Question

(a) Isobutylene and isoprene coplymerize to give “butyl rubber”. Draw the structure of the repeating unit in butyl rubber, assuming that the two monomers alternate.

(b) Styrene and butadiene copolymerize to form styrene-butadiene rubber (SBR) for automobile tires. Draw the structure of the repeating unit in SBR, assuming that the two monomers alternate.

Short answer

Copolymerisation reaction is the reaction in which more than one monomer polymerise to form a copolymer. The properties of the resulting copolymer will be different from the parent homopolymer. Cationic copolymerization of isobutylene and isoprene produces butyl rubber, an elastomer which is of commercial importance.

Step-by-step solution

Step-1. Copolymerisation of isobutylene and isoprene:

Copolymerisation reaction is the reaction in which more than one monomer polymerise to form a copolymer. The properties of the resulting copolymer will be different from the parent homopolymer. Cationic copolymerization of isobutylene and isoprene produces butyl rubber, an elastomer which is of commercial importance.

Step-2. Copolymerisation of styrene and butadiene:

Styrene-butadiene copolymer is synthetic rubber and prepared by polymerisation of styrene and butadiene monomers. SBR has good stability and abrasion resistance.