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Predicting reaction behavior of tethered polymers in shear flow
Anh Hung Nguyen1, Sagar Kania1, Alparslan Oztekin1
1Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
The Journal of Chemical Physics
|November 6, 2023
Summary
Researchers explored force-mediated reactions in polymers under shear flow. They found distinct force behaviors and reaction kinetics for short and long polymers, enabling controlled mechano-reactive polymer design.
Area of Science:
- Polymer Physics
- Chemical Kinetics
- Rheology
Background:
- End-tethered polymers are fundamental in various applications.
- Understanding their behavior under flow is crucial for material design.
- Force-mediated reactions in polymers are sensitive to chain length and flow conditions.
Purpose of the Study:
- To investigate the kinetics of force-mediated reactions in polymers subjected to shear flow.
- To determine how polymer chain length (N) and shear rate (γ̇) influence reaction dynamics.
- To explore the potential for designing polymers with tunable mechano-reactive properties.
Main Methods:
- Coarse-grained Brownian dynamics simulations were employed.
- Polymer force profiles under varying shear rates and chain lengths were analyzed.
- A stochastic model was used to compute population reaction times (tx).
Main Results:
- Polymer force (F) increased linearly with chain length (N) at fixed shear rates.
- A transition length was identified, above which the F(N) slope increased, independent of shear rate.
- Population response times (tx) showed distinct scaling for short (small N) and long (large N) polymers, differing by orders of magnitude.
Conclusions:
- Polymer chain length significantly impacts force generation and reaction kinetics under flow.
- Two distinct regimes of force scaling exist for polymers below and above a transition length.
- These findings enable the design of mechano-reactive polymer systems with controlled flow responses.
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