Unfolding Kinetics of a Wormlike Chain under Elongational Flow

Area of Science:

• Polymer Physics
• Biophysics
• Theoretical Chemistry

Background:

• Understanding polymer chain dynamics is crucial in various scientific fields.
• Semi-flexible polymers, like DNA, exhibit complex behavior during stretching.
• Existing theories may not fully capture the kinetics of polymer unfolding.

Purpose of the Study:

• To present a simple theory for the unfolding kinetics of semi-flexible polymer chains.
• To investigate the role of elongation energy and hydrodynamic interactions.
• To compare theoretical predictions with experimental data on DNA stretching.

Main Methods:

• Developed a Kramers-type model for polymer elongation energy.
• Applied slender body theory to model hydrodynamic interactions.
• Analyzed the time-dependence and viscosity-independence of chain elongation.

Main Results:

• The theory predicts that polymer chain elongation is linear with time.
• The elongation rate is predicted to be independent of fluid viscosity.
• Theoretical predictions show agreement with experimental observations of DNA stretching dynamics.

Conclusions:

• The developed theory provides a simplified framework for polymer unfolding kinetics.
• The linear time dependence and viscosity independence are key findings.
• Discrepancies between theory and experiment warrant further investigation into the overestimation of the rate.