Access to Polyethylene-Polyester Block Copolymers in Continuous Flow through Single-Step Chain-End-Functionalized...

Area of Science:

• Polymer Chemistry
• Materials Science
• Chemical Engineering

Background:

• Synthesizing polar polyolefin block copolymers in continuous flow presents challenges due to monomer selectivity requirements.
• Existing methods often involve complex, multi-step post-polymerization processes.

Purpose of the Study:

• To develop a streamlined continuous flow strategy for producing polar polyethylene-block-polyester diblock copolymers.
• To utilize a single-chain-end-functionalized polyethylene as a macroinitiator for ring-opening polymerization.

Main Methods:

• A 2-hydroxyethyl acrylate (HEA) chelated diimine Pd(II) complex was used for living coordination-insertion polymerization (CIP) to synthesize polyethylene-HEA (PE-HEA).
• The synthesized PE-HEA macroinitiator underwent ring-opening polymerization (ROP) in a separate flow system to form PE-b-polyester block copolymers.
• The process combined two distinct living polymerization techniques stepwise in a flow system.

Main Results:

• Achieved controlled synthesis of chain-end-functionalized PE with low dispersity (∼1.10) across a wide molecular weight range (5.50–38.94 kg/mol).
• Successfully polymerized poly-(δ-valerolactone) (PVL) with controlled molecular weights (1.8–7.44 kg/mol) and narrow dispersity (∼1.06).
• Produced a variety of polar-PE block copolymers (PE-b-PVL) with extended PVL and polylactide (PLA) segments.

Conclusions:

• The developed continuous flow strategy simplifies the preparation of functionalized polyethylene macroinitiators.
• This approach enables direct chain extension via ROP, efficiently forming polar-PE block copolymers.
• The method avoids multi-step post-polymerization, offering a controlled and efficient route to functional block copolymers.