They work because liquid crystallinity, a structure in which the molecules are packed regularly be aligned without

Many people are familiar with the idea that our television screens are "LC" (LCD) displays - but what exactly are liquid crystals? And how they relate why the soap is effective in cleaning us? If you know a liquid (key properties include flows and changes shape to fit the container in which it is located), and have a memory of copper sulphate crystals at the bottom of a test tube over chemistry at school, the idea of ??a liquid crystal may seem a little strange. It is, however, a well-defined state of matter that sits comfortably between the liquid crystal and its underlying molecular packing. In fact, it should be states of matter: there are a number of phases that are eligible under the "liquid crystal" banner

In a crystal, the atoms or molecules sit in well-defined positions on a regular grid, the pattern is repeated throughout the sample more like the model in many types of wallpaper. The symmetry of the network is important in many situations and experiences can be revealed by X-ray diffraction - the kind of experiences that have been historically important in revealing the structure of DNA. (You can check the symmetry of your wallpaper too, if you have nothing better to do, but you can do it with your own eyes.) In contrast, the atoms / molecules in a liquid are randomly distributed position "disorder", but with a characteristic distance between neighboring half.

So in this sense is a liquid crystal between these two structures? In a liquid crystal phase, molecules (and still are molecules, for reasons that will become apparent later) do not sit in a regular grid, but another type of symmetry - they all have the same orientation. These molecules exhibiting liquid crystallinity have their own internal asymmetry, whose type is easier to imagine a bar, but could also be disks, for example. This is why individual atoms can not form such phases.

If you take a lot of pens and pencils isolated - rod-like objects - on a table and push them together, at some point you have to queue or slides on top of the other. The structure with two dimensional plane is a type of aligned liquid crystalline phase in which there is an orientational order, as if the feathers have been subjected to a phase transition of the liquid phase in the course allowing any orientation . Although in practice it is usually spoken of three-dimensional structures, the alignment of molecular axes all (or feathers ") roughly the same direction characterized the liquid phase single crystal, known as a nematic.

were discovered in Germany in the 19th century by its appearance in polarized light (as shown in the picture), but nobody realized they were more an intellectual curiosity more good for another 50 years. They are useful in the sample due to their alignment may be enabled and disabled by an electric field, which allows each pixel on a screen to be handled separately. Get large areas of these screens to work perfectly with low power consumption and high contrast are technological issues. Physics and basic chemistry (requirement molecules) has been known for many years soap molecules are a little more complicated. Its history is also significantly longer with early versions dating from Egypt at least a couple of millennia before Christ, but they have become much more sophisticated over the centuries. They consist mainly of fat is reacted with a strong alkaline solution. In medieval times it was an animal fat such as tallow, treated with a solution of potash. This reaction leads to a molecule with a hydrophilic ("water-loving") head attached to a hydrophobic ("water-resistant") and relatively long queue, the queue or, more generally, the gallows. The rest comes from fat - which can be derived from animal or vegetable sources:. Palmolive soap was so named because it contained a mixture of palm oil and olive

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