A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Materials Science

Background:

• Norbornene polymerization via insertion yields polymers with high glass transition temperatures (Tg) and desirable optical/electrical properties.
• Polymerization of functionalized norbornenes is challenging due to the low reactivity of endo isomers and difficult isomer separation.
• Existing methods often require tedious separation of endo and exo isomers, limiting the synthesis of functionalized polynorbornenes.

Purpose of the Study:

• To develop a simple and efficient protocol for the insertion polymerization of functionalized norbornene monomers without isomer separation.
• To demonstrate the synthesis of polynorbornenes with pendant carboxylic acid or double bond functionalities.
• To showcase the versatility of the synthesized polymers through further functional group transformations.

Main Methods:

• Insertion polymerization of substituted norbornenes (endo:exo ratio approx. 80:20) using low catalyst loadings (0.01–0.02 mol%).
• Direct polymerization without prior separation of endo and exo isomers.
• Post-polymerization modification of pendant double bonds to introduce epoxy groups.

Main Results:

• Successful polymerization of functionalized norbornenes was achieved using a simple protocol, bypassing isomer separation.
• Polymers with pendant carboxylic acid or double bond groups were synthesized efficiently.
• Pendant double bonds in the polymer were readily converted to epoxy groups with high yields.
• The methodology allows for the preparation of polynorbornenes with diverse functional groups.

Conclusions:

• A facile and efficient method for the insertion polymerization of functionalized norbornenes has been established, overcoming challenges associated with isomer separation and reactivity.
• This approach provides access to a wide array of functionalized polynorbornenes, expanding their potential applications in materials science.
• The developed protocol offers a versatile platform for synthesizing advanced polymer materials with tailored properties.