- Polymer chemistry
Polymer chemistry or macromolecular chemistry is a multidisciplinary
sciencethat deals with the chemical synthesisand chemical properties of polymers or macromolecules. According to IUPACrecommendations [ IUPACdefinition [http://www.iupac.org/reports/1996/6812jenkins/substances.html#2.2 IUPACPolymer] ] [ IUPACdefinition [http://www.iupac.org/reports/1996/6812jenkins/molecules.html#1.1 Macromolecule] ] , macromolecules refer to the individual molecular chains and are the domain of chemistry. Polymers describe the bulk properties of polymer materials and belong to the field of polymer physicsas a subfield of physics.
Biopolymers produced by living organisms:
proteins: collagen, keratin, elastin…
**chemically functional proteins:
enzymes, hormones, transport proteins…
polysaccharides: cellulose, chitin…
nucleic acids: DNA, RNA
*Synthetic polymers used for
plastics — fibers, paints, building materials, furniture, mechanical parts, adhesives:
thermoplastics: polyethylene, Teflon polystyrene, polypropylene, polyester, polyurethane, polymethyl methacrylate, polyvinyl chloride, nylon, rayon, celluloid, silicone, fiberglass…
thermosetting plastics: vulcanized rubber, Bakelite, Kevlar, epoxy…
Polymers form by
polymerizationof monomers. A polymer is chemically described by its degree of polymerisation, molar mass distribution, tacticity, copolymerdistribution, the degree of branching, by its end-groups, crosslinks, crystallinityand thermal properties such as its glass transition temperatureand melting temperature. Polymers in solutionhave special characteristics with respect to solubility, viscosityand gelation.
The work of
Henri Braconnotin 1777 and Christian Schönbeinin 1846 led to the discovery of nitrocellulose, which, when treated with camphorproduced celluloid. Dissolved in etheror acetone, it is collodion, used as a wounddressing since the U.S. Civil War. Cellulose acetatewas first prepared in 1865. In 1834, Friedrich Ludersdorfand Nathaniel Haywardindependently discovered that adding sulfur to raw natural rubber(polyisoprene) helped prevent the material from becoming sticky. In 1844 Charles Goodyearreceived a U.S. patent for vulcanizing rubber with sulfurand heat. Thomas Hancockhad received a patent for the same process in the UK the year before.
Hilaire de Chardonnetstarted the first artificial fiberplant based on regenerated cellulose, or viscose rayon, as a substitute for silk, but it was very flammable. [ [http://www.plastiquarian.com/top.htm plastiquarian] ] In 1907 Leo Baekelandinvented the first synthetic polymer, a thermosetting phenol- formaldehyderesin called Bakelite. Cellophanewas invented in 1908 by Jocques Brandenbergerwho squirted sheets of viscose rayon into an acidbath. [ [http://inventors.about.com/library/inventors/blcellophane.htm inventors of blcellophane] ] In 1922 Hermann Staudingerwas the first to propose that polymers consisted of long chains of atomsheld together by covalent bonds. He also proposed to name these compounds macromolecules. Before that, scientists believed that polymers were clusters of small molecules (called colloids), without definite molecular weights, held together by an unknown force. Staudinger received the Nobel Prize in Chemistryin 1953. Wallace Carothersinvented the first synthetic rubber called neoprenein 1931, the first polyester, and went on to invent nylon, a true silk replacement, in 1935. Paul Florywas awarded the Nobel Prize in Chemistryin 1974 for his work on polymer random coilconfigurations in solution in the 1950s. Stephanie Kwolekdeveloped an aramid, or aromaticnylon named Kevlar, patented in 1966.
There are now a large number of commercial polymers, including
composite materials such as carbon fiber- epoxy, polystyrene- polybutadiene(HIPS), acrylonitrile- butadiene- styrene(ABS), and other such materials that combine the best properties of their various components, including polymers designed to work at high temperatures in automobile engines.
* [http://www.polymerchemistryhypertext.com/ Polymer Chemistry Hypertext, Educational resource]
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