Many common addition polymers are formed from unsaturated monomers (usually having a C=C double bond). The most prevalent addition polymers are polyolefins, i.e. polymers derived by the conversion of olefins (alkenes) to long-chain alkanes.  The stoichiometry is simple:
:n RCH=CH  →   [RCH-CH]
This conversion can be induced by a variety of catalysts including free radicals, acids, carbanions and metal complexes.
Examples of such polyolefins are polyethenes, polypropylene, PVC, Teflon, Buna rubbers, polyacrylates, polystyrene, and PCTFE.