Question

Which of the following is a polyamide?
A) Nylon-6, 6
B) Terylene
C) Polythene
D) Buna-S

Answer 1

Hint: Polymers are macromolecules. Many polymers contain functionalities such as amide bonds throughout their structures that link the monomeric units together. Such polymers are called polyamides.

Complete step by step solution:
Before diving into the question, we need to understand polymers. Polymers are large molecules that are composed of smaller repeating units called monomers that are chemically linked to each other. They can be single chained, they can also be branched or they can be cross-linked. Generally in synthetic polymers, the links in the chain are the same as that of its neighbours while that is not the case in many natural polymers such as proteins.
In order to prepare Nylon 6, 6, hexamethylenediamine and adipic acid (it is a dicarboxylic acid) are heated under a high pressure. Under these conditions, condensation polymerisation takes place.
$\begin{matrix} nHOOC-(C{ H }_{ 2 }{ ) }_{ 4 }-COOH \\\ Adipic\quad acid \end{matrix}+\begin{matrix} n{ H }_{ 2 }N-(C{ H }_{ 2 }{ ) }_{ 6 }-N{ H }_{ 2 } \\\ hexamethylene\quad diamine \end{matrix}\xrightarrow [ \triangle ,\quad 533K ]{ High\quad pressure } \begin{matrix} [-CO-(C{ H }_{ 2 }{ ) }_{ 4 }-CO-NH-(C{ H }_{ 2 }{ ) }_{ 6 }-NH-{ ] }_{ n } \\\ Nylon-6,6 \end{matrix}+\begin{matrix} (2n-1){ H }_{ 2 }O \\\ water \end{matrix}$
From the above chemical reaction, it is clear that Nylon-6, 6 contains amide bonds that are linking the monomer units therefore it is called a polyamide.
Terylene is also prepared through condensation polymerisation between ethylene glycol and dimethyl terephthalate. A mixture of zinc acetate and antimony trioxide is used as a catalyst.
Polyethene is prepared by the addition polymerization of ethane.
Buna-S is prepared through copolymerisation between 1, 3-butadiene and styrene in the presence of sodium metal.
Therefore the correct answer is option A) Nylon-6, 6.

Note: The addition polymerization is also called chain growth polymerization in which successive addition of monomer molecules on the growing polymer chain takes place. These polymerisation reactions require an initiator example benzoyl peroxide. Step growth polymerization takes place between monomers containing functional groups that react in order to produce polymers containing different functionalities than their parent monomers. Condensation polymerization is a type of step-growth polymerization.