Unclicking the Click: A Depolymerizable Clicked Polymer via Two Consecutive Single-Crystal-to-Single-Crystal...

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Chemistry

Background:

• Click polymers are widely used due to their efficient synthesis.
• However, most click polymers are not easily depolymerizable, limiting their application in degradable materials.
• Developing polymers with controlled depolymerization is crucial for sustainable materials.

Purpose of the Study:

• To report a novel clicked polymer synthesized via solid-state polymerization.
• To demonstrate the depolymerization of this polymer using a reverse 'declicking' reaction.
• To showcase the potential for creating degradable polymers through controlled chemical transformations.

Main Methods:

• Single-crystal-to-single-crystal (SCSC) topochemical ene-azide cycloaddition polymerization of a designed dipeptide monomer.
• Subsequent SCSC denitrogenation of the resulting triazoline-linked polymer.
• Structural characterization of polymers using single-crystal X-ray diffraction (SCXRD).
• Acid hydrolysis for quantitative depolymerization.

Main Results:

• A triazoline-linked polymer was formed quantitatively via SCSC polymerization.
• Further heating induced SCSC denitrogenation, yielding an imine-linked polymer.
• The structures of both polymers were determined at atomic resolution by SCXRD.
• Acid hydrolysis successfully depolymerized the imine-linked polymer to the original dipeptide.

Conclusions:

• A novel solid-state click polymerization and subsequent depolymerization pathway has been established.
• The developed polymers exhibit controlled degradability and depolymerizability.
• This approach offers an advantage over conventional click polymers that lack depolymerization capabilities.