Synthesis of Chain‐end Functionalized Polyolefins and Polyolefin Diblock Copolymers via the Combination of Metallocene Catalysts and Reactive Chain Transfer Agents

Abstract

AbstractThis paper discusses a facile route to prepare chain‐end functionalized polyolefins containing a terminal functional group (OH, COOH, NH2, etc.), and polyolefin diblock copolymers containing a polyolefin block and a functional polymer block. The chemistry is centered at an in situ chain transfer reaction during metallocene‐mediated α‐olefin polymerization using two reactive chain transfer (CT) agents, including dialkylborane (R2B‐H) and styrenic molecule/H2, to form polyolefin containing a reactive alkylborane and styrenic terminal group, respectively. With the appropriate choice of metallocene catalyst, the polymer formed shows narrow molecular weight distribution (Mw/Mn∼2), and the polymer molecular weight is inversely proportional to the molar ratio of [CT agent]/[α‐olefin]. In turn, the terminal borane group is very versatile in interconversion to various polar groups. More importantly, it can be quantitatively transformed to a living radical initiator for chain extension reaction with functional monomers. On the other hand, the terminal styrenic group was then selectively metallated and transformed to a stable polymeric anion for living anionic polymerization. The overall diblock co‐polymer process resembles a transformation reaction from metallocene‐mediated α‐olefin polymerization to a living free radical or a living anionic polymerization of functional monomers.