Liquid Crystals LCMRC researchers have discovered that solutions in water of pieces of DNA only a few nanometers long (nanoDNA) can form liquid crystal phases if the DNA is complementary, that is if it can form double-helixed pairs. These duplex pairs then stack up end-to-end to form rod-shaped aggregates that make the liquid crystal phases. In a mixture with some DNA that is not complementary the duplex forming DNA phase separates, condensing into liquid crystal droplets. If chemistry occurs that couples the short DNA into longer chains then the condensation strongly favors the lengthening of the already complementary DNA in the liquid crystal droplets. This appears to be a mechanism whereby early forms of nucleic acids could emerge from small chemical components in the prebiotic earth.

Experiences and outcomes I have carried out research into novel materials and can begin to explain the scientific basis of their properties and discuss the possible impacts they may have on society. SCN 4-16a

Uses violet blue - happy, romantic blue - calm, relaxed green - average, not much going on with you yellow/amber - tense, excited brown/gray - nervous, anxious black - cold temperature or damaged ring

What is a liquid crystal? A state of matter that has properties between those of a conventional liquid and those of a solid crystal.  They are not a solid as they lack the long range order of a crystalline solid, They are not a liquid as liquid crystals are not isotropic like a liquid. They are an intermediate state between the solid and liquid state.

The History They were first observed by Reinitzer, an Austrian botanist, in 1888. Lehmann realised this was another state of matter and coined the name “Liquid Crystal.” 1950s Gray at Hull University rekindled interest. Pierre-Gilles de Gennes won the Nobel Prize in 1991 for his work on liquid crystals. Industries have taken off, the thermochromic liquid crystal industry and the twisted nematic liquid crystal displays. Interest was low as no commercial applications sprung to mind. Reinitzer turned for help to the German physicist Otto Lehmann, who was an expert in crystal optics. Lehmann became convinced that the cloudy liquid had a unique kind of order. The 1991 Nobel Prize in Physics was awarded to Professor Pierre-Gilles de Gennes, College de France, Paris, France for discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymer.

The liquid crystal phase changes Nematic Molecules parallel but not in layers T2º T3º T1º Smectic Molecules parallel and in layers Solid crystal Isotropic liquid Cholesteric Molecules in helical layers

Privacy control at the flick of a switch Rapid detection and measurement of chemical and biological substances using liquid crystals Window switch off light scattered cannot see through translucent but lets light through. Switch on the window becomes clear and you can see through it. http://www.consumerenergycenter.org/home/windows/windows_future.html http://www.platypustech.com/technology.html sensor technology is the characteristic of liquid crystals (LCs) to align in a preferred direction on a chemically or biologically functionalized surface and their ability to change that orientation in response to a chemical or biological event (see Figure 1). This phenomenon is similar in principle to the reorientation of LCs in high resolution displays (LCDs) that occur in response to changes in an electric field. We are developing LC sensors that can be configured to provide a rapid optical or electronic response to the presence of a target molecule. Privacy control at the flick of a switch

Liquid crystals enable surface temperatures to be measured. Liquid crystals are used in medicine Liquid crystals enable surface temperatures to be measured.

There are different types of liquid crystals http://nobelprize.org/educational_games/physics/liquid_crystals/chrystallite/ In the so-called twisted nematic (or TN) display, the molecules are arranged in this way. More specifically, the glass surfaces are treated such that the molecular direction is parallel to the admitting direction of each neighbouring polarizer. Because these directions are crossed, the molecular direction is confined to a 90° twist from one side of the cell to the other (see figure).

How a calculator display works It has a mirror (A) in back, which makes it reflective. Then, we add a piece of glass (B) with a polarizing film on the bottom side, and a common electrode plane (C) made of indium-tin oxide on top. A common electrode plane covers the entire area of the LCD. Above that is the layer of liquid crystal substance (D). Next comes another piece of glass (E) with an electrode in the shape of the rectangle on the bottom and, on top, another polarizing film (F), at a right angle to the first one.

The structure of the liquid crystals changes as they are heated. HOT COLD Cholesteric liquid crystals contain mixtures of molecules that align in layers. Stacks of layers are rotated with respect to one another similar to DNA, spiral staircases, or screw threads. The rotation between layers increases with temperature. A colour will be reflected when the pitch, the distance between layers that have the same orientation, is approximately equal to the colour's wavelength of light. Since the pitch changes with temperature, the colour changes with temperature. http://www-outreach.phy.cam.ac.uk/camphys/xraydiffraction/xraydiffraction_exp.htm The structure of the liquid crystals changes as they are heated.

Thin film behaviour Liquid crystals have two main phases which are called the "nematic phase" and the "smectic phase."The nematic phase is the simplest of liquid crystal phases and is close to the liquid phase. The molecules float around as in a liquid phase, but are still ordered in their orientation. When the molecules are chiral* and in the nematic phase, they arrange themselves into a strongly twisted structure that often reflects visible light in different bright colors which depend on the temperature. They can therefore be used in temperature sensors (thermometers). This special case of a nematic is often called cholesteric. The name is historic as it goes back to the substances on which Reinitzer made his discovery. The nematic phase is the simplest of liquid crystal phases and is close to the liquid phase. The molecules float around as in a liquid phase, but are still ordered in their orientation. When the molecules are chiral* and in the nematic phase, they arrange themselves into a strongly twisted structure that often reflects visible light in different bright colors which depend on the temperature. They can therefore be used in temperature sensors (thermometers). This special case of a nematic is often called cholesteric. The name is historic as it goes back to the substances on which Reinitzer made his discovery.

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Melting points Cholesteryl pelargonate 74ºC – 77ºC Cholesteryl benzoate 148ºC - 150ºC Cholesteryl oleyl carbonate (not available) The melting point of a mixture is less than that of the pure substance so once the chemicals have been melted to form the liquid crystal the melting point is much less than 100ºC

Make your own liquid crystals