Optical materials

Optical materials are transparent materials from which optical lenses, prisms, windows, waveguides, and second-surface mirrors can be made. They are required in most optical instruments. Most optical materials are rigid solids, but flexible and elastic materials are used for special functions. Contained liquids can also be used as optical materials. Known optical materials include amorphous materials and crystalline materials: Glass Plastics Polycarbonate Poly(methyl methacrylate) Sodium chloride Strontium fluoride Synthetic diamond Zinc sulfide Optical materials useful with infrared light include: Silicon (1.2–7 μm) Zinc selenide Non-linear optical materials or nonlinear media transform light in various ways in nonlinear optics. Non-linear optical materials include: Barium borate Some materials (optical and non-optical) can be made into first-surface mirrors, by silvering them or plating them with metal. Some metals can be highly polished, providing both support and the reflective surface of first-surface mirrors.

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Catégories associées (5)

Concepts associés (3)

Publications associées (6)

Angle de Brewster

vignette|upright=1.5|Résultat d'une simulation électromagnétique réalisée avec le programme Moosh montrant un faisceau réfracté à l'incidence de Brewster par un dioptre entre deux milieux d'indice et . L'angle de Brewster est un angle d'incidence particulier pour lequel la lumière réfractée et réfléchie possèdent des propriétés de polarisation particulières. Lorsqu'un faisceau lumineux est incident sur un dioptre à cet angle, s'il est polarisé dans le plan d'incidence (polarisation dite p ou TM) il est alors totalement transmis (pas de réflexion), sinon il y aura un faisceau réfléchi qui sera entièrement polarisé.

Optical properties

The optical properties of a material define how it interacts with light. The optical properties of matter are studied in optical physics, a subfield of optics. The optical properties of matter include: Refractive index Dispersion Transmittance and Transmission coefficient Absorption Scattering Turbidity Reflectance and Reflectivity (reflection coefficient) Albedo Perceived color Fluorescence Phosphorescence Photoluminescence Optical bistability Dichroism Birefringence Optical activity Photosensitivity A basic distinction is between isotropic materials, which exhibit the same properties regardless of the direction of the light, and anisotropic ones, which exhibit different properties when light passes through them in different directions.

Matière molle

La matière molle rassemble des états de la matière ou des matériaux connaissant une réponse forte pour un très faible signal de commande. Par exemple, les cristaux liquides : des molécules présentes dans une fine pellicule de l'écran sont réorientées par application d'une très faible tension électrique. La matière molle est un domaine de recherche à l'interface entre la physique, chimie, et biologie qui s'intéresse à l'étude de systèmes physico-chimiques très variés, que l’on appelle aussi « fluides complexes ».

Mechanical Reinforcement of Hydrogels through Physical Crosslinks and Double Network Granular Architecture

Alvaro Lino Boris Charlet

Throughout nature, organisms fabricate a myriad of materials to sustain their lifestyle. Many of the soft materials are composed of water-swollen networks of organic molecules, so-called hydrogels. They generally contribute to the mechanical integrity of the organism, and act as scaffolds for living cells. The ability to fabricate synthetic hydrogels that mimic their natural counterparts would greatly benefit the biomedical field. In particular, synthetic hydrogels have the potential to revolutionize tissue engineering and to enable the fabrication of functional load-bearing soft implants. However, available hydrogels suffer from poor mechanical properties, as they are either too brittle or too soft. While great effort in the field of soft matter has been devoted to the development of hydrogels with improved mechanical properties, they are often not compatible with state-of-the art manufacturing techniques such as additive manufacturing.In this thesis, I present the mechanical reinforcement of hydrogels using two distinctive strategies, and demonstrate their potential as 3D printable materials. I first investigate the use of high functionality crosslinks in metal-coordinated hydrogels. I show that this crosslinking strategy greatly improves the solid-like mechanical properties of viscoelastic gels. I then present the use of hydrogel microparticles to fabricate double network granular hydrogels. I discovered that these materials exhibit an extraordinarily high strength and toughness. Furthermore, the jammed microparticle precursor ink enables the extrusion and 3D printing of this material. This allows the fabrication of hydrogels with locally varying compositions, which can be utilized for example to design stimuli responsive materials. I leverage the granular structure to design recyclable double network granular hydrogels. This is achieved by forming a percolating network that has reversible covalent bonds. I show that this method can be extended to the fabrication of degradable hard plastics. Finally, I conclude by presenting the key findings, and I present a few possible follow-up ideas to further develop the field of load-bearing hydrogels.

EPFL2022

Recycling of Load-Bearing 3D Printable Double Network Granular Hydrogels

Esther Amstad, Matteo Hirsch, Alvaro Lino Boris Charlet, Sanjay Phileas Schreiber

Sustainable materials, such as recyclable polymers, become increasingly important as they are often environmentally friendlier than their one-time-use counterparts. In parallel, the trend toward more customized products demands for fast prototyping methods which allow processing materials into 3D objects that are often only used for a limited amount of time yet, that must be mechanically sufficiently robust to bear significant loads. Soft materials that satisfy the two rather contradictory needs remain to be shown. Here, the authors introduce a material that simultaneously fulfills both requirements, a 3D printable, recyclable double network granular hydrogel (rDNGH). This hydrogel is composed of poly(2-acrylamido-2-methylpropane sulfonic acid) microparticles that are covalently crosslinked through a disulfide-based percolating network. The possibility to independently degrade the percolating network, with no harm to the primary network contained within the microgels, renders the recovery of the microgels efficient. As a result, the recycled material pertains a stiffness and toughness that are similar to those of the pristine material. Importantly, this process can be extended to the fabrication of recyclable hard plastics made of, for example, dried rDNGHs. The authors envision this approach to serve as foundation for a paradigm shift in the design of new sustainable soft materials and plastics.

WILEY-V C H VERLAG GMBH2022

Nature-inspired Circular-economy Recycling (NaCRe) for Proteins

Simone Giaveri

Since a few decades our planet has been loaded with billion tons of synthetic polymer-based materials, commonly named plastics. The large scale of plastic production, associated with its limited recyclability, are the driving force for the accumulation of such materials into the environment. Garbage patches, i.e. islands of plastics in the ocean, are striking evidences of this issue. A sustainable handling, that is production and disposal, of synthetic polymer-based materials is one of the greatest challenges that humanity has to face.Proteins and nucleic acids are natural polymers. Arguably, Nature produces an amount of such polymers that is higher with respect to man-made polymers. However, these materials do not accumulate into the environment, that is the approach used by Nature to handle these polymers is sustainable. The secret for its sustainaibility lies on the circularity in the materialsâ use. Indeed, proteins and nucleic acids are sequence-defined polymers that undergo depolymerization to monomers, and recycling into new materials by reassembling the so obtained monomers into arbitrarily different sequences. Organisms digest proteins into amino acids. These monomers are in turn polymerized to produce the protein of need, at the time of the protein synthesis.In this thesis we show that this process is achievable outside living organisms. Indeed, we depolymerized structurally different short peptides, and peptides mixtures into their constitutive amino acids, and recycled such monomers into biotechnologically relevant proteins (green, and red fluorescent proteins), by using an amino acid-free cell-free transcription-translation system. We further applied our methodology to recycle proteins with high relevance in materials engineering such as Î²-lactoglobulin films, used for water filtration, or silk fibroin solutions into green fluorescent protein. We were also successful in recycling mixtures composed of short peptides, and technologically relevant proteins into fluorescent proteins, as well as into bioactive enzymes (catechol 2,3-dioxygenase). Finally, we achieved multiple cycles of recycling (two cycles), and we demonstrated that the strategy can be expanded beyond the set of the twenty proteinogenic amino acids.Presented herein is a nature-inspired approach to recycling of soft materials, where unknown mixtures of polymers are recycled into the polymer of need, by the local community, at the time of recycling. The materials are costantly transformed into different ones, without any external feed, and there is no way to distinguish a new polymer from a recycled one. The strength of this method lies in its compatibility with the principles of circular economy.

EPFL2021

Polarisation (optique)

La polarisation est une propriété qu'ont les ondes vectorielles (ondes qui peuvent osciller selon plus d'une orientation) de présenter une répartition privilégiée de l'orientation des vibrations qui les composent. Les ondes électromagnétiques, telles que la lumière, ou les ondes gravitationnelles ont ainsi des propriétés de polarisation. Les ondes mécaniques transverses dans les solides peuvent aussi être polarisées. Cependant, les ondes longitudinales (telles que les ondes sonores) ne sont pas concernées.

Optique

L'optique est la branche de la physique qui traite de la lumière, de son comportement et de ses propriétés, du rayonnement électromagnétique à la vision en passant par les systèmes utilisant ou émettant de la lumière. Du fait de ses propriétés ondulatoires, le domaine de la lumière peut couvrir le lointain UV jusqu'au lointain IR en passant par les longueurs d'onde visibles. Ces propriétés recouvrent alors le domaine des ondes radio, micro-ondes, des rayons X et des radiations électromagnétiques.

Physique

La physique est la science qui essaie de comprendre, de modéliser et d'expliquer les phénomènes naturels de l'Univers. Elle correspond à l'étude du monde qui nous entoure sous toutes ses formes, des lois de ses variations et de leur évolution. La physique développe des représentations du monde expérimentalement vérifiables dans un domaine de définition donné. Elle produit plusieurs lectures du monde, chacune n'étant considérée comme précise que jusqu'à un certain point.