Copolymer
A polymer made from two or more different monomers.
Unit
Dimensionless
In depth
The monomers may alternate, be randomly distributed, form long blocks, or be grafted as side chains, and each arrangement gives different properties. Copolymerisation lets a material be tuned to combine the useful features of both components.
Examples in the real world
ABS plastic combining acrylonitrile, butadiene and styrene; SBR synthetic rubber for tyres.