The kinetics of anionic polymerization of isoprene initiated by organodilithium in cyclo-hexane

in which a little THF was included and the molar ratio ( R) of THF to Li was equal to 1

was investigated. The propagation reaction rate (Rp) was first order with respect to monomer concentration. However the rate order (β) relative to the concentration of active species was less than 1 and could be expressed as:β= 0.3318 + 5.3240 × 10-3 t . The conception of association and monomolecular active chain ends was replaced by the conception of association and free states of the active chain ends and a kinetic equation of isoprene polymerization initiated by organodilithium was derived as follows[C0]/k=4/(k2k12kp4)k3+2/(K1kp2)k+1/(kp)According to the equation and taking use of the concentration of initiator [ C0 ] and quasi -reaction rate constant (k)

the values of real propagation reaction rate constant (kp)

equilib -rium constants of tetra - association and di - association states K2 and equilibrium constant of di - association and free states K1 were obtained. Based on equilibrium constants (K1

K2) the dissociation energies

have been calculated ΔH1

ΔH2

and the concentrations of tetra - association state

di - association state and free state have been deduced respectively. The activation energies of kp and kap were shown to be Ep = 64.306 kJ·mol-1、Eap = 88.364 kJ·mol-1.