNPAK-5-CdS/ECZ, 16.43 cm(-1) and 4.4% for PVNPAK-15-CdS/ECZ were measured at a 647.1 nm wavelength, respectively.

Nucleobase-metal hybrid materials: Preparation of submicrometer-scale, spherical colloidal particles of adenine-gold(III) via a supramolecular hierarchical self-assembly approach

We report a simple and effective supramolecular route for facile synthesis of submicrometer-scale, hierarchically self-assembled spherical colloidal particles of adenine - gold(III) hybrid materials at room temperature. Simple mixture of the precursor aqueous solutions of adenine and HAuCl4 at room temperature could result in spontaneous formation of the hybrid colloidal particles. Optimization of the experimental conditions could yield uniform-sized, self-assembled products at 1:4 molar ration of adenine to HAuCl4. Transmission electron microscopy results reveal the formation of hierarchical self-assembled structure of the as-prepared colloidal particles. Concentration dependence, ratio dependence, time dependence, and kinetic measurements have been investigated. Moreover, spectroscopic evidence [i.e., Fourier transform infrared (FTIR) and UV-vis spectra and wide-angle X-ray scattering data] of the interaction motives causing the formation of the colloidal particles is also presented.

One-pot, high-yield synthesis of size-controlled gold particles with narrow size distribution

Here, we first report a facile one-step one-phase synthetic route to achieve size-controlled gold micro/nanoparticles with narrow size distribution by using o-diaminobenzene as a reducing agent in the presence of poly(N-vinyl-2-pyrrolidone) via a simple wet-chemical approach. All experimental data including that from scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques indicates that the gold micro/nanoparticles with a narrow size distribution were produced in high yield (similar to 100%).

Monodisperse and core-shell-structured SiO2@YBO3 : Eu3+ spherical particles: Synthesis and characterization

Y0.9Eu0.1BO3 phosphor layers were deposited on monodisperse SiO2 particles of different sizes (300, 570, 900, and 1200 nm) via a sol-gel process, resulting in the formation of core-shell-structured SiO2@Y0.9Eu0.1BO3 particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence (CL) spectra as well as lifetimes were employed to characterize the resulting composite particles. The results of XRD, FE-SEM, and TEM indicate that the 800 degrees C annealed sample consists of crystalline YBO3 shells and amorphous SiO2 cores, in spherical shape with a narrow size distribution. Under UV (240 nm) and VUV (172 nm) light or electron beam (1-6 kV) excitation, these particles show the characteristic D-5(0)-F-7(1-4) orange-red emission lines of Eu3+ with a quantum yield ranging from 36% (one-layer Y0.9Eu0.1BO3 on SiO2) to 54% (four-layer Y0.9Eu0.1BO3 on SiO2).

Photoluminescent nanoparticles of organic-inorganic hybrids prepared by phase transfer complexation at the organic-aqueous solution interface

Monodispersed nanoparticles of Ag(I)-polymer hybrids have been prepared by using designed crown-ether-centred two-armed copolymers to chelate Ag+ ions at the interface of organic-aqueous solutions. The copolymer-Ag+ complex nanoparticles, as well as the reduced copolymer-Ag nanoparticles, have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). The particle size can be varied by simply changing the polymer concentration, the monomers, and/or the molecular weight. The copolymer-Ag(I) hybrids exhibit weak photoluminescence, which was substantially enhanced after the hybrids were reduced to copolymer-silver nanoparticles with UV irradiation.

Fabrication of self-assembled palladium nanosheets using layered organic/inorganic hybrid as the template

In this paper, a simple route to the fabrication of palladium nanosheets is described. The interaction of palladium chloride (PdCl2) and n-octylamine salt resulted in the formation of a quasi-perovskite-type composite with a layered structure on a molecular scale. This composite can be employed as a template for preparing ultrathin Pd nanosheets when a {PdCl4}(2-) network is reduced in situ by hydrogen in toluene. The x-ray diffraction results indicate that the resulting Pd nanosheets are highly ordered, and they are confined inside the organic matrix as evidenced by high resolution transmission electron microscopy. These Pd nanosheets can be reorganized into layered structures in non-polarized organic solvent when the ordered structure is destroyed. This method of preparing Pd nanosheets is expected to be applicable to other layered organic/inorganic perovskite systems for obtaining the corresponding metal nanosheets.

Silica supported submicron SiO2@Y2SiO5 : Eu3+ and SiO2@Y2SiO5 : Ce3+/Tb3+ spherical particles with a core-shell structure: Sol-gel synthesis and characterization

X-1-y(2)SiO(5):Eu3+ and X-1-Y2SiO5:Ce3+ and/or Tb3+ phosphor layers have been coated on nonaggregated, monodisperse, submicron spherical SiO2 particles by a sol-gel process, followed by surface reaction at high temperature (1000 degrees C), to give core/shell structured SiO2@Y2SiO5:Eu3+ and SiO2@Y2SiO5:Ce3+/Tb3+ particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), TEM, photoluminescence (PL), low voltage cathodoluminescence (CL), and time-resolved PL spectra and lifetimes are used to characterize these materials. The XRD results indicate that X-1-Y2SiO5 layers have been successfully coated on the sur- face Of SiO2 particles, as further verified by the FESEM and TEM images. The PL and CL studies suggest that SiO2@Y2SiO5:Eu3+, SiO2@Y2SiO5:Tb3+ (or Ce3+/Tb3+), and SiO2@Y2SiO5:Ce3+ core/shell particles exhibit red (Eu3+, 613 rim: D-5(0)-F-7(2)), green (Tb3+, 542nm: D-5(4)-F-7(5)), or blue (Ce3+, 450nm: 5d-4f) luminescence, respectively. Pl, excitation, emission, and time-resolved spectra demonstrate that there is an energy transfer from Ce3+ to Tb3+ in the SiO2@Y2SiO5:Ce3+,Tb3+ core/shell particles.

Luminescent properties of organic-inorganic hybrid monoliths containing rare-earth complexes

Transparent organic-inorganic hybrid monoliths containing rare-earth complexes (Eu(TTA)(3)Phen, Tb(Sal)(3)) were prepared via the sol-gel technique. It could be observed by transmission electron microscopy that the fluorescent particles are distributed in the matrix at the microscopic level. The matrix is composed of organic-inorganic semiinterpenetrating networks, i.e., PHEMA-SiO2 system. The fluorescence emission spectra of samples are similar to those from corresponding powdered Eu(III) and Tb(III) complexes, and the half-widths of the strongest bands are less than 10 nm, which indicates that the monolith exhibits high fluorescence intensity and color purity. Furthermore, the fluorescence spectra exhibit no obvious change with decreasing nanoparticle size of the rare-earth complex. The fluorescence lifetimes of samples are longer than pure Eu(III), Tb(III) complexes, respectively. Samples irradiated with an UV lamp (365 nm) are still transparent but become bright red and green in color due to fluorescence of Eu(III) and Tb(III) complexes. (C) 2000 Elsevier Science B.V. All rights reserved.

Microstructure and mechanical behaviour of a SiC particles reinforced Al-5Cu composite under dynamic loading

The mechanical behaviour of a composite of Al–5Cu matrix reinforced with 15% SiC particles was studied at different strain rates from 1×10−3 to 2.5×103 s−1 using both a conventional universal testing machine (for low strain-rate tests) and a split Hopkinson bar (for tests at dynamic strain rates). Whilst the yield stress of the composite increases as the strain rate increases, the maximum flow stresses, 440 MPa for compression and 450 MPa for tension, are independent of strain rate. The microstructures and defect structures of the deformed composite were studied with both scanning electron microscopy and transmission electron microscopy and were correlated to the observed mechanical behaviour. Fracture surface studies of samples after dynamic tensile testing indicates that failure of the composite is controlled by ductile failure of the aluminium matrix by the nucleation, growth and coalescence of voids.