Molecular Architecture of Multi‐Block Polymer Synthesized in a Dual‐Catalyst Single CSTR

Abstract

This work aims at deriving analytical solutions for the molecular architecture of multi‐block polymer synthesized in a dual‐catalyst single CSTR. While the relevant equations are developed for homopolymerization, they can easily be extended to copolymerization. Special emphasis is placed on the quantities associated with each catalyst rather than the overall ones. However, if all rate parameters are available, the expressions can be used to calculate the properties of the material made by each catalyst as well as the overall ones under various process conditions. Given the reasonable assumption of large residence time, the solutions are simplified to elucidate the kinetics of chain‐shuttling involving two catalysts. It is shown that systems with low chain‐shuttling ability, if DPPn,0 ≠ DPQn,0, may exhibit significant deviation from Flory's most probable distribution. Furthermore, systems with high chain‐shuttling ability produce macromolecules with more uniform architecture and polydispersity index close to 2.

Synthesis of Chain Shuttling Organometallic Compounds Capable of Producing Triblock Polyolefins

“…Since the discovery of chain shuttling polymerization − leading to the commercial production of diblock and multiblock polyolefin copolymers, , it has drawn a significant amount of research interest. − Olefin block copolymers have unique and advantaged properties rendering them useful for a number of applications. − For instance, ethylene/1-octene multiblock copolymers exhibit a unique balance of high melting point and flexibility compared to random copolymers with a similar comonomer content. − While simple metal alkyls are the most commonly used chain shuttling agents, effort is being made to design and synthesize more sophisticated chain shuttling agents (CSAs), such as dual-headed CSAs (DHCSAs), to access novel polymer architectures, such as telechelic and triblock polymers. Bickelhaupt et al reported the synthesis of difunctional cyclic zinc compounds using Rieke zinc and dibromoalkane .…”