1-Octene, 1-hexene, and 1-butene are used comonomers in the manufacture of polyethylenes.  The advantages to such copolymers has led to a focus on catalysts that facilitate the incorporation of these comonomers, e.g., constrained geometry complexes.
Comonomers are often employed to improve the plastification of polymeric materials, i.e. the flexibility of the polymer.  Unlike traditional plasticizers, comonomers are not leachable.