Reactivity of Silica-Supported Hafnium Tris-neopentyl with Dihydrogen:  Formation and Characterization of Silica Surface Hafnium Hydrides and Alkyl Hydride

2007 ◽  
Vol 26 (17) ◽  
pp. 4118-4127 ◽  
Author(s):  
Géraldine Tosin ◽  
Catherine C. Santini ◽  
Anne Baudouin ◽  
Aimery De Mallman ◽  
Steven Fiddy ◽  
...  
Keyword(s):  
Silica Surface ◽  
Alkyl Hydride

CHARACTERIZATION OF A SURFACE-CHARGE MODULATION ELECTROFLUIDIC TRANSISTOR BY HYDRODYNAMIC MEASUREMENTS

2012 ◽  
Vol 11 (04) ◽  
pp. 1240021
Author(s):  
GUILLAUME LAFFITE ◽  
XU ZHENG ◽  
LOUIS RENAUD ◽  
FRANÇOIS BESSUEILLE ◽  
ELISABETH CHARLAIX ◽  
...  
Keyword(s):  
Experimental Study ◽  
Zeta Potential ◽  
Surface Charge ◽  
Gate Voltage ◽  
Silica Surface ◽  
Insulating Layer ◽  
Charge Regulation ◽  
Charge Modulation ◽  
Gating Effect

We present an experimental study on the electrofluidic transistor in this paper. A novel and easy way to integrate the transistor into a microchannel is developed. The performances of the insulating layer, especially the leakage current under gate voltage, are carefully characterized. The change of surface charge on silica surface by gate polarization is measured, however, by measuring the streaming current, the gating effect on zeta potential has not been observed. This result should imply new assumption in the understanding of the charge regulation in the electrical double layer under gate polarization.

Synthesis and Characterization of New Bimetallic Pt,Ag/SBA-15 Materials

2013 ◽  
Vol 203-204 ◽  
pp. 81-85 ◽  
Author(s):  
Małgorzata Zienkiewicz-Strzałka ◽  
Marek Rotko ◽  
Stanislaw Pikus
Keyword(s):  
Photoelectron Spectroscopy ◽  
Silica Surface ◽  
Chemical Properties ◽  
Silver Ions ◽  
Nitrogen Adsorption ◽  
Decomposition Temperature ◽  
Synthesis And Characterization ◽  
Chloride Complexes ◽  
X Ray

This paper reports, for the first time, synthesis and characterization of new bifunctional materials containing platinum and silver ions deposited on mesoporous ordered silica SBA-15. Both types of ions were incorporated on silica surface during adsorption from water solutions containing various amounts of dissolved tetraamineplatinum(II) dichloride and diamminesilver(I) hydroxide or tetraamineplatinum(II) dichloride and diamminesilver(I) chloride complexes. The silanol groups on silica surface play important role in adsorption mechanism and one of the most commonly used technique for their characterization is photoacoustic spectroscopy. This technique provides clear evidence of successfully incorporation two types of precious metal ions (Pt and Ag) on SBA-15 surface. The decomposition process of absorbed complexes was investigated according to high temperature in helium. The products of decomposition were analyzed by mass spectrometer. Obtained results show that decomposition temperature of platinum and silver complexes are quite vary. Similarly mechanisms of decomposition of ligands from silver and platinum complexes are also different. Moreover, the structural and chemical properties of Pt,Ag-SBA-15 samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS).

Synthesis and Characterization of Biomass Supported Ag, Co and Ag-Co Nanoparticles

2016 ◽  
Vol 857 ◽  
pp. 480-484
Author(s):  
Nur Izzati Mohd Anuar ◽  
Jeyashelly Andas
Keyword(s):  
Oxidation State ◽  
Silica Surface ◽  
Sol Gel ◽  
Spherical Shape ◽  
Synthesis And Characterization ◽  
Tem Analysis ◽  
Mean Size ◽  
Ft Ir ◽  
Co Nanoparticles

Silica extracted from rice husk was used as a support to synthesize the monometallic Ag, Co and bimetallic Ag-Co nanoparticles. The nanoparticles were prepared via a sol-gel method by adding glucose as the reducing agent. The prepared nanoparticles were designated as Ag-NP, Co-NP and AgCo-NP. The successful incorporation of Ag/Co onto the silica surface were evidenced by TEM, FT-IR and DR/UV-Vis analysis. The TEM analysis showed the presence of small spherical shape nanoparticles with an average mean size of 3.18-3.57 nm. Through DR/UV-Vis analysis, the presence of Ag+ and cobalt in the oxidation state of +2 and +3 were confirmed, while FT-IR verified the presence of M-O and Si-O-M+ bond.

CHARACTERIZATION OF SILICA MODIFIED WITH SILANES BY USING THERMOGRAVIMETRIC ANALYSIS COMBINED WITH INFRARED DETECTION

2018 ◽  
Vol 92 (2) ◽  
pp. 237-262 ◽  
Author(s):  
Yen Wan Ngeow ◽  
Andrew V. Chapman ◽  
Jerry Y. Y. Heng ◽  
Daryl R. Williams ◽  
Susanna Mathys ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Silica Surface ◽  
Rolling Resistance ◽  
Infrared Detection ◽  
Weight Losses ◽  
Wide Range ◽  
Similar Temperature ◽  
Silanized Silica ◽  
Wet Grip

ABSTRACT Tire treads with reduced rolling resistance and increased wet grip can be achieved by coupling hydrophilic silica to hydrocarbon rubber by using an alkoxysilane. The silica surface was modified by reaction with a wide range of coupling and non-coupling silanes. The chemistry and extent of these silanizations were elucidated using thermogravimetric analysis (TGA) combined with infrared detection. The silane grafting efficiencies were typically 52–72%, but efficiencies were lower with the bulkier 3-(di-(tridecyloxypenta(ethyleneoxy))ethoxysilyl)propyl mercaptan. However, the silica surface coverage increases with increasing size of the silane. Grafting efficiencies were lower with higher silane loadings. In the TGA, ethoxy and methoxy groups are displaced from the grafted silanes mainly at moderate temperatures (up to about 495 °C) to form siloxane bridges. Over a similar temperature range, the weaker S–S bonds present in bis(3-triethoxysilylpropyl) tetrasulfide (TESPT)- or bis[3-(triethoxysilyl)propyl] disulfide (TESPD)-modified silica are cleaved, leading to weight losses from TESPT or TESPD bound at one end to the silica and from TESPT bound at both ends. The remaining weight losses from bound silanes occurred mainly at higher temperatures. In the commercial silanized silica Coupsil 8113, TGA indicates that about two of three ethoxy groups in each triethoxysilane were lost during the silanization process.

XPS Study of a New Heterogeneous Ruthenium Catalyst Precursor

1997 ◽  
Vol 51 (12) ◽  
pp. 1807-1813 ◽  
Author(s):  
P. Smet ◽  
F. Verpoort ◽  
G. De Doncker ◽  
A. R. Bossuyt ◽  
L. Fiermans ◽  
...  
Keyword(s):  
Thin Layer ◽  
Photoelectron Spectroscopy ◽  
Surface Reaction ◽  
Silica Surface ◽  
Silicon Single Crystal ◽  
Catalyst Precursor ◽  
X Ray ◽  
Different Types ◽  
Xps Study

The catalyst precursor has been synthesized by modifying the silica surface with ClPPh2 followed by a surface reaction with RuCl3. Supports consisting of a thin layer of SiO2 on a silicon single crystal have been used. Characterization of the different stages in the reaction procedure has been performed by a combination of conventional and angle-resolved X-ray photoelectron spectroscopy (XPS) using RuCl3/P(C6H5)2/SiO2/Si(100) model precursors. Different types of ruthenium centra have been identified.

Characterization of molybdenum monomeric oxide species supported on hydroxylated silica: a DFT study

2014 ◽  
Vol 16 (34) ◽  
pp. 18253-18260 ◽  
Author(s):  
Hazar Guesmi ◽  
Robert Gryboś ◽  
Jarosław Handzlik ◽  
Frederik Tielens
Keyword(s):  
Dft Calculations ◽  
Amorphous Silica ◽  
Silica Surface ◽  
Dft Study ◽  
Periodic Dft Calculations ◽  
Periodic Dft

Periodic DFT calculations have been performed on molybdenum(vi) oxide species supported on the hydroxylated amorphous silica surface.

Covalent Grafting of Organoalkoxysilanes on Silica Surfaces in Water-Rich Medium as Evidenced by 29Si NMR

2007 ◽  
Vol 1007 ◽  
Author(s):  
Christian Bonhomme ◽  
Sophie De Monredon ◽  
François Ribot ◽  
Florence Babonneau
Keyword(s):  
Silica Surface ◽  
Point Of View ◽  
Experimental Investigations ◽  
29Si Nmr ◽  
Rich Medium ◽  
Spectroscopy Analysis ◽  
Huge Amount ◽  
Silica Surfaces ◽  
Covalent Grafting

ABSTRACTDespite the huge amount of experimental investigations dedicated to the grafting of organoalkoxysilanes on silica, the characterization of covalent linkages remains a difficult task from a spectroscopic point of view. In most cases, the formation of a covalent link is taken for granted and not discussed. 29Si NMR, IR or UV spectroscopies are commonly used to study the modification of silica surface. Herein we report an unambiguous method to evidence the formation of covalent links. It is based on NMR spectroscopy analysis coupled with a rigorous synthetic grafting protocol.

scholarly journals Characterization of Drugs with Good Glass Formers in Loaded-Mesoporous Silica and Its Theoretical Value Relevance with Mesopores Surface and Pore-Filling Capacity

2022 ◽  
Vol 15 (1) ◽  
pp. 93
Author(s):  
Arif Budiman ◽  
Diah Lia Aulifa
Keyword(s):  
Mesoporous Silica ◽  
Silica Surface ◽  
Value Relevance ◽  
Drug Loading ◽  
Surface Interaction ◽  
Pore Filling ◽  
Maximum Loading ◽  
Loading Amount ◽  
Theoretical Amount

The incorporation of a drug into mesoporous silica (MPS) is a promising strategy to stabilize its amorphous form. However, the drug within MPS has shown incomplete release, despite a supersaturated solution being generated. This indicates the determination of maximum drug loading in MPS below what is experimentally necessary to maximize the drug doses in the system. Therefore, this study aimed to characterize the drugs with good glass former loaded-mesoporous silica, determine the maximum drug loading, and compare its theoretical value relevance to monolayer covering the mesoporous (MCM) surface, as well as pore-filling capacity (PFC). Solvent evaporation and melt methods were used to load each drug into MPS. In addition, the glass transition of ritonavir (RTV) and cyclosporine A (CYP), as well as the melting peak of indomethacin (IDM) and saccharin (SAC) in mesoporous silica, were not discovered in the modulated differential scanning calorimetry (MDSC) curve, demonstrating that each drug was successfully incorporated into the mesopores. The amorphization of RTV-loaded MPS (RTV/MPS), CYP-loaded MPS (CYP/MPS), and IDM-loaded MPS (IDM/MPS) were confirmed as a halo pattern in powder X-ray diffraction measurements and a single glass transition event in the MDSC curve. Additionally, the good glass formers, nanoconfinement effect of MPS and silica surface interaction contributed to the amorphization of RTV, CYP and IDM within MPS. Meanwhile, the crystallization of SAC was observed in SAC-loaded MPS (SAC/MPS) due to its weak silica surface interaction and high recrystallization tendency. The maximum loading amount of RTV/MPS was experimentally close to the theoretical amount of MCM, showing monomolecular adsorption of RTV on the silica surface. On the other hand, the maximum loading amount of CYP/MPS and IDM/MPS was experimentally lower than the theoretical amount of MCM due to the lack of surface interaction. However, neither CYP or IDM occupied the entire silica surface, even though some drugs were adsorbed on the MPS surface. Moreover, the maximum loading amount of SAC/MPS was experimentally close to the theoretical amount of PFC, suggesting the multilayers of SAC within the MPS. Therefore, this study demonstrates that the characterization of drugs within MPS, such as molecular size and interaction of drug-silica surface, affects the loading efficiency of drugs within MPS that influence its relevance with the theoretical value of drugs.

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