ABSTRACT
Abstract .................................................................................................................282 16.1 Introduction ................................................................................................282 16.2 Experimental Part .......................................................................................282 16.3 Results and Discussion ..............................................................................283 16.4 Conclusion .................................................................................................289 Keywords ..............................................................................................................289 References .............................................................................................................289
Within radically initiated MMA and styrene polymerization systems, metallocenes are shown to be actively participating in formation of two kinds of chain propagation active centers-free radicals and living coordination active centers, and the polymerization takes place as radical coordination one. Relative contribution of each kind of centers into the observed kinetic peculiarities of the polymerization depends much on metallocene kind and the process conditions.
Radical polymerization of vinyl monomers-methyl methacrylate and styrenein the presence of some metallocenes together with increasing the process rate is characterized by some kinetic peculiarities. Basic of them are already mentioned in scientific literature, that is, conversion change of average molecular weight and MMD of polymers1-5; ability of polymers derived in the presence of metallocenes to initiate living polymerization of new monomer portions2; prolonged until complete consumption of monomer, and post-effect of polymerization after short-term UV irradiation of the polymerization system.3 Furthermore, advanced yield of stereoregular polymethyl methacrylate (PMMA) is observed as compared with free radical polymerization of monomer under the same temperature.6 Consideration of these peculiarities suggested that in the course of polymerization, there appeared coexistence of several, namely, two kinds of active centers for macromolecule growth. Availability of two kinds of active centers under styrene polymerization in the presence of ferrocenes, titanocene, and zirconocene dichloride has been proved by solution of the inverse MMD problem.5
