Nylon preparation

Procedure

• Measure 10 mL of 5% hexamethylenediamine in water and 10 mL of 5% adipoyl chloride in cyclohexane.
• Pour the hexamethylenediamine solution into a beaker, add 10 drops of NaOH solution and stir.
• Carefully, add the adipoyl chloride solution slowly. Observe the formation of two phases.
• The polymer forms at the interface, and it is possible remove it with tweezers and roll it onto a glass rod.
• The nylon 6,6 obtained is cleaned with distilled water several times to remove any remaining reagents.
• Once the nylon is removed, mix the remaining two phases well to collect the maximum amount of polymer. The excess liquid is decanted, and the polymer is cleaned with water. Nylon threads break easily, so they must be extracted gently and without force.
• Finally, dry the obtained nylon in the air on filter paper. Observe that we obtain a fibrous material similar to cotton.

Theoretical explanation

This demonstration is different from the industrial method, which requires high temperatures. In industry, molten nylon is passed through multiple holes to form the fibers.

n H₂N(CH₂)₆NH₂ + n ClOC(CH₂)₈COCl
H₂N[(CH₂)₆NHCO(CH₂)₈]_nCOCl + n HCl

The reaction that takes place is a condensation polymerization and occurs at the interface.

NOTE: Solid hexamethylenediamine can be difficult to remove from the bottle. The simplest way to handle it is to heat the bottle in a warm water bath at 42°C, obtaining a liquid that can be extracted with a pipette. This substance is irritating and has a very unpleasant odor.