Year: 2026
Type: preprint
Abstract: Covalent adaptable networks (CANs) comprise dynamic covalent bonds that allow topological reconfiguration. While this behavior underlies the reprocessability and recyclability of CANs, its influence on network topology, including defects, remains poorly understood. Prior simulations and indirect experimental studies suggest that dynamic exchange decreases the prevalence of primary loops, but direct experimental quantification has remained elusive. Here we use network disassembly spectrometry (NDS) to directly measure topological evolution during dynamic exchange. Surprisingly, activation of exchange at constant composition reveals two distinct concentration-dependent regimes. At concentrations above ~0.2 M, primary loops decrease upon activating exchange, whereas at lower concentrations, loop content increases, leading to gel-sol transitions. Temperature-dependent experiments and coarse-grained simulations suggest that these trends arise from competing entropic contributions that favor either loop formation or consumption depending on concentration. Changes in topology are accompanied by measurable changes in mechanical properties, demonstrating a direct relationship between network structure and macroscopic behavior. Furthermore, the concentration-dependent transition enables topology-mediated recycling, in which materials reversibly transition between gel and sol states through network rearrangement alone. These results provide the first direct experimental evidence of topology evolution in covalent adaptable networks and establish network topology as a measurable and tunable design parameter in dynamic polymer systems.
Source: ChemRxiv
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7212068328