Synthesis and properties of block copolymers composed of norbornene/higher α-olefin gradient segments using ansa-fluorenylamidodimethyltitanium-[Ph₃C][B(C₆F₅)₄] catalyst system

Abstract

A series of di- and triblock copolymers composed of gradient norbornene (NB)/higher α-olefin ((1-octene (O) or 1-dodecene (Do)) segments (NB/α-olefin-gradient segments) were synthesized with (t-BuNSiMe2Flu)TiMe2 (1) ‒ [Ph3C][B(C6F5)4] using 2,6-bis(1,1-dimethylethyl)-4-methylphenol...

Synthesis of Vinyl-Addition Polynorbornene Copolymers Bearing Pendant n-Alkyl Chains and Systematic Investigation of Their Properties

“…Recently, Shiono et al reported the studies for the copolymerization of NB and various α-olefins such as 1-octene, 1-decene, and 1-dodecene using titanocene-based catalysts to investigate the physical properties of COCs depending on the combination and composition of the comonomers and the sequence distribution. , NB/α-olefin copolymers with the gradient structure composed of an NB-rich segment and an α-olefin-rich terminal were produced. The strain–stress curves of these copolymers dramatically changed from brittle to ductile behaviors with the increasing length of the alkyl group of α-olefin .…”

Cyclic Olefin Copolymer Bearing Pendant Fluorenyl Groups with High Refractive Index and Low Chromatic Dispersion

“…These obtained copolymers therefore have a gradient structure, which was previously observed in NB/α-olefin copolymers synthesized with the same catalyst system. 28,29 The copolymerization rate of NB/3c was lower than the other copolymerizations, but almost quantitative yield was achieved by increasing the catalyst loading (run 9). The comonomer content can be controlled by changing the initial feed ratio (run 10−12).…”

Palladium(II)-Catalyzed Synthesis of a Vinyl-Addition Ultrahigh-Molecular-Weight Polynorbornene Copolymer with an Entanglement Network for Enhanced Fracture Resistance

“…Although reducing the weight fraction of alkyl pendants can contribute to improving both stiffness and strength, such a compositional change results in an inevitable compromise in toughness. Recently, the macromolecular design of COCs featuring separated hard and soft segments has emerged as a toughening strategy. − This approach, when combined with an entanglement network, is expected to significantly enhance the fracture resistance while minimizing reductions in the stiffness and strength.…”

“…Cyclic olefin copolymers (COCs) synthesized by Ziegler–Natta catalysis − have notable characteristics, such as high transparency, stiffness, heat distortion resistance, and low dielectric permittivity. , These COCs have found widespread application as clear engineering plastics, extending beyond packaging. − Despite the economic viability of the vinyl-addition copolymerization of cyclic olefins with ethylene, − various synthetic efforts have sought alternative macromolecules to address the inherent brittleness associated with commercially available ethylene-incorporated COCs. − Efforts to enhance the properties of COCs have included the incorporation of counter monomers, such as α-olefins or substituted cyclic olefins, capable of inducing repulsion between polymer backbones. − This approach has successfully improved the chain mobility of the COCs, leading to substantial plastic deformation. However, the accompanying loss of strength prevents the complete decoupling of stiffness and brittleness, which is a significant drawback.…”