Éthylène glycol

Résumé

L'éthylène glycol ou glycol ou encore éthane-1,2-diol est le plus simple composé chimique de la famille des glycols. Sa formule semi-développée est et sa formule brute . L'éthylène glycol est fréquemment employé en tant qu'antigel, dans le liquide de refroidissement des automobiles. À température ambiante, c'est un liquide visqueux incolore et sans odeur, avec un goût sucré. L'éthylène glycol est toxique et son ingestion nécessite des soins médicaux urgents. Nom « Éthane-1,2-diol » est le nom systématique défini par la nomenclature des composés organiques pour une molécule avec deux atomes de carbone (préfixe éth-) ayant une liaison simple entre eux (suffixe -ane) et attaché à deux groupes hydroxyle sur chacun des deux carbones (suffixe -1,2-diol). « Éthylène glycol » est l'appellation triviale communément utilisée pour l'éthane-1,2-diol. Histoire L'éthylène glycol est synthétisé pour la première fois en 1859 par le chimiste français Charles Adolphe Wurtz via

Source officielle

https://fr.wikipedia.org/wiki/%C3%89thyl%C3%A8ne_glycol

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (100)

Publications associées

Chargement

Personnes associées (41)

, , , , , , , , ,

Afficher plus

Personnes associées

Chargement

Unités associées (10)

Afficher plus

Unités associées

Chargement

Concepts associés (64)

Concepts associés

Chargement

Cours associés (32)

Cours associés

Chargement

Séances de cours associées (49)

Afficher plus

Séances de cours associées

Chargement

Preparation and characterization of Poly(Ethylene Glycol)/gamma-CD Polyrotaxanes using beta-CD derivatives as a capping reagent

Blaise Tardy

As living systems understanding got better, as life could be modeled in a batch, using immortalized cells, researches in fundamental sciences found startling applications of advanced techniques on living systems. As the biomaterial field developed various molecules were found to have very interesting applications on living systems. Polyrotaxane is one of these particularly interesting molecules. It is a non covalently bonded molecular necklace produced by the threading of cyclic molecules onto a linear polymer in order to form a pseudopolyrotaxane, the capping of this pseudopolyrotaxane to avoid de-threading of the cyclic compounds forms a polyrotaxane. This compound has already proven its versatility through various application including drug delivery systems, DNA delivery agent, molecular machine, hydrogel building block, resin stabilizer and a lot more. Cyclodextrins (CDs) and Polyester are known to form a pseudopolyrotaxane. CDs are composed of 6 to 8 glucopyranose forming a toroid shaped molecule that can contain different molecules depending on the solvent, experimental conditions and the number of sugar subunits. In this project an attempt has been made to synthesize a special type of polyrotaxane that would allow the whole complex to bare a higher degree of freedom compared to the ones currently documented. In order to do so the widest CD has been used (Gamma-CD, GCD), the chosen host has been poly(ethylene glycol) (PEG) chains of varying molecular weight and the capping reagent used was beta-CD derivatives. Furthermore since current literature hasn't documented it so well and its properties are essential to this study, some more characterization of the PEG/GCD pseudopolyrotaxane has been made. The Macromolecules have been characterized by maldi tof mass spectroscopy(MALDI-T-MS), electro spray ionization (ESI) mass detection, X-ray diffraction(XRD), gel phase chromatography (GPC) and liquid Nuclear magnetic resonance (NMR). The beta CD and poly(ethylene glycol) derivatives have been characterized using Fourier transform infra red spectroscopy (FTIR), NMR, MALDI-Toff MS, ESI and thin layer Chromatography (TLC)

2009

Chargement

Life cycle assessment of bio-based synthetic fibers: the case of polyester substitutes

Tijana Ivanovic

Numerous studies have shown that the textile sector has a high fossil-fuel dependency, emits excessive amount of greenhouse gases and uses vast amount of water. Currently, polyester (fossil-based) makes up about a half of the industry's fiber production and the volumes are expected to increase. Polyester fiber is traditionally made out of polyethylene terephthalate (PET) polymer. In order to break from the fossil-fuel dependency, textile industry has the possibility to use alternative feedstock for the polyester by reverting to bio-sourcing – strategy where the product's carbon backbone comes partially or fully from the bio-based feedstock. The polyester fiber can be entirely substituted in its current uses by three such bio-based substitutes: bio-based PET fiber as a drop-in substitute (chemically identical to the fossil counterpart); polytrimethylene terephthalate (PTT) fiber as an intra-family substitute with properties comparable to PET fiber and nylon; and polylactic acid (PLA) fiber as a novel fiber without a fossil counterpart and with properties comparable to PET fiber. All of these fibers are produced from the homonymous polymers via melt spinning and their carbon backbone comes partially or entirely from bio-based feedstock. The environmental effects of this feedstock substitution have not been studied abundantly, in spite of the existing political will to prioritize bio-based products, e.g. as the European Green Deal does. This project therefore performs a comparative, cradle-to-gate life cycle assessment of the conventional polyester fiber and these substitutes taking into account state-of-the-art production process. In order to do so Life cycle inventories (LCI) were modelled for 6 different scenarios for bio-based PET, 2 for bio-based PTT and 1 for PLA and were based on public literature and ecoInvent data. Impact assessment was performed by applying two methods – Swiss Ecological Scarcity and European Environmental Footprint, representative of the Swiss environmental policy and of a more scientific classification of environmental and health impacts respectively. The study finds that all three bio-based fibers are produced from the first-generation feedstock (crops). Currently, only the partially bio-based PET and PTT polymers are commercialized, such that the prevailing monomer, purified terephthalic acid (PTA) remains fossil-based for both. Then, monoethylene glycol (MEG) is produced from sugarcane or corn and 1,3-propanediol (PDO) from corn respectively. PLA is a fully bio-based polymer, produced from corn. Bio-sourcing for polyester is found to offer a limited improvement in a small number of impacts (with negligible contribution to the overall score) while causing substantial additional environmental burdens elsewhere (per kg of fiber). Namely, none of the bio-based alternatives perform better than the fossil-based PET fiber on the overall score. However, the partially bio-based PTT fiber may be a viable substitute for nylon (based on lower overall score). In the absence of carbon crediting for bio-based feedstock, climate impacts are found to be worse for the alternatives than the conventional polyester. Eutrophication, acidification, water scarcity impacts and land use rise with fiber's bio-content and largely stem for the agricultural practices (up to 88%, 74%, 97% and 100% respectively). It was also seen that PTA necessitates more precise modeling to raise the certainty of conclusions for the respective fully bio-based PET and PTT scenarios. At this stage, bio-based alternatives have a worse environmental performance than fossil-based polyester. The environmental performance of the bio-based fibers may be increased with alternative feedstock options or with improved agricultural practices.

2020

Chargement

Load-bearing tissues such as articular cartilage or meniscus are not infallible. They might fail due to trauma, over-solicitations, or diseases, which could subsequently alter the mobility of the patient. Repairing these damaged tissues in a minimally invasive way is nowadays widely studied. Hydrogels are promising for repairing soft tissues. However, trying to reproduce the highly hierarchical microstructures of load-bearing tissues is extremely complicated. In fact, conceiving hydrogels with optimal properties for specific applications is challenging as most of the hydrogel's properties are interrelated, such as toughness, stiffness, swelling, or deformability. The improvement of one property usually comes at the cost of another. This thesis aims to develop different hydrogel microstructures and evaluate their potential for load-bearing implants. In particular, the study focuses on (i) designing tough and fatigue resistant hydrogels, (ii) establishing a methodology to control the stiffness and the swelling of hydrogels independently, and (iii) considering processing ease by tailoring each hydrogel precursor viscosity. An extensive parametric study on hydrogels' structure and composition allowed establishing complete property charts for mechanical, swelling, and rheological properties. Seven different hydrogel structures based on poly(ethylene glycol) dimethacrylate were developed: neat, double network, composite, double network composite, granular, hybrid granular, and silk granular hydrogels. The precursors of neat hydrogels had the lowest viscosity. Microgels of similar composition were added to the precursor to adapt and increase its viscosity for unconfined applications. In parallel, adding nano-fibrillated cellulose fibers was effective for increasing toughness. This method was more efficient than creating a double network with alginate. Moreover, fatigue tests revealed that hydrogel composites successfully survive 10 million loading cycles at 20% applied strain. However, it became softer after the first loading cycles and behaved similarly to the Mullins effect. Subsequently, we assessed how cyclic loading affects fracture behavior, distribution of strain fields, and microstructure. The study demonstrated that cyclic loading on hydrogel composites re-arrange the fiber network without seriously deteriorating the mechanical properties. Additionally, we demonstrated that combining composite and microgel approaches, i.e. hybrid granular hydrogels, effectively tailored hydrogels' swelling and viscosity without significantly affecting stiffness, toughness, and deformability. Finally, the microgels were swollen in silk fibroin solution for forming self-reinforced silk granular hydrogels. Those hydrogels exhibited considerably higher stiffness and lower swelling but also reduced elongation performances. We demonstrated that hydrogels' mechanical and physical properties could be effectively controlled with the microstructures and compositions of well-known biomaterials. Subsequently, a hydrogel composite and a silk granular hydrogel, based this time on gelatin hydrogels, were synthesized, validating the potential of studied structures with other hydrogels and microgels. Finally, the analyzed material systems can be combined through a sequential layering, forming hybrid hydrogels, to obtain local or gradient properties addressing specific biomedical applications, soft robotics, sensing applications, or even food packaging.

EPFL2021

Chargement

Preparation and characterization of Poly(Ethylene Glycol)/gamma-CD Polyrotaxanes using beta-CD derivatives as a capping reagent

Blaise Tardy

2009

Life cycle assessment of bio-based synthetic fibers: the case of polyester substitutes

Tijana Ivanovic

2020

EPFL2021