Novel Wet Process Silica Prepared from Alkyl Silicates. Part III: Use in Silicone Elastomers for Optical Applications

1985 ◽  
Vol 58 (5) ◽  
pp. 965-972 ◽  
Author(s):  
Keith E. Polmanteer ◽  
Harry L. Chapman ◽  
Michael A. Lutz
Keyword(s):  
Temperature Change ◽  
Silicone Elastomer ◽  
Refractive Indices ◽  
Silicone Elastomers ◽  
Wet Process ◽  
Elastomeric Material ◽  
Specific Temperature ◽  
Optical Applications ◽  
High Consistency ◽  
Silica Synthesis

Abstract The first two papers of this three-part series of papers dealing with a novel wet-process hydrophobic (WPH) silica technology covered the silica synthesis (Part I) and reinforcement performance (Part II) respectively. The WPH silica was highly reinforcing and provided optically clear compositions as well. The first optically clear, high consistency silicone elastomer was developed in the midnineteen fifties by Polmanteer et al., using different technology from that described in this paper. Optical clarity was accomplished in the earlier work by matching the refractive indices of the filler and polymer at 25°C, making them isorefractive at this specific temperature. This paper will discuss the unique features of this new silica technology as it relates to optically clear silicone elastomers. The term, optically clear, in the context of this paper refers to an elastomeric material, 2.54 mm in thickness, that exhibits less than 4% haze, and more than 85% transmission. It will be shown that, when using the older technology based on isorefractive compositions, optical clarity is reduced with temperature change from the isorefractive temperature, due primarily to an increase in haze. The new silica technology eliminates this problem and effectively broadens the application temperatures for optically clear, thermally stable silicone elastomers.

Novel Wet-Process Silica Prepared from Alkyl Silicates. Part I: Synthesis

1985 ◽  
Vol 58 (5) ◽  
pp. 939-952 ◽  
Author(s):  
Michael A. Lutz ◽  
Keith E. Polmanteer ◽  
Harry L. Chapman
Keyword(s):  
Simple Procedure ◽  
The Novel ◽  
Silicone Elastomers ◽  
Wet Process ◽  
Silica Filler ◽  
Surface Character ◽  
Treatment Agent ◽  
One Step ◽  
Optical Applications ◽  
By Products

Abstract A simple procedure for preparing a silica filler possessing both the necessary structure and surface character to be useful as a reinforcing filler for silicone elastomers has been developed. The novel, one-step process involves hydrolysis and condensation of alkyl silicates in the presence of a silica surface treatment agent exemplified as follows: (see PDF for diagram) Only easily recycled by-products are generated during the synthesis of the new WPH silica. Performance of the resultant WPH silica filler in reinforcing silicone elastomers will be discussed in detail in Part II of this series, while their use in silicone elastomers for optical applications will be described in Part III.

scholarly journals Evaluation of Some Mechanical Properties of a Maxillofacial Silicon Elastomer Reinforced with Polyester Powder

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Yagthan Mohammed Haider ◽  
Zainab Salih Abdullah ◽  
Ghasak H. Jani ◽  
Norehan Mokhtar
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Hardness Test ◽  
Silicone Elastomer ◽  
Control Group ◽  
Silicone Elastomers ◽  
Tear Strength ◽  
To Come ◽  
Post Hoc

Maxillofacial silicone elastomers are used to replace and reconstruct missing facial parts for patients with trauma or a certain disease. Although commonly favorable silicone elastomers are not ideal in properties, many studies have been carried out to improve their mechanical properties and to come out with ideal maxillofacial prosthetic materials, so as to render patients with the best maxillofacial prostheses. The aim of the current study is to evaluate the effect of addition of different concentrations of polyester powder on hardness, tear strength, surface roughness, and tensile strength of maxillofacial A-2186 RTV silicone elastomers. Polyester powder was added to the silicone elastomer in the concentrations of 1%, 3% and 5% by using an electronic digital balance, compared with the control group of 0% polyester filler. The shore A hardness test was done according to ASTM D 2240 standards. The tear test was done according to ASTM D624 type C standards. The tensile test was done according to ISO specification number 37:2011. The surface roughness test was performed according to ISO 7619-1 2010 specifications. The data collected were then analyzed using one-way analysis of variance (ANOVA) and post hoc and Fisher’s LSD tests. All three groups showed a highly significant increase in tear strength, tensile strength, hardness, and roughness, compared to the control group. Reinforcement of A-2186 Platinum RTV Silicone Elastomer with 5% polyester significantly improved the mechanical properties tested in this study.

Effects of Fumed Silica Treated with Functional Disilazanes on Silicone Elastomers Properties

1982 ◽  
Vol 55 (1) ◽  
pp. 233-244 ◽  
Author(s):  
M. T. Maxson ◽  
C. L. Lee
Keyword(s):  
Fumed Silica ◽  
Silica Surface ◽  
Silicone Elastomer ◽  
Treatment Level ◽  
Silicone Elastomers ◽  
Hardness Values

Abstract The reinforcement obtained with disilazane-treated silica in the platinumcatalyzed silicone elastomer was found to be dependent upon not only the amount of disilazane employed but also the structure of the disilazane and its distribution on the silica surface. Incorporation of a small amount of vinyl-functional disilazane such as (ViMe2Si)2NH along with (Me3Si)2NH (major treating agent) can significantly increase the modulus and hardness of the resulting elastomer. [ViMe2Si(OMe2Si)3]2NH gave higher modulus and hardness than (ViMe2Si)2NH, whereas (HMe2Si)2NH gave lower modulus and hardness values. The random treatment resulted in greater improvement of cured elastomer properties than the heterogeneous treatment at the same treatment level.

scholarly journals Long-term stable modifications of silicone elastomer for improved hemocompatibility

2016 ◽  
Vol 2 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Cécile Boudot ◽  
Sarah Burkhardt ◽  
Miriam Haerst
Keyword(s):  
Thrombin Generation ◽  
Platelet Adhesion ◽  
Medical Engineering ◽  
Surface Modifications ◽  
Silicone Elastomer ◽  
Silicone Elastomers ◽  
Thrombin Generation Assay ◽  
Electron Microscope Analysis ◽  
Cost Efficient

AbstractSilicone elastomers are well established in medical engineering and particularly in blood-contacting applications such as catheters and medical tubing. Still, their intrinsic surface properties have potential for improvement. For example, hydrophobicity reduction can be a way to provide better hemocompatibility. In this study, several bulk and surface modifications of silicone elastomers using polyethylene glycol (PEG) were investigated. All modifications induced long-term (2 months), stable wettability of the surface. Moreover, cytotoxicity testing demonstrated their suitability as implant material. Hemocompatibility was investigated through a thrombin generation assay as well as a platelet adhesion study combining an enzymatic assay and a scanning electron microscope analysis. That the hemocompatibility of silicone was considerably improved thanks to the PEG modifications could be shown. The study introduces easily processable, cost-efficient, and long-term stable hydrophilic modifications of silicone elastomer for improved hemocompatibility.

Poly(methyl methacrylate)/polyphosphate blends with tunable refractive indices for optical applications

2020 ◽  
Vol 104 ◽  
pp. 109841
Author(s):  
Anjana K. Othayoth ◽  
Billakanti Srinivas ◽  
Karuppiah Murugan ◽  
Krishnamurthi Muralidharan
Keyword(s):  
Methyl Methacrylate ◽  
Refractive Indices ◽  
Poly Methyl Methacrylate ◽  
Optical Applications

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 Modification of Silicone Elastomers Using Silicone Comonomers Containing Hydrophilic Surface Active Endgroups

2014 ◽  
Vol 1626 ◽  
Author(s):  
Jonathan Goff ◽  
Barry Arkles ◽  
Santy Sulaiman
Keyword(s):  
Contact Angle ◽  
Mechanical Performance ◽  
Silicone Elastomer ◽  
Hydrophobic Contact ◽  
Silicone Elastomers ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Friction Measurements ◽  
Time Frames

ABSTRACTA facile technique was developed for a long-term increase in silicone elastomer surface hydrophilicity, eliminating the need for post-cure surface treatment (e.g. oxygen plasma or surface grafting). Well-defined silicones (1-4 kDa) with a central vinyl functionality and discrete PEG2, PEG3 and tetrahydrofurfuryl (THF) pendant endgroups were synthesized, characterized and used as comonomers in addition-cure, platinum catalyzed 2-part silicone elastomer formulations. The modified silicone elastomers were optically clear and maintained the mechanical performance characteristic of this class of material with up to 20 wt.% comonomer in the 2-part formulation. Contact angle measurements of deionized water on the silicone elastomer surface showed improved wettability with comonomer content. The elastomer surface shifted from hydrophobic (contact angle ∼120°C) to hydrophilic (contact angle < 90°C) at ∼5 wt.% comonomer loadings for extended time frames (> 5 months). Coefficient of friction measurements of the modified silicone elastomers revealed an increase in surface lubricity with comonomer loadings.

Preparation and characterization of luminescent silicone elastomer by thiol–ene “click” chemistry

2014 ◽  
Vol 2 (15) ◽  
pp. 2724-2734 ◽  
Author(s):  
Yujing Zuo ◽  
Haifeng Lu ◽  
Lei Xue ◽  
Xianming Wang ◽  
Liang Ning ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Ultraviolet Light ◽  
Silicone Elastomer ◽  
Silicone Elastomers ◽  
Very High

Novel transparent and luminescent silicone elastomers were prepared by thiol–ene chemistry. They show very intense photoluminescence under ultraviolet light and have very high coloric purity.

scholarly journals Preparation and Characterization of Self-Assembled Thin Film of MPS-Capped ZnS Quantum Dots for Optical Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Kenan Koç ◽  
Fatma Z. Tepehan ◽  
Galip G. Tepehan
Keyword(s):  
Heat Treatment ◽  
Quantum Dots ◽  
Optical Filter ◽  
Refractive Indices ◽  
Glass Substrates ◽  
Heat Treated ◽  
Dielectric Coefficient ◽  
Self Assembled ◽  
Optical Applications

For this study, we prepared colloidal ZnS quantum dots using 3-mercaptopropyltrimethoxysilane (MPS) as the capping agent. Colloidal ZnS quantum dots were directly deposited on glass substrates by a spin coating process. Therefore, self-assembled films made of ZnS quantum dots in a SiO2network were obtained using only one production step. The films were heat-treated at 100°, 125°, 150°, 175° and 200°C in an N2atmosphere. The results showed that the dimension of quantum dots changed from 2.8 nm to 3.2 nm by heat treatment. The refractive index, extinction coefficient, thickness, and dielectric coefficient values of the films were calculated. The present study showed that size and the refractive indices of films can be controlled by the heat treatment. Therefore, such films can be a good candidate in optical filter applications.

Surface etching of silicone elastomers by depolymerization

2012 ◽  
Vol 90 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Michael A. Brook ◽  
Shigui Zhao ◽  
Lihua Liu ◽  
Yang Chen
Keyword(s):  
Surface Roughness ◽  
Acid Catalysis ◽  
Silicone Elastomer ◽  
Surface Erosion ◽  
Triflic Acid ◽  
Independent Control ◽  
Silicone Elastomers ◽  
Surface Etching ◽  
Tetrabutylammonium Fluoride ◽  
Judicious Choice

Silicone elastomer surfaces that are rough at the nanometer to micron scales could be useful for biomaterials, but there are few efficient routes for their preparation. Silicones undergo depolymerization under equilibrating conditions. We demonstrate that surface roughness can be induced by depolymerizing silicone elastomers using triflic acid, tetrabutylammonium fluoride or KOH as catalysts. The efficiency of depolymerization, however, is decoupled from the roughness that develops. When the catalysts are dissolved in solvents that do not effectively swell silicones, the etching reaction can be mostly directed to the elastomer surface. Acid catalysis leads to slow, nearly homogenous surface erosion with surface roughnesses only increasing from 15 to about 125 nm root mean squared roughness. By contrast, once KOH partitions into the elastomer, the rate of erosion is more efficient than return of the catalyst to the solvent, leading to deep channels and roughnesses of up to ∼850 nm. The use of fluoride requires good solvents for silicone, and leads to surfaces of intermediate roughness. Thus, judicious choice of catalyst and solvent permits independent control over depolymerization and the induction of surface roughness.

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