Engineering of Porosity in Amorphous Materials. Plasma Oxidation of Hydrocarbon Templates in Polysilsesquioxanes*

1994 ◽  
Vol 346 ◽  
Author(s):  
Douglas A. Loy ◽  
Richard J. Buss ◽  
Roger A. Assink ◽  
Kenneth J. Shea ◽  
Henry Oviatt
Keyword(s):  
Amorphous Materials ◽  
Oxygen Plasma ◽  
Sol Gel ◽  
Silica Gels ◽  
Oxygen Plasma Treatment ◽  
Plasma Oxidation ◽  
Inductively Coupled ◽  
Surface Areas ◽  
Bridging Groups ◽  
Gel Processing

ABSTRACTArylene- and alkylene-bridged polysilsesquioxanes were prepared by sol-gel processing of bis(triethoxysilyl)-arylene monomers 1-4, and alkylene monomers 5-9. The arylene polysilsesquioxanes were porous materials with surface areas as high as 830 m2/g (BET). Treatment with an inductively coupled oxygen plasma resulted in the near quantitative removal of the arylene bridging groups and a coarsening of the pore structure. Solid state 29Si NMR was used to confirm the conversion of the sesquioxane silicons (T) to silica (Q). The alkylene-bridged polysilsesquioxanes were non-porous. Oxygen plasma treatment afforded silica gels with mesoporosity. The porosity in the silica gels appears to arise entirely from the oxidation of the alkylene spacers.

In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD

1999 ◽  
Vol 590 ◽  
Author(s):  
DM Pickup ◽  
G Mountjoy ◽  
RJ Newport ◽  
ME Smith ◽  
GW Wallidge ◽  
...  
Keyword(s):  
Amorphous Materials ◽  
Sol Gel ◽  
Heat Treatments ◽  
Silica Gels ◽  
Ex Situ ◽  
High Count ◽  
X Ray ◽  
Image Plate ◽  
Wide Range

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.

Preparation of Nanoporous Titania Films by Surface Sol−Gel Process Accompanied by Low-Temperature Oxygen Plasma Treatment

Langmuir ◽  
2002 ◽  
Vol 18 (23) ◽  
pp. 9048-9053 ◽  
Author(s):  
Jianguo Huang ◽  
Izumi Ichinose ◽  
Toyoki Kunitake ◽  
Aiko Nakao
Keyword(s):  
Low Temperature ◽  
Plasma Treatment ◽  
Oxygen Plasma ◽  
Sol Gel ◽  
Oxygen Plasma Treatment ◽  
Sol Gel Process ◽  
Titania Films

SYNTHESIS AND SURFACE PROPERTIES STUDIES ON BAMBOO CHARCOAL/ZnO NANOCOMPOSITE BY USING LOW-TEMPERATURE PLASMA

2017 ◽  
Vol 24 (03) ◽  
pp. 1750032
Author(s):  
K. VIGNESH ◽  
K. A. VIJAYALAKSHMI ◽  
N. KARTHIKEYAN
Keyword(s):  
Electron Microscopy ◽  
Plasma Treatment ◽  
Oxygen Plasma ◽  
Sol Gel ◽  
Oxygen Plasma Treatment ◽  
Bamboo Charcoal ◽  
X Ray Diffraction ◽  
Temperature Plasma ◽  
Transmission Electron ◽  
Surface Modified

In this work we synthesize bamboo charcoal (BC)/ZnO nanocomposite by sol–gel technique. The synthesized BC/ZnO nanocomposite is surface modified by atmospheric air and oxygen plasma to improve the surface functional properties. The structure and morphology of the resultant nanocomposite are analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDAX) and ultraviolet–visible spectroscopy (UV–vis) and its antibacterial behavior is analyzed by the disc diffusion plate technique. We obtained new bonds in FTIR results on BC/ZnO nanocomposite after oxygen plasma treatment. From SEM results we observed there was a plasma etching process that occurred on the resulting BC/ZnO nanocomposite after plasma treatment. Significantly, the antimicrobial behavior also increased after oxygen plasma treatment.

Aryl-Bridged Polysilsesquioxanes - New Microporous Materials.

1990 ◽  
Vol 180 ◽  
Author(s):  
Kenneth J. Shea ◽  
Owen Webster ◽  
Douglas A. Loy
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
Refractive Indices ◽  
Surface Areas ◽  
New Family ◽  
Rigid Rod ◽  
Optical Applications ◽  
Degree Of Condensation ◽  
Gel Processing ◽  
Thermal Stability Of

ABSTRACTThe first representatives of a new family of microporous, aryl-bridged polysilsesquioxanes have been prepared by sol-gel processing of bis-1,4-(triethoxysilyl)benzene la, bis-4,4′- (triethoxysilyl)biphenyl 2a, bis-4,4′-(triethoxysilyl)terphenyl 3a, and bis-9,10-triethoxysilyl anthracene 4a. The bis(trichlorosilyl) analogs of la and 2a (lb and 2b, respectively) were also examined. The materials produced by hydrolysis and condensation of the monomers provide an opportunity to fully condense to a network with rigid-rod organic spacers interspaced at regular intervals in the silicate-like framework. The xerogels produced upon subsesquent processing of the gels have extremely high surface areas (256–1100 m2/g; BET) with porosities confined to the micropore domain (< 200 nm). Solid state (CP MAS) 13C and 29Si NMR were used to evaluate the extent of hydrolysis and degree of condensation in the xerogels. The porosity and thermal stability of the aryl bridged polysilsesquioxanes may lead to applications as chromatographic absorbents. The transparent materials may also have optical applications arising from both the gels′ high refractive indices and the covalent incorporation of ultraviolet chromophores.

scholarly journals The effect of three-minute exposure of oxygen plasma on the properties of tin oxide films

2020 ◽  
Vol 99 (3) ◽  
pp. 38-45
Author(s):  
E.A. Dmitriyeva ◽  
◽  
I.A. Lebedev ◽  
E.A. Grushevskaya ◽  
D.O. Murzalinov ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Tin Oxide ◽  
Oxygen Plasma ◽  
Sol Gel ◽  
Oxide Films ◽  
Oxygen Plasma Treatment ◽  
Minute Exposure ◽  
Gel Method ◽  
Sol Gel Method ◽  
Tin Oxide Films

Research devoted to the effect of three-minute exposure of oxygen plasma on the properties of tin oxide films investigation. The films were obtained by sol-gel method from five-water tin tetrachloride solution. The concentration of tin ions in the SnCl4/EtOH film-forming system was 0.14 mol/l. The solution system was deposed on the glass substrate by carring out a modified dipping method. Plasma treatment was performed at a pressure of 6.5 Pa and a power of about 20 Watts. The frequency of the oscillations produced by the generator was 27.12 ± 0.6 % MHz as well. The temperature of the samples during processing did not exceed 100 ºC. As a result of the formation of tin oxide (II), the film transmittance decreased after treatment with oxygen plasma. The width of the electric forbidden zone of the obtained samples was calculated, which was 3.95 eV for glass and 3.79 eV for film. The resistance of the films was determined by 10 measurements on different parts of the samples. The film without processing has a resistance of about 4255 ± 1158 kΩ, after processing, the resistance decreased by 25 times and amounted to 167 ± 26 kΩ. A decrease in resistance indicates an increase in the concentration of charge carriers in the sample. The resulting SnO is a semiconductor that lowers the transmittance of the studied films and contributes to reducing their resistance. X-ray structural analysis of the samples was also performed. After processing in oxygen plasma, the intensity of reflection from the (110) plane have increased. It should be noted that the number of planes with (101) indexes has decreased. The study of the sample surface showed the destructive nature of three-minute exposure by oxygen plasma. Keywords: thin films, SnO2, sol-gel method, oxygen plasma treatment, transparency, structure, resist

Mesoporous Ordered Organosilicas Containing Zr and Ti Species

2010 ◽  
Vol 163 ◽  
pp. 55-58
Author(s):  
M. Zienkiewicz ◽  
Stanislaw Pikus ◽  
E. Olszewska ◽  
M. Barczak
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Surface ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Inorganic Materials ◽  
Isomorphous Substitution ◽  
Periodic Mesoporous Organosilica ◽  
Structure Directing Agent ◽  
Surface Areas ◽  
Bridging Groups

Periodic mesoporous organosilica materials (PMOs) are the new class of porous and hybrid organic-inorganic materials. They represent exceptional and functional bridged polysilsesquioxanes prepared by sol-gel processing of monomers using triblock copolymers or ionic surfactants as the structure directing agents. By changing the monomer type, various organic functional groups may be incorporated into the framework of PMO materials. Moreover it is possible to introduce heteroatoms in the structure of mesoporous materials via isomorphous substitution of the silicon atoms. In the present study, we report the preparation and characterization of the series of zirconium, titanium and mixture of them, doped mesoporous silica. The PMOs have been synthesized by the hydrolysis and the condensation of bridged silsesquioxane precursors containing two different organic bridging groups ((R’)3Si-CH2-CH2-Si(R’)3, R’ - methoxy or ethoxy). The influence of temperature of synthesis on the structure of PMOs was examined. PMO-Zr and PMO-Zr-Ti were synthesized by employing a zirconyl chloride octahydrate (ZrOCl2•8H2O), titanium isopropoxide, NaCl, bis(trimethoxysilyl)ethane (BTME) as a silica source and triblock copolymer P123 as the structure directing agent while PMO-Ti was prepared using 1,2-bis(triethoxysilyl)ethane (BTESE), titanium isopropoxide, NaOH and cetyltrimethylammonium bromide (CTABr) as a structure directing agent. The resulting materials exhibited well-ordered two-dimensional hexagonal space group p6mm, high surface areas in the range of 700-1100 m2/g. The X-ray photoelectron spectroscopy (XPS) analysis indicated the successful incorporation of heteroatoms into hybrid PMOs and the IR spectra confirmed satisfactory removal of the surfactants.

Contact Angle Measurement and Its Application To Sol-Gel Processing

1994 ◽  
Vol 346 ◽  
Author(s):  
D. J. Stein ◽  
A. Maskara ◽  
S. Hæreid ◽  
J. Anderson ◽  
D. M. Smith
Keyword(s):  
Contact Angle ◽  
Sol Gel ◽  
Dynamic Contact ◽  
Dip Coating ◽  
Contact Angles ◽  
Angle Measurement ◽  
Silica Gels ◽  
Solid Matrix ◽  
Surface Tensions ◽  
Gel Processing

ABSTRACTCapillary stresses during drying that result from the contact angle of a liquid solvent to a gel, surface tension, and pore size have an immense effect on the dried gel. The extent to which the gel shrinks is a balance between the capillary stress and the solid matrix strength. The dynamic contact angles and surface tensions of various solvents commonly employed in sol-gel processing on silica gels of various surface chemistries have been evaluated. A thin, dense coating of silica gel was formed by dip coating a standard glass slide in an acid catalyzed silica sol and drying. Some of the sample surfaces were organically modified. Dynamic contact angles were determined using a modified Wilhelmy plate technique. Solvent surface tensions were determined using the De Nouy ring technique. The bulk modulus of wet gels were determined with a three point bend experiment. We have found that contrary to previous investigators, who attributed different bulk densities obtained after drying from various alcohols to contact angles variations, gel shrinkage during drying is actually due to slightly different surface tensions and degrees of depolymerization of the gel network.

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