Covalent Adaptable Poly[2]rotaxane Networks via Dynamic C-N Bond Transalkylation

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Covalent adaptable networks (CANs) combine thermoset durability with thermoplastic reprocessability.
• Dynamic covalent bonds are key to CANs' unique properties.
• Novel backbone structures are needed to enhance CAN performance.

Purpose of the Study:

• To introduce the first poly[2]rotaxane-type covalent adaptable networks (PRCANs).
• To investigate the mechanical properties and reprocessability of these novel CANs.
• To demonstrate the potential of oligo[2]rotaxanes in creating advanced sustainable materials.

Main Methods:

• Synthesized PRCANs utilizing oligo[2]rotaxane backbones cross-linked via dynamic C-N bonds.
• Characterized mechanical properties including stretchability and toughness.
• Evaluated reprocessability through thermal cycling and dynamic bond exchange.

Main Results:

• PRCANs achieved 217% stretchability and 7.6 MJ/m³ toughness, significantly outperforming control CANs (40% stretchability, 1.5 MJ/m³ toughness).
• The oligo[2]rotaxane backbone and dynamic C-N bonds contribute to enhanced mechanical performance through synergistic motions.
• Materials demonstrated efficient reprocessability via 1,2,3-triazole alkylation and trans-N-alkylation exchanges at elevated temperatures.

Conclusions:

• Oligo[2]rotaxanes serve as effective backbones for developing advanced covalent adaptable networks.
• PRCANs offer a promising route to sustainable materials with exceptional mechanical properties and reprocessability.
• This work highlights the potential of integrating mechanical bonds into polymer networks for tailored material design.