Covalent Adaptable Networks with Associative Siloxane Exchange Enabled by Amide-Based Internal Catalysis

NU2025-056

INVENTORS

• John Torkelson*
• Tapas Debsharma
• Nathan Purwanto
• Tong Wang

SHORT DESCRIPTION
A technology that introduces internally catalyzed siloxane dynamic chemistry in covalent adaptable networks (CANs) through amide-based catalysis to produce recyclable and reprocessable polymers with maintained cross-link density at elevated temperatures.

BACKGROUND
Replacing non-recyclable thermosets with covalent adaptable networks that recover cross-link density after reprocessing can substantially reduce material waste and foster a circular polymer economy. Current approaches relying on external catalysis often face challenges such as increased creep, accelerated material aging, and catalyst leaching, creating a need for internally catalyzed systems.

ABSTRACT
This invention discloses a novel approach to internally catalyzing siloxane dynamic chemistry by employing amides covalently linked via alkyl chains to siloxanes. The resulting exchange reactions between amide-containing siloxane molecules yield polymers whose rubbery plateau modulus is proportional to absolute temperature, ensuring effective cross-link density retention even at high temperatures. Designed for applications requiring reprocessable and recyclable cross-linked networks, the technology supports processing via compression molding at 200–220°C and melt extrusion at approximately 260°C, while maintaining material integrity. The method strategically avoids the pitfalls of external catalysis, such as increased creep, catalyst leaching, and accelerated aging, thereby setting a new benchmark in dynamic covalent chemistry for high-performance polymer systems. This advancement promises significant benefits for industries seeking sustainable and efficient materials solutions.

APPLICATIONS

• Recyclable and reprocessable cross-linked polymer networks for industrial molding processes: effective retention of cross-link density up to 300°C.
• Materials processing via compression molding and melt extrusion: lower processing temperatures (200–220°C for compression, 260°C for extrusion) with complete recovery of network integrity.

ADVANTAGES

• Maintains effective cross-link density at elevated temperatures, ensuring reliable high-temperature performance.
• Enables reprocessability via compression molding and melt extrusion at significantly lower temperatures.
• Prevents issues typically associated with external catalysis, including increased creep, catalyst leaching, and accelerated material aging.

PUBLICATIONS

• John Torkelson et al., Covalent Adaptable Networks with Associative Siloxane Exchange Enabled by Amide-Based Internal Catalysis Designing for Reprocessability and Extrudability by Increasing the Cross-link Density, ChemRxiv

IP STATUS
US Patent Pending