Question

How do you explain the functionality of monomer?

Answer 1

Hint: Functionality in polymer chemistry means the number of sites present for bonding in a molecule. Functionality of monomers defines the bonding sites present in a monomer for bonding.

Complete step by step answer:
Monomer is a molecule that is mostly organic which can react with other molecules to form very large molecules or polymers. The most important feature of monomers is polyfunctionality.
Polyfunctionality means the ability to form chemical bonds to at least two other monomer molecules. Bifunctional monomers can form only linear, chainlike polymers but the monomers of higher functionality yield cross-linked polymeric products.
Additional reactions between monomers that contain either a double bond between two atoms or a ring of three to seven atoms. Condensation reactions include two or more reactive atomic groupings.
For example, ethene and propene have the functionality of ${\text{1}}$ each.
The monomers ${\text{1,3 - }}$butadiene and adipic acid have the functionality of ${\text{2}}$ each.

ADDITIONAL INFORMATION: In the case, if functionality is equal to ${\text{2}}$ a linear polymer is formed by polymerization. Thus, in the case of a functionality greater than ${\text{3}}$ leads to branching point which can lead to cross-linked polymers. Monofunctional monomers actually do not exist as they generally lead to chain termination.

Note:
Functionality holds different meanings in different aspects of chemistry. In chemistry, it is the presence of functional groups in a molecule. In organic chemistry, functionality has effects on its reactivity and in polymer chemistry it defines the number of bonding sites of a molecule.