Prospects for Chemical Control and Engineering of Organically Modified Ceramics

1998 ◽  
Vol 550 ◽  
Author(s):  
Stephen E. Rankin ◽  
Alon V. McCormick
Keyword(s):  
Material Properties ◽  
Chemical Control ◽  
Sol Gel ◽  
Polymer Structure ◽  
New Materials ◽  
Reliable Model ◽  
Organically Modified ◽  
Silicon Alkoxides ◽  
Simple Pair ◽  
Kinetics Of

AbstractHydrolytic polycondensation of silicon alkoxides and organically modified alkoxides shows promise as a route to new materials for medicine. Mathematical models of this polymerization accelerate the development of these materials and processes for their production. With a reliable model, one can rapidly explore a wide variety of options for controlling material properties. Here we describe a model for kinetics of sol-gel copolymerization of a simple pair of ethoxysilanes: (CH3)3Si(OC2H5) and (CH3)2Si(OC2H5)2. We then describe how reactor configuration alone can be used to control of polymer structure by choosing how to mix the reactants. An example is shown of maximizing homogeneity at any reactor residence time of interest in the model copolymer system by using the time of addition of the faster-reacting monomer.

scholarly journals Organically Modified Silicates by the Sol-Gel Process

1984 ◽  
Vol 32 ◽  
Author(s):  
H. Schmidt
Keyword(s):  
Sol Gel ◽  
New Materials ◽  
Organic Components ◽  
Organically Modified Silicates ◽  
Sol Gel Process ◽  
Inorganic As ◽  
Organically Modified ◽  
General Aspects

ABSTRACTThe introduction of organic groups into inorganic networks by the sol-gel process opens the possibility for the preparation of new materials, and typical properties resulting from inorganic as well as from organic components may be combined. Some general aspects and different examples of material developments are reviewed.

scholarly journals FLUORESCENCE STUDIES FOR IN SITU MONITORING OF THE HYDROLYSIS AND POLYMERIZATION REACTIONS OF ORGANICALLY –MODIFIED TETRAMETHYLORTHOSILICATE

2010 ◽  
Vol 5 (3) ◽  
pp. 290-294
Author(s):  
Eko Sri Kunarti
Keyword(s):  
Condensation Reaction ◽  
Sol Gel ◽  
In Situ Monitoring ◽  
Condensation Polymerization ◽  
Surrounding Water ◽  
Fluorescence Studies ◽  
Hydrolysis And Condensation ◽  
Organically Modified ◽  
Kinetics Of

Monitoring of hydrolysis and condensation polymerization reactions of tetramethylorthosilicate-organosiloxane have been carried out. Proton transfer from the excited state of 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (pyranine) to surrounding water molecules was used as a sensitive fluorescence method for following the kinetics of water consumption during the early stages of the sol-gel polymerisation process. Changes in water/silane ratio, type of organosiloxane, mol ratio of organosiloxane to silica precursor and pH affected markedly the kinetic behavior of the hydrolysis and condensation reaction of tetramethylorthosilicate.   Keywords: hydrolysis, polymerisation, fluorescence, pyranine, tetramethylorthosilicate, organosiloxane.

Microstructural characterization of sol-gel coating on PET films

1994 ◽  
Vol 52 ◽  
pp. 886-887
Author(s):  
R. T. Chen ◽  
R.A. Norwood
Keyword(s):  
Ion Beam ◽  
Sol Gel ◽  
Industrial Applications ◽  
Hard Coatings ◽  
Nanometer Scale ◽  
Ion Beam Sputtering ◽  
Process Technology ◽  
Refractive Index Measurement ◽  
Organically Modified ◽  
Pet Films

Sol-gel processing has been used to control the structure of a material on a nanometer scale in preparing advanced ceramics and glasses. Film coating using the sol-gel process was also found to be a viable process technology in applications such as optical, porous, antireflection and hard coatings. In this study, organically modified silicate (Ormosil) coatings are applied to PET films for various industrial applications. Sol-gel materials are known to exhibit nanometer scale structures which havepreviously been characterized by small-angle X-ray scattering (SAXS), neutron scattering and light scattering. Imaging of the ultrafine sol-gel structures has also been performed using an ultrahigh resolution replica/TEM technique. The objective of this study was to evaluate the ultrafine structures inthe sol gel coatings using a direct imaging technique: atomic force microscopy (AFM). In addition, correlation of microstructures with processing parameters, coating density and other physical properties will be discussed.The materials evaluated are organically modified silicate coatings on PET film substrates. Refractive index measurement by the prism coupling method was used to assess density of the sol-gel coating.AFM imaging was performed on a Nanoscope III AFM (by Digital Instruments) using constant force mode. Solgel coating samples coated with a thin layer of Ft (by ion beam sputtering) were also examined by STM in order to confirm the structures observed in the contact type AFM. In addition, to compare the previous results, sol-gel powder samples were also prepared by ultrasonication followed by Pt/Au shadowing and examined using a JEOL 100CX TEM.

Materials technology: Innovations and progress

Impact ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 52-53
Author(s):  
Lucy Sharp
Keyword(s):  
Material Properties ◽  
New Materials ◽  
Medical Problems ◽  
Technology Innovations ◽  
Societal Challenges ◽  
New Material ◽  
Innovative Materials ◽  
The Creation ◽  
Novel Applications

Materials technology is a constantly evolving discipline, with new materials leading to novel applications. For example, new material properties arise from combining different materials into composites. Researching materials can help solve societal challenges, with the creation of innovative materials resulting in breakthroughs in overcoming hurdles facing humankind, including energy challenges and medical problems. Innovative materials breathe new life into industries and spur on scientific and technological discovery.

Polymer structure and catalytic activity of ion exchangers

1981 ◽  
Vol 46 (7) ◽  
pp. 1577-1587 ◽  
Author(s):  
Karel Jeřábek
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Active Sites ◽  
Crosslinking Agent ◽  
Reaction Medium ◽  
Polymer Structure ◽  
Local Concentration ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene ◽  
Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

High field 1H NMR Studies of Sol-Gel Kinetics

1986 ◽  
Vol 73 ◽  
Author(s):  
Bruce D. Kay ◽  
Roger A. Assink
Keyword(s):  
Equilibrium Distribution ◽  
Sol Gel ◽  
Nmr Studies ◽  
H Nmr ◽  
Rate Limiting Step ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Product Species ◽  
Rate Limiting ◽  
Kinetics Of

ABSTRACTHigh resolution 1H NMR spectroscopy at high magnetic fields is employed to study the reaction kinetics of the Si(OCH3)4:CH3OH:H2O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.

Nanostructured Doped Silica Films Application as Sensitive Layers for Chemical Sensors

2013 ◽  
Vol 684 ◽  
pp. 7-11
Author(s):  
Sergey Krutovertsev ◽  
Alla Tarasova ◽  
Olga Ivanova ◽  
Larisa Krutovertseva
Keyword(s):  
Initial Conditions ◽  
Sol Gel ◽  
Silica Films ◽  
Adsorption Activity ◽  
Developed Surface ◽  
Sol Gel Process ◽  
Sensitive Characteristics ◽  
The Right ◽  
Kinetics Of ◽  
Matrix Factors

The sensor behavior of nanostructured doped silica films produced by sol-gel way were examined. Hygroscopic substances and polyoxometalates were used as additives to make more significant sensitive characteristics of initial matrix. Factors that have effect on sol preparation and films forming were investigated. Adsorption activity of the sensitive films was studied and it was shown that the films had a highly developed surface with nano-size pores. Change of initial conditions of sol-gel process gives opportunity to influence on kinetics of gel formation and consequently, on structure and properties of final materials. The study showed that the conditions of the environment affected the sensors characteristics markedly, which can be improved by choosing of the right procedure of forming and treatment. Influence of type and additive substances quantity into doped films was discussed in the paper

Material Properties and Design Aspects of Folding Bicycle Frame

2011 ◽  
Vol 264-265 ◽  
pp. 777-782 ◽  
Author(s):  
M.A. Maleque ◽  
M.S. Hossain ◽  
S. Dyuti
Keyword(s):  
Material Properties ◽  
Raw Material ◽  
New Materials ◽  
Materials Properties ◽  
Advantages And Disadvantages ◽  
Bicycle Frame ◽  
Successful Design ◽  
Future Direction ◽  
The Relationship ◽  
Comprehensive Study

successful design of folding bicycle should take into account the function, material properties, and fabrication process. There are some other factors that should be considered in anticipating the behavior of materials for folding bicycle. In order to understand the relationship between material properties and design of a folding bicycle and also for the future direction in new materials with new design, a comprehensive study on the design under different conditions are essential. Therefore, a systematic study on the relationship between material properties and design for folding bicycle has been performed. The advantages and disadvantages matrix between conventional bicycle and folding bicycle is presented for better understanding of the materials properties and design. It was found that the materials properties of the folding bicycle frame such as fatigue and tensile strength are the important properties for the better performance of the frame. The relationship between materials properties and design is not straight forward because the behavior of the material in the finished product could be different from that of the raw material. The swing hinge technique could be a better technique in the design for the folding bicycle frame.

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