Polymer is a word derived from Greek meaning many parts or segments; “poly†means many and “meros†means parts or segments. Polymers are very large molecules (macromolecules) made of repeating units of monomers with repeating structural bonds.
Monomers means one segment or part and are molecules that can combine into polymers. For example, ethylene is a monomer that when joined with other ethylene molecules (possibly thousands of other ethylene monomers) become the plastic polyethylene or PE.
The common water molecule H2O is not a monomer as it cannot be combined to form a larger molecule. Lots of H2O molecules equate to a puddle of water.
While we’re at it, let’s go over two other related words. A homopolymer is a polymer built from one type of monomer. A copolymer is a polymer built from more than 1 type of monomer.
The physical characteristics of polymers (stiffness, etc..) are determined by the how each monomer bonds to each other as well as the type of alignment and structure. As this is quite complicated, we will not go over this here.
The word “polymer†is sometimes used interchangeably with the word “plasticâ€. However, while all plastics are polymers, not all polymers are plastics. Polymers encompasses a large class of natural and synthetic materials with a wide variety of properties. Plastic is a type of synthetic polymer produced in labs through a process called polymerization. You can actually also find polymers in nature.
Here are examples of naturally occurring polymers:
- Cellulose – what trees and stems are made of
- Starch – found in potatoes, rice, corn…
- Protein – found in our body, built from amino acids (monomer)
- Silk – produced by silk worms
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