Evolution of primary loops in vitrimers
8 affiliations
- 1Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, 60208
- 2NSF Center for the Chemistry of Molecularly Optimized Networks
- 3Duke University
- 4Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, 60208
- 5Department of Chemistry
- 6Massachusetts Institute of Technology
- 7Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, 60208
- 8Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Rd, Evanston, 60208
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.
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BibTeX
@misc{villatoro2026evolution,
title = {{Evolution of primary loops in vitrimers}},
author = {Emmanuel A. Garcia Villatoro and Sullivan W. Fitz and Jolly Patro and Alexis Martell Monterroza and Jeremiah A. Johnson and Olvera de la Cruz and Julia A. Kalow},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008540/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008540/v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Evolution of primary loops in vitrimers
AU - Emmanuel A. Garcia Villatoro
AU - Sullivan W. Fitz
AU - Jolly Patro
AU - Alexis Martell Monterroza
AU - Jeremiah A. Johnson
AU - Olvera de la Cruz
AU - Julia A. Kalow
PY - 2026
DA - 2026/09/09
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008540/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008540/v1
AB - 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.
ER -