Polymer chemistry is a sub-discipline ofchemistry that focuses on the structures,chemical synthesis, andchemical and physical properties ofpolymers andmacromolecules. The principles and methods used within polymer chemistry are also applicable through a wide range of other chemistry sub-disciplines likeorganic chemistry,analytical chemistry, andphysical chemistry. Many materials have polymeric structures, from fully inorganicmetals andceramics toDNA and otherbiological molecules. However, polymer chemistry is typically related tosynthetic andorganic compositions.Synthetic polymers are ubiquitous in commercial materials and products in everyday use, such asplastics, andrubbers, and are major components ofcomposite materials. Polymer chemistry can also be included in the broader fields ofpolymer science or evennanotechnology, both of which can be described as encompassingpolymer physics andpolymer engineering.[1][2][3][4]
The work ofHenri Braconnot in 1777 and the work ofChristian Schönbein in 1846 led to the discovery ofnitrocellulose, which, when treated withcamphor, producedcelluloid. Dissolved inether oracetone, it becomescollodion, which has been used as awound dressing since theU.S. Civil War.Cellulose acetate was first prepared in 1865. In years 1834-1844 the properties of rubber (polyisoprene) were found to be greatly improved by heating withsulfur, thus founding thevulcanization process.
In 1884Hilaire de Chardonnet started the first artificialfiber plant based on regeneratedcellulose, orviscoserayon, as a substitute forsilk, but it was very flammable.[5] In 1907Leo Baekeland invented the first polymer made independent of the products oforganisms, athermosettingphenol-formaldehyde resin calledBakelite. Around the same time,Hermann Leuchs reported the synthesis ofamino acid N-carboxyanhydrides and their high molecular weight products upon reaction with nucleophiles, but stopped short of referring to these as polymers, possibly due to the strong views espoused byEmil Fischer, his direct supervisor, denying the possibility of any covalent molecule exceeding 6,000 daltons.[6]Cellophane was invented in 1908 by Jocques Brandenberger who treated sheets of viscose rayon withacid.[7]
The chemistHermann Staudinger first proposed that polymers consisted of long chains ofatoms held together bycovalent bonds, which he calledmacromolecules. His work expanded the chemical understanding of polymers and was followed by an expansion of the field of polymer chemistry during which such polymeric materials as neoprene, nylon and polyester were invented. Before Staudinger, polymers were thought to be clusters of smallmolecules (colloids), without definitemolecular weights, held together by an unknownforce. Staudinger received theNobel Prize in Chemistry in 1953.Wallace Carothers invented the firstsynthetic rubber calledneoprene in 1931, the firstpolyester, and went on to inventnylon, a true silk replacement, in 1935.Paul Flory was awarded theNobel Prize in Chemistry in 1974 for his work on polymerrandom coil configurations in solution in the 1950s.Stephanie Kwolek developed anaramid, oraromatic nylon namedKevlar, patented in 1966.Karl Ziegler andGiulio Natta received a Nobel Prize for their discovery ofcatalysts for the polymerization ofalkenes.Alan J. Heeger,Alan MacDiarmid, andHideki Shirakawa were awarded the 2000 Nobel Prize in Chemistry for the development ofpolyacetylene and related conductive polymers.[8] Polyacetylene itself did not find practical applications, butorganic light-emitting diodes (OLEDs) emerged as one application of conducting polymers.[9]
Teaching and research programs in polymer chemistry were introduced in the 1940s. An Institute for Macromolecular Chemistry was founded in 1940 in Freiburg, Germany under the direction of Staudinger. In America, a Polymer Research Institute (PRI) was established in 1941 byHerman Mark at thePolytechnic Institute of Brooklyn (nowPolytechnic Institute of NYU).
Polymers are high molecular mass compounds formed bypolymerization ofmonomers. They are synthesized by the polymerization process and can be modified by the additive of monomers. The additives of monomers change polymers mechanical property, processability, durability and so on. The simple reactive molecule from which the repeating structural units of a polymer are derived is called a monomer. Apolymer can be described in many ways: itsdegree of polymerisation,molar mass distribution,tacticity,copolymer distribution, the degree ofbranching, by itsend-groups,crosslinks,crystallinity and thermal properties such as itsglass transition temperature and melting temperature.Polymers insolution have special characteristics with respect tosolubility,viscosity, andgelation. Illustrative of the quantitative aspects of polymer chemistry, particular attention is paid to the number-average andweight-average molecular weights and, respectively.
The formation and properties of polymers have been rationalized by many theories includingScheutjens–Fleer theory,Flory–Huggins solution theory,Cossee–Arlman mechanism,Polymer field theory,Hoffman Nucleation Theory,Flory–Stockmayer theory, and many others.
The study of polymer thermodynamics helps improve the material properties of various polymer-based materials such aspolystyrene (styrofoam) andpolycarbonate. Common improvements includetoughening, improvingimpact resistance, improvingbiodegradability, and altering a material'ssolubility.[10]
As polymers get longer and their molecular weight increases, theirviscosity tend to increase. Thus, the measured viscosity of polymers can provide valuable information about the average length of the polymer, the progress of reactions, and in what ways the polymer branches.[11]
Polymers can be classified in many ways. Polymers, strictly speaking, comprise most solid matter: minerals (i.e. most of the Earth's crust) are largely polymers, metals are 3-d polymers, organisms, living and dead, are composed largely of polymers and water. Often polymers are classified according to their origin:
Biopolymers are the structural and functional materials that comprise most of the organic matter in organisms. One major class of biopolymers areproteins, which are derived fromamino acids.Polysaccharides, such ascellulose,chitin, andstarch, are biopolymers derived from sugars. The polynucleic acidsDNA andRNA are derived from phosphorylated sugars with pendant nucleotides that carry genetic information.
Synthetic polymers are the structural materials manifested inplastics,synthetic fibers,paints,building materials,furniture, mechanical parts, andadhesives. Synthetic polymers may be divided intothermoplastic polymers andthermoset plastics. Thermoplastic polymers includepolyethylene,teflon,polystyrene,polypropylene,polyester,polyurethane,Poly(methyl methacrylate),polyvinyl chloride,nylons, andrayon.Thermoset plastics includevulcanizedrubber,bakelite,Kevlar, andpolyepoxide. Almost all synthetic polymers are derived frompetrochemicals.
{{citation}}: CS1 maint: multiple names: authors list (link)Branches ofchemistry | |
|---|---|
| Analytical | |
| Theoretical | |
| Physical | |
| Inorganic | |
| Organic | |
| Biological | |
| Interdisciplinarity | |
| See also | |
| International | |
|---|---|
| National | |
