Question

Explain the preparation and the uses of nylon-2-nylon-6.

Answer 1

Hint: Condensation polymerization is an example of step growth polymerisation. Small monomer molecules react to form large polymers. Small molecules such as water or methanol molecules are eliminated as byproducts. Usually each monomer has two (or more) functional groups.

Complete answer:
The polymer nylon-2-nylon-6 is a polyamide and is obtained by the condensation polymerization. The polymer nylon-2-nylon-6 is a biodegradable polymer. nylon-2-nylon-6 is made from two monomers glycine and amino caproic acid. Glycine is an alpha amino acid. It has one amino group and one carboxylic group directly attached to a methylene group. The structure of glycine is \[{{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2} - {\rm{COOH}}\]. Amino caproic acid contains one amino group, one carboxylic group and five methylene groups. The structure of amino caproic acid is \[{{\rm{H}}_2}{\rm{N}} - {\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{COOH}}\].
To prepare nylon-2-nylon-6 polymer, the condensation polymerization of glycine and amino caproic acid is carried out. The Amino group of glycine condenses with the carboxylic group of aminocaproic acid to form an amide bond. A molecule of water is eliminated during this condensation reaction. Similarly, the carboxylic group of glycine condenses with the amino group of aminocaproic acid to form an amide bond. A molecule of water is eliminated during this condensation reaction.

${{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2} - {\rm{COOH +}}{{\rm{H}}_2}{\rm{N}} - {\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{COOH }} \to {{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2} - {\rm{CO}} - {\rm{HN}} - {\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{COOH + }}{{\rm{H}}_2}{\rm{O }}\\
 - {\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{COOH+}}{{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2} - {\rm{COOH }} \to {{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2}{\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{CO}} - {\rm{HN}} - {\rm{C}}{{\rm{H}}_2} - {\rm{COOH + }}{{\rm{H}}_2}{\rm{O }}\\$

Write the condensation polymerization reaction to prepare the polymer nylon-2-nylon-6.

${\rm{n}}{{\rm{H}}_2}{\rm{N}} - {\rm{C}}{{\rm{H}}_2} - {\rm{COOH + n}}{{\rm{H}}_2}{\rm{N}} - {\left( {{\rm{C}}{{\rm{H}}_2}} \right)_5} - {\rm{COOH }} \to- {\left[ {{\rm{HN}} - {\rm{C}}{{\rm{H}}_2} - {\rm{CO}} - {\rm{HN}} - {{\left( {{\rm{C}}{{\rm{H}}_2}} \right)}_5} - {\rm{CO}}} \right]_{\rm{n}}} - {\rm{ + n}}{{\rm{H}}_2}{\rm{O }}\\$

Uses of the polymer nylon-2-nylon-6:
1. In bristles of toothbrush, nylon-2-nylon-6 is used as a thread.
2. nylon-2-nylon-6 is also used in making strings of musical instruments.
3. nylon-2-nylon-6 is also used in the synthesis of artificial fibres.

Note: Broadly polymerization is of two types Condensation and Addition Polymerisation. The preparation of nylon-2-nylon-6 is done through Condensation Polymerisation.