RotaxaneUn rotaxane est une molécule constituée d'un macrocycle lié mécaniquement à un fragment moléculaire linéaire qui le traverse de part en part. Le nom est dérivé du latin rota signifiant roue et du mot axe. Les deux constituants d'un rotaxane sont cinétiquement piégés par des « bouchons » aux extrémités de l'axe, plus gros que le diamètre interne du cycle. Ainsi les deux composants du rotaxane ne peuvent se dissocier sans rupture d'une liaison covalente, car cette dissociation nécessiterait de trop grandes distorsions des liaisons du cycle.
Applications of nanotechnologyThe applications of nanotechnology, commonly incorporate industrial, medicinal, and energy uses. These include more durable construction materials, therapeutic drug delivery, and higher density hydrogen fuel cells that are environmentally friendly. Being that nanoparticles and nanodevices are highly versatile through modification of their physiochemical properties, they have found uses in nanoscale electronics, cancer treatments, vaccines, hydrogen fuel cells, and nanographene batteries.
Self-assembly of nanoparticlesNanoparticles are classified as having at least one of three dimensions be in the range of 1-100 nm. The small size of nanoparticles allows them to have unique characteristics which may not be possible on the macro-scale. Self-assembly is the spontaneous organization of smaller subunits to form larger, well-organized patterns. For nanoparticles, this spontaneous assembly is a consequence of interactions between the particles aimed at achieving a thermodynamic equilibrium and reducing the system’s free energy.
NanosheetA nanosheet is a two-dimensional nanostructure with thickness in a scale ranging from 1 to 100 nm. A typical example of a nanosheet is graphene, the thinnest two-dimensional material (0.34 nm) in the world. It consists of a single layer of carbon atoms with hexagonal lattices. Silicon nanosheets are being used to prototype future generations of small (5 nm) transistors. Carbon nanosheets (from hemp) may be an alternative to graphene as electrodes in supercapacitors. The most commonly used nanosheet synthesis methods use a bottom-up approach, e.
In situ electron microscopyIn situ electron microscopy is an investigatory technique where an electron microscope is used to watch a sample's response to a stimulus in real time. Due to the nature of the high-energy beam of electrons used to image a sample in an electron microscope, microscopists have long observed that specimens are routinely changed or damaged by the electron beam. Starting in the 1960s, and using transmission electron microscopes (TEMs), scientists made deliberate attempts to modify materials while the sample was in the specimen chamber, and to capture images through time of the induced damages.
Mechanically interlocked molecular architecturesIn chemistry, mechanically interlocked molecular architectures (MIMAs) are molecules that are connected as a consequence of their topology. This connection of molecules is analogous to keys on a keychain loop. The keys are not directly connected to the keychain loop but they cannot be separated without breaking the loop. On the molecular level, the interlocked molecules cannot be separated without the breaking of the covalent bonds that comprise the conjoined molecules; this is referred to as a mechanical bond.
NanotopographyNanotopography refers to specific surface features which form or are generated at the nanoscopic scale. While the term can be used to describe a broad range of applications ranging from integrated circuits to microfluidics, in practice it typically applied to sub-micron textured surfaces as used in biomaterials research. Several functional nanotopographies have been identified in nature. Certain surfaces like that of the lotus leaf have been understood to apply nanoscale textures for abiotic processes such as self-cleaning.
ValleytronicsValleytronics (from valley and electronics) is an experimental area in semiconductors that exploits local extrema ("valleys") in the electronic band structure. Certain semiconductors have multiple "valleys" in the electronic band structure of the first Brillouin zone, and are known as multivalley semiconductors. Valleytronics is the technology of control over the valley degree of freedom, a local maximum/minimum on the valence/conduction band, of such multivalley semiconductors. The term was coined in analogy to spintronics.
Matériau bidimensionnelUn matériau bidimensionnel, parfois appelé matériau monocouche ou matériau 2D, est un matériau constitué d'une seule couche d'atomes ou de molécules. Depuis l'isolement du graphène (une seule couche de graphite) en 2004, beaucoup de recherches ont été réalisées pour isoler d'autres matériaux bidimensionnels en raison de leurs caractéristiques inhabituelles et pour une potentielle utilisation dans des applications telles que le photovoltaïque, les semi-conducteurs et la purification de l'eau.
NanofibresLes nanofibres sont des fibres dont le diamètre est de l'ordre du nanomètre. Elles peuvent être créées à partir de différents polymères, et auront donc des propriétés physico-chimiques et des applications différentes en fonction du polymère. Parmi les polymères qui se prêtent à la réalisation de nanofibres, certains sont d'origine naturelle (collagène, cellulose, kératine, chitosane), d'autres d'origine synthétique (acide polylactique, polycaprolactone, polyuréthane, éthylène-acétate de vinyle).
