Hydrodynamic Shear Effects on Grafted and Non-Grafted Collapsed Polymers

Area of Science:

• Polymer physics
• Soft matter physics
• Computational fluid dynamics

Background:

• Understanding polymer behavior under flow is crucial in various applications.
• Polymer chain conformation and unfolding are influenced by external forces.
• Grafted and non-grafted polymers exhibit different responses to flow conditions.

Purpose of the Study:

• To investigate the tensile force profiles and globular-coil transitions of collapsed homo-polymeric molecules.
• To elucidate the distinct unfolding mechanisms of grafted and non-grafted polymer chains under linear shear flow.
• To analyze the scaling of the critical shear rate with monomer number for both polymer types.

Main Methods:

• Utilizing hydrodynamic Brownian dynamics simulations.
• Applying linear shear flow conditions to collapsed homo-polymeric molecules.
• Analyzing tensile force profiles and shear-rate-dependent transitions.

Main Results:

• The critical shear rate for the globular-coil transition scales inversely with monomer number for both grafted and non-grafted chains.
• Larger grafted chains exhibit a decreased critical shear rate, indicating easier unfolding.
• Non-grafted polymers require higher shear rates for unfolding, with protrusions governing the transition.

Conclusions:

• Grafted and non-grafted polymers display fundamentally different unfolding mechanisms under shear flow.
• The location of maximal tension differs: at the grafted end for grafted polymers and governed by protrusions for non-grafted polymers.
• The findings provide insights into polymer dynamics and conformational changes in response to shear forces.