The key difference between prepolymer and oligomer is that a prepolymer is an intermediate of a polymerization reaction, whereas an oligomer is a polymer material composed of comparatively a few monomer units.
A polymer is a chemical substance consisting of large molecules made from many smaller and simpler molecules, known as monomers. Both prepolymers and oligomers are comparatively small polymers composed of a few monomer units.
CONTENTS
1. Overview and Key Difference
2. What is Prepolymer
3. What is Oligomer
4. Side by Side Comparison – Prepolymer vs Oligomer in Tabular Form
5. Summary
What is Prepolymer?
A prepolymer is a substance which represents an intermediate stage in polymerization and can be usefully manipulated before polymerization is completed. More importantly, a prepolymer can be either a monomer or an oligomer. It has an intermediate molecular mass. A prepolymer is capable of undergoing further polymerization to form a large polymer material. This new polymer material has a high molecular weight; therefore, when a prepolymer is converted into a polymer, the molecular weight converts from a low molecular state to a higher molecular state.
Figure 01: The Structure of an Epoxy Prepolymer
Moreover, a mixture of reactive polymers containing unreacted monomers can also be called a prepolymer. Therefore, the terms prepolymer and polymer precursor are interchangeable.
What is an Oligomer?
An oligomer is a type of polymer material that has a small number of monomer units. The number of monomer units per oligomer can vary depending on the type of oligomer. For example, an oligomer may contain two, three or four monomer units which are named as dimer, trimer and tetramer respectively.
Figure 02: An Oligomer Containing Three Monomer Units
Most oils are oligomers. E.g. liquid paraffin. Typically, oligomers are produced by linking a few monomers. However, we can also obtain them from the breakdown of large polymers into short segments. Oligomerization is the process of forming an oligomer. In this process, a few monomers units are allowed to undergo a finite degree of polymerization.
As a biochemical term, an oligomer is a macromolecular compound formed via the non-covalent bond formation between few macromolecules such as proteins and nucleic acids. If the oligomer is made of the same type of monomer units, then we can call it a homo-oligomer. If there are different types of monomers involved in the formation of the oligomer, then we call it a hetero-oligomer. For example, collagen is a homo-oligomer made of three identical proteins. Moreover, oligomers made of proteins are called oligopeptides while oligomers made of nucleic acid units are called oligonucleotides (made of few nucleotide units).
Difference Between Prepolymer and Oligomer?
The key difference between prepolymer and oligomer is that a prepolymer is an intermediate of a polymerization reaction, whereas an oligomer is a polymer material composed of comparatively a few monomer units. Therefore, a prepolymer is an intermediate compound, while an oligomer is a final product.
Moreover, prepolymers are obtained from the polymerization process, while oligomers are obtained from the oligomerization process. Also, prepolymers are formed via linking of two or more monomer units, but oligomers are formed from either the linking of monomers or breakdown of a polymer.
Below infographic summarizes the difference between prepolymer and oligomer.
Summary – Prepolymer vs Oligomer
Prepolymer and oligomer are comparatively small polymers. The key difference between prepolymer and oligomer is that a prepolymer is an intermediate of a polymerization reaction, whereas an oligomer is a polymer material composed of comparatively a few monomer units.
Reference:
1. Helmenstine, Anne Marie. “Monomers and Polymers in Chemistry.” ThoughtCo, Feb. 11, 2020, Available here.
2. Helmenstine, Anne Marie. “Monomer Definition and Examples.” ThoughtCo, Feb. 11, 2020, Available here.
3. “Oligomer.” Wikipedia, Wikimedia Foundation, 24 Nov. 2019, Available here.
Image Courtesy:
1. “Epoxy prepolymer chemical structure” By Cacycle – Own work (Original text: selfmade) (CC BY-SA 3.0) via Commons Wikimedia
2. “Oligomer of compound 48-80” By Ed (Edgar181) – Own work (Public Domain) via Commons Wikimedia