
The nylon rope trick is a
scientific demonstration that illustrates some of the fundamental chemical principles of
step-growth polymerization
Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally occurring a ...
and provides students and other observers with a hands-on demonstration of the preparation of a
synthetic polymer
Some familiar household synthetic polymers include: Nylons in textiles and fabrics, Teflon in non-stick pans, Bakelite for electrical switches, polyvinyl chloride (PVC) in pipes, etc. The common PET bottles are made of a synthetic polymer, polye ...
.
The nylon rope trick typically makes use of a water solution of an aliphatic diamine with a solution of an aliphatic diacid chloride in a solvent that does not dissolve in water, yielding a synthetic polyamide of the
nylon-type. Nylon 610 is commonly used, in which
hexamethylene diamine is dissolved in water to a concentration of about 0.40
moles / deciliter. A solution of
sebacoyl chloride in
cyclohexane
Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...
(0.15 moles / deciliter concentration) is then layered on top of the water solution, the reaction typically being conducted in a
beaker. The solution is not agitated; instead the nylon 610 polymer forms as a flexible film at the interface of the water and cyclohexane layers, in an example of an
interfacial polymerization.
The experimentalist grasps the polymer film, withdrawing it from the reaction vessel, forming a filament or rope, and collecting it on a rotating rod above the reaction vessel. New polymer forms at the interface as fresh surfaces of the cyclohexane layer and the water layer form. In this way, the demonstration yields a continuous rope that is collected on the rotating rod.
Nylon 66 can also be produced at laboratory scale in this way.
Representative procedures and equipment lists for conducting the nylon rope trick demonstration are available in literature procedures.
The nylon rope trick was developed as a scientific demonstration by American
chemist Stephanie Kwolek
Stephanie Louise Kwolek (; July 31, 1923 – June 18, 2014) was a Polish-American chemist who is known for inventing Kevlar. Her career at the DuPont company spanned more than 40 years. She discovered the first of a family of synthetic fibers of ...
, who later invented
Kevlar aramid.
Gallery
File:Nylon.jpg, Nylon-66
File:Nailoni süntees 1.JPG, The nylon is pink because the solution has an indicator dye in it.
File:Nailoni süntees 2.JPG
File:Nailoni süntees 3.JPG, A nylon strand, synthesised by children at XLAB international science camp 2012 August
References
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Chemistry classroom experiments
Polymerization reactions