A Facile Approach to Produce Star Polymers Based on Coordination Polymerization

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Star polymers offer unique properties but their synthesis via coordination polymerization is underdeveloped.
• Existing methods for star polymer synthesis are less efficient than radical or ionic polymerization.

Purpose of the Study:

• To develop a facile strategy for preparing star polymers with regular arms using coordination polymerization.
• To investigate the synthesis of star polyisoprene with controlled architecture and properties.

Main Methods:

• Utilized a coordination polymerization approach involving an insertion reaction between carbon-heteroatom unsaturated bonds and metal-alkyl species.
• Employed isocyanate as a cross-linker (CL) to terminate living cis-1,4-selective isoprene polymerization.
• Conducted kinetic studies to elucidate the polymerization mechanism.

Main Results:

• Successfully synthesized star polyisoprene with low polydispersity in high yield (91.8%).
• Demonstrated that star polymer formation proceeds via a step-growth mechanism.
• Identified cross-linker type and initiator-to-cross-linker ratio as critical factors influencing arm number and yield.
• Produced synthetic isoprene rubber (IR) with a green strength of 1.99 MPa, exceeding that of natural rubber (1.43 MPa).

Conclusions:

• The proposed coordination polymerization strategy provides an efficient route to well-defined star polyisoprene.
• The synthesized star polyisoprene exhibits enhanced mechanical properties, outperforming natural rubber.
• This work advances the field of stereoselective coordination polymerization for complex polymer architectures.