Polymers are made up of small molecules called monomers. Polymers which are formed by one type of monomer called homopolymers and which are formed by more than one type of monomers are called co-polymers. Natural polymers are biodegradable whereas systhetic polymers may or may not be. Addition or chain growth polymerization involves the repeated addition of monomers to the polymer chain. The monomers are unsaturated compounds and this type of polymerization takes placed by ionic (cationic or anionic) as well as free radical a series of condensation reactions between the monomers. Each monomer normally contains two functional groups. Branch chain polymers may be condensation polymers or addition but cross linked polymers are always condensation polymers.
Which of the these are natural polymers ?