Difference Between Polymer and Macromolecule

Polymer vs Macromolecule
 

The difference between polymer and macromolecule stems from the fact that polymer is a subdivision of macromolecule. Macromolecules are extremely large molecules with a high molecular weight. Macromolecules can be subdivided into two main categories according to their structure. Some are polymerized molecules and some are non-polymerized molecules. Polymers are formed by the polymerization of small molecules, which are called monomers. Though the main focus of this article is the differences between macromolecules and polymers, it first explains polymers and macromolecules before going into the differences.

What is a Polymer?

Polymers are huge molecules containing identical building blocks. Each polymer has a repeating unit, it is called the monomer. The word polymer means many parts (“poly” = many and “mer” = parts); the term is derived from two Greek words “polus” (= many) and “meros” (= parts). There are naturally occurring polymers as well as artificially synthesized polymers; shellac, wool, silk, natural rubber and amber are some examples for natural polymeric materials. Cellulose is another natural polymer which can be found in wood and paper. Bio-polymers are found in biological systems; proteins (polyamides), nucleic acids (polynucleotides) and carbohydrates are few examples for bio-polymers.

Difference Between Polymer and Macromolecule

A large number of artificial polymers have synthesized in modern world and we have numerous uses in our day to day life. These materials are very convenient to use. Polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl chloride (PVC), synthetic rubber and phenol formaldehyde resin (Bakelite) are some of mostly abundant artificial polymers. Many of artificial polymers are not bio-degradable.

Properties of polymers vary depending on the structure and the bonding type of the molecule. Addition of polymers usually occurs across the carbon-carbon double bond. It also includes ring opening systems. Vinyl polymers mostly fall into this category.

Polymer Formula Monomer
Polyethylene
low density (LDPE)
–(CH2-CH2)n ethylene
CH2=CH2
Polyethylene
high density (HDPE)
–(CH2-CH2)n ethylene
CH2=CH2
Polypropylene
(PP) different grades
–[CH2-CH(CH3)]n propylene
CH2=CHCH3
Poly(vinyl chloride)
(PVC)
–(CH2-CHCl)n vinyl chloride
CH2=CHCl
Polystyrene
(PS)
–[CH2-CH(C6H5)]n styrene
CH2=CHC6H5
Polyacrylonitrile
(PAN, Orlon, Acrilan)
–(CH2-CHCN)n acrylonitrile
CH2=CHCN
Polytetrafluoroethylene
(PTFE, Teflon)
–(CF2-CF2)n tetrafluoroethylene
CF2=CF2
Poly(vinyl acetate)
(PVAc)
–(CH2-CHOCOCH3)n vinyl acetate
CH2=CHOCOCH3

Many of artificial polymers are solids with various and useful physical properties. Most of them are inert (water resistant, corrosion resistant), flexible (elastic), and they have a low melting point (can be molded easily).

What is a Macromolecule?

A macromolecule is a giant molecule that consists of thousands of atoms. They have a molecular weight ranging from several thousands to several millions and the size from several tens of nanometers (nm) to few centimeters (cm). Carbohydrates, proteins, lipids, and nucleic acids are some examples for macromolecules. Some macromolecules are multiples of a repeating unit (monomer), they are called polymers. Carbohydrates, proteins, and lipids contain monomers. But, some macromolecules cannot be sub-divided into individual entities; some of those molecules have macrocycles. For example, fat is a macromolecule, synthesized by condensation of four molecules (glycerol and 3-fatty acids), but it is not a polymer.

Macromolecule

What is the difference between Polymers and Macromolecule?

• Macromolecules and polymers are both giant molecules. Some macromolecules are polymers, but not all; some of them cannot be divided into small units.

• Polymers are macromolecules with a repeating unit called monomer throughout the molecular structure. But, not all macromolecules have a monomer in their structure.

• Macromolecules comprise of both polymeric and non-polymeric molecules, but polymers include only polymerized molecules.

Summary:

Polymer vs Macromolecule

Macromolecules are the molecules with a large molecular weight. Molecular weight is the factor that matters in macromolecules. Unlike in macromolecules, polymers may or may not have large molecular weights. Polymers are formed by repeating a small structural unit in their structure. Thus, most of the polymers have a large molecular weight. Polymers, that have a very large molecular weight, are considered as macromolecules. Therefore, there can be polymerized or non-polymerized molecules in macromolecules. If a polymer has a relatively high molecular weight, it is considered as a macromolecule.

 

Images Courtesy:

  1. Polymer via Wikicommons (Public Domain)
  2.  Macromolecule by Cjp24 (CC BY-SA 3.0)