- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Visualization of silica dispersion states in silicone rubber by fluorescent labeling
摘要： The internal dispersion structure of silica ?llers in polymer matrix is signi?cant for design and fabricating high-performance polymer composite. In order to explore the relationship between ?llers spatial dispersion states and mechanical properties, we use super?cial ?uorescent labeling to achieve ?llers visualization in polymer matrix with laser scanning confocal microscopy. Through the effect of ?uorescent silane coupling agent, the uniform red ?uorescence characteristics were shown on the silica surface. The 2D-planar and 3D-spatial dispersion states of silica ?llers in rubber matrix can be accurately observed with ?uorescence imaging technology. The results by Avizo software statistics show that high-content silica ?llers in composite tend to undergo dissociation of aggregates. These dissociated small volume aggregates which facilitate the interaction between particles and rubber matrix to dissipate mechanical energy effectively and rapidly improve rubber toughness. This successful visualization method opens a new avenue in spatial dispersion description of ?llers aggregates in organic–inorganic composite.
关键词： silicone rubber,fluorescent labeling,silica dispersion,mechanical properties,3D visualization
更新于2025-09-10 09:29:36
-
Optical and mechanical properties of Sol-gel prepared Titania (TiO <sub/>2</sub> ) –Silica (SiO <sub/>2</sub> ) mixed thin films ‘as prepared at 300 K’ without any post heat treatment
摘要： The mixed metal oxide (MMO) thin films like titania-silica (TiO2–SiO2) prepared by sol-gel technology have shown a variety of interesting optical, mechanical and thermo-mechanical properties; these thin films are being used in a variety of applications. In the present investigation, the TiO2–SiO2 (TS) thin films (on glass substrates) are prepared at 300 K from non-aqueous individual sols of TiO2 and SiO2 of 0.1 molar (TS-1) and 0.3 molar (TS-3) concentrations; no post heat treatment has been conducted on these films. The thicknesses of the two layer (2 l) and four layer (4 L) thin films prepared by dip coating are in the range 27 nm to 170 nm. The optical and mechanical properties of these ‘as-deposited’ thin films have been evaluated. The ‘as-deposited’ TS thin films show an optical transparency (in the visible region) of ～90% and optical band gaps are in the range 4.44 eV to 4.50 eV. The optical density has been calculated from the refractive index measurements. The refractive index of TS-1 thin films of thickness 27 nm is practically constant at 1.61 over the wavelength range 400–750 nm. Micro-cracks have been observed (Scanning electron micrographs) in TS-1-4L and TS-3-4L thin films. These micro cracks are more significant in TS-3-4L samples than those of TS-1-4L samples. These cracks are not seen in all other samples (TS-1-2L and TS-3-2L). These mixed titania-silica thin films show higher adherence and higher hardness compared to those of TiO2 thin films. The Raman spectroscopy measurements show the existence of multiple phases of Ti–O–Si. It is known that in the multi-phase structures, the phase boundaries hinder crack propagation and enhances the resistance to plastic deformation enhancing the mechanical hardness of these TS thin films.
关键词： Sol-gel,mechanical properties,optical properties,titania-silica thin films
更新于2025-09-10 09:29:36
-
Interfacial uploading of luminescent hexamolybdenum cluster units onto amino-decorated silica nanoparticles as new design of nanomaterial for cellular imaging and photodynamic therapy
摘要： The present work introduces a facile synthetic route to embed phosphorescent K2[{Mo6I8}I6] and (nBu4N)2[{Mo6I8}(CH3COO)6] clusters (C) onto silica-water interface of amino-decorated silica nanoparticles (SNs, 60±6 nm). The assembled C-SNs gain in the luminescence intensity, which remains stable within three months after their assembly. High uptake capacity of the clusters (8700 of K2[{Mo6I8}I6] and 6500 of (nBu4N)2[{Mo6I8}(CH3COO)6] per the each nanoparticle) derives from ionic self-assembly and coordination bonds between the cluster complexes and ionic (amino- and siloxy-) groups at the silica surface. The coordination via amino- or siloxy-groups restricts aquation and hydrolysis of the embedded clusters, in comparison with the parent K2[{Mo6I8}I6] and (nBu4N)2[{Mo6I8}(CH3COO)6. High potential of the assembled nanoparticles in the ROS generation was revealed by EPR measurements facilitated by spin trapping. The high positive charge and convenient colloid stability of the assembled C-SNs hybrids are the prerequisite for their efficient cellular uptake, which is exemplified in the work by MCF-7 cell line. The measured dark and photoinduced cytotoxicity of the C-SNs hybrids reveals significant photodynamic therapy effect on the MCF-7 cancer cell line versus the normal cells. This effect is entirely due to the embedded clusters and is dependent on the chemical composition of the cluster.
关键词： hexamolybdenum cluster,adsorption,silica nanoparticles,cell internalization,photodynamic therapy,luminescence
更新于2025-09-10 09:29:36
-
Systematic Investigation of Close-Packed Silica Nanospheres Monolayer under Sintering Conditions
摘要： In this paper, we have quantified and investigated the effect of various sintering temperature on close-packed Silica Nanospheres (SNs) monolayers. SNs with diameters of 140, 175 and 220 nm were fabricated by an effective and reliable spin-coating technique. The fabricated SNs monolayers were sintered up to 1200°C and were analyzed from FESEM to investigate in details for local and extended transformations in their structural and morphological properties. A distinct "neck-formation" was observed and was quantified with different particle size distribution as well as surface packing density. It was observed that SNs monolayer undergoes intra-particle reformation in the form of shrinkage in individual SNs and compactification of growth domains, followed by inter-particle sintering. A geometrical model was developed to determine the curvature radius and interpenetration depth thus enabling us to quantify the parameters that dominate the dynamics of the sintering process for such non-porous SNs.
关键词： Scanning Electron Microscopy,Geometrical Model,Silica Nanospheres,Sintering
更新于2025-09-10 09:29:36
-
Gas Sensing Mechanism of Silica with Photonic Bandgap Shift
摘要： Two physical models, Replacing model and Filling model, have been proposed to explain the mechanism of effective refractive index change of photonic crystals (PCs). Theoretically, photonic bandgap (PBG) would shift when PCs are exposed to different environment, which leads to change of effective refractive index of PCs. However, the mechanism of effective refractive index change is distinct when PCs are placed in different gases or vapors. Here, silica PCs were successfully fabricated by self-assembled method. The PGB of silica PCs exhibit similar redshift in volatile organic compounds (VOCs) or small-molecule gases. We propose Replacing model to elaborate silica PCs exposed to VOCs, while Filling model to explain silica PCs exposed to small-molecule gases. Additionally, the redshift of PBG was transformed into volume fraction of adsorbed gas in order to achieve selective sensing of silica PCs. The approach could be exploited for application in sensing.
关键词： refractive index,photonic crystals,photonic bandgap,silica,gas sensing
更新于2025-09-10 09:29:36
-
Defect-induced Fluorescence of Silica Nanoparticles for Bioimaging Applications
摘要： With biocompatibility, biodegradability, and high functionality, silica nanoparticles (SNPs) have been widely investigated for various biomedical applications. However, lack of optical fluorescence has limited the application of SNPs as a degradable imaging agent. Here, we hydrothermally synthesized fluorescent SNPs by artificially generating optically active defect centers using tetraethyl orthosilicate and (3-aminopropyl)trimethoxysilane. The synthesized SNPs demonstrated strong blue photoluminescence originating from the dioxasilyrane (=Si(O2)) and silylene (=Si:) defect centers with the aid of aminopropyl groups. Furthermore, phosphorescence was observed at 459 nm, indicating the presence of silylene in SNPs. Finally, these SNPs have been successfully utilized as a fluorescent probe for bioimaging of normal, cancer, and macrophage cells.
关键词： silica nanoparticle,silylene,dioxasilyrane,phosphorescence,defect,photoluminescence,bioimaging
更新于2025-09-10 09:29:36
-
Influence of the Tb3+ concentration on the luminescent properties of high silica glass
摘要： Tb3+- doped high silica glass was prepared by sintering porous glass. The density, valence state and amount of Tb, transmittance, photoexcitation spectra, photoluminescence spectra, and cathodoluminescence spectra (CL) were recorded and the luminescence decay kinetics analyzed in details. These results show that the doping concentration in high silica glass is in direct proportion to the concentration in solution, and the density increases with the increasing concentration of rare earth ions as well as the intensity of emission spectrum. The largest emission intensity of 0.2 mol/L is more than 2 times higher than the intensity of the 0.05 mol/L. Besides, the “red” shift phenomenon could be distinguished clearly in the transmittance spectra. There is a broad band at the “red” region in the CL spectra. The decay time which is in the millisecond range in di?erent spectral range were measured and analyzed revealing that the decay time of 5D3 is shorter than that of 5D4.
关键词： Luminescent properties,Rare earth ions,High silica porous glass
更新于2025-09-10 09:29:36
-
Separation of Carrier-Free 115mIn from Its Parent 115Cd Using the Synthesized TODGA-Impregnated Silica Gel
摘要： A radiotracer technique has been used to achieve the carrier-free separation of 115mIn from its parent 115Cd in hydrochloric acid medium on a chromatographic column packed with TODGA-impregnated silica gel. At 8 M HCl, both cations are bound at the chelating site, which results in maximum adsorption. When the column is treated with 2 M HCl, the daughter complex gets desorbed and is eluted from the column, whereas the parent remains undisturbed. Pure silica gel does not adsorb radioactivity under these conditions. The radiochemical purity of daughter was checked by its half-life (4.49 h).
关键词： 115Cd–115mIn separation,radiochemical separation,TODGA-impregnated silica gel
更新于2025-09-10 09:29:36
-
Synthesis, Characterisation and Applications of Polymer–Silica Core–Shell Microparticle Capsules
摘要： Encapsulation is a powerful method for the targeted delivery of concentrated reagents, as well as capture of valuable materials in dilute systems. To this end, many encapsulation schemes for specific scenarios have been devised, that incorporate chemospecificity or stimulus response in terms of uptake or release. However, an encapsulation platform that enables highly tailorable surface chemistry for targeting, stimulus response, and core chemistry for capture and release of reagents remains elusive. Here we present such a system comprising composite core–shell capsule particles of hydrophilic polymers coated with thin silica layers, synthesised via straightforward one-pot syntheses. Silica is found to encapsulate a range of polymer hydrogels through a mechanism independent of the specific core chemistry. The hybrid materials possess significantly enhanced rigidity, while allowing surface modification through simple yet versatile silane coupling reactions without a reduction in the functionality of the core. They are shown to have applications as diverse as recyclable catalysis and controlled delivery vehicles for agrochemicals. The successful synthesis and utilisation of this catalogue of materials indicates the broader capability of simple composite structures in an array of high value applications.
关键词： catalysis,silica,microgel,encapsulation,Hybrid materials
更新于2025-09-10 09:29:36
-
Investigations of properties of opal-like photonic crystals using combined methods
摘要： We propose a technique that combines atomic force microscopy, optical spectrophotometry and di?raction method for characterization of photonic crystals. These materials are promising for the creation of various devices, as well as for the observation of new e?ects due to their unique properties. Photonic crystals were synthesized by self-assembly of colloidal silica particles with low deviation in size. It is shown that the developed technique allows to increase the accuracy of determining the parameters of the photonic crystal.
关键词： diffraction method,photonic crystals,self-assembly,colloidal silica particles,atomic force microscopy,optical spectrophotometry
更新于2025-09-09 09:28:46