Chapter 1 General Introduction Chapter 2 Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes. Chapter 3 Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes. Chapter 4 Polymerization of Methyl Methacrylate Catalyzed by Rare Earth Metal Enolate Complexes. Chapter 5 Living Polymerization of Trimethylsilyl Substituted Methacrylate Catalyzed by Rare Earth Metal Complexes.

We studied the dielectric normal mode relaxation in dilute and semidilute solutions of poly-(e-caprolactone) (PCL) and poly(d-valerolactone) (PVL) in benzene using narrow distribution samples prepared with an initiator of a lanthanoid complex. The effect of long nonpolar groups separating the polar ester groups on the dielectric behavior was investigated by comparing the present results with those for cis-polyisoprene (PI) solutions reported previously. In dilute solutions, the longest relaxation time r for both PCL and PVL increased in proportion to AfL63±0•03. The double-logarithmic plots of r vs fytysM/RT for the dilute solutions as well as those of PI fell on the same universal straight line irrespective of the solvent quality. Here [ ] and 3 are the intrinsic viscosity and the solvent viscosity, respectively. The dielectric loss factor e" vs frequency f curves for the dilute PCL and PVL solutions agreed with the Zimm theory. In the semidilute solutions, log increased linearly with respect to C as predicted by the Muthukumar-Freed theory. The e" curve broadened with C as observed previously for PI semidilute solutions. The dynamical behavior is independent of the local structure. The dielectric relaxation strength <=, which is proportional to the mean square end-to-end distance (r2), increased with M in dilute solution but decreased with C above the overlap concentration.

Organolanthanide(III) complexes such as |(C5Me55)2SmH|2 and (C5Me5)2SmMe(THF) were found to initiate the living polymerizations of methyl methacrylate (MMA) to give high molecular weight polymers (M n > 500 × 103) with extremely low polydispersity (M w/Mn = 1.04). The syndiotacticity increased up to 95.2% by lowering the temperature to −95°C. The molecular structure of the 1:2 adduct of (C5Me5)2SmH with MMA determined by X‐ray method indicates that this intermediate assumes the 8 membered ring conformation where the Sm atom is bound to MMA in an enolate form and the ester of penultimate MMA is coordinated to the metal. Based upon these results, an anionic coordination mechanism has been proposed for the present reaction. Organolanthanide(II) complexes also exhibit high activity and proceed the living polymerizations. Organolanthanide(III) complexes also initiate the living polymerizations of lactones such as ϵ‐caprolactone and δ‐valerolactone. The stoichiometric reactions indicate that real active species assumes the alkoxylanthanide(III) form.