Complex Macromolecular Architectures Based on n-Hexyl Isocyanate and ϵ-Caprolactone Using Titanium-Mediated Coordination Polymerization

Abstract

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 CpTiCl2(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 CpTiCl3. Finally, PS(PHIC)2 and PS[P(ϵ-CL)]2 3-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.

Aliphatic polyester polymer stars: synthesis, properties and applications in biomedicine and nanotechnology

“…The versatility of these combined methodologies has led to a huge range of architectures. For clarity purposes, these miktoarm PCL polymers are all classified with A representing the PCL block and include: AB, 171,172 A 2 B, 73,[173][174][175][176] AB 2 , 177-179 AB 4 , 180 A 2 B 2 , 181-186 A 3 B 3 , 173 AB 8 , 187 ABC, 77,[188][189][190][191][192][193][194] (A-b-B) 3 (C) 3 , 195 ABCD [196][197][198] and ABCDE. 199 AB miktoarm polymers are prepared by the core cross-linking approach and thus often contain a random number of A and B arms attached to the core, dependent upon reaction conditions and polymer ratios.…”

Synthesis and characterization of brush diblock and triblock copolymers bearing polynorbornene backbone and poly(l‐lactide) and/or poly(hexyl isocyanate) side chains by a combination of coordination and ring opening metathesis polymerization

“…Another important advantage of the coordination polymerization using half‐titanocene alkoxides is the capability of incorporating the complex on OH groups of a polymer chain. Subsequent polymerization of hexyl isocyanate or lactides leads to block copolymers and very interesting macromolecular architectures …”

Titanium complexes of dialkanolamine ligands as initiators for living ring‐opening polymerization of ε‐caprolactone

“…On the other hand, structurally well‐defined non‐metallocene Ti‐based catalysts were successfully applied for the living polymerization of olefins 14. Besides, some titanium complexes having bulky alkoxo,15 bis(aryloxo)16, 17 or amine(bisphenolate)18, 19 ligands as well as half‐metallocenes (CpTiCl 3 )20 showed distinctively high activity in the polymerization of ε‐caprolactone or lactide. Poly(ε‐caprolactone) with molecular weight as high as 60,000 g mol −1 and narrow molecular weight distribution ( M w / M n ≤ 1.3) can be typically prepared by living ROP of ε‐caprolactone using aforementioned catalytic complexes 16.…”