Question

Which of the following polymers is biodegradable?
A. \[ - {\left( {{\text{C}}{{\text{H}}_{\text{2}}} - {\text{C}}\left( {{\text{Cl}}} \right) = {\text{CH}} - {\text{C}}{{\text{H}}_{\text{2}}}} \right)_n} - \]
B. \[ - {\left( {{\text{C}}{{\text{H}}_{\text{2}}} - {\text{CH}} = {\text{CH}} - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{CH}}\left( {{\text{CN}}} \right)} \right)_n} - \]
C. \[ - {\left( {{\text{O}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{COO}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - CO} \right)_n} - \]
D. \[ - {\left( {{\text{NH}} - {{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)}_6} - {\text{NH}} - {\text{CO}} - {{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)}_4} - CO} \right)_n} - \]

Answer 1

Hint: A biodegradable polymer can be easily broken into simpler molecules by the action of certain bacteria. For this purpose, the polymer should have functional groups that can be easily hydrolysed by these bacteria.

Complete answer:
Several polymers end up as polymeric wastes. They cause environmental pollution and are of great concern to the environment. To address these concerns and to create public awareness, scientists have designed synthetic polymers that are biodegradable. The functional group present in these polymers developed by the scientist is similar to the functional group present in biopolymers.
One example of such a polymer is PHBV.
PHBV is prepared by the condensation polymerisation of 3-hydroxybutanoic acid with 3-hydroxy pentanoic acid. Thus, PHBV is a copolymer containing two monomers. Both monomers are bifunctional containing one carboxyl group and one hydroxyl group. During polymerisation reaction, hydroxyl group of one monomer combines with carboxylic group of other monomer to form an ester linkage. A molecule of water is eliminated in this condensation reaction. Several such condensation reactions give PHBV polymers.
When the ester group is hydrolysed in presence of water, hydroxyl group and carboxylic group are regenerated. Thus, it is easy to break PHBV polymers into constituent monomers. Hence, PHBV is a biodegradable polymer.
\[- {\left( {{\text{O}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{COO}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - CO} \right)_n} - {\text{ }}\xrightarrow[{hydrolysis}]{{water}} \\
{\text{n HO}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{COOH + n HO}} - {\text{CH}}\left( {{\text{C}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}} \right) - {\text{C}}{{\text{H}}_{\text{2}}} - {\text{COOH}} \\\]
Thus the correct option is [C].

Note: After the intended use of polymer, the polymer is dumped into the environment. To avoid environmental pollution, it is desirable that such polymers should break into simpler molecules.