Molecular simulation study of penetrant diffusion in vitrimer networks
Min-Hsien Lin1,2, Tsai-Wei Lin1,2, Charles E Sing1,2
1Department of Chemical and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
The Journal of Chemical Physics
|April 9, 2026
Summary
In vitrimers, larger penetrants diffuse faster when the network rearranges via bond exchange. This dynamic network rearrangement enhances diffusion, particularly for larger molecules, by altering mesh confinement.
Area of Science:
- Polymer Science
- Materials Science
- Chemical Engineering
Background:
- Diffusivity in polymer networks is key for applications like separation membranes and coatings.
- Cross-linking in permanent networks impacts relaxation and mesh confinement, influencing penetrant diffusion.
- Vitrimers offer tunable network topology with dynamic bond exchange, differing from permanent networks.
Purpose of the Study:
- Investigate penetrant diffusion dynamics in vitrimers.
- Understand the role of dynamic network rearrangement via bond exchange on diffusion.
- Analyze effects of penetrant size, temperature, cross-link density, and bond exchange rates.
Main Methods:
- Utilized molecular dynamics simulations.
- Simulated various penetrant sizes, temperatures, and vitrimer cross-link densities.
- Varied bond exchange rates to observe their impact on diffusion.
Main Results:
- Small penetrant diffusion was largely unaffected by bond exchange rates.
- Larger penetrant diffusivity increased with faster bond exchange rates.
- Enhanced diffusion for larger penetrants was primarily linked to mesh confinement changes, not just hopping times.
Conclusions:
- Vitrimer network dynamics significantly influence penetrant diffusion, especially for larger molecules.
- Bond exchange kinetics are crucial for controlling mesh confinement and thus diffusion in vitrimers.
- Findings are relevant for designing advanced polymer materials with tailored transport properties.
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