What is the Difference Between Free Radical and Ionic Polymerization?

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Free radical and ionic polymerization are two different processes of forming a polymer material. They are subtypes of chain-growth polymerization. The key difference between the two lies in the nature of the initiators used and the mechanisms involved in the processes.

Free Radical Polymerization:

  • Initiated by free radicals, which are very reactive, short-lived components containing one or more unpaired electrons.
  • The radical makes the monomer a reactive radical.
  • Most free radical polymerizations can be run at or below room temperature.

Ionic Polymerization:

  • Initiated by ionic initiators, which can be anions or cations.
  • The anion or cation binds with the monomer, making a reactive charged species.
  • Ionic polymerizations employing vinyl reactants can also be run at or below room temperature, with heating typically employed only when melting is required.

In summary, the main difference between free radical and ionic polymerization is the nature of the initiators used and the mechanisms involved in the processes. Free radical polymerization uses free radicals as initiators, while ionic polymerization uses ionic initiators. Both processes are subtypes of chain-growth polymerization and are used to form polymer materials.

Comparative Table: Free Radical vs Ionic Polymerization

The main difference between free radical and ionic polymerization lies in the initiators used and the mechanisms involved in the processes. Here is a comparison table highlighting the key differences between the two types of polymerization:

Feature Free Radical Polymerization Ionic Polymerization
Initiators Free radical initiators Ionic initiators (anions or cations)
Mechanism Radicals join with monomers, forming reactive radicals Anions or cations bind with monomers, forming reactive charged species
Chain Growth Addition of radicals into the chain Addition of ions into the chain
Reaction Type Chain-growth polymerization Chain-growth polymerization
Initiation Involves formation of radicals Involves formation of ions
Propagation Radicals join with monomers, extending the chain Ions join with monomers, extending the chain
Termination Radical chain terminates, forming a polymer Ion chain terminates, forming a polymer

Both free radical and ionic polymerization are subtypes of chain-growth polymerization, and they are used to form polymer materials from a large number of monomer units via chemical bonds.