The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
François Ganachaud - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Surface and Bulk Properties of Pendant and Hybrid FluoroSilicones
Silicone Surface Science, 2012Co-Authors: C Pasquet, Claire Longuet, Siska Hamdani-devarennes, Bruno Ameduri, François GanachaudAbstract:The most common fluoroSilicone polymer commercialized to date is polymethyltrifluoropropylsiloxane. However, the low content of is the perfluorinated groups in the polymer 36.5 wt% does not fulfill the requirements of some high tech applications, particularly when swelling properties or degradation at high temperatures are concerned. A number of strategies have been employed to increase the fluorine content of fluoroSilicone polymers. One elegant way is to introduce into the Silicone chain, either as a pendant group or inside the backbone, perfluorinated groups of increasing size (typically C6 or higher). We refer to Silicones with perfluorinated chains introduced as side groups as “pendant Silicones” whereas those carrying fluorine atoms in the main backbone are called “hybrid Silicones”. The most popular synthesis techniques of such polymers are briefly discussed here. A full fuller comparison is given of the two classes of polymers in terms of surface, mechanical, swelling and thermal properties.
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flame retardancy of Silicone based materials
Polymer Degradation and Stability, 2009Co-Authors: Siska Hamdani, Claire Longuet, Didier Perrin, Josemarie Lopezcuesta, François GanachaudAbstract:This review describes some recent works related to the development of the flame retardation of Silicone elastomers and/or applications of Silicones as flame retardant agents in other polymers. First, the thermal degradation of Silicones themselves is discussed, focussing on depolymerization mechanisms, effect of structure, heating conditions, and effect of additives (i.e. less than 5 wt% fillers) on thermal degradation of Silicones. Then, the influence of several types of mineral fillers (of up to 80 wt% content) as ceramization agents of Silicones is presented. Finally, the introduction of (functionalized) Silicones as flame retardants into other polymers is described.
Bettina Pfleiderer - One of the best experts on this subject based on the ideXlab platform.
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Determination of siloxanes, silicon, and platinum in tissues of women with Silicone gel-filled implants
Analytical and Bioanalytical Chemistry, 2003Co-Authors: Daniela Flassbeck, Bettina Pfleiderer, Patrick Klemens, Elke Eltze, Klaus G. Heumann, Alfred V. HirnerAbstract:Silicone [poly(dimethylsiloxane)] gel used in breast implants has been known to migrate through intact Silicone elastomer shells, resulting in the clinically observable "gel bleed" on the implant surface. Although silicon concentrations in capsular tissues of women with Silicone prostheses have been measured with element-specific silicon analyses, no Silicone-specific investigation of these tissues has been performed as yet. A combination of element-specific inductively coupled plasma high-resolution isotope dilution mass spectrometry (ICP-HR-IDMS) and species-specific gas chromatography coupled mass spectrometry (GC-MS) was used to analyze silicon, platinum, and siloxanes in prosthesis capsule, muscle, and fat tissues of women (n=3) who had Silicone gel-filled breast implants and in breast tissue of non-augmented women (n=3) as controls. In all tissues of augmented women, siloxanes, in particular octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were identified. Depending on the siloxane species and type of tissue analyzed, siloxane levels in the range of about 10-1,400 ng g -1 were detected; total silicon was found in all tissue samples in the range of about 8,900-85,000 ng g -1 . Higher platinum levels ranging from 25-90 ng g -1 were detected in fibrin layer and fat tissue of two patients with prostheses. No siloxanes were detected in control breast tissue samples. This investigation of human tissues by a combination of element-specific and species-specific analytical techniques clearly demonstrates for the first time that platinum and siloxanes leak from prostheses and accumulate in their surrounding tissues. © Springer-Verlag 2003.
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Determination of low molecular weight Silicones in plasma and blood of women after exposure to Silicone breast implants by GC/MS
Analytical Chemistry, 2001Co-Authors: Daniela Flassbeck, Bettina Pfleiderer, R. Grümping, A. V. HimerAbstract:A sensitive, one-step sample preparation method for detection of volatile, low molecular weight (LMW) cyclic Silicones hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in plasma and blood using gas chromatography coupled with mass spectrometry (GC/MS, SIM mode) is presented. In spiked experiments, extraction efficiencies for these siloxanes (100?20?000 ng/mL) were approximately 90% for plasma and approximately 80% for blood; only in the case of D3 was the recovery very low. Plasma and blood of women who are or were exposed to Silicone gel-filled implants and of control subjects were analyzed for low molecular weight Silicones. D3?D6 were not detectable in control plasma or blood. Although the investigated numbers of patients samples are very limited, and thus, no statistical analysis is possible, our data clearly show a general increase in the amount of LMW cyclic siloxanes in the bodies of women with Silicone implants. In particular, several years after ruptured Silicone implants were removed, siloxanes could still be found in blood samples from several women. Siloxane compound D3 varied between 6 and 12 ng/mL (plasma) and between 20 and 28 ng/mL (blood), whereas the concentration range of D4 was 14?50 ng/mL (plasma) and 79?92 ng/mL (blood). D5 and D6, with one exception, could not be detected.
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Migration and Accumulation of Silicone in the Liver of Women with Silicone Gel-Filled Breast Implants
Magnetic Resonance in Medicine, 1995Co-Authors: Bettina Pfleiderer, Leoncio GarridoAbstract:1 H NMR localized spectroscopy (STEAM), combined with echocardiography (ECG), respiratory gating, and water and fat suppression, was used to quantify Silicone concentrations in the liver of women with Silicone gel-filled breast implants. Localized spectroscopy was performed on 15 patients with Silicone gel-filled breast prostheses and on eight volunteers with no implants. The 1 H spectra in the liver of patients showed Silicone resonances from 0.3 to −0.8 ppm, attributable to protons in the methyl groups of Silicone. The presence of Silicone in the liver could first be detected 3−4 years after breast prostheses implantation. No correlation between Silicone concentrations and implantation times was observed. However, our results indicated that Silicone concentrations may reflect implant integrity: detectable Silicone concentrations in the liver appeared to be higher when the implants were ruptured than when the implants appeared intact. Moreover, new resonances in the range of −2.6 to −4 ppm were observed in most patients after long-term implantation. As these species increase with implantation time, the new resonances may reflect chemically changed Silicone (paramagnetically shifted silicon complexes bound to iron) accumulated over time. The sensitivity of 1 H NMR localized spectroscopy is sufficient to detect silicon concentrations as low as 0.20 mM. Results from one patient whose implants had been removed 14 months prior to the NMR examination showed no detectable Silicone in the liver, indicating that it may have been excreted via bile or degraded to silica and high coordinated silicon complexes. Quantitative 1 H localized spectroscopy of the liver in women with Silicone gel-filled breast implants may provide valuable information concerning Silicone accumulation and degradation in vivo, as well as about the kinetics of its elimination from the body after implant removal
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In vivo degradation of Silicones.
Magnetic Resonance in Medicine, 1993Co-Authors: Leoncio Garrido, Bettina Pfleiderer, Mikhail I. Papisov, Jerome L. AckermanAbstract:29Si nuclear magnetic resonance (NMR) spectroscopy is applied to study the degradation of polysiloxanes (Silicones) in vivo. Our results with animal models show that Silicone migrates from the implant to the liver (29Si resonance at −20 ppm) and new silicon containing compounds form after the Silicones are introduced into the rats. The new 29Si resonances in the chemical shift range of −40 to −85 ppm are related to hydrolyzed Silicone, those at −90 to −115 ppm are indicative of the presence of silica (SiO2), and the peaks observed at −120 to −150 are related to high coordinated silicon complexes. These resonances are not present in the 29Si spectra of the Silicones before implantation. Our findings demonstrate that Silicones are not metabolically inert.
Siska Hamdani - One of the best experts on this subject based on the ideXlab platform.
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flame retardancy of Silicone based materials
Polymer Degradation and Stability, 2009Co-Authors: Siska Hamdani, Claire Longuet, Didier Perrin, Josemarie Lopezcuesta, François GanachaudAbstract:This review describes some recent works related to the development of the flame retardation of Silicone elastomers and/or applications of Silicones as flame retardant agents in other polymers. First, the thermal degradation of Silicones themselves is discussed, focussing on depolymerization mechanisms, effect of structure, heating conditions, and effect of additives (i.e. less than 5 wt% fillers) on thermal degradation of Silicones. Then, the influence of several types of mineral fillers (of up to 80 wt% content) as ceramization agents of Silicones is presented. Finally, the introduction of (functionalized) Silicones as flame retardants into other polymers is described.
Brian T. Nedved - One of the best experts on this subject based on the ideXlab platform.
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Fouling-Release Performance of Silicone Oil-Modified Siloxane-Polyurethane Coatings
ACS Applied Materials and Interfaces, 2016Co-Authors: Teluka P. Galhenage, Justin Daniels, Dylan Hoffman, Samantha D. Silbert, Tatjana Miljkovic, John A. Finlay, Sofia C. Franco, Anthony S. Clare, Shane J. Stafslien, Brian T. NedvedAbstract:The effect of incorporation of Silicone oils into a siloxane-polyurethane fouling-release coatings system was explored. Incorporation of phenylmethyl Silicone oil has been shown to improve the fouling-release performance of Silicone-based fouling-release coatings through increased interfacial slippage. The extent of improvement is highly dependent upon the type and composition of Silicone oil used. The siloxane-polyurethane (SiPU) coating system is a tough fouling-release solution, which combines the mechanical durability of polyurethane while maintaining comparable fouling-release performance with regard to commercial standards. To further improve the fouling-release performance of the siloxane-PU coating system, the use of phenylmethyl Silicones oils was studied. Coatings formulations were prepared incorporating phenylmethyl Silicone oils having a range of compositions and viscosities. Contact angle and surface energy measurements were conducted to evaluate the surface wettability of the coatings. X-ray photoelectron spectroscopy (XPS) depth profiling experiments demonstrated self-stratification of Silicone oil along with siloxane to the coating-air interface. Several coating formulations displayed improved or comparable fouling-release performance to commercial standards during laboratory biological assay tests for microalgae (Navicula incerta), macroalgae (Ulva linza), adult barnacles (Balanus amphitrite syn. Amphibalanus amphitrite), and mussels (Geukensia demissa). Selected Silicone-oil-modified siloxane-PU coatings also demonstrated comparable fouling-release performance in field immersion trials. In general, modifying the siloxane-PU fouling-release coatings with a small amount (1−5 wt % basis) of phenylmethyl Silicone oil resulted in improved performance in several laboratory biological assays and in long-term field immersion assessments.
Daniela Flassbeck - One of the best experts on this subject based on the ideXlab platform.
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Determination of siloxanes, silicon, and platinum in tissues of women with Silicone gel-filled implants
Analytical and Bioanalytical Chemistry, 2003Co-Authors: Daniela Flassbeck, Bettina Pfleiderer, Patrick Klemens, Elke Eltze, Klaus G. Heumann, Alfred V. HirnerAbstract:Silicone [poly(dimethylsiloxane)] gel used in breast implants has been known to migrate through intact Silicone elastomer shells, resulting in the clinically observable "gel bleed" on the implant surface. Although silicon concentrations in capsular tissues of women with Silicone prostheses have been measured with element-specific silicon analyses, no Silicone-specific investigation of these tissues has been performed as yet. A combination of element-specific inductively coupled plasma high-resolution isotope dilution mass spectrometry (ICP-HR-IDMS) and species-specific gas chromatography coupled mass spectrometry (GC-MS) was used to analyze silicon, platinum, and siloxanes in prosthesis capsule, muscle, and fat tissues of women (n=3) who had Silicone gel-filled breast implants and in breast tissue of non-augmented women (n=3) as controls. In all tissues of augmented women, siloxanes, in particular octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were identified. Depending on the siloxane species and type of tissue analyzed, siloxane levels in the range of about 10-1,400 ng g -1 were detected; total silicon was found in all tissue samples in the range of about 8,900-85,000 ng g -1 . Higher platinum levels ranging from 25-90 ng g -1 were detected in fibrin layer and fat tissue of two patients with prostheses. No siloxanes were detected in control breast tissue samples. This investigation of human tissues by a combination of element-specific and species-specific analytical techniques clearly demonstrates for the first time that platinum and siloxanes leak from prostheses and accumulate in their surrounding tissues. © Springer-Verlag 2003.
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Determination of low molecular weight Silicones in plasma and blood of women after exposure to Silicone breast implants by GC/MS
Analytical Chemistry, 2001Co-Authors: Daniela Flassbeck, Bettina Pfleiderer, R. Grümping, A. V. HimerAbstract:A sensitive, one-step sample preparation method for detection of volatile, low molecular weight (LMW) cyclic Silicones hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in plasma and blood using gas chromatography coupled with mass spectrometry (GC/MS, SIM mode) is presented. In spiked experiments, extraction efficiencies for these siloxanes (100?20?000 ng/mL) were approximately 90% for plasma and approximately 80% for blood; only in the case of D3 was the recovery very low. Plasma and blood of women who are or were exposed to Silicone gel-filled implants and of control subjects were analyzed for low molecular weight Silicones. D3?D6 were not detectable in control plasma or blood. Although the investigated numbers of patients samples are very limited, and thus, no statistical analysis is possible, our data clearly show a general increase in the amount of LMW cyclic siloxanes in the bodies of women with Silicone implants. In particular, several years after ruptured Silicone implants were removed, siloxanes could still be found in blood samples from several women. Siloxane compound D3 varied between 6 and 12 ng/mL (plasma) and between 20 and 28 ng/mL (blood), whereas the concentration range of D4 was 14?50 ng/mL (plasma) and 79?92 ng/mL (blood). D5 and D6, with one exception, could not be detected.
