双锂引发剂研究异戊二烯阴离子聚合的动力学

STUDY ON THE KINETICS OF ANIONIC POLYMERIZATION OF ISOPRENE INITIATED BY MODIFIED NAPHTHALENE - LITHIUM

环已烷为溶剂,R（[THF]/[Li]）=1时,以齐聚异戊二烯双锂为引发剂,对异戊二烯聚合增长反应动力学进行了研究。结果表明,增长反应速度对单体浓度[M]呈一级关系,对引发剂浓度[C_0]的反应级数（β）小于1并随聚合温度上升而增加。推导出普适的动力学方程。并由此分别得出了体系中在一定条件下活性种的四缔合态与二缔合态、二缔合态与游离态之间的平衡常数K_1、K_2,以及缔合态和游离态的平衡浓度;同时也求得了四缔合态解缔为二缔合态,再进一步解缔为游离态这两步的解缔焓。此外,分别计算出了该体系的表观活化能E_（ap）和真实活化能E_p。

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)k'3+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.