Organic Catalyst-Mediated Ring-Opening Polymerization for the Highly Efficient Synthesis of Polyester-Based Star...

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Materials Science

Background:

• Polyester-based core cross-linked star (CCS) polymers are advanced macromolecular architectures.
• Efficient and metal-free synthesis routes are desirable for sustainable polymer production.

Purpose of the Study:

• To develop a facile, highly efficient, and metal-free method for synthesizing well-defined polyester-based CCS polymers.
• To investigate the role of catalysts in controlling side reactions like transesterification during star polymer formation.

Main Methods:

• Ring-opening polymerization (ROP) mediated by methanesulfonic acid (an organic catalyst) at room temperature.
• Utilized poly(ε-caprolactone) (PCL) macroinitiators (MIs) and [4,4'-bioxepane]-7,7'-dione (BOD) as a cross-linker.
• Employed both two-pot and one-pot, two-step strategies for polymer synthesis.

Main Results:

• Achieved high yields (up to 96%) of CCS polymers with narrow molecular weight distributions (PDI ≤ 1.3).
• Demonstrated high macroinitiator conversions (90-96%) using PCL MIs (9.9–36.2 kDa).
• Identified transesterification as the cause of low molecular weight polymer and star-star couplings, which were minimized with methanesulfonic acid compared to stannous octoate (Sn(Oct)2).

Conclusions:

• Methanesulfonic acid provides a superior metal-free pathway for synthesizing high-purity polyester CCS polymers.
• The choice of catalyst significantly impacts star purity by influencing transesterification side-reactions.
• This method offers a controlled and efficient route to well-defined star polymers for various applications.