Difference Between Polymer and Monomer

The key difference between polymer and monomer is that polymer is a collection of a large number of molecules whereas monomer is a single molecule.

Monomers and polymers are important in various aspects. When someone hears the word polymer, they automatically think about synthetic polymers like polyethylene, PVC or nylon. Other than these, there is also a category of polymers known as biopolymers such as carbohydrates, proteins, nucleic acids, which are crucial to our life. Polymers are made out of monomers. Hence, it is also important to know the difference between polymer and monomer in order to have an understanding of their synthesizing processes.

CONTENTS

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

What is Polymer?

A polymer is a macromolecule consisting of repeating units that represents the monomers. Monomers are the building blocks of polymers. A polymer forms when monomers link with each other via covalent chemical bonds. There are several classifications of polymer materials according to the structure, properties, occurrence, etc. For example, we can classify polymers as natural and synthetic polymers. Likewise, we can classify them according to properties as thermoplastic, thermosetting polymers and elastomers. Biopolymers are another important category. This category includes carbohydrates, proteins, nucleic acids and other polymer materials that form and exists in biological systems or living organisms.

Polymerization is the process that we use to produce a polymer from monomers. Therefore, we can classify these materials according to the method of polymerization as well. For instance, addition polymers form from addition polymerization whereas condensation polymers form from condensation polymerization. These materials have some unique properties such as toughness, viscoelasticity, tendency to form glasses, etc. Some common examples include polyethylene, polypropylene, polystyrene, rubber, nylon, etc.

What is Monomer?

Monomers are building blocks of polymers. They can occur as simple or complex molecules with double bonds or functional groups such as –OH, -NH₂, –COOH, etc. The presence of unsaturated double bonds or functional groups is a requirement in the polymerization process when several monomers are linking to form a polymer.

Normally, there are two functional groups in both sides of the monomer, so it can form linear chains by binding to other from both sides. If there are several functional groups, monomers can link to form branched polymers. For example, glucose is the common monomer of carbohydrates with –OH functional groups. When joining two glucose molecules, a water molecule releases and forms a glycosidic bond. When the –OH in C-1 joins with a –OH group in C-4 of another glucose molecule, a linear chain will form. But if –OH of C-6 joins with a -OH of C-1 of another glucose it forms the branched polysaccharide.

Moreover, amino acids are the monomers of protein and nucleotides are the monomers of nucleic acid. Other than the above-mentioned biopolymers, there are synthetic polymers as well. For example, Ethene/Ethylene molecule has a carbon-carbon double bond, and it is the monomer of polyethylene.

What is the Difference Between Polymer and Monomer?

A polymer is a macromolecule consisting of repeating units that represents the monomers while monomers are building blocks of polymers. The key difference between polymer and monomer is that a polymer is a collection of a large number of molecules whereas monomer is a single molecule. Furthermore, monomers have a small molecular weight, while the polymers have a larger molecular weight, which is many times the weight of a monomer. As another important difference between polymer and monomer, polymers usually have higher boiling points, higher mechanical strengths over monomers.

Apart from that, monomers and polymers differ in their chemical and physical properties. For example, glucose is an oxidizing sugar, soluble in water, has a sweet taste. Starch is a polymer of glucose. But starch is a non-oxidizing sugar, partially soluble in water and don’t have a sweet taste.

Summary – Polymer vs Monomer

Polymers are giant molecules made out of small molecules. we name these small molecules as monomers. The key difference between polymer and monomer is that a polymer is a collection of a large number of molecules whereas monomer is a single molecule.

Reference:

1. Helmenstine, Anne Marie, and Helmenstine. “What Is a Monomer? Definition and Examples.” ThoughtCo. Available here 
2. “Polymer.” Wikipedia, Wikimedia Foundation, 5 Nov. 2018. Available here  

Image Courtesy:

1.”Nylon-3D-h bond” By GYassineMrabetTalk (CC BY 3.0) via Commons Wikimedia
2.”Example Vinyl monomer”By Chem538grp1w09 – Own work, (Public Domain) via Commons Wikimedia