Controlled Ring-Opening Polymerization of Macrocyclic Monomers Based on Ring-Opening/Ring-Closing Cascade Reaction

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Macromolecular Science

Background:

• Controlled synthesis of backbone-functionalized and sequence-controlled polymers with defined architectures from macrocyclic monomers is a significant challenge.
• Existing methods often lack precision in controlling molecular weight and dispersity.

Purpose of the Study:

• To develop a novel, general controlled ring-opening polymerization (ROP) method for macrocycles.
• To synthesize backbone-functional and sequence-controlled polyurethanes and polyamides with high precision.

Main Methods:

• Introduction of a trimethyl lock unit as a 'ring-opening trigger' into macrocyclic monomers.
• Initiation of ROP via primary amine nucleophilic attack on activated carbonate/ester groups.
• Utilizing a spontaneous cyclization of the trimethyl lock unit to regenerate the amine initiator for iterative chain growth.

Main Results:

• Successful synthesis of backbone-functional and sequence-controlled polyurethanes and polyamides.
• Achieved controlled molecular weights and narrow dispersities (Đ < 1.1).
• Demonstrated versatility in creating water-soluble, backbone-degradable, and sequence-controlled polymers.

Conclusions:

• The developed ROP method offers a powerful tool for precise polymer synthesis.
• The trimethyl lock unit acts as an effective self-immolative spacer for controlled chain propagation.
• This versatile approach enables the construction of complex polymer architectures with tailored properties.