C-H Functionalization of Poly(ethylene oxide) - Embracing Functionality, Degradability, and Molecular Delivery.

Area of Science:

• Polymer Chemistry
• Organic Chemistry
• Materials Science

Background:

• Post-polymerization modification (PPM) of poly(ethylene oxide) (PEO) traditionally targets end-group functionalization.
• Recent advancements in C-H functionalization offer opportunities for backbone modification, expanding PEO's chemical versatility.

Purpose of the Study:

• To develop an organocatalytic C-H functionalization method for PEO backbone modification.
• To introduce degradability and carboxylic acid functionalities into PEO via backbone acetal units.
• To explore the potential of functionalized PEO in energy and medical applications.

Main Methods:

• Organocatalytic C-H functionalization of PEO using a cascade process involving radical generation and oxocarbenium intermediate formation.
• Attachment of structurally diverse carboxylic acids to the PEO backbone.
• Hydrolysis studies to assess degradability and release kinetics under varying pH conditions.

Main Results:

• Successful functionalization of PEO with acetal units (2-5 mol%) in the backbone, a modification not achievable through conventional epoxide copolymerization.
• Optimized conditions minimized unwanted polymer degradation and crosslinking.
• Hydrolysis studies demonstrated sustained release of fragmented PEO and carboxylic acids over several days, with minimal pH sensitivity (pH 5-9).

Conclusions:

• The developed C-H functionalization method provides a versatile and efficient route for PEO backbone modification.
• The introduction of acetal units imparts controlled degradability and carboxylic acid delivery capabilities to PEO.
• This functionalized PEO holds promise for various energy and medical applications requiring tailored material properties.