What is a large molecule created by polymerization of monomers?

$\text{A polymer....?}$
n underbrace(H_2C=CH_2(g))_"ethylene monomer" stackrel("catalysis, MAO")rarr(-CH_2-CH_2-)_n
Another typical monomer is propylene, ${H}_{3} C - C H = C {H}_{2}$, and given a special catalyst, its polymerization can give rise to polypropylenes with specific geometries to give very high value products.