Efficient Exchange in a Bioinspired Dynamic Covalent Polymer Network via a Cyclic Phosphate Triester Intermediate

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Chemistry

Background:

• Dynamic covalent networks (DCNs) enable materials with adaptable properties.
• Neighboring group participation is crucial for reactions in biological systems like RNA.
• Efficient bond exchange in DCNs is key for mechanical relaxation and reprocessing.

Purpose of the Study:

• To design a novel DCN utilizing RNA-inspired chemistry.
• To investigate the mechanism of bond exchange and its effect on material properties.
• To assess the processability of the developed DCN.

Main Methods:

• Synthesis of a DCN based on β-hydroxyl-mediated transesterification of hydroxyethyl phosphate triesters.
• Characterization using 31P solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Evaluation of mechanical properties and processing behavior at elevated temperatures.

Main Results:

• A one-step synthesis yielded a DCN with pendant hydroxyethyl groups.
• 31P solid-state NMR confirmed a cyclic phosphate triester intermediate in transesterification.
• The intermediate facilitated dissociative network rearrangement and efficient mechanical relaxation.
• The material showed significant viscous flow between 60-100 °C.

Conclusions:

• The developed DCN effectively mimics RNA's neighboring group-assisted reactions for bond exchange.
• The cyclic intermediate mechanism enables efficient network rearrangement and mechanical relaxation.
• The material's processability via extrusion and compression molding is demonstrated.