A polymer is a long chain molecule made up of small units called monomers.
- Process of turning lots of monomer into a long polymer chain.
- The process by which alkenes monomers form long polymers, which are technically alkanes but are named with alkene names, such as poly(ethene).
- The polymer structure can be represented more simply by drawing the repeating unit.
When 2 different monomers become incorporated into the polymer chain.
Characteristics of polymers✍🏻
- The longer the chain, the stronger the polymer.
- Tensile strength is a measure of how much force needs to be applied before a polymer snaps.
- Tensile strength increases with chain length because longer chains become more entangled and they have stronger intermolecular bonds and therefore are more difficult to pull apart.
- The more polar a side group, the stronger the bonds between the polymer chains, therefore the stronger the polymer.
- Straight chain polymers can pack closer together allowing stronger bonds between the chains.
- The more rigid the chain the stronger the polymer.
- Hydrocarbon chains are flexible.
- Incorporating benzene rings makes the polymer chain stiffer.
- More extensive cross linking makes the polymer harder to melt.
- The more regular the orientation of the side groups and the closer the packing, the stronger the polymer.
- soft and springy
- they can be stretched but will return to their original shape.
- Not so springy
- When deformed, it tends to stay out of shape
- Undergoes permanent or plastic deformation
- Strong polymers
- Do not deform easily
- can be made into strong, thing threads
- Eg: Nylon
- Used for making clothing materials
- No cross-links.
- Intermolecular bonds are weak.
- Attractive forces can be overcome by warming.
- Chains can slide over each other.
- Can be deformed.
- On cooling the weak bonds reform and it will hold its new shape.
- Poly(ethene) and nylon are examples.
- Extensive cross-linking.
- Strong bonds.
- Covalent bonds cannot be broken by warming.
- Chains cannot move relative to one another.
- Cannot change shape.
- Continued heating leads to chars and burns.
- Bakelite is an example.
Uses and properties of polymers:
- Low density, flexible
- eg. Carrier bags
- Higher density, less flexible
- eg. Buckets, food storage, car petrol tanks
- Can withstand higher temperatures than HDPE; good chemical resistance
- eg. Water and gas pipes
- Hydrophobic; slippery non-stick surface; resistant to chemical attack.
- eg. ‘Gore-tex’ clothing, ‘Teflon’ non-stick pans
- Highly transparent; low density; shatterproof; resistant to stains and UV radiation.
- eg. Structural roofing material, such as used on the Eden project biomes.
- Elastomer; non-porous; very tough; resistant to heat, light and chemical attack.
- eg. Wetsuits, cases for MP3 players and mobile phones.
This is the end of the topic! Good job!
Drafted by Cherry (Chemistry)