The relationship between the value of n in the Nd(OPr1)s-nCln and the reactivity ratio (γ) of dienes was studied through the copolymerization of butadiene-isoprene with the binary catalyst system

Nd (OPri)3-nCln-AlEt3. The results indicate that the monomer (isoprene) which has higher electron density on its conjugated double bond is more reactive

as a result

both its content in copolymer and its reactivity ratio (γ) are increased with the increase of the value of n.