POLYMERS

   The word polymers comes from the union of two Greek words: polys (“many”) and mere (“parts, segments”), and they were named for the first time in 1866 by Marcellin Berthelot. Many of the materials used by humanity since ancient times are polymers, such as wood, wool or silk, and from their modification it was possible to obtain more resistant and useful forms. The first fully synthetic polymer was obtained in 1907, when Dutchman Leo Hendrik Baekeland developed Bakelite from phenol and formaldehyde. However, the formal study of polymers began in 1922, when the German Hermann Staudinger determined (1926) that they were long molecular chains and began the process of their nomenclature and understanding, laying the foundations for macromolecular science. The latter would take a definitive push after the Second World War and from the second half of the 20th century a true revolution of synthetic polymers would come.

  Chemical characteristics Polymers often have the reactivity of the molecules that make up the monomers at the ends of the chains. Synthetic polymers are not very reactive, although the presence of acids and organic solvents tend to corrode them quickly.  Physical characteristics They tend to be poor conductors of electricity, which is why they are often used as insulators. It is also frequent that they present electrochromism (change of color before electricity) and in some cases phosphorescence or fluorescence. Polymers are usually crystalline in cases of more ordered structures, although their presentation can be very varied. At low temperatures they can acquire more hardness and vitreous properties, while at high temperatures they are more elastic until they reach their melting temperature (Tf) at which their cells melt Much higher is the decomposition temperature, at which the bonds between monomers are broken. In general terms, the most interesting thing about polymers is their

  MAIN TYPES OF POLYMERS                                                       -Amorphous and Crystalline Polymers: If we could see the molecular chains of a polymer in a liquid state, we would see that they are completely elongated and relaxed and it is when they cool and solidify that these chains may or may not seek to accommodate themselves. The resins that when solidifying do not seek an accommodation or in other words, solidify without an order are those that are known as amorphous (from the Greek "a" without and "morphos" form). It is this disorder that defines its physical properties. Amorphous resins are mostly transparent because light beams pass through the gaps left by the chains in their disorder. Contrary to amorphous resins, crystalline resins have a good percentage of contraction, which represents certain considerations in their processing to achieve good dimensional stability and avoid problems such as shrinkage and deformation due to contraction. C

   Polymers are very important compounds, since some fulfill vital functions in living beings. For example: proteins, DNA. Many of them are present in nature and in practically everything that surrounds us. For example: plastic in a toy; the rubber in car tires; the wool in a sweater. Some well known are: Cellulose . It is the biopolymer from which wood and paper are made. DNA . It is the deoxyribonucleic acid present in the nucleus of our cells is a good example of a natural polymer. The PCV . Polyvinyl chloride is obtained by polymerizing vinyl chloride and is one of the most versatile plastic derivatives that exist. Starch . It is a white, odorless and tasteless substance, composed of two types of sugars. It is used by plants as an energy reserve material. Nylon . Known as nylon or nylon, it is a polyamide used in the manufacture of traditional female stockings as well as for ropes, parachutes and thousands of other textile supplies. Bakelite . It is the first synthetic plastic subs

  Beyond the established IUPAC rules for naming chemical substances, polymers are usually named by taking the name of the base monomer for their conformation, preceded by the prefix poly- ("many"). For example:  polystyrene ,  polyethylene , etc. Another common way is to add the word "rubber", "rubber" or "acrylic" before the name of the copolymers. For example:  styrene-butadiene rubber, phenol-formaldehyde resin. Finally, there are some polymers with their own names, usually derived from the brands that marketed them, such as  nylon  (polyamide),  Teflon  (polytetrafluoroethylene) or  neoprene  (polychloroprene).

 The process of building polymers is polymerization and consists of the union by covalent bonds of the different monomers that comprise it. This process can be of two types: By condensation.  It results in copolymers and homopolymers, through the loss of a small molecule (of water, for example) at each monomer bond. It is also known as step polymerization. By addition.  It occurs in a three-phase process: initiation, propagation, and termination, during which homolytic cleavage occurs and monomers come together. No low molecular mass molecules are released.