Nylon 1,6 (aka polyamide 1,6) is a type of

polyamide A polyamide is a polymer with repeating units linked by amide bonds. 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 ...

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petro ...

. Unlike most other

s, nylon 1,6 is not a condensation polymer, but instead is formed by an acid-catalyzed synthesis from

adiponitrile Adiponitrile is an organic compound with the chemical formula (CH2)4(CN)2. This viscous, colourless dinitrile is an important precursor to the polymer nylon 66. In 2005, about one million tonnes of adiponitrile were produced.M. T. Musser, "Adipi ...

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

, and water. The material was produced and studied by researchers at

DuPont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...

in the 1950s. Synthesis can be performed at room temperature in open beakers.

Synthesis of nylon 1,6

Nylon 1,6 is synthesized from

, formaldehyde, and water via acid

catalysis Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. Adiponitrile and formaldehyde (aqueous, paraformaldehyde, or trioxane) are combined with an acid (typically

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

) in a reactor. The reaction can be performed at room temperature. However, the reaction is exothermic, and especially at high ratios of formaldehyde to adiponitrile, cooling may be required. CH₂O + NC-(CH₂)₄-CN + H₂O → NH-CH₂-NH-OC-(CH₂)₄-CO-sub>n Addition of water to the reaction mixture readily precipitates the nylon 1,6 product, which can then be isolated and washed with water to afford high purity

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

Properties and applications

The DuPont evaluations of the 1950s era indicated that polyamide-1,6 was less acid stable than

nylon 66 Nylon 66 (loosely written nylon 6-6, nylon 6/6, nylon 6,6, or nylon 6:6) is a type of polyamide or nylon. It, and nylon 6, are the two most common for textile and plastic industries. Nylon 66 is made of two monomers each containing 6 carbon atoms, ...

, and melts over 300–325 °C, with some decomposition. However, films were reported to have been successfully pressed at 275–290 °C. Molecular weight determined to be ~22,000–34,000 via an osmotic pressure method. The polymer was believed to be significantly branched and cross-linked owing to side reactions occurring during the acid catalyzed polymerization, but this was not conclusively established. Similar to other formaldehyde-based thermoset resins, thermal behavior of the polymer is a function of the CH₂O/ADN ratio employed in the synthesis. Picture of nylon 16 on filter

Melting point was found to increase with increasing synthesis CH₂O/ADN ratio, along with apparent increase in cross-linking, and reduction in crystallinity. Additionally, spectral features of ¹H-NMR of nylon 1,6 samples were found to trend with CH₂O/ADN synthesis ratio as well. Collectively, these properties parallel those of other formaldehyde-based thermoset resins, and it is interesting that nylon 1,6 is a rare example of a polyamide

thermoset In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening (" curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and ...

resin rather than a

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

material. Nylon 1,6 has been reported to exhibit a high moisture absorbance owing to the significant density of amide residues in the polymer, >130% of its weight (compare to ~2–2.5% for

and

nylon 6 Nylon 6 or polycaprolactam is a polymer, in particular semicrystalline polyamide. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization; this makes it a special case in the comparis ...

References

{{Reflist Polymers