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Published on: February 7, 2017
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Isomer geometry controls local mobility in azopolymers: coarse-grained simulation insights
1Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), Colón 10850, 7600 Mar del Plata, Argentina. cbalbuena@fi.mdp.edu.ar.
Soft Matter
|January 13, 2026
Summary
Azobenzene isomer identity influences polymer dynamics. Cis-azobenzene shortens relaxation times and lowers the glass transition temperature compared to trans-azobenzene, indicating localized dynamic facilitation.
Area of Science:
- Polymer Physics
- Materials Science
- Computational Chemistry
Background:
- Azobenzene-containing polymers are photoresponsive materials.
- Understanding isomer-specific effects on polymer dynamics is crucial for material design.
- Previous studies often involve photoisomerization or covalent attachment, limiting insights into intrinsic isomer effects.
Purpose of the Study:
- To investigate how azobenzene isomer identity (cis vs. trans) affects polymer dynamics without photoisomerization or covalent bonding.
- To elucidate the microscopic origins of isomer-dependent polymer behavior in a guest-host system.
- To establish a baseline understanding of geometry-only effects on polymer dynamics.
Main Methods:
- Coarse-grained molecular dynamics simulations were employed.
- Segmental relaxation was quantified using the incoherent intermediate scattering function.
- Vogel-Fulcher-Tammann fitting was used to determine relaxation times and glass transition temperatures.
- Voronoi analysis and isoconfigurational ensemble methods were utilized.
Main Results:
- Global polymer structure (density, pair correlations) was insensitive to azobenzene isomer identity.
- Cis-azobenzene systems exhibited shorter relaxation times and lower glass transition temperatures than trans-azobenzene systems.
- Voronoi analysis indicated larger free volume around cis-azobenzene at low temperatures, and monomers near cis-azobenzene were more mobile.
Conclusions:
- Azobenzene isomer identity locally modulates polymer dynamics, suggesting a dynamic facilitation mechanism.
- The observed differences are attributed to localized effects rather than homogeneous free-volume changes.
- This study provides a geometry-dependent baseline for understanding light-driven mass transport in azobenzene materials.
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