Overview
This lecture explains how addition polymers are made from alkenes, focusing on drawing monomers, repeating units, and polymers, and covers naming conventions and reaction conditions.
Alkenes and Polymerization
- Alkenes are hydrocarbons with at least one carbon-carbon double bond (C=C).
- The double bond makes alkenes unsaturated and able to open up for new bonds.
- In addition polymerization, the double bonds break, linking monomers to form long polymer chains.
Drawing Monomers, Repeating Units, and Polymers
- Monomers are drawn with the C=C bond and groups attached directly above and below each carbon.
- Repeating units represent the structure repeated in the polymer; they must have the same atoms as the monomer.
- In repeating units, draw bonds extending left and right through brackets to show continuation.
- Use 'n' to indicate the number of repeating units (e.g., n=10 means 10 monomers).
Practical Example: Butene Polymerization
- Redraw monomer (e.g., butene) in the standard format with substituents up and down relative to the C=C.
- Simplify groups (e.g., C2H5) and arrange them directly above or below the double-bonded carbons.
- In the polymer, replace the double bond with single bonds pointing left and right through brackets.
Naming Polymers
- Name a polymer by adding 'poly' before the monomer’s name in parentheses (e.g., poly(ethene)).
- Follow the same pattern for different monomers (e.g., poly(butene), poly(chloroethene)).
Reaction Conditions
- Addition polymerization requires high pressure and a catalyst.
- Sometimes pressure and catalyst are shown above the reaction arrow in equations.
Key Terms & Definitions
- Alkene — Hydrocarbon containing a carbon-carbon double bond (C=C).
- Monomer — Small molecule that can join with others to form a polymer.
- Polymer — Large molecule made by joining many monomers.
- Repeating unit — The specific sequence of atoms repeated in the polymer chain.
- Addition polymerization — Process where unsaturated monomers join to form a saturated polymer.
Action Items / Next Steps
- Practice drawing monomers, repeating units, and naming for different alkenes.
- Review conditions needed for addition polymerization (pressure, catalyst).