Explain how does 1, 3-butadiene polymerise by different route

Explanation

1,3-Butadiene is a conjugated diene. It can polymerize either by 1,4-addition or by 1,2-addition mechanism as shown below :
(i) 1,4-Polymerization : When the polymerization occurs at the terminal carbon atoms , i.e., `C_1 and C_4` of 1,3-butadiene molecules , an unbranched polymer is formed.

Each repeating unit of this polymer contains a double bond , each carbon atom of which has two different substituents , therefore , these polymers can exist in two geometrical isomeric forms , i.e., forms , i.e., cis -and trans.
(ii) 1,2-Polymerization : Alternatively , 1,3, butadine can undergo polymerization at `C_1 and C_2` positions of 1,3-butadiene to yield the branched polymer called polyvinlylpolythene.