The stopped-flow method, by which a quasi-living polymerization process can
be realized within an extremely short period (ca. 0.2 s). has been proven
to be one of the most powerful techniques for studies on the nature of acti
ve sites and elucidation of the olefin polymerization mechanism based on th
e information from the polymers obtained in the initial stage of polymeriza
tion. It has been demonstrated that a better and deeper understanding many
controversial problems in Ziegler catalysts has been achieved, such as argu
ments concerning the non-uniformity of the active sites, the intrinsic kine
tic parameters the effects of catalyst preparation conditions, the role of
cocatalysts, hydrogen and electron donor, etc. The successive modifications
to the basic stopped-flow system have led extensive applications in invest
igating the catalyst pretreatment effects induced by various reagents, as w
ell as developing a series of novel blocks copolmers.