Functional polymers
Thermoplastics > Organics polymers
| Organic polymers funcionales |
| Conductive plastics |
The polymers are known historically for its properties as insulators, however , in the seventies teachers Alan MacDiarmid, J. Heeger and Alan Hideki Shirakawa discovered that certain polymers are capable of conducting electricity. The last half century has been defined as the time of the polymers and elastomers, as well as semiconductors and microelectronics. The common aspect of these functionalized polymers is the reversibility and the presence of carbon double bond and the ability to conduct electric current, without any additives or filler (such as graphite, metal powder etc.) Definition The conductive polymers are organic polymers which combine the properties of conventional polymers, such as good mechanical properties (lightness, flexibility and moldability), low cost and good processability of plastic, one of the most important properties of the metals, such as electrical conductivity, (as are good conductors that are called synthetic metals), and the optical properties of metals. To these advantages must be added, in addition, the chemical versatility of these materials, by which their properties can be modified by chemical synthesis. Chemical structura From a chemical standpoint, a functionalized polymer can be defined as a compound having specific functional groups which can participate in chemical processes without degradation. The common aspect of these functionalized polymers is the reversibility and the presence of carbon double bond conjugate, and the more double bonds have, the higher the conductivity of the polymer. The choice of chemical method and proper planning methodologies work to follow, ensure the success of the results. Applications Therefore, there have been other compounds such as polythiophenes, hipolipirroles, poliparafenilenos and poliparafenilenovinilenos already used as organic LED. The phenylenevinylene polypropylene is a conducting polymer which emits light with an electrical stimulation equal to 1.5 V over 2000 hours half life Some of these compounds appeared to be very promising in the field of electronics because of its low value of gap (up 1eV ) would have avoided the need for doping; Unfortunately, however, the three dimensional conformation of the single chain not allow overlapping π orbitals, indispensable for electrical conduction. Others, on the other hand (polyacetylene, polythiophene and polypyrrole) are not soluble and therefore are not very viable.On a practical level, the polyacetylene is not very useful because it is degraded in less than ten minutes, it is not doped homogeneously and has transverse electronic jumps; Therefore, its function remains scientific-educational, only useful to understand the mechanism driving the polymers. In addition, the polyacetylene, the inter-conducting and conducting inter-conductivity, in addition to the inter-chain conductivity, has abandoned the idea of creating cables without protective sheaths. To overcome this problem alkyl chains, for anthropic reasons, avoid this obstacle are added. Other polymers, such as polyethylenedioxythiophene, are used as antistatic films for coating the photosensitive, or other coating are invisible stealth aircraft. Other applications Actuators Two polymer films are glued together, of which only a driver; The undoped and remove material by applying current, the bending is obtained. of polymer films; Therefore, this movement can be exploited for the construction of conveyor belts. OLED They can be obtained organic light emitting diodes that can emit light only when they are in contact with different substances; currently they used as artificial noses to test wines, or the ammonia content in polystyrene containers. Its use is as analyzer temperature or biological analytes. Electronics They represent increasingly useful silicon chip competitors. Chips currently used in microtransmitter equipped with a low number of transistor, Benefits The spectacular electrical and optical properties of these polymers , of organic origin, have generated intense dedication of chemists, physicists and technologists in recent years in order to synthesize these materials, study their properties and apply industrially. There are many applications: solar cells, organic transistors, photodiodes, mobile phone screens and televisions and electromagnetic shielding small format, to name a few. |