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Polymers — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryPolymers3 Marks
Question
Explain the following processe with a suitable example in case:
Step growth polymerisation.
✓

Answer

Step growth polymerisation: This type of polymerisation involves a series of condensation reactions between simple monomers containing polar groups, with or without the elimination of small molecules like water, $HCl,\ NH_3,$ etc. In addition to carbon atoms, these polymers contain other atoms also in their main chain. Steps may be illustrated as follows:
  1. $\ \ \ \ \text{A}\ \ \ +\ \ \ \text{B} \ \ \ \xrightarrow{\ \ \ \ \text{Condensation}\ \ \ \ } \ \ \ \text{AB}\\^\text{Monomer} \ \ ^\text{Monomer}$
  2. $\text{A}-\text{B}+\text{A}\ \xrightarrow{\ \ \text{Condensation}\ \ } \ \text{A}-\text{B}-\text{A}$
  3. $\text{A}-\text{B}+\text{A}-\text{B}\ \xrightarrow{\ \ \text{Condensation}\ \ }\ \text{A}-\text{B}-\text{A}-\text{B}\cdots$
Examples: Terylene, nylon, etc.

The step wise growth can also occur in another manner:
  1. $\text{A}\ \ +\ \ \text{B}\ \ \xrightarrow{\ \ \ \text{Condensation}\ \ }\ \ \text{A}-\text{B}$
  2. $\text{AB}\ \ +\ \ \text{AB}\ \ \xrightarrow{ \ \ \text{Condensaton}\ \ }\ \ \text{ABAB}\cdots\text{(AB)}_\text{n}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{Plymer}$

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