Transcript Polymerization Reactions

Polymerization Reactions
Chemistry II
Types of Polymerization Reactions
• Addition polymerization – monomers are
added together, with no other products
formed
• Condensation polymerization – small
molecule, like water, is formed in the
polymerization
Types of Polymers
• Copolymer – Two different monomers form
the chain
• Homopolymer – All of the monomers are the
same
• Thermoset– when molded to a certain shape
it cannot be softened again or dissolved, like
Bakelite
• Thermoplastic – can be remelted after molded
Addition Polymerization
• Process initiated by free
radical (has unpaired
electron)
• Free radical attacks
double bond to form a
new free radical
• Termination of the
reaction occurs when 2
radicals react to form a
bond
Condensation Polymerization
• Formation of Nylon dimer
• Dimer – two monomers joined
• Amino group on left or Acid group on right can
continue to react, extending the polymer
Polymers based on Ethylene
• LDPE – Low Density Polyethylene
– Highly branched
– Not tightly packed
• HDPE – High Density Polyethylene
– Mostly straight-chain molecules
– Tightly packed
Examples
• Polypropylene –
monomer is propylene,
so X is CH3
• Isotactic chain vs.
Syndiotactic vs. Atactic
• Polystyrene
• Polyvinyl chloride (PVC)