(181ap) Coarse Grained Simulations for Observing Macromolecular Behavior Under Stress

Authors: 
Kuehster, L., University of Oklahoma
Vu, T. V., The University of Oklahoma
Papavassiliou, D. V., The University of Oklahoma
We use dissipative particle dynamics (DPD) methods to explore the behavior of macromolecules within different hydrodynamic stress fields. The stress is controlled by placing the molecules in the flow field between four rotating cylinders in a four-roll mill and turning the rolls at different radial velocities. The four-roll mill device can generate simply shear or simply extensional stresses, or it can be used to generate a mixed stress field. A lot of work has been done with such devices for rheological studies. Here we create a micro-scale model of this device to investigate the behavior of polymer molecules, like Poly-vinyl Pyrrolidone (PVP) in an aqueous solution, under different stresses. All simulations are run up to 6x106 time steps using the open source LAMMPS software package. The details of the DPD model for the interaction parameters between water and the PVP molecule have been obtained in prior work. [1,2] Here, changes in configuration of the molecule under stress will be discussed after the development and validation of the model are provided in detail. The technique developed can be used for conducting experiments for other polymers in-silico, when designing and operating a device like this for single molecules is nothing but trivial.

ACKNOWLEDGEMENTS

The use of computing facilities at the University of Oklahoma Supercomputing Center for Education and Research (OSCER) and at XSEDE (under allocation CTS-090025) is gratefully acknowledged.

REFERENCES

[1] Vo, M., and D.V. Papavassiliou, “The effects of shear and particle shape on the physical adsorption of polyvinyl pyrrolidone on carbon nanoparticles" Nanotechnology, 27(32), Art 325709, 2016

[2] Vo, M., and D.V. Papavassiliou, “Physical adsorption of PVP Polyvinyl Pyrrolidone polymer on Carbon Nanotubes under shear studied with Dissipative Particle Dynamics simulations,” Carbon, 100, 291-301, 2016