Difference Between Catenation and Polymerisation

The key difference between catenation and polymerisation is that catenation includes the biding of atoms of the same chemical element to form a macromolecule, whereas polymerisation includes the binding of monomers to form a macromolecule.

Polymerisation is also a type of catenation reaction at some points. Polymerisation may or may not use similar atoms to form the polymer material, but in the catenation process, similar atoms always attach to each other, forming chain structures.

CONTENTS

1. Overview and Key Difference
2. What is Catenation
3. What is Polymerisation
4. Side by Side Comparison – Catenation vs Polymerisation in Tabular Form
5. Summary

What is Catenation?

Catenation is the ability of atoms of a particular chemical element to bind with each other, forming a chain or ring structure. Most commonly, the chemical element carbon is involved in catenation because carbon is able to form aliphatic and aromatic structures via binding a large number of carbon atoms. Furthermore, there are some other chemical elements that can form these structures, including sulfur and phosphorous.

If a certain chemical element undergoes catenation, the atoms of that element must have a valency that is at least two. Moreover, this chemical element must be able to form strong chemical bonds between the atoms of its kind; e.g. covalent bonds. Polymerisation is also a type of catenation reaction. Examples of chemical elements that can undergo catenation include:

1. Carbon
2. Sulfur
3. Silicon
4. Germanium
5. Nitrogen
6. Selenium
7. Tellurium

What is Polymerisation?

Polymerisation is the process of forming a polymer material. This is a chemical reaction that occurs mainly in three ways: free radical polymerisation, chain growth polymerisation and step-growth polymerisation.

Free radical polymerisation is the process of forming a polymer material via the addition of free radicals. Radicals may form in several ways. Often, this formation of radicals involves an initiator molecule. Here, a polymer chain forms via the addition of the radical produced with the non-radical monomers. The three main steps involved in this process include the followings.

1. Initiation
2. Propagation
3. Termination

The initiation step has a reactive point. At this point, the polymer chain begins to form. In the second step, the polymer spends its time in growing the polymer chain. The final step, termination, includes termination of the growth of the polymer chain. That can happen in several ways:

• Combination of the ends of two growing polymer chains
• Combination of the growing end of a polymer chain with an initiator
• Radical disproportionation (removal of a hydrogen atom, forming an unsaturated group)

Chain growth polymerisation is a type of polymerisation reaction in which polymers are formed from unsaturated monomers. This method is also called addition polymerisation because monomers are added to the ends of polymer chains. During the chain growth polymerisation process, monomers are attached to the chain in the active site of the growing polymer chain, one monomer at a time.

Step growth polymerisation is a type of polymerisation process where the formation of a polymer occurs through the formation of bi-functional or multi-functional monomers. This polymerisation technique is also known as condensation polymerisation. In this process, the polymer chains are not formed at the beginning. First, dimers, trimers, and tetramers are formed. Then these oligomers combine with each other forming long polymer chains. Therefore, monomers are not attached to the ends of polymer chains as in chain growth polymerisation.

What is the Difference Between Catenation and Polymerisation?

Catenation is the ability of atoms of a particular chemical element to bind with each other, forming a chain or ring structure. Polymerisation, on the other hand, is the formation of a polymer material. So, the key difference between catenation and polymerisation is that catenation includes the biding of atoms of the same chemical element to form a macromolecule, whereas polymerisation includes the binding of monomers to form a macromolecule. However, some polymerisation reactions can be categorised as catenation reactions as well due to the common procedure.

Below infographic summarizes the difference between catenation and polymerisation.

Summary – Catenation vs Polymerisation

The key difference between catenation and polymerisation is that catenation includes the biding of atoms of the same chemical element to form a macromolecule, whereas polymerisation includes the binding of monomers to form a macromolecule. Some polymerisation reactions can be categorised as catenation reactions as well due to the common procedure.

Reference:

1. “Catenation.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 8 Aug. 2007, Available here.

Image Courtesy:

1. “Butan Lewis” By NEUROtiker ⇌ – Own work (Public Domain) via Commons Wikimedia
2. “Vinyl chloride Polymerization V1” By Jü – Own work (CC BY-SA 4.0) via Commons Wikimedia