Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through step-growth polymerization or solid-phase synthesis yielding materials such as nylons, aramids, and sodium polyaspartate. Synthetic polyamides are commonly used in textiles, automotive industry, carpets, kitchen utensils and sportswear due to their high durability and strength. The transportation manufacturing industry is the major consumer, accounting for 35% of polyamide (PA) consumption.[2]
Kevlar and Nomex from DuPont, Teijinconex, Twaron and Technora from Teijin, Kermel from Kermel.
All polyamides are made by the formation of an amide function to link two molecules of monomer together. The monomers can be amides themselves (usually in the form of a cyclic lactam such as caprolactam), α,ω-amino acids or a stoichiometric mixture of a diamine and a diacid. Both these kinds of precursors give a homopolymer. Polyamides are easily copolymerized, and thus many mixtures of monomers are possible which can in turn lead to many copolymers. Additionally many nylon polymers are miscible with one another allowing the creation of blends.
Polymerization chemistry
Production of polymers requires the repeated joining of two groups to form an amide linkage. In this case this specifically involves amide bonds, and the two groups involved are an amine group, and a terminal carbonyl component of a functional group. These react to produce a carbon-nitrogen bond, creating a singular amide linkage. This process involves the elimination of other atoms previously part of the functional groups. The carbonyl-component may be part of either a carboxylic acid group or the more reactive acyl halide derivative. The amine group and the carboxylic acid group can be on the same monomer, or the polymer can be constituted of two different bifunctional monomers, one with two amine groups, the other with two carboxylic acid or acid chloride groups.
The condensation reaction is used to synthetically produce nylon polymers in industry. Nylons must specifically include a straight chain (aliphatic) monomer. The amide link is produced from an amine group (alternatively known as an amino group), and a carboxylic acid group. The hydroxyl from the carboxylic acid combines with a hydrogen from the amine, and gives rise to water, the elimination byproduct that is the namesake of the reaction.
As an example of condensation reactions, consider that in living organisms, Amino acids are condensed with one another by an enzyme to form amide linkages (known as peptides). The resulting polyamides are known as proteins or polypeptides. In the diagram below, consider the amino-acids as single aliphatic monomers reacting with identical molecules to form a polyamide, focusing on solely the amine and acid groups. Ignore the substituent R groups – under the assumption the difference between the R groups are negligible:
The reaction of two amino acids. Many of these reactions produce long chain proteins
For fully aromatic polyamides or aramids e.g. Kevlar, the more reactive acyl chloride is used as a monomer. The polymerization reaction with the amine group eliminates hydrogen chloride. The acid chloride route can be used as a laboratory synthesis to avoid heating and obtain an almost instantaneous reaction.[3] The aromatic moiety itself does not participate in elimination reaction, but it does increase the rigidity and strength of the resulting material which leads to Kevlar's renowned strength.
In the diagram below, an aramid is made from two different monomers which continuously alternate to form the polymer chain. Aramids are aromatic polyamides:
The reaction of 1,4-phenyl-diamine (para-phenylenediamine) and terephthaloyl chloride to produce an aramid
Polyamides can also be synthesized from dinitriles using acid catalysis via an application of the Ritter reaction. This method is applicable for preparation of nylon 1,6 from adiponitrile, formaldehyde and water.[4] Additionally, polyamides can be synthesized from glycols and dinitriles using this method as well.[5]
Synthesis of Nylon 1,6 from adiponitrile, formaldehyde, and water using sulfuric acid as a catalyst
^Palmer, R. J. 2001. Polyamides, Plastics. Encyclopedia Of Polymer Science and Technology. doi:10.1002/0471440264.pst251
^Market Study Engineering Plastics, Ceresana, Sep 2013
^"Making nylon: The "nylon rope trick"". Royal Society of Chemistry. Retrieved 19 April 2015.
^Magat, Eugene E.; Faris, Burt F.; Reith, John E.; Salisbury, L. Frank (1951-03-01). "Acid-catalyzed Reactions of Nitriles. I. The Reaction of Nitriles with Formaldehyde1". Journal of the American Chemical Society. 73 (3): 1028–1031. doi:10.1021/ja01147a042. ISSN 0002-7863.
^Lakouraj, Moslem Mansour; Mokhtary, Masoud (2009-02-20). "Synthesis of polyamides from p-Xylylene glycol and dinitriles". Journal of Polymer Research. 16 (6): 681. doi:10.1007/s10965-009-9273-z. ISSN 1022-9760. S2CID 98232570.
Further reading
Kohan, Melvin I. (1995). Nylon Plastics Handbook. Hanser/Gardner Publications. ISBN9781569901892
January 11, 2023
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A polyamide is a polymer with repeating units linked by amide bonds 1 Polyamides occur both naturally and artificially Examples of naturally occurring polyamides are proteins such as wool and silk Artificially made polyamides can be made through step growth polymerization or solid phase synthesis yielding materials such as nylons aramids and sodium polyaspartate Synthetic polyamides are commonly used in textiles automotive industry carpets kitchen utensils and sportswear due to their high durability and strength The transportation manufacturing industry is the major consumer accounting for 35 of polyamide PA consumption 2 Contents 1 Classification 2 Polymerization chemistry 3 See also 4 References 5 Further readingClassification EditPolymers of amino acids are known as polypeptides or proteins According to the composition of their main chain synthetic polyamides are classified as follows Family Main chain Examples Commercial productsAliphatic polyamides Aliphatic Nylon PA 6 and PA 66 Zytel from DuPont Technyl from Solvay Rilsan and Rilsamid from Arkema Radipol from Radici GroupPolyphthalamides Semi aromatic PA 6T hexamethylenediamine terephthalic acid Trogamid T from Evonik Industries Amodel from SolvayAromatic polyamides or aramids Aromatic Paraphenylenediamine terephthalic acid Kevlar and Nomex from DuPont Teijinconex Twaron and Technora from Teijin Kermel from Kermel All polyamides are made by the formation of an amide function to link two molecules of monomer together The monomers can be amides themselves usually in the form of a cyclic lactam such as caprolactam a w amino acids or a stoichiometric mixture of a diamine and a diacid Both these kinds of precursors give a homopolymer Polyamides are easily copolymerized and thus many mixtures of monomers are possible which can in turn lead to many copolymers Additionally many nylon polymers are miscible with one another allowing the creation of blends Polymerization chemistry EditProduction of polymers requires the repeated joining of two groups to form an amide linkage In this case this specifically involves amide bonds and the two groups involved are an amine group and a terminal carbonyl component of a functional group These react to produce a carbon nitrogen bond creating a singular amide linkage This process involves the elimination of other atoms previously part of the functional groups The carbonyl component may be part of either a carboxylic acid group or the more reactive acyl halide derivative The amine group and the carboxylic acid group can be on the same monomer or the polymer can be constituted of two different bifunctional monomers one with two amine groups the other with two carboxylic acid or acid chloride groups The condensation reaction is used to synthetically produce nylon polymers in industry Nylons must specifically include a straight chain aliphatic monomer The amide link is produced from an amine group alternatively known as an amino group and a carboxylic acid group The hydroxyl from the carboxylic acid combines with a hydrogen from the amine and gives rise to water the elimination byproduct that is the namesake of the reaction As an example of condensation reactions consider that in living organisms Amino acids are condensed with one another by an enzyme to form amide linkages known as peptides The resulting polyamides are known as proteins or polypeptides In the diagram below consider the amino acids as single aliphatic monomers reacting with identical molecules to form a polyamide focusing on solely the amine and acid groups Ignore the substituent R groups under the assumption the difference between the R groups are negligible The reaction of two amino acids Many of these reactions produce long chain proteins For fully aromatic polyamides or aramids e g Kevlar the more reactive acyl chloride is used as a monomer The polymerization reaction with the amine group eliminates hydrogen chloride The acid chloride route can be used as a laboratory synthesis to avoid heating and obtain an almost instantaneous reaction 3 The aromatic moiety itself does not participate in elimination reaction but it does increase the rigidity and strength of the resulting material which leads to Kevlar s renowned strength In the diagram below an aramid is made from two different monomers which continuously alternate to form the polymer chain Aramids are aromatic polyamides The reaction of 1 4 phenyl diamine para phenylenediamine and terephthaloyl chloride to produce an aramid Polyamides can also be synthesized from dinitriles using acid catalysis via an application of the Ritter reaction This method is applicable for preparation of nylon 1 6 from adiponitrile formaldehyde and water 4 Additionally polyamides can be synthesized from glycols and dinitriles using this method as well 5 Synthesis of Nylon 1 6 from adiponitrile formaldehyde and water using sulfuric acid as a catalystSee also EditPolyamide imide Pyrrole imidazole polyamidesReferences Edit Palmer R J 2001 Polyamides Plastics Encyclopedia Of Polymer Science and Technology doi 10 1002 0471440264 pst251 Market Study Engineering Plastics Ceresana Sep 2013 Making nylon The nylon rope trick Royal Society of Chemistry Retrieved 19 April 2015 Magat Eugene E Faris Burt F Reith John E Salisbury L Frank 1951 03 01 Acid catalyzed Reactions of Nitriles I The Reaction of Nitriles with Formaldehyde1 Journal of the American Chemical Society 73 3 1028 1031 doi 10 1021 ja01147a042 ISSN 0002 7863 Lakouraj Moslem Mansour Mokhtary Masoud 2009 02 20 Synthesis of polyamides from p Xylylene glycol and dinitriles Journal of Polymer Research 16 6 681 doi 10 1007 s10965 009 9273 z ISSN 1022 9760 S2CID 98232570 Further reading EditKohan Melvin I 1995 Nylon Plastics Handbook Hanser Gardner Publications ISBN 9781569901892 Retrieved from https en wikipedia org w index php title Polyamide amp oldid 1118571672, wikipedia, wiki, book, books, library,
