Polymer chemistry

Polymer chemistry or macromolecular chemistry is a multidisciplinary science that deals with the chemical synthesis and chemical properties of polymers or macromolecules. According to IUPAC recommendations [IUPAC definition [http://www.iupac.org/reports/1996/6812jenkins/substances.html#2.2 IUPAC Polymer] ] [IUPAC definition [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 physics as a subfield of physics.

*Biopolymers produced by living organisms:
**structural proteins: collagen, keratin, elastin…
**chemically functional proteins: enzymes, hormones, transport proteins…
**structural polysaccharides: cellulose, chitin…
**storage polysaccharides: starch, glycogen…
**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 polymerization of monomers. A polymer is chemically described by its degree of polymerisation, molar mass distribution, tacticity, copolymer distribution, the degree of branching, by its end-groups, crosslinks, crystallinity and thermal properties such as its glass transition temperature and melting temperature. Polymers in solution have special characteristics with respect to solubility, viscosity and gelation.

History

The work of Henri Braconnot in 1777 and Christian Schönbein in 1846 led to the discovery of nitrocellulose, which, when treated with camphor produced celluloid. Dissolved in ether or acetone, it is collodion, used as a wound dressing since the U.S. Civil War. Cellulose acetate was first prepared in 1865. In 1834, Friedrich Ludersdorf and Nathaniel Hayward independently discovered that adding sulfur to raw natural rubber (polyisoprene) helped prevent the material from becoming sticky. In 1844 Charles Goodyear received a U.S. patent for vulcanizing rubber with sulfur and heat. Thomas Hancock had received a patent for the same process in the UK the year before.

In 1884 Hilaire de Chardonnet started the first artificial fiber plant 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 Baekeland invented the first synthetic polymer, a thermosetting phenol-formaldehyde resin called Bakelite. Cellophane was invented in 1908 by Jocques Brandenberger who squirted sheets of viscose rayon into an acid bath. [ [http://inventors.about.com/library/inventors/blcellophane.htm inventors of blcellophane] ] In 1922 Hermann Staudinger was the first to propose that polymers consisted of long chains of atoms held 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 Chemistry in 1953. Wallace Carothers invented the first synthetic rubber called neoprene in 1931, the first polyester, and went on to invent nylon, a true silk replacement, in 1935. Paul Flory was awarded the Nobel Prize in Chemistry in 1974 for his work on polymer random coil configurations in solution in the 1950s. Stephanie Kwolek developed an aramid, or aromatic nylon 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.

ee also

*Radical polymerization
*RAFT (chemistry)
*Robert Gilbert

References

External links

* [http://www.polymerchemistryhypertext.com/ Polymer Chemistry Hypertext, Educational resource]