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Excluded volume effects on the intrachain reaction kinetics
Ji-Hyun Kim1, Woojin Lee, Jaeyoung Sung
1Department of Chemistry, Seoul National University, Seoul 151-747, South Korea.
The Journal of Physical Chemistry. B
|April 19, 2008
Summary
We present an optimized Rouse-Zimm theory for polymer cyclization, accurately predicting rate constants. Incorporating corrections improves predictions for chain dynamics in good solvents.
Area of Science:
- Polymer Physics
- Theoretical Chemistry
- Computational Biophysics
Background:
- Understanding polymer chain dynamics, particularly end-to-end cyclization, is crucial in polymer physics.
- Excluded volume interactions and hydrodynamic effects significantly influence polymer behavior.
- Existing theories often struggle to accurately predict cyclization rates, especially with hydrodynamic interactions.
Purpose of the Study:
- To calculate the first-order rate constant for end-to-end cyclization of linear polymer chains using an optimized Rouse-Zimm theory.
- To assess the accuracy of the theory by comparing predictions with Brownian dynamics simulations.
- To identify and correct for deviations arising from hydrodynamic interactions and other complex effects.
Main Methods:
- Development and application of an optimized Rouse-Zimm theory incorporating excluded volume interactions.
- Calculation of longest chain relaxation times (tau(1)) for excluded volume chains.
- Application of Wilemski-Fixman rate theory in the free-draining limit.
- Analysis of deviations when hydrodynamic interactions are included, considering fluctuating hydrodynamic interactions, correlation hole effects, and non-Markovian dynamics.
Main Results:
- The optimized Rouse-Zimm theory accurately predicts longest chain relaxation times, showing excellent agreement with Brownian dynamics simulations.
- In the free-draining limit, the theory accurately predicts diffusion-controlled cyclization rates (k(1)) inversely proportional to relaxation times.
- Noticeable deviations occur when hydrodynamic interactions are included, attributed to specific dynamic effects.
Conclusions:
- The optimized Rouse-Zimm theory, with corrections for hydrodynamic interactions and other effects, accurately predicts end-to-end cyclization rate constants for finite polymer chains.
- The theory correctly captures the scaling exponent in the long-chain limit.
- This work provides a more accurate theoretical framework for understanding polymer cyclization dynamics in good solvents.
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