The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
François Ganachaud - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of Surface and Bulk Properties of Pendant and Hybrid FluoroSilicones
Silicone Surface Science, 2012Co-Authors: C Pasquet, Siska Hamdani-devarennes, Claire Longuet, 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.
-
Comparison of Surface and Bulk Properties of Pendant and Hybrid FluoroSilicones
2012Co-Authors: C Pasquet, Siska Hamdani, Claire Longuet, Bruno Ameduri, François GanachaudAbstract:This chapter aims at supplying various strategies of fluoroSilicones and the structure/property relationship. First, the "conventional" fluorosilicone are depicted and the most common one is poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS) commercialized nowadays by Dow Corning. Then various ways have thus been employed to increase the number of fluorine atoms in the materials. One elegant way of preparing these is to simply introduce in the silicone chain, either as a pendant group or inside the backbone, perfluorinated groups of increasing size (typically C6 or more). Hence, "pendant Silicones" are listed containing perfluorinated chains introduced as side groups of the silicone backbone whereas those bearying fluorine atoms into the main backbone are generally referred as "hybrid Silicones". Additionally, polymers bearing fluorinated groups both in the main chain and as pendant groups in the class of hybrid copolymers complete that chapter. In each case, the properties of such fluoropolymers and their equivalent (crosslinked) elastomers are reviewed. Particularly, a thorough comparison of the above mentioned two classes of polymers in terms of mechanical, swelling or thermal properties is lacking, especially for the hybrid fluoroSilicones. Intermediate conclusions will compare these above classes of polymers in regards with the considered property.
-
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.
Gilles Subra - One of the best experts on this subject based on the ideXlab platform.
-
direct synthesis of peptide containing Silicones a new way to bioactive materials
Chemistry: A European Journal, 2020Co-Authors: Julie Martin, Mohammad Wehbi, Cécile Echalier, Sylvie Hunger, Audrey Bethry, Xavier Garric, Coline Pinese, Jean Martinez, Lubomir Vezenkov, Gilles SubraAbstract:A simple and efficient way to synthesize peptide-containing silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si(vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active Silicones.
-
Direct Synthesis of Peptide‐Containing Silicones: A New Way to Bioactive Materials
Chemistry - A European Journal, 2020Co-Authors: Julie Martin, Mohammad Wehbi, Cécile Echalier, Sylvie Hunger, Audrey Bethry, Xavier Garric, Coline Pinese, Jean Martinez, Lubomir Vezenkov, Gilles SubraAbstract:A simple and efficient way to synthesize peptidecontaining silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si- (vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active Silicones.
Michael A. Brook - One of the best experts on this subject based on the ideXlab platform.
-
Controlling silicone-saccharide interfaces: greening Silicones
Green Chemistry, 2017Co-Authors: Benjamin Macphail, Michael A. BrookAbstract:Silicone elastomers, which are normally crosslinked using metal catalysts, are traditionally reinforced with mineral fillers. We report that renewable saccharides can instead be used to both crosslink and reinforce Silicones. The grafting of boronic acids to silicone polymers gives materials that, when added to aqueous solutions of mono- or polysaccharides, without catalysts, generated elastomers via the boronic acid interaction with saccharides. The efficiency of crosslinking, as shown by Young's moduli, depended strongly on the specific saccharide and the density of boronic acid groups on the silicone. Simple Silicones normally phase separate in water saccharide mixtures. However, pretreatment of silicone boronates with the saccharide phytoglycogen, followed by exposure to water, led to stable aqueous phytoglycogen/silicone dispersions (pastes). The different outcomes arising from the order of addition are attributed to better dispersion of the silicone and saccharide in the latter case. Rheological studies of the pastes showed that, unlike the elastomers, viscosities depended more on the fraction of silicone in saccharide; number of boronic acid contact points between the silicone and saccharide was only a minor contributor. The equilibrium concentration of sugar/boronate contacts, which stabilize the water/oil interfaces, remains high even at high concentrations of water and even when the specific binding constant for an individual saccharide is low.
-
Phototunable Cross-Linked Polysiloxanes
Macromolecules, 2015Co-Authors: Amanda S. Fawcett, Timothy C. Hughes, Laura Zepeda-velazquez, Michael A. BrookAbstract:Silicone elastomers are normally thermoset materials. While their inherent properties make them highly valuable, it would be of interest to develop stimuli-responsive Silicones whose properties could be reversibly tuned at will. In the case of silicone polymers, a particularly interesting trigger is light, since silicone elastomers can readily be formulated to be transparent. We describe the utilization of coumarin-modified Silicones for this purpose. On their own, the presence of coumarin groups converts silicone oils into thermoplastic elastomers through physical (noncovalent) cross-linking. UV-irradiation permits covalent cross-linking through [2 + 2] cycloadditions and is accompanied by loss of most physical cross-links. Higher energy photons permit, in part, photoinitiated retro-cycloaddition and a subsequent decrease in covalent cross-link density. It is thus possible to tailor the physical properties of the elastomer to increase and/or decrease the modulus of the elastomer using light and to conver...
Julie Martin - One of the best experts on this subject based on the ideXlab platform.
-
direct synthesis of peptide containing Silicones a new way to bioactive materials
Chemistry: A European Journal, 2020Co-Authors: Julie Martin, Mohammad Wehbi, Cécile Echalier, Sylvie Hunger, Audrey Bethry, Xavier Garric, Coline Pinese, Jean Martinez, Lubomir Vezenkov, Gilles SubraAbstract:A simple and efficient way to synthesize peptide-containing silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si(vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active Silicones.
-
Direct Synthesis of Peptide‐Containing Silicones: A New Way to Bioactive Materials
Chemistry - A European Journal, 2020Co-Authors: Julie Martin, Mohammad Wehbi, Cécile Echalier, Sylvie Hunger, Audrey Bethry, Xavier Garric, Coline Pinese, Jean Martinez, Lubomir Vezenkov, Gilles SubraAbstract:A simple and efficient way to synthesize peptidecontaining silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si- (vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active Silicones.
Marcelo Coelho Goiato - One of the best experts on this subject based on the ideXlab platform.
-
influence of different pigmentations and accelerated aging on the hardness and tear strength of the a 2186 and mdx4 4210 Silicones
International Journal of Dentistry, 2020Co-Authors: Estefânia Marrega Malavazi, André Pinheiro De Magalhães Bertoz, Fernanda Pereira De Caxias, Emily Vivianne Freitas Da Silva, Aldieris Alves Pesqueira, Clóvis Lamartine De Moraes Melo Neto, Lisiane Cristina Bannwart, A. Moreno, Daniela Micheline Dos Santos, Marcelo Coelho GoiatoAbstract:Objective To evaluate the influence of different pigmentations and accelerated aging on the hardness and tear strength of the A-2186 and MDX4-4210 Silicones. Materials and methods The samples A-2186 and MDX4-4210 were manufactured without and with pigmentations (black, bronze, and pink). For the Shore A hardness test, 80 samples of each silicone were fabricated, and for the tear strength test, 320 samples of each silicone were fabricated. Eight groups were created for each test (n = 10). These tests were performed before and after 252, 504, and 1008 hours of aging. Three-way repeated-measures analysis of variance and the Tukey test were performed (α = 0.05). Results The A-2186 silicone showed higher hardness and tear strength when compared with the MDX4-4210 silicone (p 0.05). All hardness values were between 25 and 35 units, regardless of the silicone type, period, and pigmentation (or no pigmentation). In most situations, the hardness of Silicones used increased after 252 hours (p 0.05). All pigmented MDX4-4210 groups showed no change in tear strength from 0 (initial) to 1008 hours of aging (p > 0.05). In all A-2186 groups, from 252 to 504 hours, there was a reduction in tear strength (p 0.05). Conclusion In most situations, the A-2186 silicone showed significantly higher values of hardness and tear strength than the MDX4-4210 silicone. All hardness values were considered clinically acceptable. Accelerated aging could increase, decrease, or not significantly change the hardness and tear strength of the Silicones used. The results of hardness and tear strength suggest that MDX4-4210 was more influenced by the presence of pigmentation after aging.
-
Biocompatibility Evaluation of 3 Facial Silicone Elastomers
Journal of Craniofacial Surgery, 2011Co-Authors: Diurianne Caroline Campos França, Alvimar Lima De Castro, Ana Maria Pires Soubhia, Sandra Maria Herondina Coelho Ávila De Aguiar, Renata Tucci, Marcelo Coelho GoiatoAbstract:Abstract The failure of facial prostheses is caused by limitations in the properties of existing materials, especially the biocompatibility. This study aimed to evaluate the biocompatibility of maxillofacial Silicones in subcutaneous tissue of rats. Thirty Wistar rats received subcutaneous implants of 3 maxillofacial silicone elastomers (LIM 6050, MDX 4-4210, and industrial Silastic 732 RTV). A histomorphometric evaluation was conducted to analyze the biocompatibility of the implants. Eight areas of 60.11 mm(2) from the surgical pieces were analyzed. Mesenchymal cells, eosinophils, and foreign-body giant cells were counted. Data were submitted to analysis of variance and Tukey test. Initially, all implanted materials exhibited an acceptable tissue inflammatory response, with tissue reactions varying from light to moderate. Afterward, a fibrous capsule around the silicone was observed. The Silicones used in the current study presented biocompatibility and can be used for implantation in both medical and dental areas. Their prosthetic indication is conditioned to their physical properties. Solid silicone is easier to adapt and does not suffer apparent modifications inside the tissues.
-
visual evaluation of color stability after accelerated aging of pigmented and nonpigmented Silicones to be used in facial prostheses
Indian Journal of Dental Research, 2009Co-Authors: Daniela Nardi Mancuso, Marcelo Coelho Goiato, Stefan Fiuza De Carvalho Dekon, Humberto GennarifilhoAbstract:Objectives: The objective of this study was to evaluate by a visual method of comparison the color stability of nonpigmented and pigmented facial Silicones after accelerated aging. Materials and Methods: Two kinds of Silicones were used in this study; one specifically formulated for facial prostheses and the other an acetic silicone for industrial use. Twenty-four trial bodies were made for each silicone. These were divided into colorless and intrinsically pigmented groups: ceramic, make-up, and iron oxide. The groups were submitted to accelerated aging for nonmetallic materials. An initial reading and subsequent readings were made at 163, 351, 692, and 1000 hours using a visual method of comparison. The values were annotated in a spreadsheet by two observers, according to scores elaborated for this study. Results: All groups presented color stability in the visual method. According to the results obtained and analyzed in this study, we can conclude that both Silicones, Silastic 732 RTV and Silastic MDX 4-4210, behaved similarly, they can therefore be indicated for use in maxillofacial prosthesis. The time factor of aging influenced negatively, independently of the pigmentation, or lack of it, and of Silicones and no group had visually noticeable alterations in any of the accelerated aging time, independently of the addition or not of pigments.
