Anionic Copolymerization of Isoprene and 1,1-Diphenylethylene

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Abstract
Anionic copolymerization of isoprene (M1) and 1,1-diphenylethylene (M2) was carried out in tetrahydrofuran (THF), dioxane, benzene, and n-heptane by using n-butyllithium (n-BuLi), Na-naphthalene, Na- and K-dispersions as initiators. An alternating copolymer was obtained in the copolymerization in THF, which proceeded without a chain transfer and a termination. Monomer reactivity ratios, r1 obtained by assuming the rate constant k22=0, were 0.12 (Li+), 0.11 (Na+), and 0.11 (K+) in THF at 0°C. The r1 value in benzene at 40°C, however, was affected by the counter ion as follows: 37 (Li+), 0.38 (Na+), and 0.05 (K+). With Li+ counter ion the values were 0.50 in dioxane at 30°C and 29 in n-heptane at 40°C. The order of rate constants in the copolymerization in THF with n-BuLi at 0°C, was k12>k11>k21, the last of which was 2.64×10−3l/mol sec.