KINETIC STUDIES OF THE ANIONIC RING-OPENING POLYMERIZATION OF HEXAMETHYLCYCLOTRISILOXANE(D3) INITIATED BY HEXAPHENYLCYCLOTRISILAZANE TRILITHIUM
硅氮负离子引发六甲基环三硅氧烷开环聚合的动力学研究

The kinetics of the anionic ring-opening polymerization of hexamethylcyclosiloxanes (D_3) initiated by hexaphenylcyclotrisilazane trilithium(P_3~ NLi ),in the presence of DMSO or THF as a promoter was studied.The conversion of D_3 at different reaction time was determined from the ratio of the peak area of the NMR spectrum of D_3 to that of the polymer.The reaction orders for THF,DMSO,D_3 and P_3~ NLi were calculated.The polymerization is a reaction of 1~ st order with respect to D_3,THF and P_3~ NLi ,and 2~ nd order with respect to DMSO.The kinetic equations of the polymerization reactions were also proposed.The kinetics of THF and DMSO is v_p=-dD_3]/dt=kI]D_3]THF] and v_p=-dD_3]/dt=kI]D_3]DMSO]~2, respectively.The accelerating effect of DMSO was stronger than that of THF,and the rate constant of polymerization with DMSO as promoter was nearly 100 times as high as that of THF.