Q.What is copolymerization? Illustrate your answer with the formation of Buna-S from buta-1,3-diene and styrene.

Copolymerization is addition polymerization carried out with two (or more) different monomers together, so the resulting chain -- a copolymer -- incorporates both kinds of monomer unit, unlike a homopolymer built from only one monomer. Buna-S (SBR) copolymerises buta-1,3-diene, $\text{CH}_2{=}\text{CH--CH=CH}_2$, with styrene, $\text{C}_6\text{H}_5\text{--CH=CH}_2$, by a free-radical addition mechanism, giving a chain in which butadiene- and styrene-derived units occur in essentially random sequence. The diene units supply most of the chain's flexibility and elasticity (a residual double bond remains at each diene unit after polymerisation), while the aromatic styrene units toughen the …

Recognise that a copolymer requires two different monomers reacting in the SAME addition chain-growth process; identify each monomer's …

Confusing Buna-S with Buna-N (which uses acrylonitrile, not styrene, as the second monomer); describing it as a condensatio …