Controlled Synthesis and Characterization of Poly[ethylene‐block‐(L,L‐lactide)]s by Combining Catalytic Ethylene Oligomerization with “Coordination‐Insertion” Ring‐Opening Polymerization

Abstract

AbstractModel poly[ethylene‐block‐(L,L‐lactide)] (PE‐block‐PLA) block copolymers were successfully synthesized by combining metallocene catalyzed ethylene oligomerization with ring‐opening polymerization (ROP) of L,L‐lactide (LA). Hydroxy‐terminated polyethylene (PE‐OH) macroinitiator was prepared by means of ethylene oligomerization on rac‐dimethyl‐silylen‐bis(2‐methyl‐benz[e]indenyl)‐zirconium(IV)‐dichloride/methylaluminoxane (rac‐MBI/MAO) in presence of diethyl zinc as a chain transfer agent, and subsequent in situ oxidation with synthetic air. Poly[ethylene‐block‐(L,L‐lactide)] block copolymers were obtained via ring‐opening polymerization of LA initiated by PE‐OH in toluene at 100 °C mediated by tin octoate. The formation of block copolymers was confirmed by 1H NMR spectroscopy, fractionation experiments, thermal behavior, and morphological characterization using AFM and light microscopy techniques.magnified image