Polymer chemistry
Polymer chemistry or macromolecular chemistry is a branch of chemistry that deals with the preparation and properties of polymers and macromolecules, and one of several fields that play an important role in polymer science and technology. Due to their commercial importance, most research in polymer chemistry is concerned with synthetic organic polymers, such as plastics or fibers. Many polymer chemists, however, work on problems related to medicine, biology and biochemistry, or materials science.
Polymers and Macromolecules
See also: polymer, macromolecule
In chemistry, the terms "polymer molecule" and "macromolecule" are used interchangeably. [1]. A polymer molecule has a high molecular mass and is comprised of many smaller, repeating subunits or monomers. Polymers may be found in nature, such as the DNA and proteins found in living cells, or created from scratch in the laboratory. Man-made polymers, such as Teflon, Kevlar, and synthetic plastics are found in many products ranging from simple household items to aircraft.
History of polymer chemistry
Naturally occuring polymers such as amber and rubber have been used by humans for millennia. Early Mesoamericans are perhaps the true pioneers in polymer chemistry, having discovered methods for treating natural rubber that were not reproduced until thousands of years later.[2]
The earliest work in modern polymer chemistry involved the chemical modification of naturally occuring polymers. The reaction between nitric acid and cellulose, studied by Henri Braconnot in 1832 and later by Christian Schönbein, led to the discovery of nitrocellulose and celluloid. The ensuing years saw the preparation of other cellulose derivatives, such as collodion, used as a wound dressing since the U.S. Civil War, and cellulose acetate, first prepared in 1865.
Other early work in polymer chemistry involved the modification of natural rubber to improve durability. 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 U.K. 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.[1] In 1907 Leo Baekeland invented the first wholly 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.[2]
The work of Wallace Carothers in the 1930s demonstrated that polymers of desired chain length and composition could be synthesized rationally from constituent monomers, laying the foundations of modern polymer chemistry and laying the framework for the now burgeoning polymer industry. Carothers is credited with the development of neoprene (1931), a synthetic rubber, the first polyester, and nylon (1935), a true silk replacement. The work of Ziegler and Natta in the 1950s laid the basis for stereospecific polymer synthesis. 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.
Working in polymer chemistry
The American Chemical Society estimates that 50% of chemistry professionals will work in a polymer-related field for some portion of their career. Though polymer chemists typically earn an advanced degree in synthetic organic chemistry, some institutions offer specialized degree programs in materials science and polymer science to meet the evolving needs of the polymer industry. Given the current commerical importance of synthetic polymers, most jobs in polymer chemistry are industrial jobs.[3]
Current areas of active interest in polymer chemistry include the following:
- Fundamental research into controlled syntheses and novel polymerization reactions
- Development of new molecular architectures, such as supramolecular polymer complexes
- Development of molecular architectures suited for molecular sensor technology
- Syntheses of polymers with energy and charge transport properties
- Biomedical applications, such as novel protein design and synthesis and targeted drug delivery
There is also emerging interest in green polymer chemistry. Most artificial hydrocarbon-based polymers are formed from petroleum products. Substantial research efforts are devoted to improved recycling methods, renewable sources of raw materials, and biodegradable polymer materials.[4]
References
- ↑ IUPAC. "Glossary of Basic Terms in Polymer Science". Pure Appl. Chem. 1996, 68, 2287-2311
- ↑ D Hosler, SL Burkett and MJ Tarkanian Science 284, 1988 (1999).
- ↑ ACS webpage on careers in polymer chemistry
- ↑ Stepto, R. et al Pure Appl. Chem., 75, 1359 (2003).