Polymers

— a large molecule formed when lots of small molecules join

• addition polymerisation
• condensation polymerisation

e.g.

The C=C bond breaks, allowing the carbon atom one more bond to join with another molecule

Synthetic polymers

— polythene

— nylon

— Terylene

— lycra

— chewing gum

— polysterene, perspex

Natural Polymers

— starch from glucose

— cellulose

— protein from amino acids

• wood → cellulose
• hair + nails → keratin
• skin + bones → collagen

Addition Polymerisation

The C=C bond breaks, allowing the carbon atom one more bond to join with another molecule

— double bond breaks → allows addition

Chain length

— the chain length varies — is never the same

— changing reaction conditions → changes average chain length

— Mr of ethene → 28 (C2H4)

— Mr of polythene could be 500,000+

Condensation Polymerisation

— does not depend on C=C bond

— two monomers join → each has two functional groups → one at each end

— join at functional group by eliminating a small molecule

Making Nylon

HCl is released and N and C joins