Nylon repeat unit structure

Examine the structure of Nylon 6,6 (amide bonds have been assumed to adopt E geometries). What is the repeating unit How many monomers are in the strand Nylon 6,6 is made by combining two different molecules, a diacid and a diamine. Draw these molecules. 

Linear condensation polymers are produced when the constituent monomers contain two functional groups each. When a single monomer is polymerized, the product is made of chains whose repeat unit corresponds to the monomer. An example of this type is nylon 6, the structure of which is shown in Fig. 1.10. If two different monomers are polymerized, the result most often is a chain whose repeat unit corresponds to the two different monomers arranged alternately. An example of this type is nylon 66, the structure of which is shown in... 

The molecular structure of nylon 6 is shown in Fig. 23.2 a). Its repeat unit consists of an amide group and a pentamethylene sequence, i.e., -(CH2)5CONH- The polar amide groups from adjacent chains interact with each other to form hydrogen bonds, which link the chains. 

Figure 23.5 Chemical structure of repeat units of various commercial nylons a) nylon 11,b) nylon 12,c) nylon 46, d) nylon 610, and e) nylon 612...

B. Where the paths are equal, such as in some nylons, the repeat unit is named so that the heteroatom N appears first and the more highly substituted (carbonyl) unit appears next. Thus nylon 3,3 with the structure... 

Draw the structure of the repeating units found in a nylon b Terylene. 

Write the structure of the monomers and that of the repeating unit in nylon 6-10. (In numbering nylons the first number indicates the number of carbon atoms in the acyl chloride and the second number refers to the number of carbon atoms in the diamine.)... 

Figure 5.1. Molecular structures of the chemical repeat units for common polymers. Shown are (a) polyethylene (PE), (b) poly(vinyl chloride) (PVC), (c) polytetrafluoroethylene (PTFE), (d) polypropylene (PP), (e) polyisobutylene (PIB), (f) polybutadiene (PBD), (g) c/5-polyisoprene (natural rubber), (h) traw5-polychloroprene (Neoprene rubber), (i) polystyrene (PS), (j) poly(vinyl acetate) (PVAc), (k) poly(methyl methacrylate) (PMMA), ( ) polycaprolactam (polyamide - nylon 6), (m) nylon 6,6, (n) poly(ethylene teraphthalate), (o) poly(dimethyl siloxane) (PDMS).

There is also an alternative numbering system for synthetic polyamides. Polymers that could be made from amino acids are called nylon-.r, where x is the number of carbon atoms in the repeating unit. Thus, polycaprolactam (1-13) is nylon-6, while the polymer from m-aminoundecanoic acid is nylon-11. Nylons from diamines and dibasic acids are designated by two numbers, in which the first represents the number of carbons in the diamine chain and the second the number of carbons in the dibasic acid. Structure 1-6 is thus nylon-6,6. Nylon-6,6 and nylon-6 differ in repeating unit length and symmetry and their physical properties are not identical. 

The styrene molecule is the monomer, and the resulting structure, enclosed in square brackets, is the polymer polystyrene. The unit in square brackets is called the repeating unit. Some polymers are derived from the mutual reaction of two or more monomers. For example, poly(hexamethylene adipamide) or nylon-6,6 is made from the reaction of hexamethylenediamine and adipic acid, as shown in the following equation ... 

Homopolymers are pol ipners consisting of a single repeating unit, such as [—CHj—CHj—]. Hornopolymers can also be made from two different monomers whose structural units form the repeating unit such as the formation of a polyamide (e.g., Nylon) from a diamine and a diadd. 

Nylon-6 which has a heat deflection temperature of 80°C was produced by the ring opening polymerization of caprolactam in Germany in the 1940 s. iZ Molded articles of these polymers may be produced in situ in the RIM process.(A3)Nylon-ll and nylon-12 produced by the anionic polymerization of 11 and 12-amino acids are also characterized by good resistance to moisture and Superior ductility. The structure of the repeating unit in monadic nylons, such as nylon-6 is ... 

Polymers may be either homopolymers or copolymers depending on the composition. Polymers composed of only one repeating unit in the polymer molecules are known as homopolymers. However, chemists have developed techniques to build polymer chains containing more than one repeating unit. Polymers composed of two different repeating units in the polymer molecule are defined as copolymers. An example is the copolymer (32) formed when styrene and acrylonitrile are polymerized in the same reactor. The repeating unit and the structural unit of a polymer are not necessarily the same. As indicated earlier, some polymers such as nylon 6,6 (5) and poly(ethylene terephthalate) (28) have repeating units composed of more than one structural unit. Such polymers are still considered homopolymers. 

The amidation reaction is the basis for the production of the polyamides or nylons. For example, nylon-6,6, which has the structural repeat unit -fHN(CH2)6NHCO(CH2)4CO is made by the condensation of hexa-methylene diamine, H2N(CH2)fiNH2, and adipic add, HOOC(CH2)4COOH, whereas nylon-6,10 results from the comparable reaction between hexa-methylene diamine and sebacic acid, HOOC(CH2)gCOOH. In the labelling of these nylons the first number is the number of carbon atoms in the amine residue and the second the number of carbon atoms in the add residue. Two nylons of somewhat simpler structure, nylon-6 and nylon-11,... 

The general formula for the repeat unit of a polyamide described as nylon-n,m is -fNH(CH2) NH.CO(CH2) , 2CO. Particularly important examples are nylon-6,6, or poly(hexamethylene adipamide), and nylon-6,10. Related polyamides of slightly simpler structure have repeat units of the type -(-NH(CH2)5C0-)-, which is polycaprolactam, or nylon-6. 

STRUCTURE These aromatic nylons consist of aliphatic and aromatic building blocks incorporating the repeat units of nylon 6 — poly(caprolactam) — and nylon 6T — poly(hexamethylene terephthalamide). Because of this composition, Ultramid T resins are often designated as nylon 6/6T materials. The basic structure is nylon 6/6T, with a majority component of nylon 6. 

STRUCTURE As described in several articles md patents/ this type of aromatic nylon resin is a polyamide consisting of varying portions of aliphatic and aromatic units. Hexamethylene diamine is the main aliphatic component, which may be augmented by various amounts of adipic acid. The main aromatic component is terephthalic acid, which may be augmented by lesser amounts of isophthalic acid. Depending on relative composition, Amodel (nylon 6,6 copolymer) resins can be regarded as co- and terpolymers consisting of repeat units of nylon 66, nylon 6T, and nylon 61 —poly (hexamethylene isophthalamide). The major potential difference of other aromatic nylons, such as Ultramid T from BASF, is the presence of the 61 component. 

Nylon 6 begins as pure caprolactam, which is a ring structured moleeule. This is unique in that the ring is opened and the molecule polymerizes with itself. Sinee eaprolaetam has six carbon atoms, the nylon that is produced is ealled Nylon 6, which is nearly the same as Nylon 66 described in Section 6.5. The structure of Nylon 6 is shown in Figure 6.5 with the repeating unit in the brackets. 

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