The key difference between dimerization and polymerization is that dimerization produces a dimer from two monomer units whereas polymerization forms a polymer from a large number of monomer units.
Dimerization is also a type of polymerization where a large unit is formed from the combination of small units. However, these two processes are different from each other according to the final products that are produced from these processes.
CONTENTS
1. Overview and Key Difference
2. What is Dimerization
3. What is Polymerization
4. Side by Side Comparison – Dimerization vs Polymerization in Tabular Form
5. Summary
What is Dimerization?
Dimerization is a type of polymerization in which a dimer is formed from the combination of two monomer units. Therefore, we can observe dimerization as an addition reaction in which two molecules of the same compound react with each other, forming a dimer. We can identify a dimer as an oligomer that has a low number of repeating units and the bonds between these two monomer units can be either strong or weak, covalent or intermolecular bonds. If there are covalent bonds between them, the dimer is a covalent dimer, but if there is an intermolecular bond between the monomers, then it is a noncovalent dimer.
Figure 01: 1,2-Dioxetane is a Dimer of Two Formaldehyde Monomers
A homodimer is formed when identical monomers combine while a heterodimer is formed when different monomers combine. The reverse process of dimerization is dissociation; in this process, two monomers break apart.
What is Polymerization?
Polymerization is a chemical process that involves the production of a polymer via the combination of a large number of monomers. There are two main types of polymerization processes: addition polymerization and condensation polymerization. In addition to these two, another important polymerization process is the radical polymerization, which is a form of addition polymerization.
Addition polymerization is the process of forming an addition polymer via linking unsaturated monomers. The most common examples for addition polymers are polyolefin polymers. These polyolefin polymers form when olefin monomers link with each other. Usually, olefins are small unsaturated compounds such as alkene. Therefore, when these olefins undergo polymerization, the unsaturated bonds of the monomers convert into saturated bonds. However, the monomer of addition polymerization can be a radical, a cation or an anion. Radical polymerization is the process of forming a polymer material via the addition of free radicals. The formation of radicals can occur in several ways. However, it often involves an initiator molecule forming a radical. A polymer chain is formed by the addition of the radical produced with the non-radical monomers.
Figure 02: Radical Polymerization
Condensation polymerization is a type of polymerization in which a polymer is formed via a condensation reaction. This polymer material is known as a condensation polymer. This reaction involves joining of molecules with each other while removing byproducts such as water molecules, methanol molecules, etc. Since this reaction forms a polymer, we can describe it as polycondensation. Moreover, it is a form of step-growth polymerization.
What is the Difference Between Dimerization and Polymerization?
Dimerization is a subtype of polymerization. The key difference between dimerization and polymerization is that dimerization produces a dimer from two monomer units whereas polymerization forms a polymer from a large number of monomer units. Hence, dimerization creates a dimer while polymerization creates a polymer.
The following table compares the key features of both processes side by side to discern the differences between dimerization and polymerization.
Summary – Dimerization vs Polymerization
Both dimerization and polymerization processes produce a large unit from the combination of two or more small units. The large units are called dimers or polymers while the small units are called monomers. The key difference between dimerization and polymerization is that dimerization produces a dimer from two monomer units whereas polymerization forms a polymer from a large number of monomer units.
Reference:
1. “Dimerization.” Chemistry LibreTexts, Libretexts, 24 Aug. 2020, Available here.
Image Courtesy:
1. “1,2-dioxetane” By Edgar181 – Own work (Public Domain) via Commons Wikimedia
2. “RadicalPolymerization ethylene” By V8rik at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia