Co-polymers

A co-polymer, by definition, is a polymer built from two or more DIFFERENT kinds of monomer unit, rather than one monomer repeated on its own (a homopolymer). SBR rubber, also called Buna-S, is the worked example -- it is built from both styrene and butadiene monomer units together. This matters because co-polymers routinely end up with properties quite different from what either monomer's own homopolymer would give -- mixing monomers is a deliberate way to engineer properties that neither pure homopolymer has on its own, exactly the strategy behi …