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Well-defined diblock copolymers {PS- b-P(ϵ-CL)} and triblock terpolymers {PS- b-PI- b-P(ϵ-CL), PI- b-PS- b-P(ϵ-CL)} of polystyrene, PS, poly(ϵ-caprolactone), P(ϵ-CL), and polyisoprene, PI, were synthesized using CpTiCl 2(OP) (P = PS, PS- b-PI, or PI- b-PS) as macroinitiator. Graft copolymers having polybutadiene, PBd, backbone and poly( n-hexyl isocyanate), PHIC, or P(ϵ-CL) branches {PBd- g-PHIC and PBd- g-P(ϵ-CL)} as well as block−graft terpolymers {PS- b-(PI- g-PHIC), PS- b-[PI- g-P(ϵ-CL)]} were also synthesized by performing hydroboration/oxidation reactions on the polydiene backbone and by transforming the introduced hydroxyl groups to initiation sites by reaction with CpTiCl 3. Finally, PS(PHIC) 2and PS[P(ϵ-CL)] 23-miktoarm star copolymers were synthesized using a heterofunctional initiator bearing one initiation site for atom transfer radical polymerization and two for titanium-mediated coordination polymerization. All intermediates and final products were characterized by size exclusion chromatography, equipped with refractive index and light scattering detectors, membrane osmometry, and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The ring‐opening polymerization of ɛ‐caprolactone (ɛ‐CL) and δ‐valerolactone (δ‐VL) using nine catalytic systems consisting of a combination of three C2v zirconocene complexes and three borate cocatalysts is discussed. The polymerizations proceed in a well‐controlled manner, producing polymers with relatively high molecular weights and narrow molecular weight distributions. Kinetic experiments of the polymerization of ɛ‐CL with the catalytic system Cp2ZrMe2/B(C6F5)3 (1) showed a linear dependence between polymerization yield and molecular weight with time, as well as between the molecular weight with the molar ratio of the monomer over the catalyst [ɛ‐CL]/[Zr], indicating sufficient control of the polymerization reaction. The catalytic system (1) was utilized for the synthesis of well‐defined block copolymers of MMA with ɛ‐CL and δ‐VL. All samples were characterized by size exclusion chromatography, nuclear magnetic resonance, and differential scanning calorimetry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3524–3537, 2007 [ABSTRACT FROM AUTHOR]