Overview
Nylons are essential commercial fibers used in various applications, including clothing, ropes, tents, and more. One of the most significant types is Nylon 6,6, invented by Wallace Carothers at DuPont in the late 1930s.
Synthesis Process
Chemical Reaction
The synthesis of Nylon 6,6 involves a polycondensation reaction between a diamine and a diacid, represented as:
Reactants:
- Diamine:
H₂N-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-NH₂ - Diacid:
HO2C-CH₂-CH₂-CH₂-CH₂-CO2H
Reaction:
H₂N-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-NH₂ + HO2C-CH₂-CH₂-CH₂-CH₂-CO2H → Nylon 6,6 + H₂O
Mechanism
The polycondensation process involves the removal of water, often facilitated by conducting the reaction under vacuum or elevated temperatures, following LeChatelier’s Principle. This enhances the conversion efficiency:
Nylon Structure → |−N−(CH2)6−N−C−(CH2)4−C−| + H₂O
Types of Nylons
- One-Type Monomer Nylons: Represented by a single number (e.g., Nylon 6, derived from an amino acid).
- Two-Type Monomer Nylons: Represented by two numbers (e.g., Nylon 6,6, indicating both monomers contain six carbon atoms).
Alternative Synthesis Method
Using a diamine and a diacid chloride increases reactivity. The reaction occurs in a two-phase system with the amine in water and the diacid chloride in an organic solvent. This method is known as the “Nylon Rope Trick.”
Polycondensation of Amino Acids
It is possible to synthesize polymers from a single type of monomer with both an acid group and an amino group (e.g., amino acids), leading to poly(amino acid) or proteins.
Nylon 6,10 Experiment
Materials
- Hexamethylene diamine (1 g)
- Sebacoyl chloride (1 g)
- Hexane (25 ml)
- 100 ml beaker
- Glass stirring rod
- Balance
Procedure
- Dissolve 1 g of hexamethylene diamine in 25 ml of water in a 100 ml beaker.
- Prepare a solution of 1 g of sebacoyl chloride in 25 ml of hexane.
- Gently pour the sebacoyl chloride solution onto the hexamethylene diamine solution in the beaker, using a glass rod.
- Draw a thread from the interface using forceps and wind it onto a glass rod.
- Wash the collected polymer thoroughly with water and allow it to dry.
- Examine the physical properties of the dried thread.
Note: The monomers may be too small to visualize, and color may not be apparent.
Source
Department of Polymer Science, University of Southern Mississippi: Polymer Science Lab