A monomer is a small molecule that can chemically bind to other monomers to form a larger and more complex structure known as a polymer. The term “monomer” comes from the Greek words “mono” (meaning “one” or “single”) and “meros” (meaning “part”). Here are some key points about monomers:
Binding Process: The process by which monomers join together to form polymers is called polymerization.
Types:
- Alkenes: These can undergo addition polymerization due to the presence of a double bond. Ethene (ethylene) is a common monomer used to produce polyethylene.
- Functional Groups: Monomers with specific functional groups can react with each other to form polymers. For example, an alcohol and a carboxylic acid can react to form an ester linkage, as seen in polyesters.
Examples:
- Ethene: When polymerized, it forms polyethylene, a common plastic.
- Propene: Forms polypropylene, another widely used plastic.
- Terephthalic acid and ethylene glycol: These are the monomers for producing polyethylene terephthalate (PET), used in making bottles and textiles.
- Styrene: Used to produce polystyrene.
Biological Monomers:
- Amino acids: The monomers of proteins.
- Nucleotides: The monomers of nucleic acids like DNA and RNA.
- Monosaccharides: The monomers of carbohydrates like cellulose and starch.
Environmental Considerations: Some monomers, such as vinyl chloride (used in PVC production), can be toxic and need to be handled with care. Moreover, the extraction and refining of monomers, especially from petrochemical sources, have environmental impacts.
In summary, monomers play a crucial role in the synthesis of polymers, which are foundational to a vast array of materials used in everyday life and in various industries. Whether derived from biological sources or synthesized chemically, monomers and the polymers they form have significantly shaped the modern world.