Polymers

• Polymers are long chain molecules, made up of many smaller repeating units called monomers, which are joined together by chemical reactions.
• Polymers can be natural or artificial and they are very useful.
• The larger a molecule is, the stronger its intermolecular forces. This means polymers can have high melting points, despite being molecular.
• Cross links are covalent bonds between polymer chains.
• Cross links are covalent bonds between polymer chains.
• When a polymer is not cross linked, the chains are held together by weak intermolecular forces so they can be separated relatively easily, giving lower melting points.
• When a polymer is cross-linked, strong covalent bonds hold the chains together, so it is much harder to separate. They do not melt because they would react at a lower temperature than they can melt.