Brief introduction of liquid crystal materials
With the gradual understanding of liquid crystal, it is found that liquid crystal substances are basically organic compounds, and one out of every 200 existing organic compounds is liquid crystal phase.
Liquid crystal materials for display are composed of many kinds of small molecular organic compounds, which have developed into many kinds, such as various benzonitrile, ester, cyclohexyl (biphenyl) benzene, oxygen-containing heterocyclic benzene, pyrimidine ring, diphenylacetylene, ethyl bridge bond, alkenyl end group and various rings containing fluorobenzene.
Second, the classification of liquid crystal materials
People usually divide liquid crystals into lyotropic liquid crystals and thermotropic liquid crystals according to their formation conditions.
1? Lyotropic liquid crystal
When some organic substances are put into a solvent, the liquid crystal formed by the solvent destroying the crystal lattice is called lyotropic liquid crystal. Such as simple fatty acid salts, ionic and nonionic surfactants, etc.
Lyotropic liquid crystal widely exists in nature and organisms, and is closely related to life, but it has not been applied in display.
2? Thermotropic liquid crystal
Thermotropic liquid crystal is a liquid crystal phase that appears due to temperature change. It is a crystal structure at low temperature and becomes a liquid at high temperature. The temperature here.
Marked by melting point (Tm) and clarification point (Tc). Liquid crystal single molecule has its own melting point and clearing point, and exists in the form of liquid crystal at medium temperature. At present, the liquid crystal materials used for display are basically thermotropic liquid crystals. According to the molecular arrangement structure of thermotropic liquid crystals, they can be divided into three categories: smectic phase, nematic phase and cholesteric phase.
Three, the main classification of liquid crystal materials for LCD.
(1)TN: calculators, electronic watches, instruments, watch dials, telephones, fax machines and household appliances.
(2)HTN: game machines, rice cookers, early education machines and vehicle-mounted systems.
(3)STN: mobile phone, MP4, MP3, electronic dictionary, PDA.
(4)TFT: rear projection TV, computer, mobile phone? , car navigator
Fourthly, the application of liquid crystal materials.
. 1? Application of liquid crystal in life
In life, the most common application of liquid crystal is liquid crystal display. Now, it has been widely used in watches, calculators, clocks, telephones, cameras, office equipment, personal computers, thermometers, pocket TVs, car dashboards and other equipment. Some color-changing windows also use liquid crystal materials.
(1) laptop LCD screen
(2) Forehead thermometer (liquid crystal color-changing thermometer) Liquid crystal thermometer: It can test the temperature safely and accurately, including body temperature, water temperature, gas and various solid surfaces. Suitable for testing the temperature of milk bottles, wine bottles, drinks, refrigerators, kettles, fish tanks, water tanks, indoors, cars and so on.
2? Liquid crystal biology ―― a new interdisciplinary subject.
In short, biological tissue must be hard enough to make it function normally; And there must be enough liquidity to enable all necessary processes to be carried out. This delicate balance can be achieved through the night scene structure. The wonderful properties of liquid crystals are undoubtedly important for many biological processes. In some fields of biology, researchers began to question the physical state of important molecules, hoping to find important new ideas to explain how organisms achieve necessary functions. Liquid crystal, a wonderful substance in nature, has become the new favorite of these researchers.
3? Liquid crystal for gas detection
Liquid crystals are more sensitive to gas and steam pollution than oxygen, nitrogen and inert gases. It can record the concentration of harmful gas, accurately determine the leakage location and ensure safety. The sensitivity of measurement can reach several parts per million. This is of great value to environmental protection monitoring. For example, cholesteric liquid crystals can display different colors for different organic solvent gases.
4? Diagnosis of superficial tumors
Using a black film coated with cholesteric liquid crystal and sticking it on the skin in the focus area, the color temperature change diagram with the temperature less than one degree can be displayed. Using liquid crystal to diagnose tumor, arterial thrombosis and venous tumor, to provide the exact location of operation, and to judge whether the nervous system and vascular system are open according to the change of skin temperature and the blockage of sympathetic nervous system. Liquid crystal in 0 ~ 250? It is very sensitive to the temperature change between℃ and℃, and the liquid crystal of the selected mixture can display 1 ~ 5? Full spectrum of temperature change between℃, even if it is less than 0 125? You can also clearly see the temperature change of℃.
The previous small series comprehensively introduced the application of liquid crystal materials in all aspects and the different classification of liquid crystal materials. I think everyone must have a deeper understanding of liquid crystal materials. Students who study electronic communication may be familiar with it and it is not difficult to understand it. After reading these introductions, other students have at least learned more about the functions of liquid crystal materials.