Monotelechelic Poly(oxa)norbornenes by Ring-Opening Metathesis Polymerization using Direct End-Capping and Cross...

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Materials Science

Background:

• Living ring-opening metathesis polymerization (ROMP) enables precise polymer synthesis.
• Monotelechelic polymers possess a single functional group at one chain end, useful for further modification.
• Developing efficient end-functionalization strategies is crucial for advanced polymer applications.

Purpose of the Study:

• To present and compare two distinct methodologies for synthesizing monotelechelic poly(oxa)norbornenes.
• To evaluate the efficiency of various functional groups as terminating agents in these methods.
• To establish reliable methods for creating well-defined functional polymers.

Main Methods:

• Direct end-capping: Addition of a cis-olefin terminating agent (TA) after living ROMP completion.
• Cross metathesis (CM): Reaction between a methylene-terminated polymer and a cis-olefin TA using a ruthenium catalyst.
• Synthesis and testing of TAs with diverse functionalities (alcohols, halides, esters, amines, biomolecules).

Main Results:

• Direct end-capping achieved >90% end-functionalization efficiency.
• Cross metathesis showed comparable efficiency for TAs lacking polar groups or significant steric hindrance.
• Both methods demonstrated versatility with a wide range of functional groups.

Conclusions:

• Both direct end-capping and cross metathesis are effective strategies for synthesizing monotelechelic poly(oxa)norbornenes.
• The choice of method can be optimized based on the specific terminating agent's properties.
• These methods provide access to well-defined functional polymers for various applications.